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      iFCP - A Protocol for Internet Fibre Channel Networking   August 2002
     
         IP Storage Working Group                              Charles Monia
         INTERNET DRAFT                                       Rod Mullendore
         Expires February 2003
         Document: draft-ietf-ips-ifcp-13.txt                 Nishan Systems
         Category: Standards Track
                                                           Franco Travostino
                                                             Nortel Networks
     
                                                               Wayland Jeong
                                                             Troika Networks
     
                                                                Mark Edwards
                                                                   Eurologic
     
                                                                 August 2002
     
     
        iFCP - A Protocol for Internet Fibre Channel Storage Networking
     
     Status of this Memo
     
         This document is an Internet-Draft and is in full conformance with
         all provisions of Section 10 of RFC 2026 [RFC2026].
     
         Internet-Drafts are working documents of the Internet Engineering
         Task Force (IETF), its areas, and its working groups. Note that
         other groups may also distribute working documents as Internet-
         Drafts. Internet-Drafts are draft documents valid for a maximum of
         six months and may be updated, replaced, or made obsolete by other
         documents at any time. It is inappropriate to use Internet-Drafts
         as reference material or to cite them other than as "work in
         progress."
     
         The list of current Internet-Drafts can be accessed at
         http://www.ietf.org/ietf/1id-abstracts.txt.
     
         The list of Internet-Draft Shadow Directories can be accessed at
         http://www.ietf.org/shadow.html.
     
     Comments
     
         Comments should be sent to the ips mailing list (ips@ece.cmu.edu)
         or to the author(s).
     
     
     
     
     
     
     
     
     
     
     
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     iFCP Revision 13                                      August 2002
     
     
     Status of this Memo...................................................1
     Comments..............................................................1
     Abstract..............................................................5
     Acknowledgements......................................................5
     1.      About This Document..........................................6
     1.1     Conventions used in this document............................6
     1.1.1   Data Structures Internal to an Implementation................6
     1.2     Purpose of this document.....................................6
     2.      iFCP Introduction............................................6
     2.1     Definitions..................................................7
     3.      Fibre Channel Communication Concepts.........................9
     3.1     The Fibre Channel Network...................................10
     3.2     Fibre Channel Network Topologies............................11
     3.2.1   Switched Fibre Channel Fabrics..............................11
     3.2.2   Mixed Fibre Channel Fabric..................................12
     3.3     Fibre Channel Layers and Link Services......................13
     3.3.1   Fabric-Supplied Link Services...............................14
     3.4     Fibre Channel Nodes.........................................14
     3.5     Fibre Channel Device Discovery..............................15
     3.6     Fibre Channel Information Elements..........................15
     3.7     Fibre Channel Frame Format..................................16
     3.7.1   N_PORT Address Model........................................16
     3.8     Fibre Channel Transport Services............................17
     3.9     Login Processes.............................................18
     4.      The iFCP Network Model......................................18
     4.1     iFCP Transport Services.....................................21
     4.1.1   Fibre Channel Transport Services Supported by iFCP..........21
     4.2     iFCP Device Discovery and Configuration Management..........21
     4.3     iFCP Fabric Properties......................................21
     4.3.1   Address Transparency........................................22
     4.3.2   Configuration Scalability...................................22
     4.3.3   Fault Tolerance.............................................23
     4.4     The iFCP N_PORT Address Model...............................23
     4.5     Operation in Address Transparent Mode.......................25
     4.5.1   Transparent Mode Domain ID Management.......................25
     4.5.2   Incompatibility with Address Translation Mode...............26
     4.6     Operation in Address Translation Mode.......................26
     4.6.1   Inbound Frame Address Translation...........................27
     4.6.2   Incompatibility with Address Transparent Mode...............28
     5.      iFCP Protocol...............................................28
     5.1     Overview....................................................28
     5.1.1   iFCP Transport Services.....................................28
     5.1.2   iFCP Support for Link Services..............................29
     5.2     TCP Stream Transport of iFCP Frames.........................30
     5.2.1   iFCP Session Model..........................................30
     5.2.2   iFCP Session Management.....................................30
     5.2.3   Terminating iFCP Sessions...................................37
     5.3     Fibre Channel Frame Encapsulation...........................39
     5.3.1   Encapsulation Header Format.................................39
     5.3.2   SOF and EOF Delimiter Fields................................43
     5.3.3   Frame Encapsulation.........................................44
     5.3.4   Frame De-encapsulation......................................44
     
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     iFCP Revision 13                                      August 2002
     
     
     6.      TCP Session Control Messages................................45
     6.1     Connection Bind (CBIND).....................................47
     6.2     Unbind Connection (UNBIND)..................................50
     6.3     LTEST -- Test Connection Liveness...........................52
     7.      Fibre Channel Link Services.................................53
     7.1     Special Link Service Messages...............................54
     7.2     Link Services Requiring Payload Address Translation.........56
     7.3     Fibre Channel Link Services Processed by iFCP...............58
     7.3.1   Special Extended Link Services..............................60
     7.3.2   Special FC-4 Link Services..................................75
     7.4     FLOGI Service Parameters Supported by an iFCP Gateway.......77
     8.      iFCP Error Detection........................................79
     8.1     Overview....................................................79
     8.2     Stale Frame Prevention......................................79
     8.2.1   Enforcing R_A_TOV Limits....................................80
     9.      Fabric Services Supported by an iFCP implementation.........81
     9.1     F_PORT Server...............................................82
     9.2     Fabric Controller...........................................82
     9.3     Directory/Name Server.......................................82
     9.4     Broadcast Server............................................83
     9.4.1   Establishing the Broadcast Configuration....................83
     9.4.2   Broadcast Session Management................................84
     9.4.3   Standby Global Broadcast Server.............................85
     10.     iFCP Security...............................................85
     10.1    Overview....................................................85
     10.2    iFCP Security Threats and Scope.............................85
     10.2.1  Context.....................................................85
     10.2.2  Security Threats............................................85
     10.2.3  Interoperability with Security Gateways.....................86
     10.2.4  Authentication..............................................86
     10.2.5  Confidentiality.............................................86
     10.2.6  Rekeying....................................................86
     10.2.7  Authorization...............................................87
     10.2.8  Policy control..............................................87
     10.2.9  iSNS Role...................................................87
     10.3    iFCP Security Design........................................87
     10.3.1  Enabling Technologies.......................................87
     10.3.2  Use of IKE and IPsec........................................89
     10.3.3  Signatures and Certificate-based Authentication.............91
     10.4    iSNS and iFCP Security......................................92
     10.5    Use of iSNS to Distribute Security Policy...................92
     10.6    Minimal Security Policy for an iFCP gateway.................92
     11.     Quality of Service Considerations...........................92
     11.1    Minimal requirements........................................92
     11.2    High-assurance..............................................93
     12.     IANA Considerations.........................................94
     13.     Author's Addresses..........................................94
     14.     Normative References........................................95
     15.     Non-Normative References....................................96
     A.      iFCP Support for Fibre Channel Link Services................99
     A.1     Basic Link Services.........................................99
     A.2     Pass-Through Link Services..................................99
     
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     A.3     Special Link Services......................................100
     B.      Supporting the Fibre Channel Loop Topology.................102
     B.1     Remote Control of a Public Loop............................102
     Full Copyright Statement............................................103
     Notice of Intellectual Property Rights..............................103
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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     iFCP Revision 13                                      August 2002
     
     
     
     
     Abstract
     
         This document specifies an architecture and gateway-to-gateway
         protocol for the implementation of fibre channel fabric
         functionality over an IP network. This functionality is provided
         through TCP protocols for fibre channel frame transport and the
         distributed fabric services specified by the fibre channel
         standards. The architecture enables internetworking of fibre
         channel devices through gateway-accessed regions having the fault
         isolation properties of autonomous systems and the scalability of
         the IP network.
     
     Acknowledgements
     
         The authors are indebted to those who contributed material or who
         took the time to carefully review and critique this specification
         including David Black (EMC), Rory Bolt (Quantum/ATL), Victor Firoiu
         (Nortel), Robert Peglar (XIOtech), David Robinson (Sun), Elizabeth
         Rodriguez, Joshua Tseng (Nishan), Naoke Watanabe (HDS) and members
         of the IPS working group.  For review of the iFCP security policy,
         the authors are further indebted to the authors of the IPS security
         draft [SECIPS], which include Bernard Aboba (Microsoft), Ofer Biran
         (IBM), Uri Elzer (Broadcom), Charles Kunziger (IBM), Venkat Rangan
         (Rhapsody Networks), Julian Satran (IBM), Joseph Tardo (Broadcom),
         and Jesse Walker (Intel).
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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     iFCP Revision 13                                      August 2002
     
     
     
     1.       About This Document
     
     1.1      Conventions used in this document
     
         The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
         "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in
         this document are to be interpreted as described in RFC-2119
         [RFC2119].
     
         Unless specified otherwise, numeric quantities are given as decimal
         values.
     
         All diagrams that portray bit and byte ordering, including the
         depiction of structures defined by fibre channel standards, adhere
         to the IETF conventions where bit 0 is the most significant bit and
         the first addressable byte is in the upper left hand corner.  This
         IETF convention differs from that used for INCITS T11 fibre channel
         standards, in which bit 0 is the least significant bit.
     
     1.1.1   Data Structures Internal to an Implementation
     
         To facilitate the specification of required behavior, this document
         may define and refer to internal data structures within an iFCP
         implementation. Such structures are intended for explanatory
         purposes only and need not be instantiated within an implementation
         as described in this specification.
     
     1.2      Purpose of this document
     
         This is a standards-track document, which specifies a protocol for
         the implementation of fibre channel transport services on a TCP/IP
         network.  Some portions of this document contain material from
         standards controlled by INCITS T10 and T11. This material is
         included here for informational purposes only. The authoritative
         information is given in the appropriate NCITS standards document.
     
         The authoritative portions of this document specify the mapping of
         standards-compliant fibre channel protocol implementations to
         TCP/IP.  This mapping includes sections of this document which
         describe the "iFCP Protocol" (see section 5).
     
     2.       iFCP Introduction
     
         iFCP is a gateway-to-gateway protocol, which provides fibre channel
         fabric services to fibre channel devices over a TCP/IP network.
         iFCP uses TCP to provide congestion control, error detection and
         recovery. iFCP's primary objective is to allow interconnection and
         networking of existing fibre channel devices at wire speeds over an
         IP network.
     
     
     
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     iFCP Revision 13                                      August 2002
     
     
         The protocol and method of frame address translation described in
         this document permit the attachment of fibre channel storage
         devices to an IP-based fabric by means of transparent gateways.
     
         The protocol achieves this transparency by allowing normal fibre
         channel frame traffic to pass through the gateway directly, with
         provisions, where necessary, for intercepting and emulating the
         fabric services required by a fibre channel device.
     
     2.1      Definitions
     
         Terms needed to describe the concepts presented in this document
         are presented here.
     
         Address-translation mode -- A mode of gateway operation in which
                 the scope of N_PORT fabric addresses for locally attached
                 devices are local to the iFCP gateway region in which the
                 devices reside.
     
         Address-transparent mode -- A mode of gateway operation in which
                 the scope of N_PORT fabric addresses for all fibre channel
                 devices are unique to the bounded iFCP fabric to which the
                 gateway belongs.
     
         Bounded iFCP Fabric -- The union of two or more gateway regions
                 configured to interoperate together in address-transparent
                 mode.
     
         DOMAIN_ID -- The value contained in the high-order byte of a 24-bit
                 N_PORT fibre channel address.
     
         F_PORT -- The interface used by an N_PORT to access fibre channel
                 switched fabric functionality.
     
         Fabric -- From [FC-FS]: "The entity which interconnects N_PORTs
                 attached to it and is capable of routing frames by using
                 only the address information in the fibre channel frame."
     
         Fabric Port -- The interface through which an N_PORT accesses a
                 fibre channel fabric.  The type of fabric port depends on
                 the fibre channel fabric topology. In this specification,
                 all fabric port interfaces are considered to be
                 functionally equivalent.
     
         FC-2 -- The fibre channel transport services layer described in
                 [FC-FS].
     
         FC-4 -- The fibre channel mapping of an upper layer protocol, such
                 as [FCP-2], the fibre channel to SCSI mapping.
     
         Fibre Channel Device -- An entity implementing the functionality
     
     
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     iFCP Revision 13                                      August 2002
     
     
                 accessed through an FC-4 application protocol.
     
         Fibre Channel Network -- A native fibre channel fabric and all
                 attached fibre channel nodes.
     
         Fibre Channel Node -- A collection of one or more N_PORTs
                 controlled by a level above the FC-2 layer. A node is
                 attached to a fibre channel fabric by means of the N_PORT
                 interface described in [FC-FS].
     
         Gateway Region -- The portion of an iFCP fabric accessed through an
                 iFCP gateway by a remotely attached N_PORT. Fibre channel
                 devices in the region consist of all those locally attached
                 to the gateway.
     
         iFCP -- The protocol discussed in this document.
     
         iFCP Frame -- A fibre channel frame encapsulated in accordance with
                 the FC Frame Encapsulation Specification [ENCAP] and this
                 specification.
     
         iFCP Portal -- An entity representing the point at which a logical
                 or physical iFCP device is attached to the IP network.  The
                 network address of the iFCP portal consists of the IP
                 address and TCP port number to which a request is sent when
                 creating the TCP connection for an iFCP session (see
                 section 5.2.1).
     
         iFCP Session -- An association comprised of a pair of N_PORTs and a
                 TCP connection that carries traffic between them.  An iFCP
                 session may be created as the result of a PLOGI fibre
                 channel login operation.
     
         iSNS -- The server functionality and IP protocol that provide
                 storage name services in an iFCP network. Fibre channel
                 name services are implemented by an iSNS name server as
                 described in [ISNS].
     
         Locally Attached Device -- With respect to a gateway, a fibre
                 channel device accessed through the fibre channel fabric to
                 which the gateway is attached.
     
         Logical iFCP Device -- The abstraction representing a single fibre
                 channel device as it appears on an iFCP network.
     
         N_PORT -- An iFCP or fibre channel entity representing the
                 interface to fibre channel device functionality. This
                 interface implements the fibre channel N_PORT semantics
                 specified in [FC-FS].  Fibre channel defines several
                 variants of this interface that depend on the fibre channel
                 fabric topology.  As used in this document, the term
     
     
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                 applies equally to all variants.
     
         N_PORT Alias --  The N_PORT address assigned by a gateway to
                 represent a remote N_PORT accessed via the iFCP protocol.
     
         N_PORT fabric address -- The address of an N_PORT within the fibre
                 channel fabric.
     
         N_PORT ID -- The address of a locally attached N_PORT within a
                 gateway region.  N_PORT IDs are assigned in accordance with
                 the fibre channel rules for address assignment specified in
                 [FC-FS].
     
         N_PORT Network Address -- The address of an N_PORT in the iFCP
                 fabric.  This address consists of the IP address and TCP
                 port number of the iFCP Portal and the N_PORT ID of the
                 locally attached fibre channel device.
     
         Port Login (PLOGI) -- The fibre channel Extended Link Service (ELS)
                 that establishes an iFCP session through the exchange of
                 identification and operation parameters between an
                 originating N_PORT and a responding N_PORT.
     
         Remotely Attached Device -- With respect to a gateway, a fibre
                 channel device accessed from the gateway by means of the
                 iFCP protocol.
     
         Unbounded iFCP Fabric -- The union of two or more gateway regions
                 configured to interoperate together in address-translation
                 mode.
     
     
     
     3.       Fibre Channel Communication Concepts
     
         Fibre channel is a frame-based, serial technology designed for
         peer-to-peer communication between devices at gigabit speeds and
         with low overhead and latency.
     
         This section contains a discussion of the fibre channel concepts
         that form the basis for the iFCP network architecture and protocol
         described in this document. Readers familiar with this material may
         skip to section 4.
     
         Material presented in this section is drawn from the following T11
         specifications:
     
         -- The Fibre Channel Framing and Signaling Interface, [FC-FS]
     
         -- Fibre Channel Switch Fabric -2, [FC-SW2]
     
         -- Fibre Channel Generic Services, [FC-GS3]
     
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     iFCP Revision 13                                      August 2002
     
     
         -- Fibre Channel Fabric Loop Attachment, [FC-FLA]
     
         The reader will find an in-depth treatment of the technology in
         [KEMCMP] and [KEMALP].
     
     3.1      The Fibre Channel Network
     
         The fundamental entity in fibre channel is the fibre channel
         network. Unlike a layered network architecture, a fibre channel
         network is largely specified by functional elements and the
         interfaces between them. As shown in Figure 1, these consist, in
         part, of the following:
     
        a) N_PORTs -- The end points for fibre channel traffic. In the FC
           standards, N_PORT interfaces have several variants, depending on
           the topology of the fabric to which they are attached.  As used
           in this specification, the term applies to any one of the
           variants.
     
        b) FC Devices -- The fibre channel devices to which the N_PORTs
           provide access.
     
        c) Fabric Ports -- The interfaces within a fibre channel network
           that provide attachment for an N_PORT.  The types of fabric port
           depend on the fabric topology and are discussed in section 3.2.
     
        d) The network infrastructure for carrying frame traffic between
           N_PORTs.
     
        e) Within a switched or mixed fabric (see section 3.2), a set of
           auxiliary servers, including a name server for device discovery
           and network address resolution.  The types of service depend on
           the network topology.
     
           +--------+   +--------+          +--------+  +--------+
           |  FC    |   |  FC    |          |  FC    |  |  FC    |
           | Device |   | Device |<-------->| Device |  | Device |
           |........|   |........|          |........|  |........|
           | N_PORT |   | N_PORT |          | N_PORT |  | N_PORT |
           +---+----+   +----+---+          +----+---+  +----+---+
               |             |                   |           |
           +---+----+   +----+---+          +----+---+  +----+---+
           | Fabric |   | Fabric |          | Fabric |  | Fabric |
           | Port   |   | Port   |          | Port   |  | Port   |
           +========+===+========+==========+========+==+========+
           |                        Fabric                       |
           |                          &                          |
           |                     Fabric Services                 |
           +-----------------------------------------------------+
                         Figure 1 -- A Fibre Channel Network
     
     
     
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         The following sections describe fibre channel network topologies
         and give an overview of the fibre channel communications model.
     
     3.2      Fibre Channel Network Topologies
     
         The principal fibre channel network topologies consist of the
         following:
     
         a)  Arbitrated Loop -- A series of N_PORTs connected together in
             daisy-chain fashion.  In [FC-FS], loop-connected N_PORTs are
             referred to as NL_PORTs. Data transmission between NL_PORTs
             requires arbitration for control of the loop in a manner
             similar to a token ring network.
     
         b)  Switched Fabric --  A network consisting of switching elements,
             as described in section 3.2.1.
     
         c)  Mixed Fabric -- A network consisting of switches and "fabric-
             attached" loops.  A description can be found in [FC-FLA].  A
             loop-attached N_PORT (NL_PORT), is connected to the loop
             through an L_PORT and accesses the fabric by way of an FL_PORT.
     
         Depending on the topology, the N_PORT and its means of network
         attachment may be one of the following:
     
              FC Network       Network Interface   N_PORT Variant
              Topology         -----------------   --------------
              ---------------
              Loop             L_PORT              NL_PORT
     
              Switched         F_PORT              N_PORT
     
              Mixed            FL_PORT via L_PORT  NL_PORT
     
                               F_PORT              N_PORT
     
     
     
         The differences in each N_PORT variant and its corresponding fabric
         port are confined to the interactions between them.  To an external
         N_PORT, all fabric ports are transparent and all remote N_PORTs are
         functionally identical.
     
     3.2.1   Switched Fibre Channel Fabrics
     
         An example of a multi-switch fibre channel fabric is shown in
         Figure 2.
     
     
     
     
     
     
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                     +----------+          +----------+
                     |    FC    |          |  FC      |
                     |   Device |          | Device   |
                     |..........|          |..........|
                     |   N_PORT |<........>| N_PORT   |
                     +----+-----+          +-----+----+
                          |                      |
                     +----+-----+          +-----+----+
                     | F_PORT   |          | F_PORT   |
           ==========+==========+==========+==========+==============
                     |  FC      |          | FC       |
                     |  Switch  |          | Switch   |
                     +----------+          +----------+ Fibre Channel
                     |Inter-    |          |Inter-    |   Fabric
                     |Switch    |          |Switch    |
                     |Interface |          |Interface |
                     +-----+----+          +-----+----+
                           |                     |
                           |                     |
                     +-----+----+----------+-----+----+
                     |Inter-    |          |Inter-    |
                     |Switch    |          |Switch    |
                     |Interface |          |Interface |
                     +----------+          +----------+
                     |            FC Switch           |
                     |                                |
                     +--------------------------------+
                    Figure 2 -- Multi-Switch Fibre Channel Fabric
     
         The interface between switch elements is either proprietary or the
         standards-compliant E_PORT interface described by the FC-SW2
         specification, [FC-SW2].
     
     3.2.2   Mixed Fibre Channel Fabric
     
         A mixed fabric contains one or more arbitrated loops connected to a
         switched fabric as shown in Figure 3.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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                     +----------+          +----------+   +---------+
                     |    FC    |          |  FC      |   |  FC     |
                     |   Device |          | Device   |   | Device  |
                     |..........| FC       |..........|   |.........|
                     |   N_PORT |<........>| NL_PORT  +---+ NL_PORT |
                     +----+-----+ Traffic  +-----+----+   +----+----+
                          |                      |   FC Loop   |
                     +----+-----+          +-----+----+        |
                     | F_PORT   |          | FL_PORT  +--------+
                     |          |          |          |
           ==========+==========+==========+==========+==============
                     |  FC      |          | FC       |
                     |  Switch  |          | Switch   |
                     +----------+          +----------+
                     |Inter-    |          |Inter-    |
                     |Switch    |          |Switch    |
                     |Interface |          |Interface |
                     +-----+----+          +-----+----+
                           |                     |
                           |                     |
                     +-----+----+----------+-----+----+
                     |Inter-    |          |Inter-    |
                     |Switch    |          |Switch    |
                     |Interface |          |Interface |
                     +----------+          +----------+
                     |            FC Switch           |
                     |                                |
                     +--------------------------------+
                        Figure 3 -- Mixed Fibre Channel Fabric
     
         As noted previously, the protocol for communications between peer
         N_PORTs is independent of the fabric topology, N_PORT variant and
         type of fabric port to which an N_PORT is attached.
     
     3.3      Fibre Channel Layers and Link Services
     
         Fibre channel consists of the following layers:
     
         FC-0 -- The interface to the physical media,
     
         FC-1 -- The encoding and decoding of data and out-of-band physical
         link control information for transmission over the physical media,
     
         FC-2 -- The transfer of frames, sequences and Exchanges comprising
         protocol information units.
     
         FC-3 -- Common Services,
     
         FC-4 -- Application protocols such as the fibre channel protocol
         for SCSI (FCP).
     
     
     
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         In addition to the layers defined above, fibre channel defines a
         set of auxiliary operations, some of which are implemented within
         the transport layer fabric, called link services. These are
         required to manage the fibre channel environment, establish
         communications with other devices, retrieve error information,
         perform error recovery and other similar services. Some link
         services are executed by the N_PORT. Others are implemented
         internally within the fabric.  These internal services are
         described in the next section.
     
     3.3.1   Fabric-Supplied Link Services
     
         Servers internal to a switched fabric handle certain classes of
         Link Service requests and service-specific commands.  The servers
         appear as N_PORTs located at the 'well-known' N_PORT fabric
         addresses specified in [FC-FS]. Service requests use the standard
         fibre channel mechanisms for N_PORT-to-N_PORT communications.
     
         All switched fabrics must provide the following services:
     
            Fabric F_PORT server -- Services N_PORT requests to access the
            fabric for communications.
     
            Fabric Controller -- Provides state change information to inform
            other FC devices when an N_PORT exits or enters the fabric (see
            section 3.5).
     
            Directory/Name Server - Allows N_PORTs to register information
            in a database, retrieve information about other N_PORTs and
            discover other devices as described in section 3.5.
     
         A switched fabric may also implement the following optional
         services:
     
            Broadcast Address/Server -- Transmits single-frame, class 3
            sequences to all N_PORTs.
     
            Time Server -- Intended for the management of fabric-wide
            expiration timers or elapsed time values and not intended for
            precise time synchronization.
     
            Management Server - Collects and reports management information,
            such as link usage, error statistics, link quality and similar
            items.
     
            Quality of Service Facilitator - Performs fabric-wide bandwidth
            and latency management.
     
     3.4      Fibre Channel Nodes
     
         A fibre channel node has one or more fabric-attached N_PORTs. The
         node and its N_PORTs have the following associated identifiers:
     
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        a) A worldwide unique identifier for the node,
     
        b) A worldwide unique identifier for each N_PORT associated with the
           node,
     
        c) For each N_PORT attached to a fabric, a 24-bit fabric-unique
           address having the properties defined in section 3.7.1.  The
           fabric address is the address to which frames are sent.
     
         Each worldwide unique identifier is a 64-bit binary quantity having
         the format defined in [FC-FS].
     
     3.5      Fibre Channel Device Discovery
     
         In a switched or mixed fabric, fibre channel devices and changes in
         the device configuration may be discovered by means of services
         provided by the fibre channel Name Server and Fabric Controller.
     
         The Name Server provides registration and query services that allow
         a fibre channel device to register its presence on the fabric and
         discover the existence of other devices.  For example, one type of
         query obtains the fabric address of an N_PORT from its 64-bit
         worldwide unique name. The full set of supported fibre channel name
         server queries is specified in [FC-GS3].
     
         The Fabric Controller complements the static discovery capabilities
         provided by the Name Server through a service that dynamically
         alerts a fibre channel device whenever an N_PORT is added or
         removed from the configuration. A fibre channel device receives
         these notifications by subscribing to the service as specified in
         [FC-FS].
     
     3.6      Fibre Channel Information Elements
     
         The fundamental element of information in fibre channel is the
         frame.  A frame consists of a fixed header and up to 2112 bytes of
         payload having the structure described in section 3.7. The maximum
         frame size that may be transmitted between a pair of fibre channel
         devices is negotiable up to the payload limit, based on the size of
         the frame buffers in each fibre channel device and the path maximum
         transmission unit (MTU) supported by the fabric.
     
         Operations involving the transfer of information between N_PORT
         pairs are performed through 'Exchanges'.  In an Exchange,
         information is transferred in one or more ordered series of frames
         referred to as Sequences.
     
         Within this framework, an upper layer protocol is defined in terms
         of transactions carried by Exchanges. Each transaction, in turn,
         consists of protocol information units, each of which is carried by
         an individual Sequence within an Exchange.
     
     
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     3.7      Fibre Channel Frame Format
     
         A fibre channel frame consists of a header, payload and 32-bit CRC
         bracketed by SOF and EOF delimiters. The header contains the
         control information necessary to route frames between N_PORTs and
         manage Exchanges and Sequences. The following diagram gives a
         schematic view of the frame.
     
                     Bit  0                          31
                         +-----------------------------+
                  Word 0 |   Start-of-frame Delimiter  |
                         +-----+-----------------------+<----+
                         |     | Destination N_PORT    |     |
                       1 |     | Fabric Address (D_ID) |     |
                         |     |  (24 bits)            |     |
                         +-----+-----------------------+   24-byte
                         |     | Source N_PORT         |   Frame
                       2 |     | Fabric Address (S_ID) |   Header
                         |     | (24 bits)             |     |
                         +-----+-----------------------+     |
                       3 |    Control information for  |     |
                       . |    frame type, Exchange     |     |
                       . |    management, IU           |     |
                       . |    segmentation and         |     |
                       6 |    re-assembly              |     |
                         +-----------------------------+<----+
                       7 |                             |
                       . |        Frame payload        |
                       . |       (0 - 2112 bytes)      |
                       . |                             |
                       . |                             |
                       . |                             |
                         +-----------------------------+
                       . |            CRC              |
                         +-----------------------------+
                       n |    End-of-Frame Delimiter   |
                         +-----------------------------+
                        Figure 4 -- Fibre Channel Frame Format
     
         The source and destination N_PORT fabric addresses embedded in the
         S_ID and D_ID fields represent the physical addresses of
         originating and receiving N_PORTs respectively.
     
     3.7.1   N_PORT Address Model
     
         N_PORT fabric addresses are 24-bit values having the following
         format defined by the fibre channel specification [FC-FS]:
     
     
     
     
     
     
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               Bit   0         7 8         15 16       23
                    +-----------+------------+----------+
                    | Domain ID | Area ID    |  Port ID |
                    +-----------+------------+----------+
                       Figure 5 -- Fibre Channel Address Format
     
         A fibre channel device acquires an address when it logs into the
         fabric. Such addresses are volatile and subject to change based on
         modifications in the fabric configuration.
     
         In a fibre channel fabric, each switch element has a unique Domain
         ID assigned by the principal switch. The value of the Domain ID
         ranges from 1 to 239 (0xEF). Each switch element, in turn,
         administers a block of addresses divided into area and port IDs. An
         N_PORT connected to a F_PORT receives a unique fabric address
         consisting of the switchÆs Domain ID concatenated with switch-
         assigned area and port IDs.
     
         A loop-attached NL_PORT (see Figure 3) obtains the Port ID
         component of its address during the loop initialization process
         described in [FC-AL2]. The area and domain IDs are supplied by the
         fabric when the fabric login (FLOGI) is executed.
     
     3.8      Fibre Channel Transport Services
     
         N_PORTs communicate by means of the following classes of service
         specified in the fibre channel standard ([FC-FS]):
     
         Class 1 - A dedicated physical circuit connecting two N_PORTs.
     
         Class 2 - A frame-multiplexed connection with end-to-end flow
         control and delivery confirmation.
     
         Class 3 - A frame-multiplexed connection with no provisions for
         end-to-end flow control or delivery confirmation.
     
         Class 4 -- A connection-oriented service, based on a virtual
         circuit model, providing confirmed delivery with bandwidth and
         latency guarantees.
     
         Class 6 -- A reliable multicast service derived from class 1.
     
         Class 2 and class 3 are the predominant services supported by
         deployed fibre channel storage and clustering systems.
     
         Class 3 service is similar to UDP or IP datagram service. Fibre
         channel storage devices using this class of service rely on the ULP
         implementation to detect and recover from transient device and
         transport errors.
     
         For class 2 and class 3 service, the fibre channel fabric is not
         required to provide in-order delivery of frames unless explicitly
     
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         requested by the frame originator (and supported by the fabric). If
         ordered delivery is not in effect, it is the responsibility of the
         frame recipient to reconstruct the order in which frames were sent
         based on information in the frame header.
     
     3.9      Login Processes
     
         The Login processes are FC-2 operations that allow an N_PORT to
         establish the operating environment necessary to communicate with
         the fabric, other N_PORTs and ULP implementations accessed via the
         N_PORT. Three login operations are supported:
     
         a)  Fabric Login (FLOGI) -- An operation whereby the N_PORT
             registers its presence on the fabric, obtains fabric parameters
             such as classes of service supported, and receives its N_PORT
             address,
     
         b)  Port Login (PLOGI) -- An operation by which an N_PORT
             establishes communication with another N_PORT.
     
         c)  Process Login (PRLOGI) -- An operation which establishes the
             process-to-process communications associated with a specific
             FC-4 ULP -- such as FCP-2, the fibre channel SCSI mapping.
     
         Since N_PORT addresses are volatile, an N_PORT originating a login
         (PLOGI) operation executes a Name Server query to discover the
         fibre channel address of the remote device.  A common query type
         involves use of the worldwide unique name of an N_PORT to obtain
         the 24-bit N_PORT fibre channel address to which the PLOGI request
         is sent.
     
     4.       The iFCP Network Model
     
         The iFCP protocol enables the implementation of fibre channel
         fabric functionality on an IP network in which IP components and
         technology replace the fibre channel switching and routing
         infrastructure described in section 3.2.
     
         The example of Figure 6 shows a fibre channel network with attached
         devices. Each device accesses the network through an N_PORT
         connected to an interface whose behavior is specified in [FC-FS] or
         [FC-AL2]. In this case, the N_PORT represents any of the variants
         described in section 3.2. The interface to the fabric may be an
         L_PORT, F_PORT or FL_PORT.
     
         Within the fibre channel device domain, addressable entities
         consist of other N_PORTs and fibre channel devices internal to the
         network that perform the fabric services defined in [FC-GS3].
     
     
     
     
     
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                         Fibre Channel Network
                     +--------+        +--------+
                     |  FC    |        |  FC    |
                     | Device |        | Device |
                     |........| FC     |........| Fibre Channel
                     | N_PORT |<......>| N_PORT | Device Domain
                     +---+----+ Traffic+----+---+       ^
                         |                  |           |
                     +---+----+        +----+---+       |
                     | Fabric |        | Fabric |       |
                     | Port   |        | Port   |       |
           ==========+========+========+========+==============
                     |       FC Network &       |       |
                     |     Fabric Services      |       v
                     |                          | Fibre Channel
                     +--------------------------+ Network Domain
                         Figure 6 -- A Fibre Channel Network
     
     
     
               Gateway Region                   Gateway Region
          +--------+  +--------+           +--------+  +--------+
          |   FC   |  |  FC    |           |   FC   |  |   FC   |
          | Device |  | Device |           | Device |  | Device |  Fibre
          |........|  |........| FC        |........|  |........|  Channel
          | N_PORT |  | N_PORT |<.........>| N_PORT |  | N_PORT |  Device
          +---+----+  +---+----+ Traffic   +----+---+  +----+---+  Domain
              |           |                     |           |         ^
          +---+----+  +---+----+           +----+---+  +----+---+     |
          | F_PORT |  | F_PORT |           | F_PORT |  | F_PORT |     |
         =+========+==+========+===========+========+==+========+==========
          |    iFCP Layer      |<--------->|     iFCP Layer     |     |
          |....................|     ^     |....................|     |
          |     iFCP Portal    |     |     |     iFCP Portal    |     v
          +--------+-----------+     |     +----------+---------+    IP
               iFCP|Gateway      Control          iFCP|Gateway      Network
                   |              Data                |
                   |                                  |
                   |                                  |
                   |<------Encapsulated Frames------->|
                   |      +------------------+        |
                   |      |                  |        |
                   +------+    IP Network    +--------+
                          |                  |
                          +------------------+
         Figure 7 -- An iFCP Fabric Example
     
         One example of an equivalent iFCP fabric is shown in Figure 7.  The
         fabric consists of two gateway regions, each accessed by a single
         iFCP gateway.
     
     
     
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         Each gateway contains two standards-compliant F_PORTs and an iFCP
         Portal for attachment to the IP network. Fibre channel devices in
         the region are those locally connected to the iFCP fabric through
         the gateway fabric ports.
     
         Looking into the fabric port, the gateway appears as a fibre
         channel switch element. At this interface, remote N_PORTs are
         presented as fabric-attached devices. Conversely, on the IP network
         side, the gateway presents each locally connected N_PORT as a
         logical fibre channel device.
     
         Extrapolating to the general case, each gateway region behaves like
         an autonomous system whose configuration is invisible to the IP
         network and other gateway regions. Consequently, in addition to the
         F_PORT shown in the example, a gateway implementation may
         transparently support the following fibre channel interfaces:
     
         Inter-Switch Link -- A fibre channel switch-to-switch interface
                 used to access a region containing fibre channel switch
                 elements. An implementation may support the E_PORT defined
                 by [FC-SW2] or one of the proprietary interfaces provided
                 by various fibre channel switch vendors.  In this case, the
                 gateway acts as a border switch connecting the gateway
                 region to the IP network.
     
         FL_PORT -- An interface that provides fabric access for loop-
                 attached fibre channel devices as specified in [FC-FLA].
     
         L_PORT -- An interface through which a gateway may emulate the
                 fibre channel loop environment specified in [FC-AL2].  As
                 discussed in appendix B, the gateway presents remotely
                 accessed N_PORTS as loop-attached devices.
     
         The manner in which these interfaces are provided by a gateway is
         implementation-specific and therefore beyond the scope of this
         document.
     
         Although each region is connected to the IP network through one
         gateway, a region may incorporate multiple gateways for added
         performance and fault tolerance.  To do so:
     
         a) The gateways MUST coordinate the assignment of N_PORT IDs and
            aliases such that each N_PORT has one and only one address and
     
         b) All iFCP traffic between a given remote and local N_PORT pair
            MUST flow through the same iFCP session (see section 5.2.1).
            However, iFCP sessions to a given remotely attached N_PORT need
            not traverse the same gateway.
     
         Coordinating address assignments and managing the flow of traffic
         is implementation-specific and outside the scope of this
         specification.
     
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     4.1      iFCP Transport Services
     
         N_PORT to N_PORT communications that traverse a TCP/IP network
         require the intervention of the iFCP layer within the gateway. This
         consists of the following operations:
     
         a) Execution of the frame addressing and mapping functions
            described in section 4.4.
     
         b) Encapsulation of fibre channel frames for injection into the
            TCP/IP network and de-encapsulation of fibre channel frames
            received from the TCP/IP network.
     
         c) Establishment of an iFCP session in response to a PLOGI directed
            to a remote device.
     
         Section 4.4 discusses the iFCP frame addressing mechanism and the
         way in which it is used to achieve communications transparency
         between N_PORTs.
     
     4.1.1   Fibre Channel Transport Services Supported by iFCP
     
         An iFCP fabric supports Class 2 and Class 3 fibre channel transport
         services as specified in [FC-FS].  An iFCP fabric does not support
         class 4, class 6 or the Class 1 (dedicated connection) service. An
         N_PORT discovers the classes of transport services supported by the
         fabric during fabric login.
     
     4.2      iFCP Device Discovery and Configuration Management
     
         An iFCP implementation performs device discovery and iFCP fabric
         management through the Internet Storage Name Service defined in
         [ISNS]. Access to an iSNS server is required to perform the
         following functions:
     
         a) Emulate the services provided by the fibre channel name server
            described in section 3.3.1, including a mechanism for
            asynchronously notifying an N_PORT of changes in the iFCP fabric
            configuration,
     
         b) Aggregate gateways into iFCP fabrics for interoperation,
     
         c) Segment an iFCP fabric into fibre channel zones through the
            definition and management of device discovery scopes, referred
            to as 'discovery domains',
     
         d) Store and distribute security policies as described in section
            10.2.9.
     
         e) Implementation of the fibre channel broadcast mechanism.
     
     4.3      iFCP Fabric Properties
     
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         A collection of iFCP gateways may be configured for interoperation
         as either a bounded or unbounded iFCP fabric.
     
         Gateways in a bounded iFCP fabric operate in address transparent
         mode as described in section 4.5. In this mode, the scope of a
         fibre channel N_PORT address is fabric-wide and is derived from
         domain IDs issued by the iSNS server from a common pool.  As
         discussed in section 4.3.2, the maximum number of domain IDs
         allowed by fibre channel limits the configuration of a bounded iFCP
         fabric.
     
         Gateways in an unbounded iFCP fabric operate in address translation
         mode as described in section 4.6.  In this mode, the scope of an
         N_PORT address is local to a gateway region. For fibre channel
         traffic between regions, the translation of frame-embedded N_PORT
         addresses is performed by the gateway.  As discussed below, the
         number of switch elements and gateways in an unbounded iFCP fabric
         may exceed the limits of a conventional fibre channel fabric.
     
         All iFCP gateways MUST support unbounded iFCP fabrics.  Support for
         bounded iFCP fabrics is OPTIONAL.
     
         The decision to support bounded iFCP fabrics in a gateway
         implementation depends on the address transparency, configuration
         scalability, and fault tolerance considerations given in the
         following sections.
     
     4.3.1   Address Transparency
     
         Although iFCP gateways in an unbounded fabric will convert N_PORT
         addresses in the frame header and payload of standard link service
         messages, a gateway cannot convert such addresses in the payload of
         vendor- or user-specific fibre channel frame traffic.
     
         Consequently, while both bounded and unbounded iFCP fabrics support
         standards-compliant FC-4 protocol implementations and link services
         used by mainstream fibre channel applications, a bounded iFCP
         fabric may also support vendor- or user-specific protocol and link
         service implementations that carry N_PORT IDs in the frame payload.
     
     4.3.2   Configuration Scalability
     
         The scalability limits of a bounded fabric configuration are a
         consequence of the fibre channel address allocation policy
         discussed in section 3.7.1. As noted, a bounded iFCP fabric using
         this address allocation scheme is limited to a combined total of
         239 gateways and fibre channel switch elements. As the system
         expands, the network may grow to include many switch elements and
         gateways, each of which controls a small number of devices.  In
         this case, the limitation in switch and gateway count may become a
         barrier to extending and fully integrating the storage network.
     
     
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         Since N_PORT fibre channel addresses in an unbounded iFCP fabric
         are not fabric-wide, the limits imposed by fibre channel address
         allocation only apply within the gateway region. Across regions,
         the number of iFCP gateways, fibre channel devices and switch
         elements that may be internetworked are not constrained by these
         limits. In exchange for improved scalability, however,
         implementations must consider the incremental overhead of address
         conversion as well as the address transparency issues discussed in
         section 4.3.1.
     
     4.3.3   Fault Tolerance
     
         In a bounded iFCP fabric, address reassignment caused by a fault or
         reconfiguration, such as the addition of a new gateway region, may
         cascade to other regions, causing fabric-wide disruption as new
         N_PORT addresses are assigned. Furthermore, before a new gateway
         can be merged into the fabric, its iSNS server must be slaved to
         the iSNS server in the bounded fabric to centralize the issuance of
         domain IDs. In an unbounded iFCP fabric coordinating the iSNS
         databases requires only that the iSNS servers exchange client
         attributes with one another.
     
         A bounded iFCP fabric also has an increased dependency on the
         availability of the iSNS server, which must act as the central
         address assignment authority. If connectivity with the server is
         lost, new DOMAIN_ID values cannot be automatically allocated as
         gateways and fibre channel switch elements are added.
     
     4.4      The iFCP N_PORT Address Model
     
         This section discusses iFCP extensions to the fibre channel
         addressing model of section 3.7.1, which are required for the
         transparent routing of frames between locally and remotely attached
         N_PORTs.
     
         In the iFCP protocol an N_PORT is represented by the following
         addresses:
     
         a) A 24-bit N_PORT ID.  The fibre channel N_PORT address of a
            locally attached device. Depending on the gateway addressing
            mode, the scope is either local to a region or a bounded iFCP
            fabric. In either mode, communications between N_PORTs in the
            same gateway region use the N_PORT ID.
     
         b) A 24-bit N_PORT alias. The fibre channel N_PORT address assigned
            by each gateway operating in address translation mode to
            identify a remotely attached N_PORT. Frame traffic is
            intercepted by an iFCP gateway and directed to a remotely
            attached N_PORT by means of the N_PORT alias. The address
            assigned by each gateway is unique within the scope of the
            gateway region.
     
     
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         c) An N_PORT network address.  A tuple consisting of the gateway IP
            address, TCP port number and N_PORT ID.  The N_PORT network
            address identifies the source and destination N_PORTs for fibre
            channel traffic on the IP network.
     
         To provide transparent communications between a remote and local
         N_PORT, a gateway MUST maintain an iFCP session descriptor (see
         section 5.2.2.2) reflecting the association between the fibre
         channel address representing the remote N_PORT and the remote
         device's N_PORT network address. To establish this association the
         iFCP gateway assigns and manages fibre channel N_PORT fabric
         addresses as described in the following paragraphs.
     
         In an iFCP fabric, the iFCP gateway performs the address assignment
         and frame routing functions of an FC switch element. Unlike an FC
         switch, however, an iFCP gateway must also direct frames to
         external devices attached to remote gateways on the IP network.
     
         In order to be transparent to FC devices, the gateway must deliver
         such frames using only the 24-bit destination address in the frame
         header. By exploiting its control of address allocation and access
         to frame traffic entering or leaving the gateway region, the
         gateway is able to achieve the necessary transparency.
     
         N_PORT addresses within a gateway region may be allocated in one of
         two ways:
     
         a) Address Translation Mode - A mode of N_PORT address assignment
            in which the scope of an N_PORT fibre channel address is unique
            to the gateway region. The address of a remote device is
            represented in that gateway region by its gateway-assigned
            N_PORT alias.
     
         b) Address Transparent Mode - A mode of N_PORT address assignment
            in which the scope of an N_PORT fibre channel address is unique
            across the set of gateway regions comprising a bounded iFCP
            fabric.
     
         In address transparent mode, gateways within a bounded fabric
         cooperate in the assignment of addresses to locally attached
         N_PORTs. Each gateway in control of a region is responsible for
         obtaining and distributing unique domain IDs from the address
         assignment authority as described in section 4.5.1. Consequently,
         within the scope of a bounded fabric, the address of each N_PORT is
         unique.  For that reason, gateway-assigned aliases are not required
         to represent remote N_PORTs.
     
         All iFCP implementations MUST support operation in address
         translation mode. Implementation of address transparent mode is
         OPTIONAL but, of course, must be provided if bounded iFCP fabric
         configurations are to be supported.
     
     
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         The mode of gateway operation is settable in an implementation-
         specific manner.  The implementation MUST NOT:
     
         a) Allow the mode to be changed after the gateway begins processing
            fibre channel frame traffic
     
         b) Permit operation in more than one mode at a time or
     
         c) Establish an iFCP session with a gateway that is not in the same
            mode.
     
     4.5      Operation in Address Transparent Mode
     
         The following considerations and requirements apply to this mode of
         operation:
     
         a) iFCP gateways in address transparent mode will not interoperate
            with iFCP gateways that are not in address transparent mode.
     
         b) When interoperating with locally attached fibre channel switch
            elements, each iFCP gateway MUST assume control of DOMAIN_ID
            assignments in accordance with the appropriate fibre channel
            standard or vendor-specific protocol specification.  As
            described in section 4.5.1, DOMAIN_ID values assigned to FC
            switches internal to the gateway region must be issued by the
            iSNS server.
     
         c) When operating in address transparent Mode, fibre channel
            address translation SHALL NOT take place.
     
         When operating in address transparent mode, however, the gateway
         MUST establish and maintain the context of each iFCP session in
         accordance with section 5.2.2.
     
     4.5.1   Transparent Mode Domain ID Management
     
         As described in section 4.5, each gateway and fibre channel switch
         in a bounded iFCP fabric has a unique domain ID.  In a gateway
         region containing fibre channel switch elements, each element
         obtains a domain ID by querying the principal switch as described
         in [FC-SW2] -- in this case the iFCP gateway itself.  The gateway
         in turn obtains domain IDs on demand from the iSNS name server
         acting as the central address allocation authority. In effect, the
         iSNS server assumes the role of principal switch for the bounded
         fabric. In that case, the iSNS database contains:
     
         a) The definition for one or more bounded iFCP fabrics,
     
         b) For each bounded fabric, a worldwide unique name identifying
            each gateway in the fabric. A gateway in address transparent
            mode MUST reside in one and only one bounded fabric.
     
     
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         As the Principal Switch within the gateway region, an iFCP gateway
         in address transparent mode SHALL obtain domain IDs for use in the
         gateway region by issuing the appropriate iSNS query using its
         worldwide name.
     
     4.5.2   Incompatibility with Address Translation Mode
     
         Except for the session control frames specified in section 6, iFCP
         gateways in address transparent mode SHALL NOT originate or accept
         frames that do not have the TRP bit set to one in the iFCP flags
         field of the encapsulation header (see section 5.3.1).  The iFCP
         gateway SHALL immediately terminate all iFCP sessions with the iFCP
         gateway from which it receives such frames.
     
     4.6      Operation in Address Translation Mode
     
         This section describes the process for managing the assignment of
         addresses within a gateway region that is part of an unbounded iFCP
         fabric, including the modification of FC frame addresses embedded
         in the frame header for frames sent and received from remotely
         attached N_PORTs.
     
         As described in section 4.4, the scope of N_PORT addresses in this
         mode is local to the gateway region.  A principal switch within the
         gateway region, possibly the iFCP gateway itself, oversees the
         assignment of such addresses in accordance with the rules specified
         in [FC-FS] and [FC-FLA].
     
         The assignment of N_PORT addresses to locally attached devices is
         controlled by the switch element to which the device is connected.
     
         The assignment of N_PORT addresses for remotely attached devices is
         controlled by the gateway through which the remote device is
         accessed. In this case, the gateway MUST assign a locally
         significant N_PORT alias to be used in place of the N_PORT ID
         assigned by the remote gateway. The N_PORT alias is assigned during
         device discovery as described in section 5.2.2.1.
     
         To perform address conversion and enable the appropriate routing,
         the gateway MUST establish an iFCP session and generate the
         information required to map each N_PORT alias to the appropriate
         TCP/IP connection context and N_PORT ID of the remotely accessed
         N_PORT.  The means by which these mappings are created and updated
         are specified in section 5.2.2.2.  As described in that section,
         the required mapping information is represented by the iFCP session
         descriptor reproduced in Figure 8.
     
     
     
     
     
     
     
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                              +-----------------------+
                              |TCP Connection Context |
                              +-----------------------+
                              |  Local N_PORT ID      |
                              +-----------------------+
                              |  Remote N_PORT ID     |
                              +-----------------------+
                              |  Remote N_PORT Alias  |
                              +-----------------------+
              Figure 8 -- iFCP Session Descriptor (from section 5.2.2.2)
     
         Except for frames comprising special link service messages (see
         section 7.2), outbound frames are encapsulated and sent without
         modification. Address translation is deferred until receipt from
         the IP network as specified in section 4.6.1.
     
     4.6.1   Inbound Frame Address Translation
     
         For inbound frames received from the IP network, the receiving
         gateway SHALL reference the session descriptor to fill in the D_ID
         field with the destination N_PORT ID and the S_ID field with the
         N_PORT alias it assigned. The translation process for inbound
         frames is shown in Figure 9.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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              Network Format of Inbound Frame
         +--------------------------------------------+            iFCP
         |          FC Encapsulation Header           |           Session
         +--------------------------------------------+           Descriptor
         |            SOF Delimiter Word              |              |
         +========+===================================+              V
         |        |         D_ID Field                |     +--------+-----+
         +--------+-----------------------------------+     | Lookup source|
         |        |         S_ID Field                |     | N_PORT Alias |
         +--------+-----------------------------------+     | and          |
         |        Control Information, Payload        |     | destination  |
         |        and FC CRC                          |     | N_PORT ID    |
         |                                            |     +--------+-----+
         |                                            |              |
         |                                            |              |
         +============================================+              |
         |         EOF Delimiter Word                 |              |
         +--------------------------------------------+              |
                                                                     |
                                                                     |
         Frame after Address Translation and De-encapsulation        |
         +--------+-----------------------------------+              |
         |        |  Destination N_PORT ID            |<-------------+
         +--------+-----------------------------------+              |
         |        |  Source N_PORT Alias              |<-------------+
         +--------+-----------------------------------+
         |                                            |
         |        Control information, Payload,       |
         |        and FC CRC                          |
         +--------------------------------------------+
         Figure 9 -- Inbound Frame Address Translation
     
         The receiving gateway SHALL consider the contents of the S_ID and
         D_ID fields to be undefined when received. After replacing these
         fields, the gateway MUST recalculate the FC CRC.
     
     4.6.2   Incompatibility with Address Transparent Mode
     
         iFCP gateways in address translation mode SHALL NOT originate or
         accept frames that have the TRP bit set to one in the iFCP flags
         field of the encapsulation header.  The iFCP gateway SHALL
         immediately abort all iFCP sessions with the iFCP gateway from
         which it receives such frames as described in section 5.2.3.
     
     5.       iFCP Protocol
     
     5.1      Overview
     
     5.1.1   iFCP Transport Services
     
         The main function of the iFCP protocol layer is to transport fibre
         channel frame images between locally and remotely attached N_PORTs.
     
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         When transporting frames to a remote N_PORT, the iFCP layer
         encapsulates and routes the fibre channel frames comprising each
         fibre channel Information Unit via a predetermined TCP connection
         for transport across the IP network.
     
         When receiving fibre channel frame images from the IP network, the
         iFCP layer de-encapsulates  and delivers each frame to the
         appropriate N_PORT.
     
         The iFCP layer processes the following types of traffic:
     
         a)  FC-4 frame images associated with a fibre channel application
             protocol.
     
         b)  FC-2 frames comprising fibre channel link service requests and
             responses
     
         c)  Fibre channel broadcast frames
     
         d)  iFCP control messages required to setup, manage or terminate an
             iFCP session.
     
         For FC-4 N_PORT traffic and most FC-2 messages the iFCP layer never
         interprets the contents of the frame payload.
     
         iFCP does interpret and process iFCP control messages and certain
         link service messages as described in section 5.1.2
     
     5.1.2   iFCP Support for Link Services
     
         iFCP must intervene in the processing of those fibre channel link
         service messages that contain N_PORT addresses in the message
         payload or require other special handling, such as an N_PORT login
         request (PLOGI).
     
         In the former case, an iFCP gateway operating in address
         translation mode MUST supplement the payload with additional
         information that enables the receiving gateway to convert such
         embedded N_PORT addresses to its frame of reference.
     
         For out-bound fibre channel frames comprising such a link service,
         the iFCP layer creates the supplemental information based on frame
         content, modifies the frame payload, then transmits the resulting
         fibre channel frame with supplemental data through the appropriate
         TCP connection.
     
         For incoming iFCP frames containing supplemented fibre channel link
         service frames, iFCP must interpret the frame, including any
         supplemental information, modify the frame content, and forward the
         resulting frame to the destination N_PORT for further processing.
     
     
     
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         Section 7.1 describes the processing of these link service messages
         in detail.
     
     5.2      TCP Stream Transport of iFCP Frames
     
     5.2.1   iFCP Session Model
     
         An iFCP session consists of the pair of N_PORTs comprising the
         session endpoints joined by a single TCP/IP connection.  No more
         than one iFCP session SHALL exist between a given pair of N_PORTs.
     
         An N_PORT is identified by its network address consisting of:
     
         a) The N_PORT ID assigned by the gateway to which the N_PORT is
            locally attached and
     
         b) The iFCP Portal address, consisting of its IP address and TCP
            port number.
     
         Since only one iFCP session may exist between a pair of N_PORTs,
         the iFCP session is uniquely identified by the network addresses of
         the session end points.
     
         TCP connections that may be used for iFCP sessions between pairs of
         iFCP portals are either "bound" or "unbound".  An unbound
         connection is a TCP connection that is not actively supporting an
         iFCP session.  A gateway implementation MAY establish a pool of
         unbound connections to reduce the session setup time.  Such pre-
         existing TCP connections between iFCP Portals remain unbound and
         uncommitted until allocated to an iFCP session through a CBIND
         message (see section 6.1).
     
         When the iFCP layer creates an iFCP session, it may select an
         existing unbound TCP connection or establish a new TCP connection
         and send the CBIND message down that TCP connection.  This
         allocates the TCP connection to that iFCP session.
     
     5.2.2   iFCP Session Management
     
         This section describes the protocols and data structures required
         to establish and terminate an iFCP session.
     
     5.2.2.1  The Remote N_PORT Descriptor
     
         In order to establish an iFCP session, an iFCP gateway MUST
         maintain information allowing it to locate a remotely attached
         N_PORT. For explanatory purposes, such information is assumed to
         reside in a descriptor having the format shown in Figure 10.
     
     
     
     
     
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                          +--------------------------------+
                          |  N_PORT Worldwide Unique Name  |
                          +--------------------------------+
                          |  iFCP Portal Address           |
                          +--------------------------------+
                          |  N_PORT ID of Remote N_PORT    |
                          +--------------------------------+
                          |  N_PORT Alias                  |
                          +--------------------------------+
                        Figure 10 -- Remote N_PORT Descriptor
     
         Each descriptor aggregates the following information about a
         remotely attached N_PORT:
     
             N_PORT Worldwide Unique Name -- 64-bit N_PORT world wide name
             as specified in [FC-FS]. A Remote N_PORT descriptor is uniquely
             identified by this parameter.
     
             iFCP Portal Address -- The IP address and TCP port number
             referenced when requesting creation of the TCP connection
             associated with an iFCP session.
     
             N_PORT ID --  N_PORT fibre channel address assigned to the
             remote device by the remote iFCP gateway.
     
             N_PORT Alias -- N_PORT fibre channel address assigned to the
             remote device by the 'local' iFCP gateway when operating in
             address translation mode.
     
         An iFCP gateway SHALL have one and only one descriptor for each
         remote N_PORT it accesses. If a descriptor does not exist, one
         SHALL be created using the information returned by an iSNS name
         server query. Such queries may be result from:
     
         a) A fibre channel Name Server request originated by a locally
           attached N_PORT (see sections 3.5 and 9.3), or
     
         b) A CBIND request received from a remote fibre channel device (see
           section 5.2.2.2).
     
         When creating a descriptor in response to an incoming CBIND
         request, the iFCP gateway SHALL perform an iSNS name server query
         using the worldwide port name of the remote N_PORT in the SOURCE
         N_PORT NAME field within the CBIND payload.  The descriptor SHALL
         be filled in using the query results.
     
         After creating the descriptor, a gateway operating in address
         translation mode SHALL create and add the 24-bit N_PORT alias.
     
     5.2.2.1.1  Updating a Remote N_PORT Descriptor
     
     
     
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         A Remote N_PORT descriptor SHALL only be updated as the result of
         an iSNS query to obtain information for the specified worldwide
         port name or from information returned by an iSNS state change
         notification. Following such an update, a new N_PORT alias SHALL
         NOT be assigned.
     
         Before such an update, the contents of a descriptor may have become
         stale as the result of an event that invalidated or triggered a
         change in the N_PORT network address of the remote device, such as
         a fabric reconfiguration or the device's removal or replacement.
     
         A collateral effect of such an event is that a fibre channel device
         that has been added or whose N_PORT ID has changed will have no
         active N_PORT logins. Consequently, FC-4 traffic directed to such
         an N_PORT as the result of a stale descriptor will be rejected or
         discarded.
     
         Once the originating N_PORT learns of the reconfiguration, usually
         through the name server state change notification mechanism,
         information returned in the notification or the subsequent name
         server lookup needed to reestablish the iFCP session will
         automatically purge such stale data from the gateway.
     
     5.2.2.1.2  Deleting a Remote N_PORT Descriptor
     
         Deleting a remote N_PORT descriptor is equivalent to freeing up the
         corresponding N_PORT alias for reuse, consequently the descriptor
         MUST NOT be deleted while there are any iFCP sessions that
         reference the remote N_PORT.
     
         Descriptors eligible for deletion should be removed based on a last
         in, first out policy.
     
     5.2.2.2  Creating an iFCP Session
     
         An iFCP session may be in one of the following states:
     
         OPEN  --  The session state in which fibre channel frame images may
         be sent and received.
     
         OPEN PENDING -- The session state after a gateway has issued a
         CBIND request but no response has yet been received.  No fibre
         channel frames may be sent.
     
         The session may be initiated in response to a PLOGI ELS (see
         section 7.3.1.7) or for any other implementation-specific reason.
     
         The gateway SHALL create the iFCP session as follows:
     
         a) Locate the remote N_PORT descriptor corresponding to the session
            end point.  If creating the session in order to forward a fibre
            channel frame, the session endpoint may be obtained by
     
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            referencing the remote N_PORT alias contained in the frame
            header D_ID field.  If no descriptor exists, an iFCP session
            SHALL NOT be created.
     
         b) Allocate a TCP connection to the gateway to which the remote
            N_PORT is locally attached. An implementation may use an
            existing connection in the Unbound state or a new connection may
            be created and placed in the Unbound state.
     
            When creating a connection, the IP address and TCP Port number
            SHALL be obtained by referencing the remote N_PORT descriptor as
            specified in section 5.2.2.1.
     
         c) If the TCP connection cannot be allocated or cannot be created
            due to limited resources the gateway SHALL terminate session
            creation.
     
         d) If the TCP connection is aborted for any reason before the iFCP
            session enters the OPEN state, the gateway SHALL respond in
            accordance with section 5.2.3 and MAY terminate the attempt to
            create a session or MAY try again to establish the TCP
            connection.
     
         e) The gateway SHALL then issue a CBIND session control message
            (see section 6.1) and place the session in the OPEN PENDING
            state.
     
         f) If a CBIND response is returned with a status other than
            "Success" or "iFCP session already exists", the session SHALL be
            terminated and the TCP connection returned to the Unbound state.
     
         g) A CBIND STATUS of "iFCP session already exists" indicates that
            the remote gateway has concurrently initiated a CBIND request to
            create an iFCP session between the same pair of N_PORTs. A
            gateway receiving such a response SHALL terminate this attempt
            and process the incoming CBIND request in accordance with
            section 5.2.2.3.
     
         h) In response to a CBIND STATUS of "Success", the gateway SHALL
            place the session in the OPEN state.
     
         Once the session is placed in the OPEN state, an iFCP session
         descriptor SHALL be created containing the information shown in
         Figure 11:
     
     
     
     
     
     
     
     
     
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                              +-----------------------+
                              |TCP Connection Context |
                              +-----------------------+
                              |  Local N_PORT ID      |
                              +-----------------------+
                              |  Remote N_PORT ID     |
                              +-----------------------+
                              |  Remote N_PORT Alias  |
                              +-----------------------+
                         Figure 11 -- iFCP Session Descriptor
     
         TCP Connection Context -- Information required to identify the TCP
         connection associated with the iFCP session.
     
         Local N_PORT ID --  N_PORT ID of the locally attached fibre channel
         device.
     
         Remote N_PORT ID -- N_PORT ID assigned to the remote device by the
         remote gateway.
     
         Remote N_PORT Alias -- Alias assigned to the remote N_PORT by the
         local gateway when operating in address translation mode. If in
         this mode, the gateway SHALL copy this parameter from the Remote
         N_PORT descriptor. Otherwise, it is not filled in.
     
     5.2.2.3  Responding to a CBIND Request
     
         The gateway receiving a CBIND request SHALL respond as follows:
     
         a) If the receiver has a duplicate iFCP session in the OPEN PENDING
            state, then the receiving gateway SHALL compare the Source
            N_PORT Name in the incoming CBIND payload with the Destination
            N_PORT Name.
     
         b) If the Source N_PORT Name is greater, the receiver SHALL issue a
            CBIND response of "Success" and SHALL place the session in the
            OPEN state.
     
         c) If the Source N_PORT Name is less, the receiver shall issue a
            CBIND RESPONSE of Failed - N_PORT session already exists. The
            state of the receiver-initiated iFCP session SHALL BE unchanged.
     
         d) If there is no duplicate iFCP session in the OPEN PENDING state,
            the receiving gateway SHALL issue a CBIND response. If a status
            of Success is returned, the receiving gateway SHALL create the
            iFCP session and place it in the OPEN state.  An iFCP session
            descriptor SHALL be created as described in section 5.2.2.2.
     
         e) If a remote N_PORT descriptor does not exist, one SHALL be
            created and filled in as described in section 5.2.2.1.
     
     5.2.2.4  Monitoring iFCP Connectivity
     
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         During extended periods of inactivity, an iFCP session may be
         terminated due to a hardware failure within the gateway or through
         loss of TCP/IP connectivity.  The latter may occur when the session
         traverses a stateful intermediate device, such as a NA(P)T box or
         firewall, that detects and purges connections it believes are
         unused.
     
         To test session liveness, expedite the detection of connectivity
         failures, and avoid spontaneous connection termination, an iFCP
         gateway may maintain a low level of session activity and monitor
         the session by requesting that the remote gateway periodically
         transmit the LTEST message described in section 6.3.  All iFCP
         gateways SHALL support liveness testing as described in this
         specification.
     
         A gateway requests the LTEST heartbeat by specifying a non-zero
         value for the LIVENESS TEST INTERVAL in the CBIND request or
         response message as described in section 6.1.  If both gateways
         wish to monitor liveness, each must set the LIVENESS TEST INTERVAL
         in the CBIND request or response.
     
         Upon receiving such a request, the gateway providing the heartbeat
         SHALL transmit LTEST messages at the specified interval.  The first
         message SHALL be sent as soon as the iFCP session enters the OPEN
         state.  LTEST messages SHALL NOT be sent when the iFCP session is
         not in the OPEN state.
     
         An iFCP session SHALL be terminated as described in section 5.2.3
         if:
     
         a)  The contents of the LTEST message are incorrect, or
     
         b)  An LTEST message is not received within twice the specified
             interval or the iFCP session has been quiescent for longer than
             twice the specified interval.
     
             The gateway to receive the LTEST message SHALL measure the
             interval for the first expected LTEST message from when the
             session is placed in the OPEN state.  Thereafter, the interval
             SHALL be measured relative to the last LTEST message received.
     
         To maximize liveness test coverage, LTEST messages SHOULD flow
         through all the gateway components used to enter and retrieve fibre
         channel frames from the IP network, including the mechanisms for
         encapsulating and de-encapsulating fibre channel frames.
     
         In addition to monitoring a session, information in the LTEST
         message encapsulation header may also be used to compute an
         estimate of network propagation delay as described in section
         8.2.1.  However, the propagation delay limit SHALL NOT be enforced
         for LTEST traffic.
     
     
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     5.2.2.5  Use of TCP Features and Settings
     
         This section describes ground rules for the use of TCP features in
         an iFCP session.  The core TCP protocol is defined in [RFC793].
         TCP implementation requirements and guidelines are specified in
         [RFC1122].
     
         +-----------+------------+--------------+------------+------------+
         | Feature   | Applicable |  RFC         |  Peer-wise | Requirement|
         |           | RFCs       |  Status      |  agreement | Level      |
         |           |            |              |  required? |            |
         +===========+============+==============+============+============+
         | Keep Alive| [RFC1122]  |  None        |  No        | Should not |
         |           |(discussion)|              |            | use        |
         +-----------+------------+--------------+------------+------------+
         | Tiny      | [RFC896]   |  Standard    |  No        | Should not |
         | Segment   |            |              |            | use        |
         | Avoidance |            |              |            |            |
         | (Nagle)   |            |              |            |            |
         +-----------+------------+--------------+------------+------------+
         | Window    | [RFC1323]  |  Proposed    |  No        | Should use |
         | Scale     |            |  Standard    |            |            |
         +-----------+------------+--------------+------------+------------+
         | Wrapped   | [RFC1323]  |  Proposed    |  No        | SHOULD use |
         | Sequence  |            |  Standard    |            |            |
         | Protection|            |              |            |            |
         | (PAWS)    |            |              |            |            |
         +-----------+------------+--------------+------------+------------+
                      Table 1 -- Usage of Optional TCP Features
     
         The following sections describe these options in greater detail.
     
     5.2.2.5.1  Keep Alive
     
         Keep Alive speeds the detection and cleanup of dysfunctional TCP
         connections by sending traffic when a connection would otherwise be
         idle.  The issues are discussed in [RFC1122].
     
         In order to test the device more comprehensively, fibre channel
         applications, such as storage, may implement an equivalent keep
         alive function at the FC-4 level.  Alternatively, periodic liveness
         test messages may be issued as described in section 5.2.2.4.
         Because of these more comprehensive end-to-end mechanisms and the
         considerations described in [RFC1122], keep alive at the transport
         layer should not be implemented.
     
     5.2.2.5.2  'Tiny' Segment Avoidance (Nagle)
     
         The Nagle algorithm described in [RFC896] is designed to avoid the
         overhead of small segments by delaying transmission in order to
         agglomerate transfer requests into a large segment.  In iFCP, such
         small transfers often contain I/O requests.  Hence, the
     
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         transmission delay of the Nagle algorithm may decrease I/O
         throughput.  Therefore, the Nagle algorithm should not be used.
     
     5.2.2.5.3  Window Scale
     
         Window scaling, as specified in [RFC1323], allows full utilization
         of links with large bandwidth - delay products and should be
         supported by an iFCP implementation.
     
     5.2.2.5.4  Wrapped Sequence Protection (PAWS)
     
         TCP segments are identified with 32-bit sequence numbers. In
         networks with large bandwidth - delay products, it is possible for
         more than one TCP segment with the same sequence number to be in
         flight.  In iFCP, receipt of such a sequence out of order may cause
         out-of-order frame delivery or data corruption.  Consequently, this
         feature SHOULD be supported as described in [RFC1323].
     
     5.2.3   Terminating iFCP Sessions
     
         iFCP sessions SHALL be terminated in response to one of the  events
         in Table 2:
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         +-------------------------------------------+---------------------+
         |                Event                      |     iFCP Sessions   |
         |                                           |     to Terminate    |
         +===========================================+=====================+
         | PLOGI terminated with LS_RJT response     | Peer N_PORT         |
         +-------------------------------------------+---------------------+
         | State change notification indicating      | All iFCP Sessions   |
         | N_PORT removal or reconfiguration.        | from the            |
         |                                           | reconfigured N_PORT |
         +-------------------------------------------+---------------------+
         | LOGO ACC response from peer N_PORT        | Peer N_PORT         |
         +-------------------------------------------+---------------------+
         | ACC response to LOGO ELS sent to F_PORT   | All iFCP sessions   |
         | server (D_ID = 0xFF-FF-FE) (fabric        | from the originating|
         | logout)                                   | N_PORT              |
         +-------------------------------------------+---------------------+
         | Implicit N_PORT LOGO as defined in        | All iFCP sessions   |
         | [FC-FS]                                   | from the N_PORT     |
         |                                           | logged out          |
         +-------------------------------------------+---------------------+
         | LTEST Message Error (see section 5.2.2.4) | Peer N_PORT         |
         +-------------------------------------------+---------------------+
         | Non fatal encapsulation error as          | Peer N_PORT         |
         | specified in section 5.3.3                |                     |
         +-------------------------------------------+---------------------+
         | Failure of the TCP connection associated  | Peer N_PORT         |
         | with the iFCP session                     |                     |
         +-------------------------------------------+---------------------+
         | Receipt of an UNBIND session control      | Peer N_PORT         |
         | message                                   |                     |
         +-------------------------------------------+---------------------+
         | Gateway enters the Unsynchronized state   | All iFCP sessions   |
         | (see section 8.2.1)                       |                     |
         +-------------------------------------------+---------------------+
         | Gateway detects incorrect address mode    | All iFCP sessions   |
         | to peer gateway(see section 4.6.2)        | with peer gateway   |
         +-------------------------------------------+---------------------+
                         Table 2-- Session Termination Events
     
         If a session is being terminated due to an incorrect address mode
         with the peer gateway, the TCP connection SHALL be aborted by means
         of a connection reset (RST) without performing an UNBIND.
         Otherwise, if the TCP connection is still open following the event,
         the gateway SHALL shut down the connection as follows:
     
         a) Stop sending fibre channel frames over the TCP connection.
     
         b) Discard all incoming traffic, except for an UNBIND session
            control message.
     
         c) If an UNBIND message is received at any time, return a response
            in accordance with section 6.2.
     
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         d) If session termination was not triggered by an UNBIND message,
            issue the UNBIND session control message as described in section
            6.2.
     
         e) If the UNBIND message completes with a status of Success, the
            TCP connection MAY remain open at the discretion of either
            gateway and may be kept in a pool of unbound connections in
            order to speed the creation of a new iFCP session.
     
            If the UNBIND fails for any reason, the TCP connection MUST be
            terminated.  In this case, the connection SHOULD be aborted with
            a connection reset (RST).
     
         For each terminated session, the session descriptor SHALL be
         deleted.  If a session was terminated by an event other than an
         implicit LOGO or a LOGO ACC response, the gateway shall issue a
         LOGO to the locally attached N_PORT on behalf of the remote N_PORT.
     
         To recover resources, either gateway may spontaneously close an
         unbound TCP connection at any time. If a gateway terminates a
         connection with a TCP close operation, the peer gateway MUST
         respond by executing a TCP close.
     
     5.3      Fibre Channel Frame Encapsulation
     
         This section describes the iFCP encapsulation of fibre channel
         frames.  The encapsulation complies with the common encapsulation
         format defined in [ENCAP], portions of which are included here for
         convenience.
     
         The format of an encapsulated frame is shown below:
     
                           +--------------------+
                           |       Header       |
                           +--------------------+-----+
                           |        SOF         |   f |
                           +--------------------+ F r |
                           |  FC frame content  | C a |
                           +--------------------+   m |
                           |        EOF         |   e |
                           +--------------------+-----+
                        Figure 12 -- Encapsulation Format
     
         The encapsulation consists of a 7-word header, an SOF delimiter
         word, the FC frame (including the fibre channel CRC), and an EOF
         delimiter word.  The header and delimiter formats are described in
         the following sections.
     
     5.3.1   Encapsulation Header Format
     
     
     
     
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         W|------------------------------Bit------------------------------|
         o|                                                               |
         r|                    1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3|
         d|0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1|
          +---------------+---------------+---------------+---------------+
         0|   Protocol#   |    Version    |  -Protocol#   |   -Version    |
          +---------------+---------------+---------------+---------------+
         1|                  Reserved (must be zero)                      |
          +---------------+---------------+---------------+---------------+
         2| LS_COMMAND_ACC|  iFCP Flags   |     SOF       |      EOF      |
          +-----------+---+---------------+-----------+---+---------------+
         3|   Flags   |   Frame Length    |   -Flags  |   -Frame Length   |
          +-----------+-------------------+-----------+-------------------+
         4|                      Time Stamp [integer]                     |
          +---------------------------------------------------------------+
         5|                      Time Stamp [fraction]                    |
          +---------------------------------------------------------------+
         6|                              CRC                              |
          +---------------------------------------------------------------+
                      Figure 13 --- Encapsulation Header Format
     
         Common Encapsulation Fields:
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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     iFCP Revision 13                                      August 2002
     
     
          Protocol#            IANA-assigned protocol number
                                identifying the protocol using the
                                encapsulation.  For iFCP, the value
                                assigned by [ENCAP] is 2.
     
          Version              Encapsulation version as specified in
                                [ENCAP]
     
          -Protocol#           Ones complement of the protocol#
     
          -Version             Ones complement of the version
     
          Flags                Encapsulation flags (see 5.3.1.1)
     
          Frame Length         Contains the length of the entire FC
                                Encapsulated frame including the FC
                                Encapsulation Header and the FC frame
                                (including SOF and EOF words) in units
                                of 32-bit words.
     
          -Flags               Ones-complement of the Flags field.
     
          -Frame Length        Ones-complement of the Frame Length
                                field.
     
          Time Stamp [integer] Integer component of the frame time
                                stamp as specified in [ENCAP].
     
          Time Stamp           Fractional component of the time stamp
          [fraction]           as specified in [ENCAP].
     
          CRC                  Header CRC.  MUST be valid for iFCP.
     
     
     
             The time stamp fields are used to enforce the limit on the
             lifetime of a fibre channel frame as described in section
             8.2.1.
     
          iFCP-specific fields:
     
     
     
     
     
     
     
     
     
     
     
     
     
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     iFCP Revision 13                                      August 2002
     
     
          LS_COMMAND_ACC       For a special link service ACC
                                response to be processed by iFCP, the
                                LS_COMMAND_ACC field SHALL contain a
                                copy of bits 0 through 7 of the
                                LS_COMMAND to which the ACC applies.
                                Otherwise the LS_COMMAND_ACC field
                                SHALL be set to zero.
     
          iFCP Flags           iFCP-specific flags (see below)
     
          SOF                  Copy of the SOF delimiter encoding
                                (see section 5.3.2)
     
          EOF                  Copy of the EOF delimiter encoding
                                (see section 5.3.2)
     
     
     
         The iFCP flags word has the following format:
     
              |------------------------Bit----------------------------|
              |                                                       |
              |   8      9     10     11     12     13     14    15   |
              +------+------+------+------+------+------+------+------+
              |             Reserved             | SES  | TRP  |  SPC |
              +------+------+------+------+------+------+------+------+
                             Figure 14 -- iFCP Flags Word
     
         iFCP Flags:
     
         SES         1 = Session control frame (TRP and SPC MUST be
                          0)
     
         TRP         1 = Address transparent mode enabled
     
                      0 = Address translation mode enabled
     
         SPC         1 = Frame is part of a link service message
                          requiring special processing by iFCP prior
                          to forwarding to the destination N_PORT.
     
     
     
     5.3.1.1  Common Encapsulation Flags
     
         The iFCP usage of the common encapsulation flags defined in [ENCAP]
         is shown in Figure 15:
     
     
     
     
     
     
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     iFCP Revision 13                                      August 2002
     
     
               |------------------------Bit--------------------------|
               |                                                     |
               |    0        1        2        3        4        5   |
               +--------------------------------------------+--------+
               |                  Reserved                  |  CRCV  |
               +--------------------------------------------+--------+
                   Figure 15 -- iFCP Common Encapsulation Flags
     
         For iFCP, the CRC field MUST be valid and CRCV MUST be set to one.
     
     5.3.2   SOF and EOF Delimiter Fields
     
         The format of the delimiter fields is shown below.
     
         W|------------------------------Bit------------------------------|
         o|                                                               |
         r|                      1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3|
         d|0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1|
          +---------------+---------------+---------------+---------------+
         0|      SOF      |      SOF      |     -SOF      |     -SOF      |
          +---------------+---------------+---------------+---------------+
         1|                                                               |
          +-----                   FC frame content                  -----+
          |                                                               |
          +---------------+---------------+---------------+---------------+
         n|      EOF      |      EOF      |     -EOF      |     -EOF      |
          +---------------+---------------+---------------+---------------+
                      Figure 16 -- FC Frame Encapsulation Format
     
          SOF (bits 0-7 and bits 8-15 in word 0):  iFCP uses the following
          subset of the SOF fields specified in [ENCAP]. For convenience,
          these are reproduced in Table 3.  The authoritative encodings
          should be obtained from [ENCAP].
     
                                 +-------+----------+
                                 |  FC   |          |
                                 |  SOF  | SOF Code |
                                 +-------+----------+
                                 | SOFi2 |   0x2D   |
                                 | SOFn2 |   0x35   |
                                 | SOFi3 |   0x2E   |
                                 | SOFn3 |   0x36   |
                                 +-------+----------+
             Table 3-- Translation of FC SOF Values to SOF Field Contents
     
         -SOF (bits 16-23 and 24-31 in word 0): The -SOF fields contain the
         ones complement of the value in the SOF fields.
     
         EOF (bits 0-7 and 8-15 in word n):  iFCP uses the following subset
         of EOF fields specified in [ENCAP].  For convenience, these are
         reproduced in Table 4. The authoritative encodings should be
         obtained from [ENCAP].
     
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     iFCP Revision 13                                      August 2002
     
     
                                 +-------+----------+
                                 |  FC   |          |
                                 |  EOF  | EOF Code |
                                 +-------+----------+
                                 | EOFn  |   0x41   |
                                 | EOFt  |   0x42   |
                                 +-------+----------+
            Table 4 -- Translation of FC EOF Values to EOF Field Contents
     
         -EOF (bits 16-23 and 24-31 in word n): The -EOF fields contain the
         one's complement of the value in the EOF fields.
     
         iFCP implementations SHALL place a copy of the SOF and EOF
         delimiter codes in the appropriate header fields.
     
     5.3.3   Frame Encapsulation
     
         A fibre channel Frame to be encapsulated MUST first be validated as
         described in [FC-FS].  Any frames received from a locally attached
         fibre channel device that do not pass the validity tests in [FC-FS]
         SHALL be discarded by the gateway.
     
         If the frame is a PLOGI ELS, the creation of an iFCP session as
         described in section 7.3.1.7 may precede encapsulation.  Once the
         session has been created, frame encapsulation SHALL proceed as
         follows.
     
         The S_ID and D_ID fields in the frame header SHALL be referenced to
         lookup the iFCP session descriptor (see section 5.2.2.2).  If no
         iFCP session descriptor exists, the frame SHALL be discarded.
     
         Frame types submitted for encapsulation and forwarding on the IP
         network SHALL have one of the SOF delimiters in Table 3 and an EOF
         delimiter from Table 4.  Other valid frame types MUST be processed
         internally by the gateway as specified in the appropriate fibre
         channel specification.
     
         If operating in address translation mode and processing a special
         link service message requiring the inclusion of supplemental data,
         the gateway SHALL format the frame payload and add the supplemental
         information specified in section 7.1.  The gateway SHALL then
         calculate a new FC CRC on the reformatted frame.
     
         Otherwise, the frame contents SHALL NOT be modified and the gateway
         MAY encapsulate and transmit the frame image without recalculating
         the FC CRC.
     
         The frame originator MUST then create and fill in the header and
         the SOF and EOF delimiter words as specified in sections 5.3.1 and
         5.3.2.
     
     5.3.4   Frame De-encapsulation
     
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         The receiving gateway SHALL perform de-encapsulation as follows:
     
         Upon receiving the encapsulated frame, the gateway SHALL check the
         header CRC. If the header CRC is valid, the receiving gateway SHALL
         check the iFCP flags field. If one of the error conditions in Table
         5 is detected, the gateway SHALL handle the error as specified in
         section 5.2.3.
     
         +------------------------------+-------------------------+
         |      Condition               |      Error Type         |
         +==============================+=========================+
         | Header CRC Invalid           | Encapsulation error     |
         +------------------------------+-------------------------+
         | SES = 1, TRP or SPC not 0    | Encapsulation error     |
         +------------------------------+-------------------------+
         | SES = 0, TRP set incorrectly | Incorrect address mode  |
         +------------------------------+-------------------------+
                        Table 5 -- Encapsulation Header Errors
     
         The receiving gateway SHALL then verify the frame propagation delay
         as described in section 8.2.1. If the propagation delay is too
         long, the frame SHALL be discarded. Otherwise, the gateway SHALL
         check the SOF and EOF in the encapsulation header.  A frame SHALL
         be discarded if it has an SOF code that is not in Table 3 or an EOF
         code that is not in Table 4.
     
         The gateway SHALL then de-encapsulate the frame as follows:
     
         a) Check the FC CRC and discard the frame if the CRC is invalid.
     
         b) If operating in address translation mode, replace  the S_ID
            field with the N_PORT alias of the frame originator and the D_ID
            with the N_PORT ID of the frame recipient.  Both parameters
            SHALL be obtained from the iFCP session descriptor.
     
         c) If processing a special link service message, replace the frame
            with a copy whose payload has been modified as specified in
            section 7.1.
     
         The de-encapsulated frame SHALL then be forwarded to the N_PORT
         specified in the D_ID field.  If the frame contents have been
         modified by the receiving gateway, a new FC CRC SHALL be
         calculated.
     
     6.       TCP Session Control Messages
     
         TCP session control messages are used to create and manage an iFCP
         session as described in section 5.2.2. They are passed between peer
         iFCP Portals and are only processed within the iFCP layer.
     
         The message format is based on the fibre channel extended link
         service message template shown below.
     
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         Word
           0<--Bits-->7 8<---------------Bits------------------------>31
          +------------+------------------------------------------------+
         0| R_CTL      |            D_ID [0x00 00 00]                   |
          |[Req = 0x22]| [Destination of extended link Service request] |
          |[Rep = 0x23]|                                                |
          +------------+------------------------------------------------+
         1| CS_CTL     |            S_ID [0x00 00 00]                   |
          | [0x0]      | [Source of extended link service request]      |
          +------------+------------------------------------------------+
         2|TYPE [0x1]  |               F_CTL [0]                        |
          +------------+------------------+-----------------------------+
         3|SEQ_ID      | DF_CTL [0x00]    |          SEQ_CNT [0x00]     |
          |[0x0]       |                  |                             |
          +------------+------------------+-----------------------------+
         4|         OX_ID [0x0000]        |          RX_ID_[0x0000]     |
          +-------------------------------+-----------------------------+
         5|                           Parameter                         |
          |                         [ 00 00 00 00 ]                     |
          +-------------------------------------------------------------+
         6|                        LS_COMMAND                           |
          |                [Session Control Command Code]               |
          +-------------------------------------------------------------+
         7|                                                             |
         .|             Additional Session Control Parameters           |
         .|                      ( if any )                             |
         n|                                                             |
          +=============================================================+
         n|                    Fibre Channel CRC                        |
         +|                                                             |
         1+=============================================================+
                    Figure 17 -- Format of Session Control Message
     
     
         The LS_COMMAND value for the response remains the same as that used
         for the request.
     
         The session control frame is terminated with a fibre channel CRC.
         The frame SHALL be encapsulated and de-encapsulated according to
         the rules specified in section 5.3.
     
         The encapsulation header for the link Service frame carrying a
         session control message SHALL be set as follows:
     
         Encapsulation Header Fields:
     
     
     
     
     
     
     
     
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          LS_COMMAND_ACC       0
     
          iFCP Flags           SES = 1
     
                                TRP = 0
     
                                INT = 0
     
          SOF code             SOFi3 encoding (0x2E)
     
          EOF code             EOFt encoding (0x42)
     
     
     
         The encapsulation time stamp words SHALL be set as described for
         each message type.
     
         The SOF and EOF delimiter words SHALL be set based on the SOF and
         EOF codes specified above.
     
         Table 6 lists the values assigned to byte 0 of the LS_COMMAND field
         for iFCP session control messages.
     
         +--------------+-------------------------+----------+-------------+
         | LS_COMMAND   |       Function          | Mnemonic | iFCP        |
         | field, byte 0|                         |          | Support     |
         +--------------+-------------------------+----------+-------------+
         |    0xE0      |    Connection Bind      |  CBIND   |  REQUIRED   |
         +--------------+-------------------------+----------+-------------+
         |    0xE4      |    Unbind Connection    |  UNBIND  |  REQUIRED   |
         +--------------+-------------------------+----------+-------------+
         |    0xE5      | Test Connection Liveness|  LTEST   |  REQUIRED   |
         +--------------+-------------------------+----------+-------------+
         | 0x01-0x7F    |    Vendor-specific      |          |             |
         +--------------+-------------------------+----------+-------------+
         |    0x00      | Reserved -- Unassignable|          |             |
         +--------------+-------------------------+----------+-------------+
         | All other    |    Reserved             |          |             |
         | values       |                         |          |             |
         +--------------+-------------------------+----------+-------------+
              Table 6 -- Session Control LS_COMMAND Field, Byte 0 Values
     
     6.1      Connection Bind (CBIND)
     
         As described in section 5.2.2.2, the CBIND message and response are
         used to bind an N_PORT login to a specific TCP connection and
         establish an iFCP session.  In the CBIND request message, the
         source and destination N_PORTs are identified by their worldwide
         port names. The time stamp words in the encapsulation header SHALL
         be set to zero in the request and response message frames.
     
         The following shows the format of the CBIND request.
     
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         +------+------------+------------+-----------+----------+
         | Word |   Byte 0   |   Byte 1   |   Byte 2  |  Byte 3  |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0xE0 |   0x00     |   0x00    |  0x00    |
         +------+------------+------------+-----------+----------+
         | 1    |  LIVENESS TEST INTERVAL | Addr Mode | iFCP Ver |
         |      |        (Seconds)        |           |          |
         +------+-------------------------+-----------+----------+
         | 2    |                  USER INFO                     |
         +------+------------+------------+-----------+----------+
         | 3    |                                                |
         +------+              SOURCE N_PORT NAME                |
         | 4    |                                                |
         +------+------------------------------------------------+
         | 5    |                                                |
         +------+              DESTINATION N_PORT NAME           |
         | 6    |                                                |
         +------+------------------------------------------------+
     
         Addr Mode:             The addressing mode of the originating
                                 gateway.  0 = Address Translation mode, 1 =
                                 Address Transparent mode.
     
         iFCP Ver:              iFCP version number. SHALL be set to 1.
     
         LIVENESS TEST          If non-zero, requests that the receiving
         INTERVAL:              gateway transmit an LTEST message at the
                                 specified interval in seconds. If set to
                                 zero, LTEST messages SHALL NOT be sent.
     
         USER INFO:             Contains any data desired by the requestor.
                                 This information MUST be echoed by the
                                 recipient in the CBIND response message.
     
         SOURCE N_PORT NAME:    The Worldwide Port Name (WWPN) of the
                                 N_PORT locally attached to the gateway
                                 originating the CBIND request.
     
         DESTINATION N_PORT     The Worldwide Port Name (WWPN) of the
         NAME:                  N_PORT locally attached to the gateway
                                 receiving the CBIND request.
     
     
     
     
         The following shows the format of the CBIND response.
     
     
     
     
     
     
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     iFCP Revision 13                                      August 2002
     
     
         +------+------------+------------+-----------+----------+
         | Word |   Byte 0   |   Byte 1   |   Byte 2  |  Byte 3  |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0xE0 |   0x00     |   0x00    |  0x00    |
         +------+------------+------------+-----------+----------+
         | 1    |  LIVENESS TEST INTERVAL | Addr Mode | iFCP Ver |
         |      |      (Seconds)          |           |          |
         +------+-------------------------+-----------+----------+
         | 2    |                  USER INFO                     |
         +------+------------+------------+-----------+----------+
         | 3    |                                                |
         +------+               SOURCE N_PORT NAME               |
         | 4    |                                                |
         +------+------------------------------------------------+
         | 5    |                                                |
         +------+              DESTINATION N_PORT NAME           |
         | 6    |                                                |
         +------+-------------------------+----------------------+
         | 7    |        Reserved         |     CBIND Status     |
         +------+-------------------------+----------------------+
         | 8    |        Reserved         |  CONNECTION HANDLE   |
         +------+-------------------------+----------------------+
                                   Total Length = 36
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         Addr Mode:             The address translation mode of the
                                 responding gateway.  0 = Address
                                 Translation mode, 1 = Address Transparent
                                 mode.
     
         iFCP Ver:              iFCP version number. Shall be set to 1.
     
         LIVENESS TEST          If non-zero, requests that the gateway
         INTERVAL:              receiving the CBIND RESPONSE transmit an
                                 LTEST message at the specified interval in
                                 seconds.  If zero, LTEST messages SHALL NOT
                                 be sent.
     
         USER INFO:             Echoes the value received in the USER INFO
                                 field of the CBIND request message.
     
         SOURCE N_PORT NAME:    Contains the Worldwide Port Name (WWPN) of
                                 the N_PORT locally attached to the gateway
                                 issuing the CBIND request.
     
         DESTINATION N_PORT     Contains the Worldwide Port Name (WWPN) of
         NAME:                  the N_PORT locally attached to the gateway
                                 issuing the CBIND response.
     
         CBIND STATUS:          Indicates success or failure of the CBIND
                                 request.  CBIND values are shown below.
     
         CONNECTION HANDLE:     Contains a value assigned by the gateway to
                                 identify the connection. The connection
                                 handle is required when issuing the UNBIND
                                 request.
     
     
     
         CBIND Status       Description
         ------------       -----------
     
             0              Success
           1 - 15           Reserved
             16             Failed - Unspecified Reason
             17             Failed - No such device
             18             Failed - iFCP session already exists
             19             Failed - Lack of resources
             20             Failed - Incompatible address translation mode
             21             Failed - Incorrect protocol version number
             22             Failed - Gateway not Synchronized (see section
                            8.2)
             Others         Reserved
     
     
     6.2      Unbind Connection (UNBIND)
     
     
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         UNBIND is used to terminate an iFCP session and disassociate the
         TCP connection as described in section 5.2.3.
     
         The UNBIND message is transmitted over the connection that is to be
         unbound.  The time stamp words in the encapsulation header shall be
         set to zero in the request and response message frames.
     
         The following is the format of the UNBIND request message.
     
         +------+------------+------------+-----------+----------+
         | Word |   Byte 0   |   Byte 1   |   Byte 2  |  Byte 3  |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0xE4 |   0x00     |   0x00    |  0x00    |
         +------+------------+------------+-----------+----------+
         | 1    |                  USER INFO                     |
         +------+------------+------------+-----------+----------+
         | 2    |       Reserved          |  CONNECTION HANDLE   |
         +------+------------+------------+----------------------+
         | 3    |                  Reserved                      |
         +------+------------+------------+-----------+----------+
         | 4    |                  Reserved                      |
         +------+------------+------------+-----------+----------+
     
     
         USER INFO              Contains any data desired by the requestor.
                                 This information MUST be echoed by the
                                 recipient in the UNBIND response message.
     
         CONNECTION HANDLE:     Contains the gateway-assigned value from
                                 the CBIND request.
     
     
     
         The following shows the format of the UNBIND response message.
     
         +------+------------+------------+-----------+----------+
         | Word |   Byte 0   |   Byte 1   |   Byte 2  |  Byte 3  |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0xE4 |   0x00     |   0x00    |  0x00    |
         +------+------------+------------+-----------+----------+
         | 1    |                  USER INFO                     |
         +------+------------+------------+-----------+----------+
         | 2    |       Reserved          |  CONNECTION HANDLE   |
         +------+------------+------------+-----------+----------+
         | 3    |                  Reserved                      |
         +------+------------+------------+-----------+----------+
         | 4    |                  Reserved                      |
         +------+------------+------------+-----------+----------+
         | 5    |         Reserved        |     UNBIND STATUS    |
         +------+------------+------------+-----------+----------+
     
     
     
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         USER INFO              Echoes the value received in the USER INFO
                                 field of the UNBIND request message.
     
         CONNECTION HANDLE:     Echoes the CONNECTION HANDLE specified in
                                 the UNBIND request message.
     
         UNBIND STATUS:         Indicates the success or failure of the
                                 UNBIND request as follows:
     
     
     
         Unbind Status      Description
         -------------      -----------
     
                  0         Successful - No other status
               1 - 15       Reserved
                 16         Failed - Unspecified Reason
                 18         Failed - Connection ID Invalid
               Others       Reserved
     
     
     6.3      LTEST -- Test Connection Liveness
     
         The LTEST message is sent at the interval specified in the CBIND
         request or response payload.  The LTEST encapsulation time stamp
         SHALL be set as described in section 8.2.1 and may be used by the
         receiver to compute an estimate of propagation delay.  However, the
         propagation delay limit SHALL NOT be enforced.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word |   Byte 0   |   Byte 1   |   Byte 2  |  Byte 3  |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0xE5 |   0x00     |   0x00    |  0x00    |
         +------+------------+------------+-----------+----------+
         | 1    |  LIVENESS TEST INTERVAL |        Reserved      |
         |      |        (Seconds)        |                      |
         +------+-------------------------+----------------------+
         | 2    |                   COUNT                        |
         +------+------------+------------+-----------+----------+
         | 3    |                                                |
         +------+              SOURCE N_PORT NAME                |
         | 4    |                                                |
         +------+------------------------------------------------+
         | 5    |                                                |
         +------+              DESTINATION N_PORT NAME           |
         | 6    |                                                |
         +------+------------------------------------------------+
     
         LIVENESS TEST          Copy of the LIVENESS TEST INTERVAL
         INTERVAL:              specified in the CBIND request or reply
                                 message.
     
         COUNT:                 Monotonically increasing value, initialized
                                 to 0 and incremented by one for each
                                 successive LTEST message.
     
         SOURCE N_PORT NAME:    Contains a copy of the SOURCE N_PORT NAME
                                 specified in the CBIND request.
     
         DESTINATION N_PORT     Contains a copy of the DESTINATION N_PORT
         NAME:                  NAME specified in the CBIND request.
     
     
     
     7.       Fibre Channel Link Services
     
         Link services provide a set of fibre channel functions that allow a
         port to send control information or request another port to perform
         a specific control function.
     
         There are three types of link services:
     
         a) Basic
     
         b) Extended
     
         c) ULP-specific (FC-4)
     
         Each link service message (request and reply) is carried by a fibre
         channel sequence, and can be segmented into multiple frames.
     
     
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         The iFCP Layer is responsible for transporting link service
         messages across the IP network.  This includes mapping Link Service
         messages appropriately from the domain of the fibre channel
         transport to that of the IP network.  This process may require
         special processing and the inclusion of supplemental data by the
         iFCP layer.
     
         Each link service MUST be processed according to one of the
         following rules:
     
         a) Pass-through - The link service message and reply MUST be
            delivered to the receiving N_PORT by the iFCP protocol layer
            without altering the message payload. The link service message
            and reply are not processed by the iFCP protocol layer.
     
         b) Special -  Applies to a link service reply or request requiring
            the intervention of the iFCP layer before forwarding to the
            destination N_PORT. Such messages may contain fibre channel
            addresses in the payload or may require other special
            processing.
     
         c) Rejected - When issued by a locally attached N_PORT, the
            specified link service request MUST be rejected by the iFCP
            gateway.   The gateway SHALL return an LS_RJT response with a
            Reason Code of 0x0B (Command Not Supported) and a Reason Code
            Explanation of 0x0 (No Additional Explanation).
     
         This section describes the processing for special link services,
         including the manner in which supplemental data is added to the
         message payload.
     
         Appendix A enumerates all link services and the iFCP processing
         policy that applies to each.
     
     7.1      Special Link Service Messages
     
         Special link service messages require the intervention of the iFCP
         layer before forwarding to the destination N_PORT.  Such
         intervention is required in order to:
     
         a) Service any link service message that requires special handling,
            such as a PLOGI.
     
         b) In address translation mode only, service any link service
            message that has an N_PORT address in the payload.
     
         Unless otherwise specified in the link service description, support
         for each special link service is MANDATORY.
     
         Such messages SHALL be transmitted in a fibre channel frame having
         the format shown in Figure 18 for extended link services or Figure
         19 for FC-4 link services.
     
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         Word
           0<---Bit-->7 8<-------------------------------------------->31
          +------------+------------------------------------------------+
         0| R_CTL      |                     D_ID                       |
          |[Req = 0x22]|[Destination of extended link Service request]  |
          |[Rep = 0x23]|                                               |
          +------------+------------------------------------------------+
         1| CS_CTL     |                     S_ID                       |
          |            | [Source of extended link service request]      |
          +------------+------------------------------------------------+
         2| TYPE       |                     F_CTL                      |
          | [0x01]     |                                                |
          +------------+------------------+-----------------------------+
         3| SEQ_ID     |        DF_CTL    |          SEQ_CNT            |
          +------------+------------------+-----------------------------+
         4|          OX_ID                |             RX_ID           |
          +-------------------------------+-----------------------------+
         5|                         Parameter                           |
          |                      [ 00 00 00 00 ]                        |
          +-------------------------------------------------------------+
         6|                         LS_COMMAND                          |
          |               [Extended Link Service Command Code]          |
          +-------------==----------------------------------------------+
         7|                                                             |
         .|             Additional Service Request Parameters           |
         .|                      ( if any )                             |
         n|                                                             |
          +-------------------------------------------------------------+
                Figure 18 -- Format of an Extended Link Service Frame
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         Word
           0<---Bit-->7 8<-------------------------------------------->31
          +------------+------------------------------------------------+
         0| R_CTL      |                     D_ID                       |
          |[Req = 0x32]|   [Destination of FC-4 link Service request]   |
          |[Rep = 0x33]|                                                |
          +------------+------------------------------------------------+
         1| CS_CTL     |                     S_ID                       |
          |            |    [Source of FC-4 link service request]       |
          +------------+------------------------------------------------+
         2| TYPE       |                     F_CTL                      |
          | (FC-4      |                                                |
          |  specific) |                                                |
          +------------+------------------+-----------------------------+
         3| SEQ_ID     |        DF_CTL    |          SEQ_CNT            |
          +------------+------------------+-----------------------------+
         4|         OX_ID                 |             RX_ID           |
          +-------------------------------+-----------------------------+
         5|                        Parameter                            |
          |                     [ 00 00 00 00 ]                         |
          +-------------------------------------------------------------+
         6|                        LS_COMMAND                           |
          |               [FC-4 Link Service Command Code]              |
          +-------------------------------------------------------------+
         7|                                                             |
         .|             Additional Service Request Parameters           |
         .|                      ( if any )                             |
         n|                                                             |
          +-------------------------------------------------------------+
                  Figure 19 -- Format of an FC-4 Link Service Frame
     
     7.2      Link Services Requiring Payload Address Translation
     
         This section describes the handling for link service frames
         containing N_PORT addresses in the frame payload. Such addresses
         SHALL only be translated when the gateway is operating in address
         translation mode.  When operating in address transparent mode,
         these addresses SHALL NOT be translated and such link service
         messages SHALL NOT be sent as special frames unless other
         processing by the iFCP layer is required.
     
         Supplemental data includes information required by the receiving
         gateway to convert an N_PORT address in the payload to an N_PORT
         address in the receiving gatewayÆs address space. The following
         rules define the manner in which such supplemental data shall be
         packaged and referenced.
     
         For an N_PORT address field, the gateway originating the frame MUST
         set the value in the payload to identify the address translation
         type as follows:
     
     
     
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             0x00 00 01 - The gateway receiving the frame from the IP
             network MUST replace the contents of the field with the N_PORT
             alias of the frame originator.  This translation type MUST be
             used when the address to be converted is that of the source
             N_PORT.
     
             0x00 00 02 - The gateway receiving the frame from the IP
             network MUST replace the contents of the field with the N_PORT
             ID of the destination N_PORT.  This translation type MUST be
             used when the address to be converted is that of the
             destination N_PORT
     
             0x00 00 03 - The gateway receiving the frame from the IP
             network MUST reference the specified supplemental data to set
             the field contents. The supplemental information is the 64-bit
             world wide identifier of the N_PORT as set forth in the fibre
             channel specification [FC-FS]. If not otherwise part of the
             link service payload, this information MUST be appended in
             accordance with the applicable link service description. Unless
             specified otherwise, this translation type SHALL NOT be used if
             the address to be converted corresponds to that of the frame
             originator or recipient.
     
         Since fibre channel addressing rules prohibit the assignment of
         fabric addresses with a domain ID of 0, the above codes will never
         correspond to valid N_PORT fabric IDs.
     
         If the sending gateway cannot obtain the worldwide identifier of an
         N_PORT, the gateway SHALL terminate the request with an LS_RJT
         message as described in [FC-FS].  The Reason Code SHALL be set to
         0x07 (protocol error) and the Reason Explanation SHALL be set to
         0x1F (Invalid N_PORT identifier).
     
         Supplemental data is sent with the link service request or ACC
         frames in one of the following ways:
     
         a) By appending the necessary data to the end of the link service
            frame.
     
         b) By extending the sequence with additional frames.
     
         In the first case, a new frame SHALL be created whose length
         includes the supplemental data. The procedure for extending the
         link service sequence with additional frames is dependent on the
         link service type.
     
         For each field requiring address translation, the receiving gateway
         SHALL reference the translation type encoded in the field and
         replace it with the N_PORT address as shown in Table 7:
     
     
     
     
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         +------------------+------------------------------------+
         |    Translation   |          N_PORT Translation        |
         |    Type Code     |                                    |
         +------------------+------------------------------------+
         | 0x00 00 01       | Replace field contents with N_PORT |
         |                  | alias of frame originator.         |
         +------------------+------------------------------------+
         | 0x00 00 02       | Replace field contents with N_PORT |
         |                  | ID of frame recipient.             |
         +------------------+------------------------------------+
         |                  | Lookup N_PORT via iSNS query.      |
         |                  | If locally attached, replace with  |
         | 0x00 00 03       | N_PORT ID.                         |
         |                  | If remotely attached, replace with |
         |                  | N_PORT alias from remote N_PORT .  |
         |                  | descriptor (see section 5.2.2.1).  |
         +------------------+------------------------------------+
                     Table 7 -- Link Service Address Translation
     
         For translation type 3, the receiving gateway SHALL obtain the
         information needed to fill in the field in the link service frame
         payload by converting the specified N_PORT worldwide identifier to
         a gateway IP address and N_PORT ID.  This information MUST be
         obtained through an iSNS name server query. If the query is
         unsuccessful, the gateway SHALL terminate the request with an
         LS_RJT response message as described in [FC-FS].  The Reason Code
         SHALL be set to 0x07 (protocol error) and the Reason Explanation
         SHALL be set to 0x1F (Invalid N_PORT identifier).
     
         After applying the supplemental data, the receiving gateway SHALL
         forward the resulting link service frames to the destination N_PORT
         with the supplemental information removed.
     
     7.3      Fibre Channel Link Services Processed by iFCP
     
         The following Extended and FC-4 Link Service Messages must receive
         special processing.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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             Extended Link Service            LS_COMMAND   Mnemonic
             Messages                         ----------   --------
             ----------------------
             Abort Exchange                  0x06 00 00 00 ABTX
             Discover Address                0x52 00 00 00 ADISC
             Discover Address Accept         0x02 00 00 00 ADISC ACC
             FC Address Resolution           0x55 00 00 00 FARP-REPLY
             Protocol Reply
             FC Address Resolution           0x54 00 00 00 FARP-REQ
             Protocol Request
             Logout                          0x05 00 00 00 LOGO
             Port Login                      0x30 00 00 00 PLOGI
             Read Exchange Status Block      0x08 00 00 00 RES
             Read Exchange Status Block      0x02 00 00 00 RES ACC
             Accept
             Read Link Error Status          0x0F 00 00 00 RLS
             Block
             Read Sequence Status Block      0x09 00 00 00 RSS
             Reinstate Recovery              0x12 00 00 00 RRQ
             Qualifier
             Request Sequence                0x0A 00 00 00 RSI
             Initiative
             Scan Remote Loop                0x7B 00 00 00 SRL
             Third Party Process Logout      0x24 00 00 00 TPRLO
             Third Party Process Logout      0x02 00 00 00 TPRLO ACC
             Accept
     
     
     
             FC-4 Link Service Messages       LS_COMMAND   Mnemonic
             --------------------------       ----------   --------
             FCP Read Exchange Concise       0x13 00 00 00 REC
             FCP Read Exchange Concise       0x02 00 00 00 REC ACC
             Accept
     
         Each encapsulated fibre channel frame that is part of a special
         link service MUST have the SPC bit set to one in the iFCP FLAGS
         field of the encapsulation header as specified in section 5.3.1.
         If an ACC link service response requires special processing, the
         responding gateway SHALL place a copy of LS_COMMAND bits 0 through
         7 from the link service request frame in the LS_COMMAND_ACC field
         of the ACC encapsulation header. Supplemental data (if any) MUST be
         appended as described in the following section.
     
         The format of each special link service message, including
         supplemental data where applicable, is shown in the following
         sections.  Each description shows the basic format, as specified in
         the applicable FC standard, followed by supplemental data as shown
         in the example below.
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    |                  LS_COMMAND                    |
         +------+------------+------------+-----------+----------+
         | 1    |                                                |
         | .    |                                                |
         | .    |          Link Service Frame Payload            |
         |      |                                                |
         | n    |                                                |
         +======+============+============+===========+==========+
         | n+1  |                                                |
         |  .   |            Supplemental Data                   |
         |  .   |               (if any)                         |
         | n+k  |                                                |
         +======+================================================+
                 Figure 20 -- Special Link Service Frame Payload
     
     
     7.3.1   Special Extended Link Services
     
         The following sections define extended link services for which
         special processing is required.
     
     7.3.1.1  Abort Exchange (ABTX)
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x6  |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | RRQ Status |     Exchange Originator S_ID      |
         +------+------------+------------+-----------+----------+
         | 2    |   OX_ID of Tgt exchange | RX_ID of tgt exchange|
         +------+------------+------------+-----------+----------+
         | 3-10 |  Optional association header (32 bytes         |
         +======+============+============+===========+==========+
     
     
         Fields Requiring       Translation   Supplemental Data
         Address Translation     Type (see      (type 3 only)
         -------------------    section 7.2)     ------------
                                 -----------
     
         Exchange Originator        1, 2              N/A
         S_ID
     
     
         Other Special Processing:
     
     
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             None
     
     7.3.1.2  Discover Address (ADISC)
     
         Format of ADISC ELS:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x52 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Reserved   |  Hard address of ELS Originator   |
         +------+------------+------------+-----------+----------+
         | 2-3  |     Port Name of Originator                    |
         +------+------------+------------+-----------+----------+
         | 4-5  |     Node Name of originator                    |
         +------+------------+------------+-----------+----------+
         | 6    |  Rsvd      |  N_PORT ID  of ELS Originator     |
         +======+============+============+===========+==========+
     
     
     
         Fields Requiring       Translation    Supplemental Data
         Address Translation     Type (see       (type 3 only)
         -------------------   section 7.2)      ------------
                                -------------
     
         N_PORT ID of ELS            1                N/A
         Originator
     
     
     
         Other Special Processing:
     
             The Hard Address of the ELS originator SHALL be set to 0.
     
     7.3.1.3  Discover Address Accept (ADISC ACC)
     
         Format of ADISC ACC ELS:
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x20 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Reserved   |  Hard address of ELS Originator   |
         +------+------------+------------+-----------+----------+
         | 2-3  |     Port Name of Originator                    |
         +------+------------+------------+-----------+----------+
         | 4-5  |     Node Name of originator                    |
         +------+------------+------------+-----------+----------+
         | 6    |  Rsvd      |  N_PORT ID of ELS Originator      |
         +======+============+============+===========+==========+
     
     
         Fields Requiring       Translation    Supplemental Data
         Address Translation     Type (see       (type 3 only)
         -------------------   section 7.2)      ------------
                                ------------
     
         N_PORT ID of ELS            1                N/A
         Originator
     
     
         Other Special Processing:
     
             The Hard Address of the ELS originator SHALL be set to 0.
     
     7.3.1.4  FC Address Resolution Protocol Reply (FARP-REPLY)
     
         The FARP-REPLY ELS is used in conjunction with the FARP-REQ ELS
         (see section 7.3.1.5) to perform the address resolution services
         required by the FC-VI protocol [FC-VI] and the fibre channel
         mapping of IP and ARP specified in RFC 2625 [RFC2625].
     
         Format of FARP-REPLY ELS:
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x55 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Match Addr |  Requesting N_PORT Identifier     |
         |      | Code Points|                                   |
         +------+------------+------------+-----------+----------+
         | 2    | Responder  |  Responding N_PORT Identifier     |
         |      | Action     |                                   |
         +------+------------+------------+-----------+----------+
         | 3-4  |     Requesting N_PORT Port_Name                |
         +------+------------+------------+-----------+----------+
         | 5-6  |     Requesting N_PORT Node_Name                |
         +------+------------+------------+-----------+----------+
         | 7-8  |     Responding N_PORT Port_Name                |
         +------+------------+------------+-----------+----------+
         | 9-10 |     Responding N_PORT Node_Name                |
         +------+------------+------------+-----------+----------+
         | 11-14|     Requesting N_PORT IP Address               |
         +------+------------+------------+-----------+----------+
         | 15-18|     Responding N_PORT IP Address               |
         +======+============+============+===========+==========+
     
     
     
     
         Fields Requiring       Translation    Supplemental Data
         Address Translation     Type (see       (type 3 only)
         -------------------   section 7.2)   -----------------
                                -------------
     
         Requesting N_PORT           2                N/A
         Identifier
     
         Responding N_PORT           1                N/A
         identifier
     
     
     
         Other Special Processing:
     
             None.
     
     
     7.3.1.5  FC Address Resolution Protocol Request (FARP-REQ)
     
         The FARP-REQ ELS is used to in conjunction with the FC-VI protocol
         [FC-VI] and IP to FC mapping of RFC 2625 [RFC2625] to perform IP
         and FC address resolution in an FC fabric.  The FARP-REQ ELS is
         usually directed to the fabric broadcast server at well-known
         address 0xFF-FF-FF for retransmission to all attached N_PORTs.
     
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         Section 9.4 describes the iFCP implementation of FC broadcast
         server functionality in an iFCP fabric.
     
         Format of FARP_REQ ELS:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x54 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Match Addr |  Requesting N_PORT Identifier     |
         |      | Code Points|                                   |
         +------+------------+------------+-----------+----------+
         | 2    | Responder  |  Responding N_PORT Identifier     |
         |      | Action     |                                   |
         +------+------------+------------+-----------+----------+
         | 3-4  |     Requesting N_PORT Port_Name                |
         +------+------------+------------+-----------+----------+
         | 5-6  |     Requesting N_PORT Node_Name                |
         +------+------------+------------+-----------+----------+
         | 7-8  |     Responding N_PORT Port_Name                |
         +------+------------+------------+-----------+----------+
         | 9-10 |     Responding N_PORT Node_Name                |
         +------+------------+------------+-----------+----------+
         | 11-14|     Requesting N_PORT IP Address               |
         +------+------------+------------+-----------+----------+
         | 15-18|     Responding N_PORT IP Address               |
         +======+============+============+===========+==========+
     
     
         Fields Requiring       Translation   Supplemental Data
         Address Translation     Type (see      (type 3 only)
         -------------------   section 7.2)   -----------------
                                 -----------
     
         Requesting N_PORT           3        Requesting N_PORT
         Identifier                           Port Name
     
         Responding N_PORT           3        Responding N_PORT
         Identifier                           Port Name
     
     
         Other Special Processing:
     
             None.
     
     
     7.3.1.6  Logout (LOGO) and LOGO ACC
     
         ELS Format:
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x5  |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     N_PORT ID being logged out    |
         +------+------------+------------+-----------+----------+
         | 2-3  |  Port name of the LOGO originator (8 bytes)    |
         +======+============+============+===========+==========+
     
     
         This ELS SHALL always be sent as a special ELS regardless of the
         translation mode in effect.
     
         Fields Requiring       Translation   Supplemental Data
         Address Translation     Type(see       (type 3 only)
         -------------------   section 7.2)    --------------
                                 -----------
     
         N_PORT ID Being             1               N/A
         Logged Out
     
     
     
         Other Special Processing:
     
         See section 5.2.3.
     
     
     
     7.3.1.7  Port Login (PLOGI) and PLOGI ACC
     
         A PLOGI ELS establishes fibre channel communications between two
         N_PORTs and triggers the creation of an iFCP session if one does
         not exist.
     
         The PLOGI request and ACC response carry information identifying
         the originating N_PORT, including a specification of its
         capabilities.  If the destination N_PORT accepts the login request,
         it sends an Accept response (an ACC frame with PLOGI payload),
         specifying its capabilities.  This exchange establishes the
         operating environment for the two N_PORTs.
     
         The following figure is duplicated from [FC-FS], and shows the
         PLOGI message format for both the request and Accept (ACC)
         response.  An N_PORT will reject a PLOGI request by transmitting an
         LS_RJT message containing no payload.
     
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x3  |   0x00     |    0x00   |   0x00   |
         |      | Acc = 0x2  |            |           |          |
         +------+------------+------------+-----------+----------+
         | 1-4  |            Common Service Parameters           |
         +------+------------+------------+-----------+----------+
         | 5-6  |            N_PORT Name                         |
         +------+------------+------------+-----------+----------+
         | 7-8  |            Node Name                           |
         +------+------------+------------+-----------+----------+
         | 9-12 |            Class 1 Service Parameters          |
         +------+------------+------------+-----------+----------+
         |13-17 |            Class 2 Service Parameters          |
         +------+------------+------------+-----------+----------+
         |18-21 |            Class 3 Service Parameters          |
         +------+------------+------------+-----------+----------+
         |22-25 |            Class 4 Service Parameters          |
         +------+------------+------------+-----------+----------+
         |26-29 |            Vendor Version Level                |
         +======+============+============+===========+==========+
                Figure 21 -- Format of PLOGI Request and ACC Payloads
     
         Details of the above fields, including common and class-based
         service parameters, can be found in [FC-FS].
     
         Special Processing
     
             As specified in section 5.2.2.2, a PLOGI request addressed to a
             remotely attached N_PORT MUST cause the creation of an iFCP
             session if one does not exist. Otherwise, the PLOGI and PLOGI
             ACC payloads MUST be passed through without modification to the
             destination N_PORT using the existing iFCP session.  In either
             case, the SPC bit must be set in the frame encapsulation header
             as specified in 5.3.3.
     
             If the CBIND to create the iFCP session fails, the issuing
             gateway SHALL terminate the PLOGI with an LS_RJT response. The
             Reason Code and Reason Code Explanation SHALL be selected from
             Table 8 based on the CBIND failure status.
     
     
     
     
     
     
     
     
     
     
     
     
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            +---------------+-------------------+---------------------+
            | CBIND Failure | LS_RJT Reason     | LS_RJT Reason Code  |
            | Status        | Code              | Explanation         |
            +===============+===================+=====================+
            | Unspecified   | Unable to Perform | No additional       |
            | Reason (16)   | Command Request   | explanation (0x00)  |
            |               | (0x09)            |                     |
            +---------------+-------------------+---------------------+
            | No Such       | Unable to Perform | Invalid N_PORT      |
            | Device (17)   | Command Request   | Name (0x0D)         |
            |               | (0x09)            |                     |
            +---------------+-------------------+---------------------+
            | Lack of       | Unable to Perform | Insufficient        |
            | Resources (19)| Command Request   | Resources to Support|
            |               | (0x09)            | Login (0x29)        |
            +---------------+-------------------+---------------------+
            | Incompatible  | Unable to Perform | No additional       |
            | Address       | Command Request   | explanation (0x00)  |
            | Translation   | (0x09)            |                     |
            | Mode (20)     |                   |                     |
            +---------------+-------------------+---------------------+
            | Incorrect iFCP| Unable to Perform | No additional       |
            | Protocol      | Command Request   | explanation (0x00)  |
            | version number| (0x09)            |                     |
            | (21)          |                   |                     |
            +---------------+-------------------+---------------------+
            | Gateway not   | Unable to Perform | No additional       |
            | Synchronized  | Command Request   | explanation (0x00)  |
            | (22)          | (0x09)            |                     |
            +---------------+-------------------+---------------------+
                  Table 8 -- PLOGI LS_RJT Status for CBIND Failures
     
     7.3.1.8  Read Exchange Status Block (RES)
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x13 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     Exchange Originator S_ID      |
         +------+------------+------------+-----------+----------+
         | 2    |          OX_ID          |         RX_ID        |
         +------+------------+------------+-----------+----------+
         | 3-10 |  Association header (may be optionally reqÆd)  |
         +======+============+============+===========+==========+
         | 11-12| Port name of the Exchange Originator (8 bytes) |
         +======+============+============+===========+==========+
     
     
     
     
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         Fields Requiring       Translation     Supplemental Data
         Address Translation     Type(see        (type 3 only)
         -------------------   section 7.2)    ------------------
                                 -----------
     
         Exchange Originator  1, 2 or 3      Port Name of the
         S_ID                                 Exchange Originator
     
     
     
         Other Special Processing:
     
             None.
     
     7.3.1.9  Read Exchange Status Block Accept (RES ACC)
     
         Format of ELS Accept Response:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Acc = 0x02 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    |          OX_ID          |         RX_ID        |
         +------+------------+------------+-----------+----------+
         | 2    | Rsvd       | Exchange Originator N_PORT ID     |
         +------+------------+------------+-----------+----------+
         | 3    | Rsvd       | Exchange Responder N_PORT ID      |
         +------+------------+------------+-----------+----------+
         | 4    |          Exchange Status Bits                  |
         +------+------------+------------+-----------+----------+
         | 5    |               Reserved                         |
         +------+------------+------------+-----------+----------+
         | 6-n  |    Service Parameters and Sequence Statuses    |
         |      |    as described in [FCS]                       |
         +======+============+============+===========+==========+
         |n+1-  | Port name of the Exchange Originator (8 bytes) |
         |n+2   |                                                |
         +======+============+============+===========+==========+
         |n+3-  | Port name of the Exchange Responder (8 bytes)  |
         |n+4   |                                                |
         +======+============+============+===========+==========+
     
     
     
     
     
     
     
     
     
     
     
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         Fields Requiring       Translation     Supplemental Data
         Address Translation     Type(see         (type 3 only)
         -------------------   section 7.2)    ------------------
                                 -----------
     
         Exchange Originator  1, 2 or 3      Port Name of the
         N_PORT ID                            Exchange Originator
     
         Exchange Responder   1, 2 or 3      Port Name of the
         N_PORT ID                            Exchange Responder
     
     
     
         When supplemental data is required, the ELS SHALL be extended by 4
         words as shown above. If the translation type for the Exchange
         Originator N_PORT ID or the Exchange Responder N_PORT ID is 1 or 2,
         the corresponding 8-byte port name SHALL be set to all zeros.
     
         Other Special Processing:
     
             None.
     
     7.3.1.10 Read Link Error Status (RLS)
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x0F |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     N_PORT Identifier             |
         +======+============+============+===========+==========+
         | 2-3  |           Port name of the N_PORT (8 bytes)    |
         +======+============+============+===========+==========+
     
         Fields Requiring       Translation   Supplemental Data (type
         Address Translation     Type(see            3 only)
         -------------------   section 7.2)     ------------------
                                 -----------
     
         N_PORT Identifier    1, 2 or 3      Port Name of the N_PORT
     
     
     
         Other Special Processing:
     
             None.
     
     7.3.1.11 Read Sequence Status Block (RSS)
     
         ELS Format:
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x09 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | SEQ_ID     |     Exchange Originator S_ID      |
         +------+------------+------------+-----------+----------+
         | 2    |          OX_ID          |         RX_ID        |
         +======+============+============+===========+==========+
         | 3-4  |Port name of the Exchange Originator (8 bytes)  |
         +======+============+============+===========+==========+
     
         Fields Requiring       Translation    Supplemental Data
         Address Translation     Type(see        (type 3 only)
         -------------------   section 7.2)   ------------------
                                 -----------
     
         Exchange Originator  1, 2 or 3      Port Name of the
         S_ID                                 Exchange Originator
     
     
     
         Other Special Processing:
     
             None.
     
     7.3.1.12 Reinstate Recovery Qualifier (RRQ)
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x12 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     Exchange Originator S_ID      |
         +------+------------+------------+-----------+----------+
         | 2    |          OX_ID          |         RX_ID        |
         +------+------------+------------+-----------+----------+
         | 3-10 |  Association header (may be optionally reqÆd)  |
         +======+============+============+===========+==========+
     
     
         Fields Requiring       Translation   Supplemental Data
         Address Translation     Type(see       (type 3 only)
         -------------------   section 7.2)  ------------------
                                 -----------
     
         Exchange Originator      1 or 2             N/A
         S_ID
     
     
     
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         Other Special Processing:
     
             None.
     
     7.3.1.13 Request Sequence Initiative (RSI)
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x0A |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     Exchange Originator S_ID      |
         +------+------------+------------+-----------+----------+
         | 2    |          OX_ID          |         RX_ID        |
         +------+------------+------------+-----------+----------+
         | 3-10 |  Association header (may be optionally reqÆd)  |
         +======+============+============+===========+==========+
     
         Fields Requiring       Translation   Supplemental Data
         Address Translation     Type(see       (type 3 only)
         -------------------   section 7.2)  ------------------
                                 -----------
     
         Exchange Originator      1 or 2             N/A
         S_ID
     
     
     
         Other Special Processing:
     
             None.
     
     7.3.1.14 Scan Remote Loop (SRL)
     
         SRL allows a remote loop to be scanned to detect changes in the
         device configuration.  Any changes will trigger a fibre channel
         state change notification and subsequent update of the iSNS
         database.
     
         ELS Format:
     
     
     
     
     
     
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  | Bits 16-24|Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x7B |           Reserved                |
         +------+------------+------------+-----------+----------+
         | 1    | Flag       | Address Identifier of the FL_PORT |
         |      |            | (see B.1)                         |
         +======+============+============+===========+==========+
         | 2-3  | World-Wide Name of the Remote FL_PORT          |
         +======+============+============+===========+==========+
     
         Fields Requiring       Translation   Supplemental Data
         Address Translation     Type(see       (type 3 only)
         -------------------   section 7.2)  ------------------
                                 -----------
     
         Address Identifier          3        World-Wide Name of
         of the FL_PORT                       the remote FL_PORT
     
     
     
         Other Special Processing:
     
         The D_ID field is the address of the Domain Controller associated
         with the remote loop. The format of the Domain Controller address
         is hex æFF FC' || Domain_ID, where Domain_ID is the gateway-
         assigned alias representing. the remote gateway or switch element
         being queried.  The D_ID after translation by the remote gateway
         identifies the gateway or switch element to be scanned within the
         remote gateway region.
     
         The FLAG field defines the scope of the SRL.  If set to 0, all loop
         port interfaces on the given switch element or gateway are scanned.
         If set to one, the loop port interface on the gateway or switch
         element to be scanned MUST be specified in bits 8 through 31.
     
         If the Flag field is zero the SRL request SHALL NOT be sent as a
         special ELS.
     
         If the Domain_ID represents a remote switch or gateway and an iFCP
         session to the remote Domain Controller does not exist, the
         requesting gateway SHALL create the iFCP session.
     
     7.3.1.15 Third Party Process Logout (TPRLO)
     
         TPRLO provides a mechanism for an N_PORT (third party) to remove
         one or more process login sessions that exist between the
         destination N_PORT and other N_PORTs specified in the command.
         This command includes one or more TPRLO LOGOUT PARAMETER PAGEs,
         each of which when combined with the destination N_PORT identifies
         a process login to be terminated by the command.
     
     
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         +--------+------------+--------------------+----------------------+
         | Word   | Bits 0-7   |     Bits 8-15      |     Bits 16 - 31     |
         +--------+------------+--------------------+----------------------+
         | 0      | Cmd = 0x24 | Page Length (0x10) |    Payload Length    |
         +--------+------------+--------------------+----------------------+
         | 1      |          TPRLO Logout Parameter Page 0                 |
         +--------+--------------------------------------------------------+
         | 5      |          TPRLO Logout Parameter Page 1                 |
         +--------+--------------------------------------------------------+
                                  ....
         +--------+--------------------------------------------------------+
         |(4*n)+1 |          TPRLO Logout Parameter page n                 |
         +--------+--------------------------------------------------------+
                         Figure 22 -- Format of TPRLO ELS
     
         Each TPRLO parameter page contains parameters identifying one or
         more image pairs and may be associated with a single FC-4 protocol
         type, common to all FC-4 protocol types between the specified image
         pair, or global to all specified image pairs. The format of a TPRLO
         page requiring address translation is shown in Figure 23.
         Additional information on TPRLO can be found in [FC-FS].
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  |       Bits 16-31     |
         +------+------------+------------+-----------+----------+
         | 0    | TYPE Code  | TYPE CODE  |                      |
         |      | or         | EXTENSION  |      TPRLO Flags     |
         |      | Common SVC |            |                      |
         |      | Parameters |            |                      |
         +------+------------+------------+-----------+----------+
         | 1    |         Third Party Process Associator         |
         +------+------------+------------+-----------+----------+
         | 2    |         Responder Process Associator           |
         +------+------------+------------+-----------+----------+
         | 3    | Reserved   | Third Party Originator N_PORT ID  |
         +======+============+============+===========+==========+
         | 4-5  | Worldwide Name of Third Party Originator       |
         |      | N_PORT                                         |
         +------+------------------------------------------------+
          Figure 23 -- Format of an Augmented TPRLO Parameter Page
     
         The TPRLO flags that affect supplemented ELS processing are as
         follows:
     
         Bit 18:   Third party Originator N_PORT Validity.  When set to
                    one, this bit indicates that word 3, bits 8-31 (Third
                    Party Originator N_PORT ID) are meaningful.
     
         Bit 19:   Global Process logout.  When set to one, this bit
                    indicates that all image pairs for all N_PORTs of the
                    specified FC-4 protocol shall be invalidated. When the
                    value of this bit is one, only one logout parameter page
     
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                    is permitted in the TPRLO payload.
     
     
     
         If bit 18 has a value of zero and bit 19 has a value of one in the
         TPRLO flags field, then the ELS SHALL NOT be sent as a special ELS.
     
         Otherwise the originating gateway SHALL process the ELS as follows:
     
         a)  The first word of the TPRLO payload SHALL NOT be modified.
     
         b)  Each TPRLO parameter page shall be extended by two words as
             shown in Figure 23.
     
         c)  If word 0, bit 18 (Third Party Originator N_PORT ID validity)
             in the TPRLO flags field has a value of one, then the sender
             shall place the worldwide port name of the fibre channel
             device's N_PORT in the extension words. The N_PORT ID SHALL be
             set to 3. Otherwise, the contents of the extension words and
             the Third Party Originator N_PORT ID SHALL be set to zero.
     
         d)  The ELS originator SHALL set the SPC bit in the encapsulation
             header of each augmented frame comprising the ELS (see section
             5.3.1).
     
         e)  If the ELS contains a single TPRLO parameter page, the
             originator SHALL increase the frame length as necessary to
             include the extended parameter page.
     
         f)  If the ELS to be augmented contains multiple TPRLO parameter
             pages, the FC frames created to contain the augmented ELS
             payload SHALL NOT exceed the maximum frame size that can be
             accepted by the destination N_PORT.
     
             Each fibre channel frame SHALL contain an integer number of
             extended TPRLO parameter pages. The maximum number of extended
             TPRLO parameter pages in a frame SHALL be limited to the number
             that can be held without exceeding the above upper limit. New
             frames resulting from the extension of the TPRLO pages to
             include the supplemental data SHALL be created by extending the
             SEQ_CNT in the fibre channel frame header. The SEQ_ID SHALL NOT
             be modified.
     
         The gateway receiving the augmented TPRLO ELS SHALL generate ELS
         frames to be sent to the destination N_PORT by copying word 0 of
         the ELS payload and processing each augmented parameter page as
         follows:
     
         a) If word 0, bit 18 has a value of one, create a parameter page by
            copying words 0 through 2 of the augmented parameter page.  The
            Third Party Originator N_PORT ID in word 3 shall be generated by
            referencing the supplemental data as described in section 7.2.
     
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         b) If word 0, bit 18 has a value of zero, create a parameter page
            by copying words 0 through 3 of the augmented parameter page.
     
         The size of each frame to be sent to the destination N_PORT MUST
         NOT exceed the maximum frame size that the destination N_PORT can
         accept.  The sequence identifier in each frame header SHALL be
         copied from the augmented ELS and the sequence count SHALL be
         monotonically increasing.
     
     7.3.1.16 Third Party Logout Accept (TPRLO ACC)
     
         The format of the TPRLO ACC frame is shown in Figure 24.
     
         +--------+------------+--------------------+----------------------+
         | Word   |  Bits 0-7  |     Bits 8-15      |     Bits 16 - 31     |
         +--------+------------+--------------------+----------------------+
         | 0      | Cmd = 0x2  | Page Length (0x10) |    Payload Length    |
         +--------+------------+--------------------+----------------------+
         | 1      |          TPRLO Logout Parameter Page 0                 |
         +--------+--------------------------------------------------------+
         | 5      |          TPRLO Logout Parameter Page 1                 |
         +--------+--------------------------------------------------------+
                                  ....
         +--------+--------------------------------------------------------+
         |(4*n)+1 |          TPRLO Logout Parameter page n                 |
         +--------+--------------------------------------------------------+
                         Figure 24 -- Format of TPRLO ACC ELS
     
         The format of the parameter page and rules for parameter page
         augmentation are as specified in section 7.3.1.15.
     
     7.3.2   Special FC-4 Link Services
     
         The following sections define FC-4 link services for which special
         processing is required.
     
     7.3.2.1  FC-4 Link Services defined by FCP
     
     7.3.2.1.1  Read Exchange Concise (REC)
     
         Link Service Request Format:
     
     
     
     
     
     
     
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  |Bits 16-24 |Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x13 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     Exchange Originator S_ID      |
         +------+------------+------------+-----------+----------+
         | 2    |          OX_ID          |         RX_ID        |
         +======+============+============+===========+==========+
         | 3-4  |Port name of the exchange originator (8 bytes)  |
         |      |   (present only for translation type 3)        |
         +======+============+============+===========+==========+
     
     
         Fields Requiring       Translation   Supplemental Data
         Address Translation     Type(see       (type 3 only)
         -------------------   section 7.2)  ------------------
                                 -----------
     
         Exchange Originator  1, 2 or 3      Port Name of the
         S_ID                                 Exchange
                                               Originator
     
     
     
         Other Special Processing:
     
             None.
     
     7.3.2.1.2  Read Exchange Concise Accept (REC ACC)
     
         Format of REC ACC Response:
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  |Bits 16-24 |Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Acc = 0x02 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    |          OX_ID          |         RX_ID        |
         +------+------------+------------+-----------+----------+
         | 2    | Rsvd       | Exchange Originator N_PORT ID     |
         +------+------------+------------+-----------+----------+
         | 3    | Rsvd       | Exchange Responder N_PORT ID      |
         +------+------------+------------+-----------+----------+
         | 4    |         Data Transfer Count                    |
         +------+------------+------------+-----------+----------+
         | 5    |         Exchange Status                        |
         +======+============+============+===========+==========+
         | 6-7  |Port name of the Exchange Originator (8 bytes)  |
         +======+============+============+===========+==========+
         | 8-9  |Port name of the Exchange Responder (8 bytes)   |
         +======+============+============+===========+==========+
     
         Fields Requiring       Translation     Supplemental Data
         Address Translation     Type(see        (type 3 only)
         -------------------   section 7.2)    ------------------
                                 -----------
     
         Exchange Originator  1, 2 or 3      Port Name of the
         N_PORT ID                            Exchange Originator
     
         Exchange Responder   1, 2 or 3      Port Name of the
         N_PORT ID                            Exchange Responder
     
     
     
         When supplemental data is required, the frame SHALL always be
         extended by 4 words as shown above.  If the translation type for
         the Exchange Originator N_PORT ID or the Exchange Responder N_PORT
         ID is 1 or 2, the corresponding 8-byte port name SHALL be set to
         all zeros.
     
         Other Special Processing:
     
         None.
     
     7.4      FLOGI Service Parameters Supported by an iFCP Gateway
     
         The FLOGI ELS is issued by an N_PORT that wishes to access the
         fabric transport services.
     
         The format of the FLOGI request and FLOGI ACC payloads are
         identical to the PLOGI request and ACC payloads described in
         section 7.3.1.7.
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 0-7   | Bits 8-15  |Bits 16-24 |Bits 25-31|
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x4  |   0x00     |    0x00   |   0x00   |
         |      | Acc = 0x2  |            |           |          |
         +------+------------+------------+-----------+----------+
         | 1-4  |            Common Service Parameters           |
         +------+------------+------------+-----------+----------+
         | 5-6  |            N_PORT Name                         |
         +------+------------+------------+-----------+----------+
         | 7-8  |            Node Name                           |
         +------+------------+------------+-----------+----------+
         | 9-12 |            Class 1 Service Parameters          |
         +------+------------+------------+-----------+----------+
         |13-17 |            Class 2 Service Parameters          |
         +------+------------+------------+-----------+----------+
         |18-21 |            Class 3 Service Parameters          |
         +------+------------+------------+-----------+----------+
         |22-25 |            Class 4 Service Parameters          |
         +------+------------+------------+-----------+----------+
         |26-29 |            Vendor Version Level                |
         +======+============+============+===========+==========+
                  Figure 25 -- FLOGI Request and ACC Payload Format
     
         A full description of each parameter is given in [FC-FS].
     
         This section tabulates the protocol-dependent service parameters
         supported by a fabric port attached to an iFCP gateway.
     
         The service parameters carried in the payload of an FLOGI extended
         link service request MUST be set in accordance with
         Table 9.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         +-----------------------------------------+---------------+
         |                                         | Fabric Login  |
         |          Service Parameter              |    Class      |
         |                                         +---+---+---+---+
         |                                         | 1 | 2 | 3 | 4 |
         +-----------------------------------------+---+---+---+---+
         | Class Validity                          | n | M | M | n |
         +-----------------------------------------+---+---+---+---+
         | Service Options                         |               |
         +-----------------------------------------+---+---+---+---+
         |   Intermix Mode                         | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Stacked Connect-Requests              | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Sequential Delivery                   | n | M | M | n |
         +-----------------------------------------+---+---+---+---+
         |   Dedicated Simplex                     | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Camp on                               | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Buffered Class 1                      | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Priority                              | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         | Initiator/Recipient Control             |               |
         +-----------------------------------------+---+---+---+---+
         |   Clock synchronization ELS capable     | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
                     Table 9 --  FLOGI Service Parameter Settings
     
         Notes:
     
              1) "n" indicates a parameter or capability that is not
                  supported by the iFCP protocol.
     
              2) "M" indicates an applicable parameter that MUST be
                  supported by an iFCP gateway.
     
     8.       iFCP Error Detection
     
     8.1      Overview
     
         This section specifies provisions for error detection and recovery
         in addition to those in [FC-FS], which continue to be available in
         the iFCP network environment.
     
     8.2      Stale Frame Prevention
     
         Recovery from fibre channel protocol error conditions requires that
         frames associated with a failed or aborted exchange drain from the
         fabric before exchange resources can be safely reused.
     
     
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         Since a fibre channel fabric may not preserve frame order, there is
         no deterministic way to purge such frames. Instead, the fabric
         guarantees that frame the lifetime will not exceed a specific limit
         (R_A_TOV).
     
         R_A_TOV is defined in [FC-FS] as "the maximum transit time within a
         fabric to guarantee that a lost frame will never emerge from the
         fabric".  For example, a value of 2 x R_A_TOV is the minimum time
         that the originator of an ELS request or FC-4 link service request
         must wait for the response to that request. The fibre channel
         default value for R_A_TOV is 10 seconds.
     
         An iFCP gateway SHALL actively enforce limits on R_A_TOV as
         described in section 8.2.1.
     
     8.2.1   Enforcing R_A_TOV Limits
     
         The R_A_TOV limit on frame lifetimes SHALL be enforced by means of
         the time stamp in the encapsulation header (see section 5.3.1) as
         described in this section.
     
         The budget for R_A_TOV SHOULD include allowances for the
         propagation delay through the gateway regions of the sending and
         receiving N_PORTs plus the propagation delay through the IP
         network.  This latter component is referred to in this
         specification as IP_TOV.
     
         IP_TOV should be set well below the value of R_A_TOV specified for
         the iFCP fabric and should be stored in the iSNS server. IP_TOV
         should be set to 50 percent of R_A_TOV.
     
         The following paragraphs describe the requirements for
         synchronizing gateway time bases and the rules for measuring and
         enforcing propagation delay limits.
     
         The protocol for synchronizing a gateway time base is SNTP
         [RFC2030]. In order to insure that all gateways are time-aligned, a
         gateway SHOULD obtain the address of an SNTP-compatible time server
         via an iSNS query.  If multiple time server addresses are returned
         by the query, the servers must be synchronized and the gateway may
         use any server in the list. Alternatively, the server may return a
         multicast group address in support of operation in Anycast mode.
         Implementation of Anycast mode is as specified in [RFC2030],
         including the precautions defined in that document.  Multicast mode
         SHOULD NOT be used.
     
         An SNTP server may use any one of the time reference sources listed
         in [RFC2030]. The resolution of the time reference MUST be 125
         milliseconds or better.
     
         Stability of the SNTP server and gateway time bases should be 100
         ppm or better.
     
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     With regard to its time base, the gateway is in either the Synchronized
     or Unsynchronized state.
     
         When in the synchronized state, the gateway SHALL
     
         a)  Set the time stamp field for each outgoing frame in accordance
             with the gateway's internal time base
     
         b)  Check the time stamp field of each incoming frame, following
             validation of the encapsulation header CRC as described in
             section 5.3.4.
     
         c)  If the incoming frame has a time stamp of 0,0 and is not one of
             the session control frames that require a 0,0 time stamp (see
             section 6), the frame SHALL be discarded.
     
         d)  If the incoming frame has a non-zero time stamp, the receiving
             gateway SHALL compute the absolute value of the time in flight
             and SHALL compare it against the value of IP_TOV specified for
             the IP fabric.
     
         e)  If the result in step (d) exceeds IP_TOV, the encapsulated
             frame shall be discarded.  Otherwise, the frame shall be de-
             encapsulated as described in section 5.3.4.
     
         A gateway SHALL enter the Synchronized state upon receiving a
         successful response to an SNTP query.
     
         A gateway shall enter the Unsynchronized state:
     
         a)  Upon power up and before successful completion of an SNTP query
     
         b)  Whenever the gateway looses contact with the SNTP server such
             that the gateway's time base may no longer be in alignment with
             that of the SNTP server. The criterion for determining loss of
             contact is implementation specific.
     
         Following loss of contact, it is recommended that the gateway enter
         the Unsynchronized state when the estimated time base drift
         relative to the SNTP reference is greater than ten percent of the
         IP_TOV limit. (Assuming all timers have an accuracy of 100 ppm and
         IP_TOV equals 5 seconds, the maximum allowable loss of contact
         duration would be about 42 minutes.)
     
         As the result of a transition from the Synchronized to the
         Unsynchronized state, a gateway MUST abort all iFCP sessions as
         described in section 5.2.3.  While in the Unsynchronized state, a
         gateway SHALL NOT permit the creation of new iFCP sessions.
     
     9.       Fabric Services Supported by an iFCP implementation
     
     
     
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         An iFCP gateway implementation MUST support the following fabric
         services:
     
          N_PORT ID Value           Description             Section
          ---------------           -----------             -------
          0xFF-FF-FE             F_PORT Server              9.1
     
          0xFF-FF-FD           Fabric Controller            9.2
     
          0xFF-FF-FC         Directory/Name Server          9.3
     
     
     
     
     
         In addition, an iFCP gateway MAY support the FC broadcast server
         functionality described in section 9.4.
     
     9.1      F_PORT Server
     
         The F_PORT server SHALL support the FLOGI ELS as described in
         section 7.4 as well as the following ELSs specified in [FC-FS]:
     
         a) Request for fabric service parameters (FDISC),
     
         b) Request for the link error status (RLS),
     
         c) Read Fabric Timeout Values (RTV).
     
     9.2      Fabric Controller
     
         The Fabric Controller SHALL support the following ELSs as specified
         in [FC-FS]:
     
         a) State Change Notification (SCN),
     
         b) Registered State Change Notification (RSCN),
     
         c) State Change Registration (SCR).
     
     9.3      Directory/Name Server
     
         The Directory/Name server provides a registration service allowing
         an N_PORT to record or query the database for information about
         other N_PORTs.  The services are defined in [FC-GS3].  The queries
         are issued as FC-4 transactions using the FC-CT command transport
         protocol specified in [FC-GS3].
     
         In iFCP, each name server request MUST be translated to the
         appropriate iSNS query defined in [ISNS]. The definitions of name
         server objects are specified in [FC-GS3].
     
     
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         The name server SHALL support record and query operations for
         directory subtype 0x02 (Name Server) and 0x03 (IP Address Server)
         and MAY support the FC-4 specific services as defined in [FC-GS3].
     
     9.4      Broadcast Server
     
         Fibre channel frames are broadcast throughout the fabric by
         addressing them to the fibre channel broadcast server at well-known
         fibre channel address 0xFF-FF-FF.   The broadcast server then
         replicates and delivers the frame to each attached N_PORT in all
         zones to which the originating device belongs.  Only class 3
         (datagram) service is supported.
     
         In an iFCP system, the fibre channel broadcast function is emulated
         by means of a two-tier architecture comprised of the following
         elements:
     
         a)  A local broadcast server residing in each iFCP gateway. The
             local server distributes broadcast traffic within the gateway
             region and forwards outgoing broadcast traffic to a global
             server for distribution throughout the iFCP fabric.
     
         b)  A global broadcast server which re-distributes broadcast
             traffic to the local server in each participating gateway.
     
         c)  An iSNS discovery domain defining the scope over which
             broadcast traffic is propagated. The discovery domain is
             populated with a global broadcast server and the set of local
             servers it supports.
     
         The local and global broadcast servers are logical iFCP devices
         that communicate using the iFCP protocol. The servers have an
         N_PORT Network Address consisting of an iFCP portal address and an
         N_PORT ID set to the well-known fibre channel address of the FC
         broadcast server (0xFF-FF-FF).
     
         As noted above, an N_PORT originates a broadcast by directing frame
         traffic to the fibre channel broadcast server. The gateway-resident
         local server distributes a copy of the frame locally and forwards a
         copy to the global server for redistribution to the local servers
         on other gateways.  The global server MUST NOT echo a broadcast
         frame to the originating local server.
     
     9.4.1   Establishing the Broadcast Configuration
     
         The broadcast configuration is managed using facilities provided by
         the iSNS server. Specifically:
     
         a)  An iSNS discovery domain is created and seeded with the network
             address of the global broadcast server N_PORT.  The global
             server is identified as such by setting the appropriate N_PORT
             entity attribute.
     
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         b)  Using the management interface, each broadcast server is preset
             with the identity of the broadcast domain.
     
         During power up, each gateway SHALL invoke the iSNS service to
         register its local broadcast server in the broadcast discovery
         domain.  After registration, the local server SHALL wait for the
         global broadcast server to establish an iFCP session.
     
         The global server SHALL register with the iSNS server as follows:
     
         a) The server SHALL query the iSNS name server by attribute to
            obtain the worldwide port name of the N_PORT pre-configured to
            provide global broadcast services.
     
         b) If the worldwide port name obtained above does not correspond to
            that of the server issuing the query, the N_PORT SHALL NOT
            perform global broadcast functions for N_PORTs in that discovery
            domain.
     
         c) Otherwise, the global server N_PORT SHALL register with the
            discovery domain and query the iSNS server to identify all
            currently-registered local servers.
     
         d) The global broadcast server SHALL initiate an iFCP session with
            each local broadcast server in the domain. When a new local
            server registers, the global server SHALL receive a state change
            notification and respond by initiating an iFCP session with the
            newly added server.  The gateway SHALL obtain these
            notifications using the iSNS provisions for lossless delivery.
     
         Upon receiving the CBIND request to initiate the iFCP session, the
         local server SHALL record the worldwide port name and N_PORT
         network address of the global server.
     
     9.4.2   Broadcast Session Management
     
         After the initial broadcast session is established, the local or
         global broadcast server MAY choose to manage the session in one of
         the following ways depending on resource requirements and the
         anticipated level of broadcast traffic:
     
         a)  A server MAY keep the session open continuously.  Since
             broadcast sessions are often quiescent for long periods of
             time, the server SHOULD monitor session connectivity as
             described in section 5.2.2.4.
     
         b)  A server MAY open the broadcast session on demand only when
             broadcast traffic is to be sent. If the session is reopened by
             the global server, the local server SHALL replace the
             previously recorded network address of the global broadcast
             server.
     
     
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     9.4.3   Standby Global Broadcast Server
     
         An implementation may designate a local server to assume the duties
         of the global broadcast server in the event of a failure.  The
         local server may use the LTEST message to determine if the global
         server is functioning and may assume control if not.
     
         When assuming control, the standby server must register with the
         iSNS server as the global broadcast server in place of the failed
         server and must install itself in the broadcast discovery domain as
         specified in steps c) and d)of section 9.4.1.
     
     10.      iFCP Security
     
     10.1     Overview
     
         iFCP relies upon the IPSec protocol suite to provide data
         confidentiality and authentication services, and IKE as the key
         management protocol. Section 10.2 describes the security
         requirements arising from iFCPÆs operating environment while
         Section 10.3 describes the resulting design choices, their
         requirement levels, and how they apply to the iFCP protocol.
     
         Detailed considerations for use of IPsec and IKE with the iFCP
         protocol can be found in [SECIPS].
     
     10.2     iFCP Security Threats and Scope
     
     10.2.1  Context
     
         iFCP is a protocol designed for use by gateway devices deployed in
         enterprise data centers.  Such environments typically have security
         gateways designed to provide network security through isolation
         from public networks.  Furthermore, iFCP data may need to traverse
         security gateways in order to support SAN-to-SAN connectivity
         across public networks.
     
     10.2.2  Security Threats
     
         Communicating iFCP gateways may be subjected to attacks, including
         attempts by an adversary to:
     
         a) Acquire confidential data and identities by snooping data
            packets.
     
         b) Modify packets containing iFCP data and control messages.
     
         c) Inject new packets into the iFCP session.
     
         d) Hijack the TCP connection carrying the iFCP session.
     
         e) Launch denial of service attacks against the iFCP gateway.
     
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         f) Disrupt the security negotiation process.
     
         g) Impersonate a legitimate security gateway.
     
         h) Compromise communication with the iSNS server.
     
         It is imperative to thwart these attacks, given that an iFCP
         gateway is the last line of defense for a whole fibre channel
         island, which may include several hosts and fibre channel switches.
         To do so, the iFCP gateway must implement and may use
         confidentiality, data origin authentication, integrity, and replay
         protection on a per-datagram basis. The iFCP gateway must implement
         and may use bi-directional authentication of the communication
         endpoints. Finally, it must implement and may use a scalable
         approach to key management.
     
     10.2.3  Interoperability with Security Gateways
     
         Enterprise data center networks are considered mission-critical
         facilities that must be isolated and protected from all possible
         security threats.  Such networks are usually protected by security
         gateways, which at a minimum provide a shield against denial of
         service attacks.  The iFCP security architecture is capable of
         leveraging the protective services of the existing security
         infrastructure, including firewall protection, NAT and NAPT
         services, and IPSec VPN services available on existing security
         gateways.  Considerations regarding intervening NAT and NAPT boxes
         along the iFCP-iSNS path can be found in [iSNS].
     
     10.2.4  Authentication
     
         iFCP is a peer-to-peer protocol.  iFCP sessions may be initiated by
         either or both peer gateways.  Consequently, bi-directional
         authentication of peer gateways must be provided in accordance with
         the requirement levels specified in section 10.3.1.
     
         N_PORT identities used in the Port Login (PLOGI) process shall be
         considered authenticated provided the PLOGI request is received
         from the remote gateway over a secure, IPSec-protected connection
     
         There is no requirement that the identities used in authentication
         be kept confidential.
     
     10.2.5  Confidentiality
     
         iFCP traffic may traverse insecure public networks, and therefore
         implementations must have per-packet encryption capabilities to
         provide confidentiality in accordance with the requirements
         specified in section 10.3.1.
     
     10.2.6  Rekeying
     
     
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         Due to the high data transfer rates and the amount of data
         involved, an iFCP implementation must support the capability to
         rekey each phase 2 security association in the time intervals
         dictated by sequence number space exhaustion at a given link rate.
         In the rekeying scenario described in [SECIPS], for example,
         rekeying events happen as often as every 27.5 seconds at 10 Gbps
         rates.
     
         The iFCP gateway must provide the capability for forward secrecy in
         the rekeying process.
     
     10.2.7  Authorization
     
         Basic access control properties stem from the requirement that two
         communicating iFCP gateways be known to one or more iSNS servers
         before they can engage in iFCP exchanges. The optional use of
         discovery domains [ISNS], Identity Payloads (e.g., ID_FQDNs), and
         certificate-based authentication (e.g., with X509v3 certificates)
         enables authorization schemas of increasing complexity. The
         definition of such schemas (e.g., role-based access control) is
         outside of the scope of this specification.
     
     10.2.8   Policy control
     
         This specification allows any and all security mechanisms in an
         iFCP gateway to be administratively disabled.  Security policies
         MUST have at most iFCP Portal resolution. Administrators may gain
         control over security policies through an adequately secured
         interaction with a management interface or with iSNS.
     
     10.2.9  iSNS Role
     
         iSNS [ISNS] is an invariant in all iFCP deployments.  iFCP gateways
         MUST use iSNS for discovery services, and MAY use security policies
         configured in the iSNS database as the basis for algorithm
         negotiation in IKE. The iSNS specification defines mechanisms to
         secure communication between an iFCP gateway and iSNS server(s).
         Additionally, such specification indicates how elements of security
         policy concerning individual iFCP sessions can be retrieved from
         iSNS server(s).
     
     10.3     iFCP Security Design
     
     10.3.1  Enabling Technologies
     
         Applicable technology from IPsec and IKE is defined in the
         following suite of specifications:
     
           [RFC2401] Security Architecture for the Internet Protocol
     
           [RFC2402] IP Authentication Header
     
     
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           [RFC2404] The Use of HMAC-SHA-1-96 Within ESP and AH
     
           [RFC2405] The ESP DES-CBC Cipher Algorithm With Explicit IV
     
           [RFC2406] IP Encapsulating Security Payload
     
           [RFC2407] The Internet IP Security Domain of Interpretation for
                      ISAKMP
     
           [RFC2408] Internet Security Association and Key Management
                      Protocol (ISAKMP)
     
           [RFC2409] The Internet Key Exchange (IKE)
     
           [RFC2410] The NULL Encryption Algorithm and Its use with IPSEC
     
           [RFC2451] The ESP CBC-Mode Cipher Algorithms
     
           [RFC2709] Security Model with Tunnel-mode IPsec for NAT Domains
     
     
     
         The implementation of IPsec and IKE is required according the
         following guidelines.
     
         Support for the IP Encapsulating Security Payload (ESP) [RFC2406]
         is MANDATORY to implement. When ESP is utilized, per-packet data
         origin authentication, integrity and replay protection MUST be
         used.
     
         For data origin authentication and integrity with ESP, HMAC with
         SHA1 [RFC2404] MUST be implemented, and the Advanced Encryption
         Standard [AES] in CBC MAC mode with Extended Cipher Block Chaining
         SHOULD be implemented in accordance with [AESCBC].
     
         For confidentiality with ESP, 3DES in CBC mode [RFC2451] MUST be
         implemented, and AES counter mode encryption [AESCTR] SHOULD be
         implemented. NULL encryption MUST be supported as well, as defined
         in [RFC2410]. DES in CBC mode SHOULD NOT be used due to its
         inherent weakness. Since it is known to be crackable with modest
         computation resources, it is inappropriate for use in any iFCP
         deployment scenario.
     
         A conformant iFCP protocol implementation MUST implement IPsec ESP
         [RFC2406] in tunnel mode [RFC2401] and MAY implement IPsec ESP in
         transport mode.
     
         Regarding key management, iFCP implementations MUST support IKE
         [RFC2409] for bi-directional peer authentication, negotiation of
         security associations, and key management, using the IPsec DOI.
         There is no requirement that the identities used in authentication
         be kept confidential. Manual keying MUST NOT be used since it does
     
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         not provide the necessary keying support. According to [RFC2409],
         pre-shared secret key authentication is MANDATORY to implement,
         whereas certificate-based peer authentication using digital
         signatures MAY be implemented (see section 10.3.3 regarding the use
         of certificates). [RFC2409] defines the following requirement
         levels for IKE Modes:
     
         Phase-1 Main Mode MUST be implemented
     
         Phase-1 Aggressive Mode SHOULD be implemented
     
         Phase-2 Quick Mode MUST be implemented
     
         Phase-2 Quick Mode with key exchange payload MUST be implemented.
     
         With iFCP, Phase-1 Main Mode SHOULD NOT be used in conjunction with
         pre-shared keys, due to Main ModeÆs vulnerability to man-in-the-
         middle-attackers when group pre-shared keys are used. In this
         scenario, Aggressive Mode SHOULD be used instead. Peer
         authentication using the public key encryption methods outlined in
         [RFC2409] SHOULD NOT be used.
     
         The DOI [RFC2407] provides for several types of Identification
         Payloads.
     
         When used for iFCP, IKE Phase 1 exchanges MUST explicitly carry the
         Identification Payload fields (IDii and IDir). Conformant iFCP
         implementations MUST use ID_IPV4_ADDR, ID_IPV6_ADDR (if the
         protocol stack supports IPv6), or ID_FQDN Identification Type
         values.  The ID_USER_FQDN, IP Subnet, IP Address Range,
         ID_DER_ASN1_DN, ID_DER_ASN1_GN Identification Type values SHOULD
         NOT be used. The ID_KEY_ID Identification Type values MUST NOT be
         used. As described in [RFC2407], the port and protocol fields in
         the Identification Payload MUST be set to zero or UDP port 500.
     
         When used for iFCP, IKE Phase 2 exchanges MUST explicitly carry the
         Identification Payload fields (IDci and IDcr). Conformant iFCP
         implementations MUST  use either ID_IPV4_ADDR or ID_IPV6_ADDR
         Identification  Type values (according to the version of IP
         supported). Other Identification Type values MUST NOT be used.  As
         described in section 5.2.2, the gateway creating the iFCP session
         must query the iSNS server to determine the appropriate port on
         which to initiate the associated TCP connection.  Upon a successful
         IKE Phase 2 exchange, the IKE responder enforces the negotiated
         selectors on the IPsec SAs. Any subsequent iFCP session creation
         requires the iFCP peer to query its iSNS server for access control
         (in accordance with the session creation requirements specified in
         section 5.2.2.1).
     
     10.3.2  Use of IKE and IPsec
     
     
     
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         A conformant iFCP Portal is capable of establishing one or more IKE
         Phase-1 Security Associations (SAs) to a peer iFCP Portal. A Phase-
         1 SA may be established when an iFCP Portal is initialized, or may
         be deferred until the first TCP connection with security
         requirements is established.
     
         An IKE Phase-2 SA protects one or more TCP connections within the
         same iFCP Portal. More specifically, the successful establishment
         of an IKE Phase-2 SA results in the creation of two uni-directional
         IPsec SAs fully qualified by the tuple <SPI, destination IP
         address, ESP>.
     
         These SAs protect the setup process of the underlying TCP
         connections and all their subsequent TCP traffic. The number of TCP
         connections in an IPsec SA as well as the number of SAs is
         practically driven by security policy considerations (i.e.,
         security services are defined at the granularity of an IPsec SA
         only), QoS considerations (e.g., multiple QoS classes within the
         same IPsec SA increase odds of packet reordering, possibly falling
         outside the replay window), and failure compartmentalization
         considerations. Each of the TCP connections protected by an IPsec
         SA is either in the unbound state, or is bound to a specific iFCP
         session.
     
         In summary, at any point in time:
     
            -- There exist 0..M IKE Phase-1 SAs between peer iFCP portals
     
            -- Each IKE Phase-1 SA has 0..N IKE Phase-2 SAs
     
            -- Each IKE Phase-2 SA protects 0..Z TCP connections
     
         The creation of an IKE Phase-2 SA may be triggered by a policy rule
         supplied through a management interface or by iFCP Portal
         properties registered with the iSNS server. Similarly, the use of a
         Key Exchange payload in Quick Mode for perfect forward secrecy may
         be dictated through a management interface or by an iFCP Portal
         policy rule registered with the iSNS server.
     
         If an iFCP implementation makes use of unbound TCP connections, and
         such connections belong to an iFCP Portal with security
         requirements, then the unbound connections MUST be protected by an
         SA at all times just like bound connections.
     
         Upon receiving an IKE Phase-2 delete message, there is no
         requirement to terminate the protected TCP connections or delete
         the associated IKE Phase-1 SA. Since an IKE Phase-2 SA may be
         associated with multiple TCP connections, terminating such
         connections might in fact be inappropriate and untimely.
     
         To minimize the number of active Phase-2 SAs, IKE Phase-2 delete
         messages may be sent for Phase-2 SAs whose TCP connections have not
     
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         handled data traffic for a while. To minimize the use of SA
         resources while the associated TCP connections are idle, creation
         of a new SA should be deferred until new data are to be sent over
         the connections.
     
     10.3.3  Signatures and Certificate-based Authentication
     
         Conformant iFCP implementations MAY support peer authentication via
         digital signatures and certificates. When certificate
         authentication is chosen within IKE, each iFCP gateway needs the
         certificate credentials of each peer iFCP gateway in order to
         establish a security association with that peer.
     
         Certificate credentials used by iFCP gateways MUST be those of the
         machine. Certificate credentials MAY be bound to the interface (IP
         Address or FQDN) of the iFCP gateway used for the iFCP session, or
         the fabric WWN of the iFCP gateway itself. Since the value of a
         machine certificate is inversely proportional to the ease with
         which an attacker can obtain one under false pretenses, it is
         advisable that the machine certificate enrollment process be
         strictly controlled. For example, only administrators may have the
         ability to enroll a machine with a machine certificate. User
         certificates SHOULD NOT be used by iFCP gateways for establishment
         of SA's protecting iFCP sessions.
     
         If the gateway does not have the peer iFCP gateway's certificate
         credentials, then it can obtain them by
     
         a) Using the iSNS protocol to query for the peer gateway's
            certificate(s) stored in a trusted iSNS server, or
     
         b) Through use of the ISAKMP Certificate Request Payload (CRP)
            [RFC2408] to request the certificate(s) directly from the peer
            iFCP gateway.
     
         When certificate chains are long enough, then IKE exchanges using
         UDP as the underlying transport may yield IP fragments, which are
         known to work poorly across some intervening routers, firewalls,
         and NA(P)T boxes. As a result, the endpoints may be unable to
         establish an IPsec security association.
     
         Due to these fragmentation shortcomings, IKE is most appropriate
         for intra-domain usage. Known solutions to the fragmentation
         problem are to send the end-entry machine certificate rather than
         the chain, to reduce the size of the certificate chain, to use IKE
         implementations over a reliable transport protocol (e.g., TCP)
         assisted by Path MTU discovery and code against black-holing as in
         [RFC2923], or to install network components that can properly
         handle fragments.
     
     
     
     
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         IKE negotiators SHOULD check the pertinent Certificate Revocation
         List (CRL) [RFC2408] before accepting a certificate for use in
         IKE's authentication procedures.
     
     10.4     iSNS and iFCP Security
     
         iFCP implementations MUST use iSNS for discovery and management
         services. Consequently, the security of the iSNS protocol has an
         impact on the security of iFCP gateways.  For a discussion of
         potential threats to iFCP gateways through use of iSNS, see [ISNS].
     
         To provide security for iFCP gateways using the iSNS protocol for
         discovery and management services, the IPSec ESP protocol in tunnel
         mode MUST be supported for iFCP gateways.  Further discussion of
         iSNS security implementation requirements is found in [ISNS].  Note
         that iSNS security requirements match those for iFCP described in
         section 10.3.
     
     10.5     Use of iSNS to Distribute Security Policy
     
         Once communication between iFCP gateways and the iSNS server have
         been secured through use of IPSec, the iFCP gateways have the
         capability to discover the security settings that they need to use
         (or not use) to protect iFCP traffic.  This provides a potential
         scaling advantage over device-by-device configuration of individual
         security policies for each iFCP gateway.  It also provides an
         efficient means for each iFCP gateway of discovering the use or
         non-use of specific security capabilities by peer gateways.
     
         Further discussion on use of iSNS to distribute security policies
         is found in [ISNS].
     
     10.6     Minimal Security Policy for an iFCP gateway
     
         An iFCP implementation may be able to administratively disable
         security mechanisms for an iFCP Portal through a management
         interface or through security policy elements set in the iSNS
         server. As a consequence, IKE or IPsec security associations will
         not be established for any iFCP sessions that traverse the portal.
     
         For most IP networks, it is inappropriate to assume physical
         security, administrative security, and correct configuration of the
         network and all attached nodes (a physically isolated network in a
         test lab may be an exception).  Therefore, authentication SHOULD be
         used in order to provide a minimal assurance that connections have
         initially been opened with the intended counterpart. The minimal
         iFCP security policy thus only states that an iFCP gateway SHOULD
         authenticate its iSNS server(s) as described in [ISNS].
     
     11.      Quality of Service Considerations
     
     11.1     Minimal requirements
     
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         Conforming iFCP protocol implementations SHALL correctly
         communicate gateway-to-gateway even across one or more intervening
         best-effort IP regions. The timings with which such gateway-to
         gateway communication is performed, however, will greatly depend
         upon BER, packet losses, latency, and jitter experienced throughout
         the best-effort IP regions. The higher these parameters, the higher
         will be the gap measured between iFCP observed behaviors and
         baseline iFCP behaviors (i.e., as produced by two iFCP gateways
         directly connected to one another).
     
     11.2     High-assurance
     
         It is expected that many iFCP deployments will benefit from a high
         degree of assurance regarding the behavior of intervening IP
         regions, with resulting high-assurance on the overall end-to-end
         path, as directly experienced by fibre channel applications. Such
         assurance on the IP behaviors stems from the intervening IP regions
         supporting standard Quality-of-Service (QoS) techniques, fully
         complementary to iFCP, such as:
     
         a) Congestion avoidance by over-provisioning of the network,
     
         b) Integrated Services [RFC1633] QoS,
     
         c) Differentiated Services [RFC2475] QoS
     
         d) Multi-Protocol Label Switching [RFC3031].
     
            One may load an MPLS forwarding equivalence class (FEC) with QoS
            class significance, in addition to other considerations such as
            protection and diversity for the given path. The complementarity
            and compatibility of MPLS with Differentiated Services is
            explored in [MPSLDS], wherein the PHB bits are copied to the EXP
            bits of the MPLS shim header.
     
         In the most general definition, two iFCP gateways are separated by
         one or more independently managed IP regions, some of which
         implement some of the QoS solutions mentioned above. A QoS-capable
         IP region supports the negotiation and establishment of a service
         contract specifying the forwarding service through the region. Such
         contract and its negotiation rules are outside the scope of this
         document. In the case of IP regions with DiffServ QoS, the reader
         should refer to Service Level Specifications (SLS) and Traffic
         Conditioning Specifications (TCS) (as defined in [DIFTERM]). Other
         aspects of a service contract are expected to be non-technical and
         thus outside of the IETF scope.
     
         Due to the fact that fibre channel Class 2 and Class 3 do not
         currently support fractional bandwidth guarantees, and that iFCP is
         committed to supporting fibre channel semantics, it is impossible
         for an iFCP gateway to autonomously infer bandwidth requirements
         from streaming fibre channel traffic. Rather, the requirements on
     
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         bandwidth or other network parameters need to be administratively
         set into an iFCP gateway, or into the entity that will actually
         negotiate the forwarding service on the gateway's behalf. Depending
         on the QoS techniques available, the stipulation of a forwarding
         service may require interaction with network ancillary functions
         such admission control and bandwidth brokers (via RSVP or other
         signaling protocols that an IP region may accept).
     
         The administrator of a iFCP gateway may negotiate a forwarding
         service with IP region(s) for one, several, or all of an iFCP
         gateway's TCP sessions used by an iFCP gateway. Alternately, this
         responsibility may be delegated to a node downstream. Since one TCP
         connection is dedicated to each iFCP session, the traffic in an
         individual N_PORT to N_PORT session can be singled out by iFCP-
         unaware network equipment as well.
     
         To render the best emulation of fibre channel possible over IP, it
         is anticipated that typical forwarding services will specify a
         fixed amount of bandwidth, null losses, and, to a lesser degree of
         relevance, low latency, and low jitter. For example, an IP region
         using DiffServ QoS may support SLSs of this nature by applying EF
         DSCPs to the iFCP traffic.
     
     12.      IANA Considerations
     
         The IANA-assigned port for iFCP traffic is port number 3420.
     
         An iFCP Portal may initiate a connection using any TCP port number
         consistent with its implementation of the TCP/IP stack, provided
         each port number is unique.  To prevent the receipt of stale data
         associated with a previous connection using a given port number,
         the provisions of [RFC1323], Appendix B SHOULD be observed.
     
     13.      Author's Addresses
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         Charles Monia                    Franco Travostino
         Rod Mullendore                    Director, Content
                                           Internetworking Lab,
         Nishan Systems                   Nortel Networks
         3850 North First Street          3 Federal Street
         San Jose, CA  95134              Billerica, MA  01821
         Phone: 408-519-3986              Phone:  978-288-7708
         Email:                               Email:
         cmonia@nishansystems.com
                                          travos@nortelnetworks.com
     
     
         Wayland Jeong                    Mark Edwards
         Troika Networks                  Senior Systems Architect
         Vice President, Hardware         Eurologic Development, Ltd.
         Engineering                      4th Floor, Howard House
         2829 Townsgate Road Suite        Queens Ave, UK.  BS8 1SD
         200                              Phone: +44 (0)117 930 9600
         Westlake Village, CA  91361      Email:
         Phone: 805-370-2614              medwards@eurologic.com
         Email:
         wayland@troikanetworks.com
     
     
     
     14.      Normative References
     
         [AESCBC] Frankel, S., Hebert, H., "The AES Cipher Algorithm and Its
                 Use with IPsec", Internet draft (work in progress), draft-
                 ietf-ipsec-ciph-aes-xcbc-mac-02.txt, June 2002.
     
         [AESCTR] Housley, R., "Using AES Counter Mode With IPsec ESP",
                 Internet draft (work in progress), draft-ietf-ipsec-ciph-
                 aes-ctr-00.txt, July 2002
     
         [FC-GS3] dpANS X3.XXX-200X, "Fibre Channel Generic Services -3 (FC-
                 GS3)", revision 7.01, NCITS Project 1356-D, November 2000
     
         [FC-SW2] dpANS X3.XXX-2000X, "Fibre Channel Switch Fabric -2 (FC-
                 SW2)", revision 5.2, NCITS Project 1305-D, May 2001
     
         [ISNS] Tseng, J., et-al., "iSNS Internet Storage Name Service",
                 draft-ietf-ips-08.txt, February 2002
     
         [RFC1119] Mills, D., "Network Time Protocol (Version 3)
                 Specification, Implementation and Analyses", RFC 1305,
                 March 1992
     
         [RFC2026] Bradner, S., "The Internet Standards Process -- Revision
                 3", BCP 9, RFC 2026, October 1996.
     
         [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
     
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                 Requirement Levels", BCP 14, RFC 2119, March 1997
     
         [RFC2401] Kent, S., Atkinson, R., RFC 2401, "Security Architecture
                 for the Internet Protocol", November 1998
     
         [RFC2402] Kent, S., Atkinson, R., RFC 2402, "IP Authentication
                 Header", November 1998
     
         [RFC2404] Glenn, R., Madson, C., "The Use of HMAC-SHA-1-96 Within
                 ESP and AH", RFC 2404, November 1998
     
         [RFC2404] Glenn, R., Madson, C., "The Use of HMAC-SHA-1-96 Within
                 ESP and AH", RFC 2404, November 1998
     
         [RFC2406] Kent, S., Atkinson, R., RFC 2406, "Encapsulating Security
                 Protocol", November 1998
     
         [RFC2407] Piper, D., RFC 2407, " The Internet IP Security Domain of
                 Interpretation for ISAKMP", November 1998
     
         [RFC2408] Maughan, D., Schertler, M., Schneider, M., Turner, J.,
                 RFC 2408, "Internet Security Association and Key Management
                 Protocol (ISAKMP)" November 1998
     
         [RFC2409] D. Harkins, D. Carrel, RFC 2409, "The Internet Key
                 Exchange (IKE)",  November 1998
     
         [RFC2410] Glenn, R., Kent, S., "The NULL Encryption Algorithm and
                 Its use with IPSEC", RFC 2410, November 1998
     
         [RFC2451] Adams, R., Pereira, R., "The ESP CBC-Mode Cipher
                 Algorithms", RFC 2451, November 1998
     
         [RFC791] Postel, J., RFC 791, "The Internet Protocol", September
                 1981
     
         [RFC793] Postel, J., "Transmission Control Protocol", RFC 793,
                 September, 1981
     
         [SECIPS] Aboba, B., et-al., "Securing Block Storage Protocols Over
                 IP", Internet draft (work in progress), draft-ietf-ips-
                 security-12.txt, May 2002
     
     
     
     15.      Non-Normative References
     
         [AES] FIPS Publication XXX, "Advanced Encryption Standard (AES)",
                 Draft, 2001, Available from
                 http://csrc.nist.gov/publications/drafts/dfips-AES.pdf
     
         [DIFTERM] Grossman, D., "New Terminology and Clarifications for
     
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                 Diffserv", draft-ietf-diffserv-new-terms-07.txt, December
                 2001
     
         [FC-AL2] dpANS X3.XXX-199X, "Fibre Channel Arbitrated Loop (FC-AL-
                 2)", revision 7.0, NCITS Project 1133D, April 1999
     
         [FC-FLA] TR-20-199X, "Fibre Channel Fabric Loop Attachment (FC-
                 FLA)", revision 2.7, NCITS Project 1235-D, August 1997
     
         [KEMALP] Kembel, R., "The Fibre Channel Consultant, Arbitrated
                 Loop", Robert W. Kembel, Northwest Learning Associates,
                 2000, ISBN 0-931836-84-0
     
         [KEMCMP] Kembel, R., "Fibre Channel, A Comprehensive Introduction",
                 Northwest Learning Associates Inc., 2000, ISBN 0-931836-84-
                 0
     
         [MPSLDS] F. Faucheur, L. Wu, B. Davie, S. Davari, P. Vaananen, R.
                 Krishnan, P. Cheval, J. Heinanen, "MPLS Support of
                 Differentiated Services", draft-ietf-mpls-diff-ext-09.txt,
                 April 2001.
     
         [RFC1122] Braden, S., "Requirements for Internet Hosts --
                 Communication Layers", RFC 1122, October 1989
     
         [RFC1323] Jacobsen, V., et-al., "TCP Extensions for High
                 Performance", RFC 1323, May, 1992
     
         [RFC1633] Braden, R., Clark, D. and S. Shenker, "Integrated
                 Services in the Internet Architecture: an Overview", RFC
                 1633, June 1994
     
         [RFC2030] Mills, D., RFC 2030, "Simple Network Time Protocol
                 (SNTP)" Version 4, October 1996
     
         [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
                 2131, March 1997
     
         [RFC2405] Doraswamy, N., Madson, C., "The ESP DES-CBC Cipher
                 Algorithm With Explicit IV" RFC 2405, November 1998
     
         [RFC2405] Doraswamy, N., Madson, C., "The ESP DES-CBC Cipher
                 Algorithm With Explicit IV" RFC 2405, November 1998
     
         [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.
                 and W. Weiss, "An Architecture for Differentiated
                 Services", RFC 2475, December 1998
     
         [RFC2625] Rajagopal, M., et-al., RFC 2625, "IP and ARP over Fibre
                 Channel", June 1999
     
         [RFC2709] Srisuresh, P., "Security Model with Tunnel-mode IPsec for
     
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                 NAT Domains", RFC 2709, October 1999
     
         [RFC2923] Lahey, K., "TCP Problems with Path MTU Discovery", RFC
                 2923, September 2000
     
         [RFC3031] Rosen, E., Viswanathan, A. and Callon, R., "Multi-
                 Protocol Label Switching Architecture", RFC 3031, January
                 2001
     
         [RFC896] Nagle, J., "Congestion Control in IP/TCP Networks", RFC
                 896, January 1984
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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                                    Appendix A
     
     A.       iFCP Support for Fibre Channel Link Services
     
         For reference purposes, this appendix enumerates all the fibre
         channel link services and the manner in which each shall be
         processed by an iFCP implementation. The iFCP processing policies
         are defined in section 7.
     
         In the following sections, the name of a link service specific to a
         particular FC-4 protocol is prefaced by a mnemonic identifying the
         protocol.
     
     A.1      Basic Link Services
     
         The basic link services are shown in the following table.
     
                                   Basic Link Services
     
               Name              Description               iFCP Policy
               ----              -----------               ----------
     
           ABTS            Abort Sequence                Transparent
           BA_ACC          Basic Accept                  Transparent
           BA_RJT          Basic Reject                  Transparent
           NOP             No Operation                  Transparent
           PRMT            Preempted                     Rejected
                                                           (Applies to
                                                           Class 1 only)
           RMC             Remove Connection             Rejected
                                                           (Applies to
                                                           Class 1 only)
     
     
     A.2      Pass-Through Link Services
     
         As specified in section 7, the link service requests of Table 10
         and the associated ACC response frames MUST be passed through to
         the receiving N_PORT without altering the payload.
     
               Name                Description
               ----                -----------
     
               ADVC         Advise Credit
               CSR          Clock Synchronization Request
               CSU          Clock Synchronization Update
               ECHO         Echo
               ESTC         Estimate Credit
               ESTS         Establish Streaming
               FACT         Fabric Activate Alias_ID
               FAN          Fabric Address Notification
               FCP_RJT      FCP FC-4 Link Service Reject
     
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               FCP SRR      FCP Sequence Retransmission
                             Request
               FDACT        Fabric Deactivate Alias_ID
               FDISC        Discover F_Port Service
                             Parameters
               FLOGI        F_Port Login
               GAID         Get Alias_ID
               LCLM         Login Control List Management
               LINIT        Loop Initialize
               LIRR         Link Incident Record
                             Registration
               LPC          Loop Port Control
               LS_RJT       Link Service Reject
               LSTS         Loop Status
               NACT         N_Port Activate Alias_ID
               NDACT        N_Port Deactivate Alias_ID
               PDISC        Discover N_Port Service
                             Parameters
               PRLI         Process Login
               PRLO         Process Logout
               QoSR         Quality of Service Request
               RCS          Read Connection Status
               RLIR         Registered Link Incident
                             Report
               RNC          Report Node Capability
               RNFT         Report Node FC-4 Types
               RNID         Request Node Identification
                             Data
               RPL          Read Port List
               RPS          Read Port Status Block
               RPSC         Report Port Speed
                             Capabilities
               RSCN         Registered State Change
                             Notification
               RTV          Read Timeout Value
               RVCS         Read Virtual Circuit Status
               SBRP         Set Bit-error Reporting
                             Parameters
               SCN          State Change Notification
               SCR          State Change Registration
               TEST         Test
               TPLS         Test Process Login State
         Table 10 -- Pass-Through link Services
     
     A.3      Special Link Services
     
         The extended and FC-4 link services of Table 11 are processed by an
         iFCP implementation as described in the sections referenced in the
         table.
     
     
     
     
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               Name              Description             Section
               ----              -----------             -------
     
               ABTX         Abort Exchange                 7.3.1.1
               ADISC        Discover Address               7.3.1.2
               ADISC        Discover Address Accept        7.3.1.3
               ACC
               FARP-        Fibre Channel Address          7.3.1.4
               REPLY        Resolution Protocol
                             Reply
               FARP-        Fibre Channel Address          7.3.1.5
               REQ          Resolution Protocol
                             Request
               LOGO         N_PORT Logout                  7.3.1.6
               PLOGI        Port Login                     7.3.1.7
               FCP REC      FCP Read Exchange             7.3.2.1.1
                             Concise
               FCP REC      FCP Read Exchange             7.3.2.1.2
               ACC          Concise Accept
               RES          Read Exchange Status           7.3.1.8
                             Block
               RES ACC      Read Exchange Status           7.3.1.9
                             Block Accept
               RLS          Read Link Error Status         7.3.1.10
                             Block
               RRQ          Reinstate Recovery             7.3.1.12
                             Qualifier
               RSI          Request Sequence               7.3.1.13
                             Initiative
               RSS          Read Sequence Status           7.3.1.11
                             Block
               SRL          Scan Remote Loop               7.3.1.14
               TPRLO        Third Party Process            7.3.1.15
                             Logout
               TPRLO        Third Party Process            7.3.1.16
               ACC          Logout Accept
                        Table 11 -- Special Link Services
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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                                    Appendix B
     
     B.       Supporting the Fibre Channel Loop Topology
     
         A loop topology may be optionally supported by a gateway
         implementation in one of the following ways:
     
         a)  By implementing the FL_PORT public loop interface specified in
             [FC-FLA],
     
         b)  By emulating the private loop environment specified in [FC-
             AL2].
     
         Private loop emulation allows the attachment of fibre channel
         devices that do not support fabrics or public loops. The gateway
         presents such devices to the fabric as though they were fabric-
         attached.  Conversely, the gateway presents devices on the fabric,
         whether locally or remotely attached, as though they were connected
         to the private loop.
     
         Private loop support requires gateway emulation of the loop
         primitives and control frames specified in [FC-AL2].  These frames
         and primitives MUST be locally emulated by the gateway. Loop
         control frames MUST NOT be sent over an iFCP session.
     
     B.1      Remote Control of a Public Loop
     
         A gateway MAY disclose that a remotely-attached device is connected
         to a public loop. If so, it MUST also provide aliases representing
         the corresponding Loop Fabric Address (LFA), DOMAIN_ID and FL_PORT
         Address Identifier through which the public loop may be remotely
         controlled.
     
         The LFA and FL_PORT address identifier both represent an N_PORT
         that services remote loop management requests contained in the
         LINIT and SRL extended link service messages.  To support these
         messages, the gateway MUST allocate an NL_PORT alias such that the
         corresponding alias for the LFA or FL_PORT address identifier can
         be derived by setting the Port ID component of the NL_PORT alias to
         zero.
     
     
     
     
     
     
     
     
     
     
     
     
     
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     Full Copyright Statement
     
     
         "Copyright (C) The Internet Society, August 2002. All Rights
         Reserved. This document and translations of it may be copied and
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         prepared, copied, published and distributed, in whole or in part,
         without restriction of any kind, provided that the above copyright
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         derivative works. However, this document itself may not be modified
         in any way, such as by removing the copyright notice or references
         to the Internet Society or other Internet organizations, except as
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         Standards process must be followed, or as required to translate it
         into languages other than English.
     
         The limited permissions granted above are perpetual and will not be
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         This document and the information contained herein is provided on
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         ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
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     Notice of Intellectual Property Rights
     
         The IETF has been notified of intellectual property rights claimed
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