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Versions: (draft-monia-ips-ifcp) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 RFC 4172

     IP Storage Working Group                                  Charles Monia
     INTERNET DRAFT                                           Rod Mullendore
     Expires January 2002                                         Josh Tseng
     <draft-ietf-ips-ifcp-03.txt>                             Nishan Systems
     
                                                           Franco Travostino
                                                               Victor Firoiu
                                                             Nortel Networks
     
                                                              David Robinson
                                                            Sun Microsystems
     
                                                               Wayland Jeong
                                                             Troika Networks
     
                                                                   Rory Bolt
                                                                 Quantum/ATL
     
                                                             Paul Rutherford
                                                                        ADIC
     
                                                                Mark Edwards
                                                                   Eurologic
     
                                                                   July 2001
     
     
        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 RFC2026 [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 obsoleted 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).
     
     Monia, et al.              Standards Track                   [Page 1]


     iFCP Revision 3                                         July 2001
     
     
     
     Status of this Memo...................................................1
     Comments..............................................................1
     1.      Abstract.....................................................4
     2.      About This Document..........................................4
     2.1     Conventions used in this document............................4
     2.2     Purpose of this document.....................................4
     3.      iFCP Introduction............................................4
     3.1     Definitions..................................................5
     4.      Fibre Channel Communication Concepts.........................6
     4.1     The Fibre Channel Network....................................7
     4.2     Fabric Topologies............................................8
     4.2.1    Switched Fibre Channel Fabrics..............................9
     4.2.2    Mixed Fibre Channel Fabric..................................9
     4.3     Fibre Channel Layers and Link Services......................10
     4.3.1    Fabric-Supplied Link Services..............................11
     4.4     Fibre Channel Devices.......................................11
     4.5     Fibre Channel Information Elements..........................12
     4.6     Fibre Channel Frame Format..................................12
     4.7     Fibre Channel Transport Services............................13
     4.8     Login Processes.............................................14
     5.      The iFCP Network Model......................................14
     5.1     Fabric Topologies Supported by the iFCP Network Architecture 15
     5.2     iFCP Transport Services.....................................16
     5.2.1    Fibre Channel Transport Services Supported by iFCP.........16
     5.3     The N_PORT Addressing Model.................................16
     5.3.1    Operation in Address Transparent Mode......................19
     5.3.2    Operation in Address Translation Mode......................20
     6.      iFCP Protocol...............................................23
     6.1     Overview....................................................23
     6.1.1    iFCP Transport Services....................................23
     6.1.2    iFCP Support for  Link Services............................24
     6.2     TCP Stream Transport of iFCP Frames.........................24
     6.2.1    iFCP Session Model.........................................25
     6.2.2    iFCP Session Management....................................25
     6.2.3    Terminating an N_PORT Login Session........................27
     6.3     TCP Port Numbers............................................28
     6.4     Encapsulation of Fibre Channel Frames.......................28
     6.4.1    Encapsulation Header Format................................29
     6.4.2    SOF and EOF Delimiter Fields...............................32
     6.4.3    Frame Encapsulation........................................33
     6.4.4    Frame De-encapsulation.....................................33
     7.      Fibre Channel Link Services.................................34
     7.1     Augmented Link Service Messages.............................35
     7.2     Augmented Link Services Requiring Payload Address Translation35
     7.3     Augmented Link Services.....................................37
     7.3.1    Abort Exchange (ABTX)......................................38
     7.3.2    Discover Address (ADISC)...................................39
     7.3.3    Discover Address Accept (ADISC ACC)........................40
     7.3.4    FC Address Resolution Protocol Reply (FARP-REPLY)..........40
     7.3.5    FC Address Resolution Protocol Request (FARP-REQ)..........41
     7.3.6    Logout (LOGO)..............................................42
     
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     iFCP Revision 3                                         July 2001
     
     
     7.3.7    Port Login (PLOGI).........................................43
     7.3.8    Read Exchange Concise......................................44
     7.3.9    Read Exchange Concise Accept...............................45
     7.3.10     Read Exchange Status Block (RES).........................46
     7.3.11     Read Exchange Status Block Accept........................46
     7.3.12     Read Link Error Status (RLS).............................47
     7.3.13     Read Sequence Status Block (RSS).........................48
     7.3.14     Reinstate Recovery Qualifier (RRQ).......................49
     7.3.15     Request Sequence Initiative (RSI)........................49
     7.3.16     Third Party Process Logout (TPRLO).......................50
     7.4     FLOGI Service Parameters Supported by an iFCP Gateway.......51
     8.      TCP Session Control Messages................................54
     8.1     Connection Bind (CBIND).....................................55
     8.2     Unbind Connection (UNBIND)..................................58
     9.      iFCP Error Detection........................................59
     9.1     Overview....................................................59
     9.2     Stale Frame Prevention......................................59
     9.2.1    Enforcing R_A_TOV Limits...................................59
     10.     Fabric Services Supported by an iFCP implementation.........61
     10.1    iFCP Support for the FC Broadcast Service...................61
     11.     Security....................................................62
     11.1    Overview....................................................62
     11.2    Physical Security...........................................62
     11.3    Controlling Access..........................................62
     11.4    Authentication and Encryption...............................63
     11.5    Storage Firewalls...........................................63
     12.     Quality of Service Considerations...........................64
     12.1    Minimal requirements........................................64
     12.2    High-assurance..............................................64
     13.     References..................................................65
     13.1    Relevant SCSI (T10) Specifications..........................65
     13.2    Relevant Fibre Channel (T11) Specifications.................66
     13.3    Relevant RFC Documents......................................66
     13.4    Other Reference Documents...................................67
     14.     Author's Addresses..........................................67
     A.      iFCP Support for Fibre Channel Link Services................69
     A.1     Basic Link Services.........................................69
     A.2     Link Services Processed Transparently.......................69
     A.3     Augmented Link Services.....................................70
     B.      Implementing an IP to FC Router with an iFCP Fabric.........72
     C.      Performance of The Multi-Connection iFCP Session Model......73
     C.1     Relationship of Throughput to Packet Losses.................73
     C.2     Background..................................................75
     Full Copyright Statement.............................................76
     
     
     
     
     
     
     
     
     
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     iFCP Revision 3                                         July 2001
     
     
     
     
     1.       Abstract
     
         This document specifies an architecture and gateway-to-gateway
         protocol for the implementation of Fibre Channel fabric
         functionality on a network in which TCP/IP switching and routing
         elements replace Fibre Channel components. The protocol enables the
         attachment of existing Fibre Channel storage products to an IP
         network by supporting the fabric services required by such devices.
     
     2.       About This Document
     
     2.1      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].
     
         All frame formats are in big endian network byte order.
     
     2.2      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 NCITS 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 protocol
         for mapping standards-compliant fibre Channel storage and adapter
         implementations to TCP/IP.  This mapping includes sections of this
         document which describe the "iFCP Protocol" (see section 6).
     
     3.       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.
     
         The protocol and method of frame 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 through a process that
         allows normal Fibre Channel frame traffic to pass through the
         gateway directly, with provisions, where necessary, for
     
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     iFCP Revision 3                                         July 2001
     
     
         intercepting and emulating the fabric services required by an FCP
         device.
     
     3.1      Definitions
     
         Terms needed to clarify 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.
     
         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 logical fabric to which the
                 gateway belongs.
     
         Gateway Region - The portion of the iFCP storage network accessed
                 through an iFCP gateway. Devices in the region consist of
                 all Fibre Channel devices locally attached to the gateway.
     
         Logical Fabric - The union of two or more  gateway regions
                 configured to interoperate together in address-transparent
                 mode.
     
         Fibre Channel Device - A device attached to a Fibre Channel fabric
                 by means of the N_PORT interface described in [FC-FS].
     
         Fibre Channel Network - A native Fibre Channel fabric and all
                 attached Fibre Channel devices.
     
         Fabric - The components of a Fibre Channel network that provides
                 the transport services defined in [FC-FS]. A fabric may be
                 implemented in the IP framework by means of the
                 architecture and protocols discussed in this document.
     
         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 functionally equivalent.
     
         FC-2 - The Fibre Channel transport services layer described in [FC-
                 FS].
     
         FCP Portal - An IP-addressable entity representing the point at
                 which a logical or physical iFCP device is attached to the
                 IP 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
     
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     iFCP Revision 3                                         July 2001
     
     
                 interface that are dependant on the Fibre Channel fabric
                 topology.  As used in this document, the term applies
                 equally to all variants.
     
         N_PORT fabric address - The address of an N_PORT within the Fibre
                 Channel fabric.
     
         N_PORT Alias --  The N_PORT address assigned by a gateway to
                 represent a remote N_PORT accessed via the iFCP network.
                 When routing frame traffic in address translation mode, the
                 gateway automatically converts N_PORT aliases to N_PORT
                 network addresses and vice versa.
     
         N_PORT Network Address - The address of an N_PORT in the IP fabric.
                 This address consists of the IP address of the FCP Portal
                 and the N_PORT ID of the locally-attached Fibre Channel
                 device.
     
         F_PORT - The interface used by an N_PORT to access Fibre Channel
                 switched fabric functionality.
     
         iFCP - The protocol discussed in this document.
     
         Logical FCP Device - The abstraction representing a single Fibre
                 Channel device as it appears on an iFCP network.
     
         iSNS - The protocol by which storage name services are implemented.
                 Resolution of Fibre Channel network object names is
                 provided by an iSNS name server.
     
         N_PORT Session - An association created when two N_PORTS have
                 executed a PLOGI operation.  It is comprised of the N_PORTs
                 and TCP connection that carries traffic between them.
     
         iFCP Frame - The frame inserted into the TCP stream which contains
                 the Fibre Channel frame and iFCP header.
     
         Port Login (PLOGI) - The Fibre Channel Extended Link Service (ELS)
                 that establishes an N_PORT login session through the
                 exchange of identification and operation parameters between
                 an originating N_PORT and a responding N_PORT.
     
         DOMAIN_ID - The value contained in the high-order byte of a 24-bit
                 N_PORT Fibre Channel address.
     
     4.       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.
     
     
     
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     iFCP Revision 3                                         July 2001
     
     
         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 5.
     
         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]
     
         -- Fibre Channel Fabric Loop Attachment, [FC-FLA]
     
         The reader will find an in-depth treatment of the technology in
         [Kembel].
     
     4.1      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 interface within a fabric that provides Fibre
           Channel attachment for an N_PORT.  The types of fabric port
           depend on the fabric topology and are discussed in section 4.2.
     
        d) The fabric infrastructure for carrying frame traffic between
           N_PORTs.
     
        e) Within a switched or mixed fabric (see section 4.2), 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.
     
     
     
     
     
     
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     iFCP Revision 3                                         July 2001
     
     
       +--------+   +--------+          +--------+  +--------+
       |  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
     
         The following sections describe Fibre Channel fabric topologies and
         give an overview of the Fibre Channel communications model.
     
     4.2      Fabric Topologies
     
         The principal Fibre Channel fabric topologies consist of the
         following:
     
         a)  Arbitrated Loop -- A series of N_PORTs connected together in
             daisy-chain fashion.  Data transmission between N_PORTs
             requires arbitration for control of the loop in a manner
             similar to a token ring network.
     
         b)  Switched Fabric --  A fabric consisting of switching elements,
             as described in section 4.2.1.
     
         c)  Mixed Fabric -- A fabric consisting of switches and "fabric-
             attached" loops.  A description can be found in [FC-FLA].
     
         Depending on the topology, the N_PORT and fabric port variants
         through which a Fibre Channel device is attached to the network may
         be one of the following:
     
              Fabric Topology  Fabric Port Type    N_PORT Variant
              ---------------  ----------------    --------------
     
              Loop             L_PORT              NL_PORT
     
              Switched         F_PORT              N_PORT
     
              Mixed            FL_PORT             NL_PORT
     
                               F_PORT              N_PORT
     
     
     
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     iFCP Revision 3                                         July 2001
     
     
         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.
     
     4.2.1   Switched Fibre Channel Fabrics
     
         The internals of a multi-switch Fibre Channel fabric are shown
         below.
     
                 +----------+          +----------+
                 |    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].
     
     4.2.2   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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     iFCP Revision 3                                         July 2001
     
     
                 +----------+          +----------+   +---------+
                 |    FC    |          |  FC      |   |  FC     |
                 |   Device |          | Device   |   | Device  |
                 |..........|          |..........|   |.........|
                 |   N_PORT |<........>| NL_PORT  +---+ NL_PORT |
                 +----+-----+          +-----+----+   +----+----+
                      |                      |   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.
     
     4.3      Fibre Channel Layers and Link Services
     
         Fibre channel consists of the following layers:
     
         FC0 -- The interface to the physical media,
     
         FC1 -- The encoding and decoding of data and out-of-band physical
         link control information for transmission over the physical media,
     
         FC2 -- The transfer of frames, sequences and exchanges comprising
         protocol information units.
     
         FC3 -- Common Services,
     
         FC4 -- Application protocols, such as FCP, the Fibre Channel SCSI
         protocol.
     
     
     
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     iFCP Revision 3                                         July 2001
     
     
         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.
     
     4.3.1   Fabric-Supplied Link Services
     
         Servers internal to a switched fabric handle certain classes of
         Link Service requests.  The servers appear as N_PORTS located at
         well-known N_PORT fabric addresses. 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 an N_PORT request to access the
            fabric for communications.
     
            Fabric Controller -- Provides state change information to other
            N_PORTS. Used to inform other FC devices when an N_PORT exits or
            enters the fabric.
     
            Directory/Name Server - Allows N_PORTs to register information
            in a database or retrieve information about other N_PORTs.
     
         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 is 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.
     
     4.4      Fibre Channel Devices
     
         A Fibre Channel device has one or more fabric-attached N_PORTs. The
         device and its N_PORTs have the following associated identifiers:
     
     
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        a) A world-wide unique identifier for the device,
     
        b) A world-wide unique identifier for each N_PORT attached to the
           device,
     
        c) For each N_PORT, a fabric-assigned N_PORT fabric address provided
           when the device is granted fabric access.  This address is unique
           within the scope of the fabric.
     
         Each identifier is a 64-bit binary quantity having the format
         defined in [FC-FS].
     
         Information about a Fibre Channel device, such as the Fibre Channel
         addresses and world wide names of its N_PORTs, can be discovered
         through the appropriate Fibre Channel name service queries.
     
     4.5      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 4.6. 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 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.
     
     4.6      Fibre Channel Frame Format
     
         A Fibre Channel frame consists of the payload and a header
         containing the control information necessary to route frames
         between N_PORTs and manage exchanges and sequences. The following
         diagram gives a highly simplified view of the frame.
     
     
     
     
     
     
     
     
     
     
     
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                     +-----------------------------+
                     |   Start-of-frame Delimiter  |
                     +-----+-----------------------+<----+
                     |     | Destination N_PORT    |     |
                     |     | Fabric Address (D_ID) |     |
                     |     |  (24-bits)            |     |
                     +-----+-----------------------+   24-byte
                     |     | Source N_PORT         |   Frame
                     |     | Fabric Address (S_ID) |   Header
                     |     | (24 bits)             |     |
                     +-----+-----------------------+     |
                     |    Control information for  |     |
                     |    frame type, exchange     |     |
                     |    management, IU           |     |
                     |    segmentation and         |     |
                     |    re-assembly              |     |
                     +-----------------------------+<----+
                     |                             |
                     |        Frame payload        |
                     |       (0 - 2112 bytes)      |
                     |                             |
                     |                             |
                     |                             |
                     +-----------------------------+
                     |    End-of-Frame Delimiter   |
                     +-----------------------------+
                        Figure 4 -- Fibre Channel Frame Format
     
     
         The source and destination N_PORT fabric addresses are embedded in
         the S_ID and D_ID fields respectively.
     
     4.7      Fibre Channel Transport Services
     
         The Fibre Channel standard ([FC-FS])  defines the following classes
         of service provided by a fabric implementation:
     
         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 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.
     
         In addition to the above services, fabrics may implement additional
         quality of service policies.
     
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         For service classes other than class 1, the Fibre Channel fabric is
         not required to provide in-order delivery of frames. Within an
         exchange, it is the responsibility of the frame recipient to
         reconstruct the order in which frames were sent based on sequence
         information in the frame header.
     
     4.8      Login Processes
     
         The Login processes are the means whereby an N_PORT establishes the
         operating environment necessary to communicate with the fabric and
         other N_PORTs.  Fabric login and destination N_PORT login are
         established through procedures by which an N_PORT exchanges
         operating parameters with the fabric or another N_PORT.
     
     5.       The iFCP Network Model
     
         The purpose of the iFCP protocol is to enable the implementation of
         Fibre Channel mixed or switched fabric functionality on an IP
         network in which IP components and technology replace the Fibre
         Channel switching and routing infrastructure described in section
         4.2.
     
         The following diagram shows a Fibre Channel fabric with attached
         devices. These are connected to the fabric through an N_PORT
         interface attached to a Fabric Port whose behavior is specified in
         [FC-FS]. In this case, the N_PORT and Fabric Port represent any of
         the variants described in section 4.2.
     
         Within the Fibre Channel device domain, fabric-addressable entities
         consist of other N_PORTs and devices internal to the fabric that
         perform the fabric services defined in [FC-GS3].
     
                     Fibre Channel Network
                 +--------+        +--------+
                 |  FC    |        |  FC    |
                 | Device |        | Device |
                 |........|        |........| Fibre Channel
                 | N_PORT |<......>| N_PORT | Device Domain
                 +---+----+        +----+---+       ^
                     |                  |           |
                 +---+----+        +----+---+       |
                 | Fabric |        | Fabric |       |
                 | Port   |        | Port   |       |
       ==========+========+========+========+==============
                 |         Fabric &         |       |
                 |     Fabric Services      |       v
                 |                          | Fibre Channel
                 +--------------------------+ Fabric Domain
                          Figure 5 -- A Fibre Channel Fabric
     
     
     
     
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           Gateway Region                   Gateway Region
      +--------+  +--------+           +--------+  +--------+
      |   FC   |  |  FC    |           |   FC   |  |   FC   |
      | Device |  | Device | Fibre     | Device |  | Device |  Fibre
      |........|  |........| Channel   |........|  |........|  Channel
      | N_PORT |  | N_PORT |<.........>| N_PORT |  | N_PORT |  Device
      +---+----+  +---+----+ Traffic   +----+---+  +----+---+  Domain
          |           |                     |           |         ^
      +---+----+  +---+----+           +----+---+  +----+---+     |
      | Fabric |  | Fabric |           | Fabric |  | Fabric |     |
      | Port   |  | Port   |           | Port   |  | Port   |     |
     =+========+==+========+===========+========+==+========+==========
      |    iFCP Layer      |<--------->|     iFCP Layer     |     |
      |....................|     ^     |....................|     |
      |     FCP Portal     |     |     |      FCP Portal    |     v
      +--------+-----------+     |     +----------+---------+    IP
           iFCP|Gateway      Control          iFCP|Gateway      Fabric
               |              Data                |
               |                                  |
               |                                  |
               |<------Encapsulated Frames------->|
               |      +------------------+        |
               |      |                  |        |
               +------+    IP Network    +--------+
                      |                  |
                      +------------------+
                    Figure 6 -- An iFCP Network with iFCP Gateways
     
     
         The above diagram shows one implementation of an equivalent iFCP
         fabric.  Two gateway regions are shown. Each consists of Fibre
         Channel devices directly connected to the iFCP fabric through
         fabric ports implemented as part of the edge switch or gateway.
     
         Looking into the fabric port on the Fibre Channel side of the
         gateway, the network appears as a Fibre Channel fabric. Here, the
         gateway presents remote N_PORTs as directly attached devices.
         Conversely, on the IP network side, the gateway presents each
         locally connected N_PORT as a logical Fibre Channel device.
     
     5.1      Fabric Topologies Supported by the iFCP Network Architecture
     
         An important property of this gateway architecture is that the
         fabric configuration and topology within the gateway region are
         opaque to the IP network and other gateway regions.  That is, the
         topology in the gateway region, whether it is loop- or switch-
         based, is hidden from the IP network and from other gateway
         regions. As a result, support for specific FC fabric topologies
         becomes a gateway implementation issue.  In such cases, the gateway
     
     
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         incorporates whatever functionality is required to distill and
         present locally attached N_PORTs as logical iFCP devices.
     
         Regarding fabric topologies, the examples in this specification
         show an N_PORT directly attached to a gateway fabric port,  this is
         done to keep the illustrations simple and does not reflect any
         fundamental limitation in the fabric configuration that an
         implementation can support.
     
     5.2      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 5.3.
     
         b) Execution of fabric-supplied link services addressed to one of
            the well-known Fibre Channel N_PORT addresses.
     
         c) 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.
     
         d) Establishment of an N_PORT login session in response to a PLOGI
            directed to a remote device.
     
         The following sections discuss the frame addressing mechanism and
         the way in which it is used to achieve communications transparency
         between N_PORTs.
     
     5.2.1   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 1 (dedicated connection).
     
     5.3      The N_PORT Addressing Model
     
         This section discusses the role of the N_PORT addressing model in
         the routing of frames between locally and remotely attached
         N_PORTs.
     
         In the case of a remote N_PORT, where the frame traffic must
         traverse the IP network, the gateway must perform this routing
         transparently with respect to the locally attached N_PORT.
     
         To provide such transparency, the gateway maintains an association
         between the Fibre Channel address of a remote N_PORT, as seen by a
         locally attached device, and the corresponding address of the
         remote device on the IP network. To establish this association the
     
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         iFCP gateway assigns and manages Fibre Channel N_PORT fabric
         addresses as described in the following sections.
     
         The fabric address of an N_PORT device is a 24-bit value having the
         following format defined by the Fibre Channel specification [FC-
         FS]:
     
               Bit   23       16 15         8 7        0
                    +-----------+------------+----------+
                    | Domain ID | Area ID    |  Port ID |
                    +-----------+------------+----------+
                     Figure 7 -- Fibre Channel Address Format
     
         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 Domain I/D
         assigned by the principal switch. The value of the Domain I/D
         ranges from 1 to 239 (0xEF). Each switch element in turn
         administers a block of addresses divided into area and port IDs.
         N_PORTs logging into the fabric receive a unique fabric address
         consisting of the switch's Domain I/D concatenated with switch-
         assigned area and port I/Ds.
     
         These N_PORT addresses are carried in the Fibre Channel frame as
         shown in the following diagram.
     
               Bit  31    24 23                                0
                   +--------+-----------------------------------+
         Word 0    |        | Destination N_PORT Address (D_ID) |
                   +--------+-----------------------------------+
         Word 1    |        | Source N_PORT Address (S_ID)      |
                   +--------+-----------------------------------+
            .      |                                            |
            .      |              Control information           |
            .      |              and Payload                   |
         Word 534  +--------------------------------------------+
         (Max)
     
               Figure 8 --  Fibre Channel Address Fields within a Frame
     
         The D_ID and S_ID fields represent the fabric addresses of the
         source and destination N_PORTs respectively.
     
         In an iFCP storage 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 route
         frames to external devices attached to remote gateways on the IP
         network.
     
         In order to be transparent to FC devices, the gateway must route
         such frames using only the embedded 24-bit address. By exploiting
     
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         its control of address allocation and access to frame traffic
         entering or leaving the gateway region, it is able to achieve the
         necessary transparency.
     
         The gateway may allocate device addresses in one of two ways:
     
         a) Address Translation Mode - A mode of address assignment in which
            the gateway allocates an N_PORT device address that is unique to
            the gateway region. The address of a remote device is
            represented in that gateway region by a gateway assigned N_PORT
            alias.
     
         b) Address Transparent Mode - A mode of address assignment in which
            the gateway allocates an N_PORT address that is unique across
            the set of gateway regions comprising a logical fabric.
     
         Gateways within a logical 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
         I/Ds from the address assignment authority as described in section
         5.3.1.1. Consequently, within the scope of the logical 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. Support for address transparent mode is optional.
     
         The choice of addressing mode involves the tradeoffs between
         scalability and transparency discussed below.
     
         The scalability constraints are a consequence of the Fibre Channel
         address allocation policy described above. As noted, an IP fabric
         using this address allocation scheme is limited to a combined total
         of 239 gateways and Fibre Channel switch elements. As the system
         expands, an IP fabric may consist of many switch elements
         distributed throughout the enterprise, each of which controls a
         small number of devices.  In this case, the limitation in switch
         count may become a barrier to extending and fully integrating the
         storage network.
     
         Address Translation mode avoids this limitation by decoupling
         N_PORT fabric addresses from the constraints of fabric-wide address
         space management. Consequently, a virtually unlimited number of
         iFCP gateways, Fibre Channel devices and switch elements may be
         internetworked.  This mode of address allocation also simplifies
         management of the IP storage fabric configuration by eliminating
         the need for a centralized address-assignment authority.
     
         A consequence of address translation mode is that the 24-bit N_PORT
         address is no longer unique across the storage network. As a
         result, when processing frame traffic to or from remote N_PORTs,
         the gateway must intervene to translate the 24-bit N_PORT addresses
     
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         between the sending and receiving gateway regions.  These address
         operations involve:
     
         a)  Translating the N_PORT I/Ds in the frame header and
     
         b)  Translating N_PORT I/Ds carried in the payload of certain
             extended link service messages.
     
         The process of N_PORT I/D translation for the frame header is
         described in section 5.3.2.  The processing for link services with
         frame addresses in the payload is described in section 7.1.
     
         The details of the address transparent and address translation
         operational modes are discussed in the following sections.
     
     5.3.1   Operation in Address Transparent Mode
     
         In addition to the scalability limits discussed above, the
         following considerations and requirements apply to this mode of
         operation:
     
         a) There is increased dependency on the services of a central
            address assignment authority, such as iSNS. If connectivity with
            the server is lost, new DOMAIN_ID values cannot be automatically
            allocated as gateways and Fibre Channel switch elements are
            added to the logical fabric.  As a result, new gateways and
            switch elements cannot be automatically added to the ip fabric.
            Of course, it is always possible to add and manage such
            additional components manually.
     
         b) Coordination of iSNS servers is required. Multiple iFCP gateways
            set up with independently-administered address servers must be
            completely torn down and slaved under a single iSNS name server
            before they can be configured into the same logical fabric.  In
            contrast, operation in address translation mode requires only
            that the independent iSNS servers import client attributes from
            other iSNS servers, before clients under different iSNS
            authorities can be made to interoperate.
     
         c) iFCP gateways in transparent mode will not interoperate with
            iFCP gateways that are not in transparent mode.
     
         d) When interoperating with locally attached Fibre Channel fabrics,
            the iFCP gateway MUST assume control of DOMAIN_ID assignments in
            accordance with the appropriate Fibre Channel standard or
            specification.  As described in section 5.3.1.1, DOMAIN_ID
            values assigned to FC switches in attached fabrics must be
            issued by the iSNS server or manually assigned.
     
         e) When operating in address transparent Mode, no Fibre Channel
            address translation SHALL take place, and no link service
     
     
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            Messages shall be augmented with additional information by the
            iFCP layer.
     
         The process for establishing the TCP/IP context associated with an
         N_PORT login session in this mode is similar to that specified for
         address translation mode (section 5.3.2).
     
     5.3.1.1  Transparent Mode Domain I/D Management
     
         As described above, each gateway and Fibre Channel switch in a
         logical fabric must have a unique domain I/D.  In a gateway region
         containing Fibre Channel switch elements, each element obtains a
         domain I/D by querying  the principal switch as described in [FC-
         SW2] -- in this case the iFCP gateway itself.  The gateway in turn
         may obtain domain I/Ds on demand from a central address allocation
         authority, such as an iSNS name server or manually from a pre-
         assigned block of IDs.  In that sense, the address authority (e.g.,
         iSNS) assumes the role of master switch for the logical fabric.
     
     5.3.1.2  Incompatibility with Address Translation Mode
     
         iFCP gateways in address transparent mode shall not originate or
         accept frames that do not have the TRN bit  set to one in the  iFCP
         flags field of the encapsulation header (see section 6.4.1).  The
         iFCP gateway shall immediately terminate any N_PORT sessions with
         the iFCP gateway from which it receives such frames.
     
     5.3.2   Operation in Address Translation Mode
     
         This section summarizes the process for managing the assignment of
         addresses within a gateway region, including the modification of FC
         frame addresses embedded in the frame header for frames sent and
         received from remotely attached N_PORTs.
     
         As described above, 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-
         SW2] 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.
     
         When a remotely attached N_PORT is accessed, the gateway assigns a
         locally significant N_PORT alias.  This alias is used in place of
         the N_PORT I/D assigned by the remote gateway.  To perform address
         conversion and enable the appropriate routing, the gateway
         maintains a table mapping N_PORT aliases to the appropriate TCP/IP
         connection context and N_PORT ID of all remotely accessed  N_PORTs.
     
     
     
     
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         The gateway opportunistically builds the table of N_PORT addresses
         and TCP/IP connections for remotely attached devices in the IP
         fabric by:
     
         a) Intercepting name service requests issued by locally-attached
            N_PORTs as described below or,
     
         b) Intercepting incoming N_PORT login requests from external Fibre
            Channel devices and outgoing N_PORT login requests directed to
            remote N_PORTs.  Such requests are used to establish the N_PORT
            login session as described in section 6.2.1.
     
         In response to name server requests, the iSNS server returns the IP
         address and N_PORT ID pair of the remote device. The IP address is
         mapped to the connection context. After saving the context and
         N_PORT ID, the iFCP layer creates the 24-bit N_PORT alias that is
         returned to the local N_PORT as the Fibre Channel address of the
         remotely attached device.
     
     5.3.2.1  Translation Table Maintenance
     
         The contents of the gateway's address translation tables are
         updated opportunistically, in response to the name service queries
         and PLOGI requests described previously. There is no need to
         invalidate entries in response to changes in the fabric
         configuration, since any potentially stale entries caused by such
         events are self-correcting as described below.
     
         Once a fabric has achieved steady-state operation, any event that
         causes a change in the Fibre Channel address of a device also
         causes the device to terminate all N_PORT sessions. In the process
         of resuming operation, the status of the device, including its new
         address, is reflected in the name server's database. The new state
         of the device is advertised using the appropriate state change
         notifications. These, in turn, trigger the series of port login
         operations described below.
     
         For inbound PLOGI requests, the iFCP gateway simply updates the
         translation table, generates the N_PORT alias and forwards the
         request to the local N_PORT for processing as described above.
     
         For outbound requests, a fabric-attached Fibre Channel device
         usually precedes the PLOGI with a name server query to obtain the
         device's new N_PORT address. At this point, the iFCP gateway
         intercepts such a request, performs the necessary iSNS query,
         creates the translation table entry and returns the assigned N_PORT
         alias to the requester.
     
         After issuing the PLOGI, the N_PORT verifies that it has logged in
         with the expected device by checking the device name returned in
         the PLOGI response.
     
     
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         An N_PORT that attempts to execute a PLOGI without first querying
         the name server is still required to confirm the device name as
         described above.
     
     5.3.2.2  Frame Address Translation
     
         For outbound frames, the table of external N_PORT network addresses
         are referenced to map the Destination N_PORT alias and Source
         N_PORT ID to the TCP connection context and the N_PORT ID assigned
         by the remote gateway. The translation process for outbound frames
         is shown below.
     
              Raw Fibre Channel Frame
     +--------+-----------------------------------+    +--------------+
     |        |  Destination N_PORT Alias         |--->| Lookup TCP   |
     +--------+-----------------------------------+    | connection   |
     |        |  Source N_PORT ID                 |    | context      |
     +--------------------------------------------+    | and N_PORT ID|
     |                                            |    +------+-------+
     |        Control information,                |           | TCP
     |        Payload and FC CRC                  |           | conn
     |                                            |           | context
     +--------------------------------------------+           | &
                                                              | N_PORT
                                                              | ID
                                                              |
     After Address Translation and Encapsulation              |
     +--------------------------------------------+           |
     |          FC Encapsulation Header           |           |
     +--------------------------------------------+           |
     |            SOF Delimiter Word              |           |
     +============================================+           |
     |        |  Destination N_PORT ID            |<----------+
     +--------+-----------------------------------+
     |        |  Source N_PORT ID                 |
     +--------+-----------------------------------+
     |                                            |
     |        Control information, Payload        |
     |        and FC CRC                          |
     +============================================+
     |         EOF Delimiter Word                 |
     +--------------------------------------------+
         Figure 9 -- Outbound Frame Address Translation
     
         For inbound frames, a translation table lookup is performed to
         regenerate the N_PORT alias from the TCP connection context and
         N_PORT ID contained in the encapsulated FC frame. The translation
         process for inbound frames is shown below.
     
     
     
     
     
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          Network Format of Inbound Frame
     +--------------------------------------------+     TCP
     |          FC Encapsulation Header           |     Connection
     +--------------------------------------------+     Context
     |            SOF Delimiter Word              |         |
     +============================================+         V
     |        |  Destination N_PORT ID            |     +---+----+
     +--------+-----------------------------------+     | Lookup |
     |        |  Source N_PORT ID                 |---->| Source |
     +--------+-----------------------------------+     | N_PORT |
     |                                            |     | Alias  |
     |        Control information, Payload        |     +----+---+
     |        and FC CRC                          |          | Source
     +============================================+          | N_PORT
     |         EOF Delimiter Word                 |          | Alias
     +--------------------------------------------+          |
                                                             |
                                                             |
     Frame after Address Translation and De-encapsulation    |
     +--------+-----------------------------------+          |
     |        |  Destination N_PORT ID            |          |
     +--------+-----------------------------------+          |
     |        |  Source N_PORT Alias              |<---------+
     +--------+-----------------------------------+
     |                                            |
     |        Control information, Payload,       |
     |        and FC CRC                          |
     +--------------------------------------------+
         Figure 10 -- Inbound Frame Address Translation
     
     
     5.3.2.3  Incompatibility with Address Transparent Mode
     
         iFCP gateways in address translation mode shall not originate or
         accept frames that have the TRN bit set to one in the iFCP flags
         field of the encapsulation header.  The iFCP gateway shall
         immediately abort any N_PORT login sessions with the iFCP gateway
         from which it receives such frames as described in section 6.2.3.2.
     
     6.       iFCP Protocol
     
     6.1      Overview
     
     6.1.1   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.
     
         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.
     
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         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)  FC4 frame images associated with a Fibre Channel application
             protocol.
     
         b)  FC2 frames comprising Fibre Channel link service requests and
             responses
     
         c)  Fibre Channel broadcast frames
     
         d)  iFCP control messages required to setup or terminate an iFCP
             session.
     
         For FC4 N_PORT traffic and most FC2 messages the iFCP layer never
         interprets the contents of the frame payload.
     
         iFCP does interpret and process iFCP control messages and certain
         FC2 extended link service messages as described in section 6.1.2
     
     6.1.2   iFCP Support for  Link Services
     
         iFCP must intervene in the processing of those Fibre Channel
         Extended Link Service (ELS) messages which 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 an ELS, 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
         ELSs, iFCP interprets the frame, including any supplemental
         information, modifies the frame content, and forwards the resulting
         frame to the destination N_PORT for further processing.
     
         Section 7.1 describes the processing of these Extended Link Service
         messages in detail.
     
     
     
     6.2      TCP Stream Transport of iFCP Frames
     
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     6.2.1   iFCP Session Model
     
         An iFCP session consists of the pair of N_PORTs comprising the
         session endpoints joined by a single TCP/IP connection.
     
         An N_PORT is identified by its network address consisting of:
     
         a) The N_PORT I/D assigned by the gateway to which the N_PORT is
            locally attached and
     
         b) The IP address of the gateway's iFCP Portal.
     
         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 pool of unbound connections may be established to
         reduce the session setup time.  Pre-existing TCP connections
         between FCP Portals remain unbound and uncommitted until allocated
         to an iFCP session through a CBIND message (see section 8.1).
     
         When the iFCP layer detects a Port Login (PLOGI) message creating
         an iFCP session between a pair of N_PORTs, 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 PLOGI login session.
     
     6.2.2   iFCP Session Management
     
         This section describes the protocols for establishing and
         terminating an N_PORT login session.
     
     6.2.2.1  Creating an iFCP Session
     
         An iFCP session may be in one of the following states:
     
         a) OPEN  --  The session state in which Fibre Channel frame images
            may be sent and received.
     
         b) 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 gateway SHALL initiate the creation of an iFCP session in
         response to a PLOGI ELS directed to a remote N_PORT from a locally
         attached N_PORT as described in the following steps.
     
         a) If no iFCP session exists, allocate a TCP connection to the
            remote gateway.  An existing connection in the Unbound state may
     
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            be used or a new connection may be created and placed in the
            Unbound state.
     
         b) If a connection cannot be allocated or created, the gateway
            SHALL terminate the PLOGI with an LS_RJT response. The Reason
            Code field in the LS_RJT message shall be set to 0x09 (Unable to
            Perform Command Request) and the Reason Explanation SHALL be set
            to 0x29 (Insufficient Resources to Support Login).
     
         c) If an iFCP session in the OPEN state already exists to the
            remote N_PORT, the gateway SHALL forward the PLOGI ELS using the
            existing session.
     
         d) If the iFCP session does not exist, the gateway SHALL issue a
            CBIND session control message (see section 8.1) and place the
            session in the OPEN PENDING state.
     
         e) In the event that a CBIND response is returned with one of the
            following statuses, the PLOGI shall be terminated with an LS_RJT
            message.  Depending on the CBIND failure status, the Reason Code
            and Reason Explanation SHALL be set to the following values
            specified in [FC-FS].
     
             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 Device    Unable to Perform Invalid N_PORT Name
             (17)              Command Request   (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 mode  (0x09)
             (20)
     
             Incorrect         Unable to Perform No additional
             protocol version  Command Request   explanation (0x00)
             number (21)       (0x09)
     
         f) A CBIND response with a CBIND STATUS of "N_PORT 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. The receiving gateway SHALL terminate this
     
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            attempt and prepare to respond to an incoming CBIND request as
            described below.
     
         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 IP address
            of the sender with the receiver's IP address.
     
         b) If the sender's IP address is greater, the receiver shall issue
            a CBIND response of "Success" and SHALL place the session in the
            OPEN state.
     
         c) If the sender's IP address 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, 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.
     
     6.2.3   Terminating an N_PORT Login Session
     
         An N_PORT login session SHALL be terminated or aborted in response
         to one of the following events:
     
         a)  An LS_RJT response is returned to the gateway that issued the
             PLOGI ELS.  The gateway SHALL forward the LS_RJT to the local
             N_PORT and complete the session as described in section
             6.2.3.1.
     
         b)  An ACC received from a remote device in response to a LOGO. The
             gateway SHALL forward the ACC to the local N_PORT and complete
             the session as described in section 6.2.3.1.
     
         c)  For an FC frame received from the IP network, a gateway detects
             a CRC error in the encapsulation header. The gateway shall
             abort the session as described in section 6.2.3.2.
     
         d)  The TCP connection associated with the login session fails for
             any reason.  The gateway detecting the failed connection shall
             abort the session as described in section 6.2.3.2.
     
     6.2.3.1  N_PORT Login Session Completion
     
         An N_PORT login session is completed in response to a rejected
         PLOGI request or a successful LOGO ELS.
     
         The gateway receiving one of the above responses shall issue an
         Unbind session control ELS as described in section 8.2.  An Unbind
         error shall be considered a fatal gateway error.
     
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         In response to the Unbind message, either gateway may choose to
         close the connection or return it to the pool of unbound
         connections.
     
     6.2.3.2  Aborting an N_PORT Login Session
     
         An N_PORT login session SHALL be aborted if the TCP connection is
         spontaneously terminated or whenever one of the following occurs:
     
         a) An encapsulation error is detected as described in section
            6.4.3.
     
         b) The gateway receives an encapsulated frame from a gateway
            operating in an incompatible address translation mode as
            specified in section 5.3.2.3 or 5.3.1.2.
     
         In any event, the TCP connection shall be closed.  If the local
         N_PORT has logged in to the remote N_PORT, the gateway SHALL send a
         LOGO to the local N_PORT.
     
     6.3      TCP Port Numbers
     
         An FCP Portal uses a single port number to receive TCP connection
         requests for iFCP over TCP.  All TCP connections established
         between FCP Portals must be directed to the registered well known
         port number assigned by the IANA.
     
         An FCP Portal may use any TCP port number consistent with its
         implementation of the TCP/IP stack to initiate a TCP connection,
         but each port number must be unique.
     
     6.4      Encapsulation of Fibre Channel Frames
     
         This section describes the iFCP encapsulation of Fibre Channel
         frames.  The encapsulation is based on the common encapsulation
         format defined in [ENCAP].
     
         The format of an encapsulated frame is shown below:
     
                       +--------------------+
                       |       Header       |
                       +--------------------+-----+
                       |        SOF         |   f |
                       +--------------------+ F r |
                       |  FC frame content  | C a |
                       +--------------------+   m |
                       |        EOF         |   e |
                       +--------------------+-----+
                        Figure 11 -- 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
     
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         delimiter word.  The header and delimiter formats are described in
         the following sections.
     
     6.4.1   Encapsulation Header Format
     
     W|------------------------------Bit------------------------------|
     o|                                                               |
     r|3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1                    |
     d|1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0|
      +---------------+---------------+---------------+---------------+
     0|   Protocol#   |    Version    |  -Protocol#   |   -Version    |
      +---------------+---------------+---------------+---------------+
     1|                  Reserved (must be zero)                      |
      +---------------+---------------+---------------+---------------+
     2| LS_COMMAND    |  iFCP Flags   |     SOF       |      EOF      |
      +-----------+---+---------------+-----------+---+---------------+
     3|   Flags   |   Frame Length    |   -Flags  |   -Frame Length   |
      +-----------+-------------------+-----------+-------------------+
     4|                      Time Stamp [integer]                     |
      +---------------------------------------------------------------+
     5|                      Time Stamp [fraction]                    |
      +---------------------------------------------------------------+
     6|                              CRC                              |
      +---------------------------------------------------------------+
     
     
         Common Encapsulation Fields:
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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          Protocol#            IANA-assigned protocol number
                                identifying the protocol using the
                                encapsulation.  For iFCP the value is
                                (/TBD/).
     
          Version              Encapsulation version
     
          -Protocol#           Ones complement of the protocol#
     
          -Version             Ones complement of the version
     
          Flags                Encapsulation flags (see 6.4.1.1)
     
          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 in SNTP format [RFC2030].
     
          Time Stamp           Fractional component of the time stamp
          [fraction]           in SNTP format [RFC2030].
     
          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
             9.2.1.
     
          iFCP-specific fields:
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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          LS_COMMAND           For an augmented ELS ACC response, the
                                LS_COMMAND field SHALL contain bits 31
                                through 24 of the LS_COMMAND to which
                                the ACC applies. Otherwise the
                                LS_COMMAND field shall be set to zero.
     
          iFCP Flags           iFCP-specific flags (see below)
     
          SOF                  Copy of the SOF delimiter encoding
                                (see section 6.4.2)
     
          EOF                  Copy of the EOF delimiter encoding
                                (see section 6.4.2)
     
     
     
         The iFCP flags word has the following format:
     
            |------------------------Bit----------------------------|
            |                                                       |
            |  23     22     21     20     19     18     17    16   |
            +------+------+------+------+------+------+------+------+
            |             Reserved             | SES  | TRN  |  AUG |
            +------+------+------+------+------+------+------+------+
                             Figure 12 -- iFCP Flags Word
     
         iFCP Flags:
     
         SES         1 = Session control frame (TRN and AUG MUST be
                          0)
     
         TRN         1 = Address transparent mode enabled
     
                      0 = Address translation mode enabled
     
         AUG         1 = Augmented frame.
     
     
     
     6.4.1.1  Common Encapsulation Flags
     
         The iFCP usage of the common encapsulation flags is shown below:
     
           |------------------------Bit--------------------------|
           |                                                     |
           |   31       30       29       28       27       26   |
           +--------------------------------------------+--------+
           |                  Reserved                  |  CRCV  |
           +--------------------------------------------+--------+
     
     
         For iFCP, the CRC field MUST be valid and CRCV MUST be set to one.
     
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     6.4.2   SOF and EOF Delimiter Fields
     
         The format of the delimiter fields is shown below.
     
     W|------------------------------Bit------------------------------|
     o|                                                               |
     r|3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1                    |
     d|1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0|
      +---------------+---------------+-------------------------------+
     0|      SOF      |      SOF      |     -SOF      |     -SOF      |
      +---------------+---------------+-------------------------------+
     1|                                                               |
      +-----                   FC frame content                  -----+
      |                                                               |
      +---------------+---------------+-------------------------------+
     n|      EOF      |      EOF      |     -EOF      |     -EOF      |
      +---------------+---------------+-------------------------------+
     Figure 13 -- FC Frame Encapsulation Format
     
          SOF (bits 31-24 and bits 23-16 in word 0):  iFCP uses the
          following subset of the SOF fields described in [ENCAP].
     
                               +-------+----------+
                               |  FC   |          |
                               |  SOF  | SOF Code |
                               +-------+----------+
                               | SOFi2 |   0x2D   |
                               | SOFn2 |   0x35   |
                               | SOFi3 |   0x2E   |
                               | SOFn3 |   0x36   |
                               +-------+----------+
             Table 1-- Translation of FC SOF Values to SOF Field Contents
     
         -SOF (bits 15-8 and 7-0 in word 0): The -SOF fields contain the
         ones complement of the value in the SOF fields.
     
         EOF (bits 31-24 and 23-16 in word n):  iFCP uses the following
         subset of EOF fields specified in [ENCAP].
     
                               +-------+----------+
                               |  FC   |          |
                               |  EOF  | EOF Code |
                               +-------+----------+
                               | EOFn  |   0x41   |
                               | EOFt  |   0x42   |
                               +-------+----------+
            Table 2 -- Translation of FC EOF Values to EOF Field Contents
     
         -EOF (bits 15-8 and 7-0 in word n): The -EOF fields contain the
         one's complement of the value in the EOF fields.
     
     
     
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         iFCP implementations SHALL place a copy of the SOF and EOF
         delimiter codes in the appropriate header fields.
     
     6.4.3   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.
     
         Frames types submitted for encapsulation and forwarding on the IP
         network SHALL have one of the SOF delimiters in Table 1 and an EOF
         delimiter from Table 2.  Other valid frame types MUST be processed
         internally by the gateway as specified in the appropriate Fibre
         Channel Specification.
     
         Prior to submitting a frame for encapsulation, a gateway in address
         translation mode SHALL replace the D_ID address, and, if processing
         an augmented ELS, SHALL format the frame payload and add the
         supplemental information as specified in section 7.1.  The gateway
         SHALL then calculate a new FC CRC on the reformatted frame.
     
         A gateway in address transparent mode 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 above.
     
     6.4.4   Frame De-encapsulation
     
         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 invalid, the gateway SHALL
         terminate the N_PORT login session as described in section 6.2.3.2.
     
         After validating the header CRC, the receiving gateway MAY verify
         the frame propagation delay as described in section 9.2.1. 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 1 or an EOF code that is not in Table 2.
     
         The gateway shall then de-encapsulate the frame.  If operating in
         address translation mode, the gateway shall:
     
         a) Check the FC CRC  and discard the frame if the CRC is invalid.
     
         b) Replace the S_ID with the N_PORT alias of the frame originator
     
     
     
     
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         c) If processing an augmented ELS, replace the ELS frame with a
            copy whose payload has been modified as specified in section
            7.1.
     
         The resulting frame SHALL then be delivered 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.
     
     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.
     
         Each Link Service message (request and reply) is carried by a Fibre
         Channel sequence, and can be segmented into multiple frames.
     
         The iFCP Layer is responsible for transporting link service
         messages across the IP fabric.  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 augmented data by the iFCP
         layer.
     
         Each link service or extended link service is processed according
         to one of the following rules:
     
         a) Transparent - The link service message and reply MUST be
            transported to the receiving N_PORT by the iFCP gateway without
            altering the message payload. The link service message and reply
            are not processed by the iFCP implementation.
     
         b) Augmented -  Applies to an extended link service reply or
            request containing Fibre Channel addresses in the payload or
            requiring other special processing by the iFCP implementation.
            The processing for augmented link services is described in this
            section.
     
         c) Rejected - When issued by a locally attached N_PORT, the
            specified link service request MUST be rejected by the iFCP
            implementation.   The gateway SHALL respond to a rejected link
            service message by returning 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 augmented link services,
         including the manner in which augmentation data is transmitted over
         the IP network.
     
         Appendix A enumerates all link services and the iFCP processing
         policy that applies to each.
     
     
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     7.1      Augmented Link Service Messages
     
         Augmentation applies to extended link service requests that require
         the intervention of the iFCP layer.  Such intervention is required
         in order to:
     
         a) Service any ELS that requires special handling, such as a PLOGI.
     
         b) In address translation mode only, service any ELS which has an
            N_PORT address in the payload.
     
         Such ELS messages are transmitted in a Fibre Channel frame having
         the following format:
     
         Word
           31      24 23                                             0
          +----------+------------------------------------------------+
         0| R_CTL    |                     D_ID                       |
          | [22]     | [Destination of extended link Service request] |
          +----------+------------------------------------------------+
         1| CS_CTL   |                     S_ID                       |
          |          | [Source of extended link service request]      |
          +----------+------------------------------------------------+
         2| TYPE     |                     F_CTL                      |
          +----------+------------------+-----------------------------+
         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 14 -- Format of Extended Link Service Frame
     
     
     
     7.2      Augmented Link Services Requiring Payload Address Translation
     
         This section describes the handling for ELS frames containing
         N_PORT addresses in the ELS 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 ELS messages SHALL not be sent as
         augmented frames unless other special processing is required.
     
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         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 gateway's address space. The following
         rules define the manner in which such supplemental data is 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:
     
             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
             I/D 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 augmentation data to set the field
             contents. The augmentation 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 ELS, this
             information MUST be appended as described below. This
             translation type SHALL NOT be used when 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 I/D of 0, the above codes will never
         correspond to valid N_PORT fabric IDs.
     
         For translation type 3, the receiving gateway SHALL obtain the
         information needed to fill in the ELS field by converting the
         specified N_PORT world-wide identifier to a gateway IP address and
         N_PORT ID.  This information MUST be obtained through a name server
         query. If the N_PORT is locally attached, the gateway MUST fill in
         the field with the N_PORT ID.  If the N_PORT is remotely attached,
         the gateway MUST assign and fill in the field with an N_PORT alias.
         If an N_PORT alias has already been assigned, it MUST be reused.
     
         In the event that the sending gateway cannot obtain the world wide
         identifier of an N_PORT, or a receiving gateway cannot obtain the
         IP address and N_PORT ID, the gateway detecting the error SHALL
         terminate the request with an LS_RJT message as described in [FCS].
         The Reason Code SHALL be set to 0x07 (protocol error) and the
     
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         Reason Explanation SHALL be set to 0x1F (Invalid N_PORT
         identifier).
     
         [Editor's note: Such errors, when detected by the receiving
         gateway, may be indicative of a serious problem requiring a more
         drastic response. Therefore, this section should be regarded as
         tentative.]
     
         Supplemental data is sent with the ELS request or ACC frames in one
         of the following ways:
     
         a) By appending the necessary data to the end of the ELS frame.
     
         b) By extending the sequence with the addition of additional
            frames.
     
         In the first case, a new frame SHALL be created whose length
         includes the supplemental data. The procedure for extending the ELS
         sequence with additional frames is /TBS/.
     
         After applying the supplemental data, the receiving gateway SHALL
         forward the resulting ELS to the destination N_PORT with the
         supplemental information removed.
     
         When the ACC response must be augmented, the receiving gateway MUST
         act as a proxy for the originator, retaining the state needed to
         process the response from the N_PORT to which the request was
         directed.
     
     7.3      Augmented Link Services
     
         The following Link Service Messages must receive special processing
         or be supplemented with additional control data.
     
         An encapsulated Fibre Channel frame that is part of an augmented
         ELS MUST have the AUG bit set to one in the iFCP FLAGS field of the
         encapsulation header as specified in section 6.4.1. The
         supplemental data (if any) MUST be appended as described in the
         following section.  An ELS ACC frame that is augmented must be
         similarly formatted.
     
     
     
     
     
     
     
     
     
     
     
     
     
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         Link Service Message               LS_COMMAND      Mnemonic
         --------------------               ----------      --------
         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 Protocol    0x55 00 00 00    FARP-REPLY
         Reply
         FC Address Resolution Protocol    0x54 00 00 00     FARP-REQ
         Request
         Logout                            0x05 00 00 00       LOGO
         Port Login                        0x30 00 00 00      PLOGI
         Read Exchange Concise             0x13 00 00 00       REC
         Read Exchange Concise Accept      0x02 00 00 00     REC ACC
         Read Exchange Status Block        0x08 00 00 00       RES
         Read Exchange Status Block        0x02 00 00 00     RES ACC
         Accept
         Read Link Error Status Block      0x0F 00 00 00       RLS
         Read Sequence Status Block        0x09 00 00 00       RSS
         Reinstate Recovery Qualifier      0x12 00 00 00       RRQ
         Request Sequence Initiative       0x0A 00 00 00       RSI
         Third Party Process Logout        0x24 00 00 00      TPRLO
     
         The formats of each augmented ELS, including supplemental data
         where applicable, are shown in the following sections.  Each ELS
         diagram shows the basic format, as specified in the applicable FC
         standard, followed by supplemental data as shown below.
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 0    |                  LS_COMMAND                    |
         +------+------------+------------+-----------+----------+
         | 1    |                                                |
         | .    |                                                |
         | .    |                ELS Payload                     |
         |      |                                                |
         | n    |                                                |
         +======+============+============+===========+==========+
         | n+1  |                                                |
         |  .   |            Supplemental Data                   |
         |  .   |               (if any)                         |
         | n+k  |                                                |
         +======+================================================+
                      ELS Diagram (single FC Frame Format)
     
     7.3.1   Abort Exchange (ABTX)
     
         ELS Format:
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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:
     
             None
     
     7.3.2   Discover Address (ADISC)
     
         Format of ADISC ELS:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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 I/D of ELS Originator     |
         +======+============+============+===========+==========+
     
     
     
     
     
     
     
     
     
     
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         Fields Requiring       Translation    Supplemental Data
         Address Translation     Type (see       (type 3 only)
         -------------------   section 7.2)      ------------
                                -------------
     
         N_PORT I/D of ELS           1                N/A
         Originator
     
     
     
         Other Special Processing:
     
             The Hard Address of the ELS originator shall be set to 0.
     
     7.3.3   Discover Address Accept (ADISC ACC)
     
         Format of ADISC ACC ELS:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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 I/D of ELS Originator     |
         +======+============+============+===========+==========+
     
     
         Fields Requiring       Translation    Supplemental Data
         Address Translation     Type (see       (type 3 only)
         -------------------   section 7.2)      ------------
                                ------------
     
         N_PORT I/D of ELS           1                N/A
         Originator
     
     
         Other Special Processing:
     
             The Hard Address of the ELS originator SHALL be set to 0.
     
     7.3.4   FC Address Resolution Protocol Reply (FARP-REPLY)
     
         The FARP-REPLY ELS is used in conjunction with the FARP-REQ ELS
         (see section 7.3.5) to perform the address resolution services
         required by the FC-VI protocol [FC-VI].
     
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         Format of FARP-REPLY ELS:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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.
     
     
     7.3.5   FC Address Resolution Protocol Request (FARP-REQ)
     
         The FARP-REQ ELS is used to in conjunction with the FC-VI protocol
         [FC-VI] to perform IP and FC address resolution in an FC fabric.
         The FARP-REQ ELS is usually directed to the fabric broadcast server
     
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         at well-known address 0xFF-FF-FF for retransmission to all attached
         N_PORTs. Section 10.1 describes the iFCP implementation of FC
         broadcast server functionality in an iFCP fabric.
     
         Format of FARP_REQ ELS:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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
     
     
         Other Special Processing:
     
             None.
     
     
     7.3.6   Logout (LOGO)
     
         ELS Format:
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x5  |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     N_PORT I/D being logged out   |
         +------+------------+------------+-----------+----------+
         | 2-3  |  Port name of the LOGO originator (8 bytes)    |
         +======+============+============+===========+==========+
     
     
         This ELS shall always be sent as an augmented 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 I/D Being            1               N/A
         Logged Out
     
     
     
         Other Special Processing:
     
             See section 6.2.3.1.
     
     
     7.3.7   Port Login (PLOGI)
     
         PLOGI provides the mechanism for establishing a login session
         between two N_PORTs. In iFCP, a PLOGI request addressed to a
         remotely attached N_PORT may trigger the creation of an iFCP
         session, if one does not already exist.  Otherwise, the PLOGI and
         ACC payloads MUST be passed transparently to the destination
         N_PORT.
     
         The PLOGI request and ACC response carry information identifying
         the originating N_PORT, including specification of its capabilities
         and limitations.  If the destination N_PORT accepts the login
         request, it sends an accept (an ACC frame with PLOGI payload),
         specifying its capabilities and limitations.  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 request and accept (ACC) response.  A
         port will reject a PLOGI request by transmitting an LS_RJT message,
         which contains no payload.
     
     
     
     
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        Byte
        Offset
               +----------------------------------+
           0   |            LS_COMMAND            |     4 Bytes
               +----------------------------------+
           4   |     COMMON SERVICE PARAMETERS    |    16 Bytes
               +----------------------------------+
          20   |            PORT NAME             |     8 Bytes
               +----------------------------------+
          28   |            NODE NAME             |     8 Bytes
               +----------------------------------+
          36   |     CLASS 1 SERVICE PARAMETERS   |    16 Bytes
               +----------------------------------+
          52   |     CLASS 2 SERVICE PARAMETERS   |    16 Bytes
               +----------------------------------+
          68   |     CLASS 3 SERVICE PARAMETERS   |    16 Bytes
               +----------------------------------+
          86   |     CLASS 4 SERVICE PARAMETERS   |    16 Bytes
               +----------------------------------+
         102   |        VENDOR VERSION LEVEL      |    16 Bytes
               +----------------------------------+
                        Total Length = 116 bytes
                Figure 15 -- Format of PLOGI Request and ACC Payloads
     
     
     
         Details on the above fields, including common and class-based
         service parameters, can be found in [FC-FS].
     
     7.3.8   Read Exchange Concise
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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)        |
         +======+============+============+===========+==========+
     
     
     
     
     
     
     
     
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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.
     
     7.3.9   Read Exchange Concise Accept
     
         Format of ACC Response:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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 I/D                           Exchange Originator
     
         Exchange Responder   1, 2 or 3      Port Name of the
         N_PORT I/D                           Exchange Responder
     
     
     
     
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         When supplemental data is required, the ELS shall always be
         extended by 4 words as shown above.  If the translation type for
         the Exchange Originator N_PORT I/D or the Exchange Responder N_PORT
         I/D is 1 or 2, the corresponding 8-byte port name SHALL be set to
         all zeros.Other Special Processing:
     
             None.
     
     7.3.10  Read Exchange Status Block (RES)
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x13 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     Exchange Originator S_ID      |
         +------+------------+------------+-----------+----------+
         | 2    |          OX_ID          |         RX_ID        |
         +------+------------+------------+-----------+----------+
         | 3-10 |  Association header (may be optionally req'd)  |
         +======+============+============+===========+==========+
         | 11-12| 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.
     
     7.3.11  Read Exchange Status Block Accept
     
         Format of ELS Accept Response:
     
     
     
     
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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  |                                                |
         +======+============+============+===========+==========+
     
         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 I/D                           Exchange Originator
     
         Exchange Responder   1, 2 or 3      Port Name of the
         N_0ORT I/D                           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 I/D or the Exchange Responder N_PORT I/D is 1 or
         2, the corresponding 8-byte port name SHALL be set to all zeros.
     
         Other Special Processing:
     
             None.
     
     7.3.12  Read Link Error Status (RLS)
     
         ELS Format:
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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.
     
     7.3.13  Read Sequence Status Block (RSS)
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 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:
     
     
     
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             None.
     
     7.3.14  Reinstate Recovery Qualifier (RRQ)
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x12 |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     Exchange Originator S_ID      |
         +------+------------+------------+-----------+----------+
         | 2    |          OX_ID          |         RX_ID        |
         +------+------------+------------+-----------+----------+
         | 3-10 |  Association header (may be optionally req'd)  |
         +======+============+============+===========+==========+
     
     
         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.
     
     7.3.15  Request Sequence Initiative (RSI)
     
         ELS Format:
     
         +------+------------+------------+-----------+----------+
         | Word | Bits 31-24 | Bits 23-16 | Bits 15-8 | Bits 7-0 |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0x0A |   0x00     |    0x00   |   0x00   |
         +------+------------+------------+-----------+----------+
         | 1    | Rsvd       |     Exchange Originator S_ID      |
         +------+------------+------------+-----------+----------+
         | 2    |          OX_ID          |         RX_ID        |
         +------+------------+------------+-----------+----------+
         | 3-10 |  Association header (may be optionally req'd)  |
         +======+============+============+===========+==========+
     
     
     
     
     
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         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.
     
     7.3.16  Third Party Process Logout (TPRLO)
     
         TPRLO provides a mechanism for an N_PORT (third party) to remove
         one or more process login sessions that exists 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 SCSI login session which shall be terminated by the command.
     
        Byte
        Offset
               +----------------------------------+
           0   |           LS_COMMAND             |     1 Byte
               +----------------------------------+
           1   |        PAGE LENGTH (0x10)        |     1 Byte
               +----------------------------------+
           2   |      PAYLOAD LENGTH (0x14)       |     2 Bytes
               +----------------------------------+
           4   |  TPRLO LOGOUT PARAMETER PAGE 1   |     2-4 Bytes
               +----------------------------------+
               |             . . . .              |     M Bytes
               +----------------------------------+
               |  TPRLO LOGOUT PARAMETER PAGE N   |     2-4 Bytes
               +----------------------------------+
                     Total Length = Variable
     
         Each TPRLO LOGOUT PARAMETER PAGE identifies a remote N_PORT which
         when combined with the destination N_PORT identifies a SCSI session
         to be terminated.  The TPRLO LOGOUT PARAMETER PAGE is of the
         following format:
     
     
     
     
     
     
     
     
     
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        Byte
        Offset
               +----------------------------------+
           0   |           TYPE CODE              |     1 Byte
               +----------------------------------+
           1   |        TYPE CODE EXTENSION       |     1 Byte
               +----------------------------------+
           2   |           TPRLO FLAGS            |     2 Bytes
               +----------------------------------+
           4   | ORIG PROCESS ASSOC (if present)  |     4 Bytes
               +----------------------------------+
           8   | RESP PROCESS ASSOC (if present)  |     4 Bytes
               +----------------------------------+
          12   |            RESERVED              |     1 Byte
               +----------------------------------+
          13   | THIRD PARTY ORIGINATOR N_PORT ID |     3 Bytes
               +----------------------------------+
     
     
         When the iFCP header contains a TPRLO message (including the ACC
         response), iFCP supplemental data field will contain the
         PORT_NAME(s) (WWPN) identifying the N_PORT described by the
         equivalent TPRLO LOGOUT PARAMETER PAGE(s). If more than one TPRLO
         LOGOUT PARAMETER PAGE is contained in the Link Service message, the
         corresponding PORT_NAME shall also be included.  PORT_NAMEs shall
         be listed in the same order as the equivalent TPRLO LOGOUT
         PARAMETER PAGEs in the original Link Service message.
     
         [The format for passing supplemental data is /TBS/]
     
         Additionally, the THIRD PARTY ORIGINATOR N_PORT ID field in each
         TPRLO LOGOUT PARAMETER PAGE shall be cleared when it is sent by the
         originating gateway.  This applies to both the original Link
         Service message and the ACC response.
     
         When the iFCP layer receives a TPRLO message, it shall use the
         latter to replace the THIRD PARTY ORIGINATOR N_PORT ID in the
         original Link Service message, before forwarding it on to the upper
         Fibre Channel layers.
     
         Additional information on TPRLO can be found in [FC-FS].
     
     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 7.3.7.  The figure in that section is duplicated below for
         convenience.
     
     
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         Byte
         Offset
               +----------------------------------+
           0   |            LS_COMMAND            |     4 Bytes
               +----------------------------------+
           4   |     COMMON SERVICE PARAMETERS    |    16 Bytes
               +----------------------------------+
          20   |            PORT NAME             |     8 Bytes
               +----------------------------------+
          28   |            NODE NAME             |     8 Bytes
               +----------------------------------+
          36   |     CLASS 1 SERVICE PARAMETERS   |    16 Bytes
               +----------------------------------+
          52   |     CLASS 2 SERVICE PARAMETERS   |    16 Bytes
               +----------------------------------+
          68   |     CLASS 3 SERVICE PARAMETERS   |    16 Bytes
               +----------------------------------+
          86   |     CLASS 4 SERVICE PARAMETERS   |    16 Bytes
               +----------------------------------+
         102   |        VENDOR VERSION LEVEL      |    16 Bytes
               +----------------------------------+
                  Figure 16 -- FLOGI Request and ACC Payload Format
     
         A full description of each parameter is given in [FC-FS].
     
         This section tabulates the service parameters supported by a fabric
         port attached to an iFCP gateway.
     
         FC service parameters are carried in the payload of a PLOGI or
         FLOGI extended link service request having the following format:
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         +-----------------------------------------+---------------+
         |                                         | Fabric Login  |
         |          Service Parameter              |    Class      |
         |                                         +---+---+---+---+
         |                                         | 1 | 2 | 3 | 4 |
         +-----------------------------------------+---+---+---+---+
         | Class Validity                          | X | a | a | 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 | a | a | n |
         +-----------------------------------------+---+---+---+---+
         | Initiator Control                       |               |
         +-----------------------------------------+---+---+---+---+
         |   Initial Responder Process Associator  | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   ACK_0 capable                         | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   ACK generation assistance             | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Clock synchronization ELS capable     | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         | Recipient Control                       |               |
         +-----------------------------------------+---+---+---+---+
         |   ACK_0 capable                         | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   X_ID interlock                        | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Error policy support                  | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Categories per sequence               | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Clock synchronization ELS capable     | n | n | n | n |
         +-----------------------------------------+---+---+---+---+
         |   Reserved - Fabric Specific            | n | y | y | n |
         +-----------------------------------------+---+---+---+---+
     
         Notes:
     
              1) "y" indicates a parameter that applies to an iFCP gateway
     
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              2) "n" indicates the parameter is not applicable to an iFCP
                  gateway
     
              3) "M" indicates a parameter that MUSY be supported by an
                  iFCP gateway
     
              4) "X" indicates a parameter that MUST NOT be supported by an
                  iFCP gateway
     
     8.       TCP Session Control Messages
     
         TCP session control messages are used to create and manage an iFCP
         session as described in section 6.2.2. They are passed between peer
         FCP Portals, and are only processed within the iFCP layer.
     
         The message format is based on the extended link service message
         template shown below.
     
         Word
           31<Bits>24 23<---------------Bits------------------------->0
          +----------+------------------------------------------------+
         0| R_CTL    |            D_ID [0x00 00 00]                   |
          |[Req = 22]| [Destination of extended link Service request] |
          |[Rep = 23]|                                                |
          +----------+------------------------------------------------+
         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
     
     
     
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         The LS_COMMAND value for the response remains the same as that used
         for the request.
     
         The session control ELS frame is terminated with a Fibre Channel
         CRC.
     
         The encapsulation header for the link Service frame carrying a TCP
         ELS message SHALL be set as follows:
     
         Encapsulation Header Fields:
     
          LS_COMMAND           0
     
          iFCP Flags           SES = 1
     
                                TRN = 0
     
                                AUG = 0
     
          SOF code             SOFi3 encoding (0x2E)
     
          EOF code             EOFt encoding (0x42)
     
          Time Stamp Integer   0,0
          and Fraction fields
     
     
     
         The SOF and EOF delimiter words SHALL be set based on the SOF and
         EOF codes specified above.
     
         The following lists the session control messages and their
         corresponding LS_COMMAND values.
     
                     Request            LS_COMMAND Short Name  iFCP Support
                     -------            ---------- ----------  -----------
         Connection Bind                  0xE0       CBIND      REQUIRED
         Unbind Connection                0xE4      UNBIND      REQUIRED
     
     
     8.1      Connection Bind (CBIND)
     
         As described in section 6.2.2.1, the CBIND message and response are
         used to bind an N_PORT login session to a specific TCP
         connectionand establish iFCP session.  In the CBIND request
         message, the source and destination N_Ports are identified by the
         N_PORT network address (iFCP portal address and N_PORT ID).
     
         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    |         Reserved        | Addr Mode | iFCP Ver |
         +------+-------------------------+-----------+----------+
         | 2    |                  User Info                     |
         +------+------------+------------+-----------+----------+
         | 3    |                                                |
         +------+                SOURCE PORT NAME                |
         | 4    |                                                |
         +------+------------------------------------------------+
         | 5    |                                                |
         +------+                DESTINATION PORT NAME           |
         | 6    |                                                |
         +------+------------------------------------------------+
     
         Addr Mode -  The address translation mode of the originating
         gateway.  0 = Address Translation mode, 1 = Address Transparent
         mode.
     
         iFCP Ver - iFCP version number. SHALL be set to 1.
     
         USER INFO - Contains any data desired by the requester.  This info
         MUST be echoed by the recipient in the CBIND response message.
     
         SOURCE PORT NAME - Contains the originating N_PORT's World Wide
         Port Name (WWPN).
     
         DESTINATION PORT NAME - Contains the destination N_PORT's World
         Wide Port Name (WWPN).
     
         The following shows the format of the CBIND response.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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         +------+------------+------------+-----------+----------+
         | Word |   Byte 0   |   Byte 1   |   Byte 2  |  Byte 3  |
         +------+------------+------------+-----------+----------+
         | 0    | Cmd = 0xE0 |   0x00     |   0x00    |  0x00    |
         +------+------------+------------+-----------+----------+
         | 1    |         Reserved        | Addr Mode | iFCP Ver |
         +------+-------------------------+-----------+----------+
         | 2    |                  User Info                     |
         +------+------------+------------+-----------+----------+
         | 3    |                                                |
         +------+                SOURCE PORT NAME                |
         | 4    |                                                |
         +------+------------------------------------------------+
         | 5    |                                                |
         +------+                DESTINATION PORT NAME           |
         | 6    |                                                |
         +------+-------------------------+----------------------+
         | 7    |        Reserved         |     CBIND Status     |
         +------+-------------------------+----------------------+
         | 8    |        Reserved         |  CONNECTION HANDLE   |
         +------+-------------------------+----------------------+
                                   Total Length = 32
     
         Addr Mode -  The address translation mode of the responding
         gateway.  0 = Address Translation mode, 1 = Address Transparent
         mode.
     
         iFCP Ver - iFCP version number of the responding gateway. SHALL be
         set to 1.
     
         USER INFO - Contains the same value received in the USER INFO field
         of the CBIND request message.
     
         DESTINATION PORT NAME - Contains the destination N_PORT's World
         Wide Port Name (WWPN).
     
         CBIND STATUS - Indicates success or failure of the CBIND request.
         CBIND values are shown below.
     
              Value     Description
              -----     -----------
     
                0       Successful - No other status
             1 - 15     Reserved
               16       Failed - Unspecified Reason
               17       Failed - No such device
               18       Failed - N_PORT session already exists
               19       Failed - Lack of resources
               20       Failed - Incompatible address translation mode
               21       Failed - Incorrect protocol version number
             Others     Reserved
     
     
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         CONNECTION HANDLE (CHANDLE) - Contains a value assigned by the FCP
         Portal to identify the connection.
     
     8.2      Unbind Connection (UNBIND)
     
         UNBIND is used to release a bound TCP connection and return it to
         the pool of unbound TCP connections.  This message is transmitted
         in the connection that is to be unbound.
     
         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                      |
         +------+------------+------------+-----------+----------+
     
     
         CONNECTION HANDLE (CHANDLE) - Contains a value assigned by the FCP
         Portal to identify the connection
     
         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    |
         +------+------------+------------+-----------+----------+
     
     
         UNBIND STATUS - Indicates the success or failure of the UNBIND
         request.
     
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              Value     Description
              -----     -----------
     
                0       Successful - No other status
             1 - 15     Reserved
               16       Failed - Unspecified Reason
               17       Failed - No such device
               18       Failed - Connection ID Invalid
             Others     Reserved
     
     
         CONNECTION HANDLE (CHANDLE) - Contains a value assigned by the FCP
         Portal to identify the unbound connection.
     
     9.       iFCP Error Detection
     
     9.1      Overview
     
         [FC-FS] defines error detection and recovery procedures.  These
         Fibre Channel-defined mechanisms continue to be available in the
         iFCP environment.
     
     9.2      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.
     
         Since a Fibre Channel fabric does 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 FC4 ELS request must wait
         for the response to that request. The Fibre Channel default value
         for R_A_TOV is 10 seconds.
     
         The iFCP fabric MAY actively enforce limits on R_A_TOV as described
         in section 9.2.1.
     
     9.2.1   Enforcing R_A_TOV Limits
     
         The R_A_TOV limit on frame lifetimes MAY be enforced by means of
         the time stamp in the encapsulation header (see section 6.4.1) 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
     
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         network.  This latter component is referred to in this
         specification as IP_TOV.
     
         If enforced by a gateway, 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. A rule of thumb is to set IP_TOV 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 RFC 2030,
         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 RFC 2030. The resolution of the time reference MUST be 125
         milliseconds or better.
     
         With regard to the time base, the gateway is in either the
         synchronized or unsychronized state.  When in the unsynchronized
         state, the gateway SHALL:
     
         a)  Set the time stamp field to 0,0 for all outgoing frames
     
         b)  Ignore the time stamp field for all incoming frames.
     
         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 6.4.4.
     
         c)  If the incoming frame has a time stamp of 0,0, the receiving
             gateway SHALL NOT test the frame to determine if it is stale.
     
         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.
     
     
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         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 6.4.4.
     
         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.
     
         If synchronization is lost, the gateway MAY choose to abort all
         N_PORT login sessions with all remote gateways.
     
     10.      Fabric Services Supported by an iFCP implementation
     
         An iFCP gateway implementation MUST support the following fabric
         services:
     
        N_PORT ID Value           Description             Section
        ---------------           -----------             -------
          0xFF-FF-FE             F_PORT Server             /TBS/
     
          0xFF-FF-FD           Fabric Controller           /TBS/
     
          0xFF-FF-FC         Directory/Name Server         /TBS/
     
     
     
     
     
         In addition, an iFCP gateway MAY support the FC broadcast server
         functionality described in section 10.1.
     
     10.1     iFCP Support for the FC Broadcast Service
     
         In Fibre Channel, frames are broadcast by addressing them to the
         broadcast server at well-known 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/iSNS system, outgoing frames to be broadcast are
         directed to the gateway-resident broadcast server by locally
         attached N_PORTs.  The broadcast server then redistributes such
         frames as follows:
     
         a)  One copy is sent to each locally attached N_PORT in the same
             discovery domain  as the originator.
     
     
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         b)  One copy is sent to the broadcast server in each remote gateway
             via a UDP datagram. The D_ID field is set to the well-known
             address of the FC broadcast server.  The datagram encapsulation
             format is identical to the iFCP encapsulation format described
             in section 6.4. The UDP datagram SHALL be sent with the DF bit
             set to 0 in the IP header to allow IP fragmentation (see
             [RFC791]).
     
         On receiving an iFCP broadcast datagram via UDP, the broadcast
         server SHALL:
     
         a) Validate the encapsulation header as described in section 6.4.3.
            If the header is invalid, the frame SHALL be discarded.
     
         b) Convert the S_ID N_PORT address in the frame to an N_PORT alias
            as described in section 5.3.2, if address translation mode is in
            effect.
     
         c) If the AUG bit is set in the iFCP flags field, perform any
            special processing required by the ELS, including translation of
            any addresses in the payload.
     
         d) Replicate and redistribute the frame to all locally attached
            N_PORTs in the discovery domain of the sender.
     
         If no broadcast server is implemented, the receiving gateway SHALL
         discard an incoming broadcast frame from a remote gateway.
         Broadcast frames received from locally attached N_PORTs shall be
         processed as specified in[FC-GS3].
     
     11.      Security
     
     11.1     Overview
     
         As with any other IP-based network, an iFCP storage network has
         security issues which must be addressed with the appropriate
         security policies and enforcement resources.  There are various
         levels of security paradigms which when applied appropriately to an
         iFCP network can provide sufficient levels of security, including
         data integrity, authentication, and privacy, depending on user
         needs.
     
     11.2     Physical Security
     
         Most existing SCSI and Fibre Channel interconnections are deployed
         in private, physically isolated environments where hostile entities
         are not provided access to the SCSI and Fibre Channel
         interconnects.  This is the most basic security mechanism, and may
         be a sufficient model in some cases for an iFCP network.
     
     11.3     Controlling Access
     
     
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         A second level of security is the use of zoning.  Zoning specifies
         which devices are allowed to communicate, and is similar in concept
         to VLAN (Virtual Local Area Network) technology.  Zoning
         information is maintained in a Name Server.
     
     11.4     Authentication and Encryption
     
         Where additional levels of data integrity and privacy are required
         for iFCP, existing IPSec specifications can be applied to iFCP.
         Because IPSec is a layer-3 technology and has no knowledge of TCP,
         UDP, or higher-level protocols such as iFCP and FCP, it can be
         applied transparently to iFCP.  The following IETF documents
         describe the operational framework and automatic keying mechanisms
         for IPSec.
     
           [RFC2401] Security Architecture for the Internet Protocol
     
           [RFC2402] IP Authentication Header
     
           [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)
     
     
     
     11.5     Storage Firewalls
     
         Firewalls are a common and proven methodology for securing access
         to IP-based networks, and they can be appropriate for use in IP-
         based storage networks as well.  A firewall is a choke point
         through which all transit traffic must transit in order to pass
         between two separate networks.  Since all iFCP traffic uses a well-
         known IANA-assigned TCP port number, it can easily be recognized
         and inspected.
     
         Access to storage resources can be secured by setting up a single
         gateway through which all outside non-secured traffic must pass
         through in order to access resources in the storage network.  Such
         a firewall can be a proxy host operating at the session or
         application layer, requiring authentication before allowing traffic
         to pass.  It can also be a stateful inspection gateway which
         understands the iFCP protocol, and can passively inspect and
         discover security threats as they transit the gateway.  A third
         option is to use a standard router access control list to filter
         authorized traffic based upon static parameters such as IP
         addresses and TCP port numbers.
     
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     12.      Quality of Service Considerations
     
     12.1     Minimal requirements
     
         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 attached to one another).
     
     12.2     High-assurance
     
         It is expected that many iFCP deployments will benefit from a high
         degree of assurance on the behaviors of the 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 [IntServ] QoS
     
         c) .Differentiated Services [DiffServ] QoS
     
         d) .Multi-Protocol Label Switching [MPLS]
     
         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. The IP regions
         with these QoS solutions are said to support Service Level
         Agreements (SLAs). Such agreements finalize requirements on network
         parameters such as bandwidth, loss, latency, jitter, burst length.
         The requirements may be expressed in absolute or relative terms,
         and apply to a unidirectional flow of packets. Depending on the QoS
         techniques available, the dynamic stipulation of a SLA may require
         the iFCP gateway to interact with network ancillary functions such
         admission control and bandwidth brokers (with RSVP or other
         signalling protocols that an IP region may accept).
     
         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
         bandwidth or other network parameters need to be injected out-of-
         band into a iFCP gateway (or the node that will actually negotiate
     
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         the SLA on the gateway's behalf) through mechanisms outside the
         scope of this specification (e.g., through a management interface
         into the iFCP gateway).
     
         The administrator of a iFCP gateway MAY thus stipulate a Service
         Level Agreement with the local IP region for one, several, or all
         of an iFCP gateway's TCP sessions used by iFCP. Alternately, this
         responsibility may be delegated to a node downstream. Since one TCP
         connection is dedicated to each N_PORT login session , an
         individual N_PORT to N_PORT flow can enjoy a customized SLA.
     
         To render the best emulation of Fibre Channel possible over IP, it
         is anticipated that typical SLAs 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 SLAs of this nature by applying EF DSCPs to the
         iFCP traffic. For the same SLA, another IP region might as well use
         a different DSCP or different QoS techniques alltogether. The way
         different QoS techniques are re-mapped at the edge of different
         intervening IP regions is beyond the scope of this specification.
     
         [00-603] describes a proposal to add fractional bandwidth
         guarantees to Class 2 and 3 (migrating it from Class 4). In such
         proposal, the bandwidth parameters would surface in the FLOGI
         request and accept, and PLOGI request and accept. In this case, it
         will become possible for an iFCP gateway to trap this information
         and autonomously remap it onto the SLA negotiation mechanism
         required by the local IP region, without resorting to out-of-band
         QoS management. Such an in-band QoS mechanism would result in true
         end-to-end provisioning of network resources. Forthcoming revisions
         of this iFCP specification will build upon this new opportunity.
     
     13.      References
     
     13.1     Relevant SCSI (T10) Specifications
     
         The following documents are available from:  Global Engineering, 15
         Inverness Way East, Englewood, CO  80112-5704.  Telephone (800)
         854-7179 or (303) 792-2181, Fax: (303) 792-2192
     
           [SAM]     SCSI-3 Architecture Model (SAM), ANSI X3.270-1996
     
           [SAM-2]   SCSI Architecture Model-2 (SAM-2), Project 1157-D,
                     revision 11
     
           [SPC]     SCSI Primary Commands (SPC), ANSI X3.301-1997
     
           [SPC-2]   SCSI Primary Commands-2 (SPC-2), Project 1236-D,
                     revision 16
     
           [FCP]     Fibre Channel Protocol for SCSI (FCP), ANSI X3.269-1996
     
     
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           [FCP-2]   Fibre Channel Protocol for SCSI, Second Revision (FCP-
                     2), Project 1144D, revision 04
     
     
     
     13.2     Relevant Fibre Channel (T11) Specifications
     
         The following documents are available from:  Global Engineering, 15
         Inverness Way East, Englewood, CO  80112-5704.  Telephone (800)
         854-7179 or (303) 792-2181, Fax: (303) 792-2192
     
           [FC-PH]    Fibre Channel Physical and Signaling Interface (FC-PH)
                       Rev 4.3, ANSI X3.230:1994
     
           [FC-PH-2]  Fibre Channel Physical and Signaling Interface (FC-PH-
                       2) Rev 7.4, ANSI X3.297:1997
     
           [FC-PH-3]  Fibre Channel Physical and Signaling Interface (FC-PH-
                       3) Rev 9.4, ANSI X3.303:1998
     
           [FC-FG]    Fibre Channel Generic Requirements (FC-FG) Rev 3.5 ANSI
                       X3.289:1996
     
           [FC-GS-2]  Fibre Channel Generic Services (FC-GS-2) Rev 5.2, ANSI
                       NCITS 288
     
           [FC-AL]    Fibre Channel Arbitrated Loop (FC-AL) Rev 4.5, ANSI
                       X3.272:1996
     
           [FC-AL-2]  Fibre Channel Arbitrated Loop (FC-AL-2) Rev 7.0, NCITS
                       32:1999
     
           [FC-PLDA]  Fibre Channel Private Loop SCSI Direct Attachment (FC
                       LDA), NCITS TR-19:1998
     
           [FC-FLA]   Fibre Channel Fabric Loop Attachment (FC-FLA), NCITS
                       TR-20:1998
     
           [FC-TAPE]  Fibre Channel Tape and Tape Medium Changers (FC-TAPE),
                       NCITS TR-24:1999
     
     
     
     13.3     Relevant RFC Documents
     
           [RFC768]   User Datagram Protocol
     
     
     
           [RFC791]   Internet Protocol, DARPA Internet Program Protocol
                       Specification
     
     
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     iFCP Revision 3                                         July 2001
     
     
           [RFC2401]  Security Architecture for Internet Protocol
     
           [RFC2402]  IP Authentication Header
     
           [RFC2406]  Encapsulating Security Protocol (ESP)
     
           [RFC2407]  The Internet IP Security Domain for ISAKMP
     
           [RFC2408]  Internet Security Association and Key Management
                       Protocol (ISAKMP)
     
           [RFC2409]  The Internet Key Exchange (IKE)
     
           [RFC2460]  Internet Protocol, Version 6 (IPv6) Specification
     
     
     
     13.4     Other Reference Documents
     
         The Fibre Channel Consultant, A Comprehensive Introduction, Robert
         W. Kembel, Northwest Learning Associates, ISBN 0-931836-82-6
     
         The Fibre Channel Consultant, Arbitrated Loop, Robert W. Kembel,
         Connectivity Solutions, a division of Northwest Learning
         Associates, ISBN 0-931836-84-0
     
     14.      Author's Addresses
     
     
         Charles Monia                    Franco Travostino
         Rod Mullendore                   Director, Content
         Josh Tseng                       Internetworking Lab,
     
         Nishan Systems                   Victor Firoiu
         3850 North First Street
         San Jose, CA  95134              Nortel Networks
         Phone: 408-519-3986              3 Federal Street
         Email:                           Billerica, MA  01821
         cmonia@nishansystems.com         Phone:  978-288-7708
                                          Email:
                                          travos@nortelnetworks.com
     
     
     
     
     
     
     
     
     
     
     
     
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     iFCP Revision 3                                         July 2001
     
     
         David Robinson                   Wayland Jeong
         Sun Microsystems                 Troika Networks
         Senior Staff Engineer            Vice President, Hardware
         M/S UNWK16-301                   Engineering
         901 San Antonio Road             2829 Townsgate Road Suite
         Palo Alto, CA  94303-4900        200
         Phone: 510-936-2337               Westlake Village, CA  91361
         Email:                            Phone: 805-370-2614
         David.Robinson@sun.com            Email:
                                           wayland@troikanetworks.com
     
         Rory Bolt                        Paul Rutherford
         Quantum/ATL                      ADIC
         Director, System Design          Vice President, Technology &
         101 Innovation Drive             Software
         Irvine, CA 92612                 1143 Willows Road N.E.
         Phone: 949-856-7760              P.O. Box 97057
         Email: rbolt@atlp.com            Redmond, WA  98073-9757
                                           Phone: 425-881-8004
                                           Email:
                                           paul.rutherford@adic.com
     
         Mark Edwards
         Senior Systems Architect
         Eurologic Development, Ltd.
         4th Floor, Howard House
         Queens Ave, UK.  BS8 1SD
         Phone: +44 (0)117 930 9600
         Email:
         medwards@eurologic.com
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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     iFCP Revision 3                                         July 2001
     
     
                                    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.
     
     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      Link Services Processed Transparently
     
         The following link service requests and responses MUST be processed
         transparently as defined in section 7.
     
                  ELSs Processed Transparently
     
             Name              Description
             ----              -----------
     
           ACC       Accept
           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
           FDACT     Fabric Deactivate Alias_ID
           FDISC     Discover F_Port Service
                     Parameters
     
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           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
           RTIN      Request Topology Information
           RTV       Read Timeout Value
           RVCS      Read Virtual Circuit Status
           SBRP      Set Bit-error Reporting
                     Parameters
           SCL       Scan Remote Loop
           SCN       State Change Notification
           SCR       State Change Registration
           TEST      Test
           TPLS      Test Process Login State
     
     
     A.3      Augmented Link Services
     
         The following extended link services are augmented with additional
         data and processed by the iFCP implementation as described in the
         referenced section listed in the table.
     
                          Augmented Link Services
     
             Name              Description             Section
             ----              -----------             -------
     
           ABTX      Abort Exchange                     7.3.1
           ADISC     Discover Address                   7.3.2
     
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           ADISC     Discover Address Accept            7.3.3
           ACC
           FARP-     Fibre Channel Address              7.3.4
           REPLY     Resolution Protocol Reply
           FARP-REQ  Fibre Channel Address              7.3.5
                     Resolution Protocol Request
           LOGO      N_PORT Logout                      7.3.6
           PLOGI     Port Login                         7.3.7
           REC       Read Exchange Concise              7.3.8
           REC ACC   Read Exchange Concise Accept       7.3.9
           RES       Read Exchange Status Block         7.3.10
           RES ACC   Read Exchange Status Block         7.3.11
                     Accept
           RLS       Read Link Error Status Block       7.3.12
           RRQ       Reinstate Recovery Qualifier       7.3.14
           RSI       Request Sequence Initiative        7.3.15
           RSS       Read Sequence Status Block         7.3.13
           TPRLO     Third Party Process Logout         7.3.16
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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     iFCP Revision 3                                         July 2001
     
     
     
     
                                      Appendix B
     
     B.       Implementing an IP to FC Router with an iFCP Fabric
     
         This informational appendix describes a method for implementing IP-
         to-FC router functionality in an iFCP gateway. An IP-to-FC router
         is a two-port device that converts IP datagrams received over a GBE
         link to FC frames in accordance with RFC 2625 [RFC2625].
     
         This RFC specifies the all the elements needed to internetwork
         Fibre Channel devices to an IP network and access IP protocol
         stacks including:
     
         a) The Fibre Channel encapsulation of IP datagrams received from
            gigbit ethernet.
     
         b) Support for ARP, the address resolution protocol specified by
            [RFC826]
     
         c) Use of FARP-REQ and FARP-REPLY for address resolution in a Fibre
            Channel fabric.
     
         In the Fibre Channel device domain, the router has appears as a
         Fibre Channel N_PORT with a standard 24-bit N_PORT I/D. In the IP
         network domain, the router has an IP address which MUST be
         different from the gateway's iFCP portal address.
     
         /  The remainder of this section is TBS /
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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                                      Appendix C
     
     C.       Performance of The Multi-Connection iFCP Session Model
     
         This appendix provides a quantitative analysis of the claim that N
         TCP connections carrying the traffic of all the <N_PORT, N_PORT>
         sessions active between gateways provide significantly higher
         aggregate average throughput than a single TCP connection carrying
         the same <N_PORT, N_PORT> sessions. The analysis shows that the
         difference is proportional to the square of the number of TCP
         sessions, N.
     
         This analyses is based on three fundamental assumptions: (i) all
         the available bandwidth in a link is available to iFCP traffic,
         (ii) the sender has always data ready to send (as is most likely
         the case with a backup application), and (iii) the maximum window
         size at the two TCP ends (i.e., the iFCP gateways) is set to the
         link nominal capacity multiplied by the round-trip-time (so as to
         have the highest chances of saturating the link yet without unduly
         raising buffering requirements at the end nodes). The N^2 factor
         that emerges from this analysis is essentially due to the way TCP
         congestion control reacts to packet losses.
     
     C.1      Relationship of Throughput to Packet Losses
     
         There are several reasons for packet losses: network congestion,
         link errors and network errors. Network congestion is pervasive in
         current IP networks, where the only way to control congestion is
         through dropping packets. Techniques for loss prevention, such as
         traffic engineering, admission control and bandwidth reservation,
         are not widely deployed and hence are not a factor in the behavior
         of existing networks.
     
         Even in a perfectly engineered network, link errors occur. Assuming
         a link error rate equal to that specified for Fibre Channel (10^-
         12) and a 10Gb/s link, there is one error every 100 seconds.
         Network errors also occur with significant frequency in IP
         networks. Jonathan Stone and Craig Partridge recently reported in
         Sigcomm 2000 that network errors caught by the TCP checksum occur
         with significant frequency. Between one packet in 1100 and 1 in
         32000 have errors get past the link CRC and are detected by the
         TCP/IP checksum.
     
         [Editor's note: During the 5/31/2001 internal review, the reviewers
         requested that the editor clarify the wording in the above
         paragraph regarding the incidence of TCP/IP checksum errors.  The
         requested clarification will be included in a subsequent revision.]
     
         TCP throughput is impacted by each packet loss. Following TCP's
         congestion control algorithm (supported by the Tahoe, Reno, New-
     
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     iFCP Revision 3                                         July 2001
     
     
         Reno, and SACK implementations) each packet loss results in the TCP
         sender's congestion window being reduced to half of its current
         value, and therefore (assuming constant Round Trip Time), TCP's
         throughput is halved. After that, the window increases by roughly
         one packet every two Round Trip Times (assuming the widely-used
         Delayed-Acknowledgement algorithm). The temporary decrease in TCP's
         rate translates into a missed opportunity to transmit a given
         amount of data. As we show in the following Background section, for
         N storage connections sharing an IP "pipe" of rate E, the amount of
         data missing the opportunity to be transmitted due to a packet loss
         is:
     
                            D(N) = E^2/(N^2)*RTT^2/(256*M)
     
         where RTT = Round Trip Time, M = packet size.
     
         For example, for a set of N=100 connections totaling E=10Gb/s,
         RTT=10ms, M=1500B, the data not transmitted in time due to a packet
         loss is D(N)=2.6MB. For the same set transported over one TCP
         session, the data not sent in time is D(1)= 26GB, a 10,000 fold
         increase. The time interval for TCP to recover its sending rate to
         its initial value after a packet loss is I(N)= 0.833 seconds in the
         case N TCP connections, and I(1)=83.3seconds in the case of a
         single TCP connection. Observe that in the latter case, the time to
         recover its rate, I(1)=83.3s, is of the same order of magnitude as
         the time between two packet losses due exclusively to a link Bit
         Error Rate of 10^-12. In other words, a packet loss occurs almost
         immediately after TCP has recovered its rate.
     
         This means that a single TCP connection delivers on average about
         3/4 of the required 10Gb/s rate, since 1/4 of the rate is lost
         during the time the TCP rate is increasing linearly from 1/2 to
         full rate. (More precisely, the effective rate is 8.27Gb/s because
         1/4 of the rate is lost during 83.3s, and the time between two
         errors is now 120.825s due to a decreased sending rate). By
         comparison, N TCP connections deliver approximately 9.99979Gb/s
         (i.e., lost 1/4 of one TCP full rate of 100Mb/s during 0.833s out
         of a 100s interval).
     
         If the impact of TCP checksum errors is also considered, the TCP
         sending rate is limited to an average of (8M/RTT)sqrt(3/4p), where
         p is the probability of packet loss (see [Padhye] for details). For
         M=1500, RTT=10ms and p=1/32000, TCP throughput is about 240Mb/s.
         For p=1/1100, maximum TCP throughput is 34.4Mb/s. Therefore, to
         fill a 10Gb/s line, about 42 simultaneous TCP flows are required
         (in the case where p=1/32000) or 291 TCP flows (in the case where
         p=1/1100).
     
         Practically, for these reasons the iFCP protocol supports
         combinations of M <N_PORT, N_PORT> tuples using N TCP connections,
         with M, N >= 1, and with an individual  <N_PORT, N_PORT> tuple
         using at most one TCP connection (thus M >= N).
     
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     C.2      Background.
     
         For a TCP session to sustain a rate of C bits/second, the TCP's
         maximum congestion window W (measured in number of packets) has to
         be at least W0=RTT*C/(8*M) where RTT = Round Trip Time in seconds,
         M = packet size in Bytes. The following analyses assumes W=W0.
         Later, the problems with the alternative W>W0 are discussed.
     
         The time needed by the TCP sender to recover from a single packet
         loss and have its sending rate reach the previous C value is
     
                        I = 2*RTT*W/2 = RTT*W = RTT^2*C/(8*M).
     
         The total amount of data (in Bytes) missing the opportunity to be
         transmitted in this time interval I is:
     
                           D = C/8*I/4 = C^2*RTT^2/(256*M)
     
     
     
         Consider a set of <N_PORT, N_PORT> tuples sharing an IP "pipe" of
         rate E to be transported in N TCP sessions. Assuming all
         connections are processed equally, each TCP session sends at a rate
         of E/N. One packet loss impacts only one TCP session, and thus, the
         total amount of data missing the opportunity to be transmitted due
         to a packet loss is
     
                           D(N) = E^2/(N^2)*RTT^2/(256*M).
     
         On the other hand, if the same set of <N_PORT, N_PORT> tuples
         sharing an IP "pipe" of rate E is transported in one TCP session
         only, the total amount of data losing the opportunity to be
         transmitted due to a packet loss is
     
                         D(1) = E^2*RTT^2/(256*M) = D(N)*N^2.
     
         The impact of packet losses on the single-TCP solution can be
         reduced by configuring the maximum congestion window to be larger
         than the bandwidth*delay product, W>W0.  But in this case, only W0
         packets can be in transit on the line, while the rest (up to the
         current window size) need to be stored in a queue at the line's
         ingress. In order to provide full line rate utilization assuming
         periodic losses, the maximum congestion window should be at least
         2*W0, due to TCP's congestion
     
     
     
     
     
     
     
     
     
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     Full Copyright Statement
     
     
         "Copyright (C) The Internet Society, July 2001. All Rights
         Reserved. This document and translations of it may be copied and
         furnished to others, and derivative works that comment on or
         otherwise explain it or assist in its implmentation may be
         prepared, copied, published and distributed, in whole or in part,
         without restriction of any kind, provided that the above copyright
         notice and this paragraph are included on all such copies and
         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
         needed for the purpose of developing Internet standards in which
         case the procedures for copyrights defined in the Internet
         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
         revoked by the Internet Society or its successors or assigns.
     
         This document and the information contained herein is provided on
         an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET
         ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR
         IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
         THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
         WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE."
     
     
     
     
        [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
           Requirement Levels", BCP 14, RFC 2119, March 1997
     
        [FC-FS] dpANS X3.XXX-200X, "Fibre Channel Framing and Signaling
           Interface", Revision 1.2, NCITS Project 1331-D, February, 2001
     
        [FC-SW2] dpANS X3.XXX-2000X, "Fibre Channel Switch Fabric -2 (FC-
           SW2)", revision 5.2, NCITS Project 1305-D, May, 2001
     
        [FC-GS3] dpANS X3.XXX-200X, "Fibre Channel Generic Services -3 (FC-
           GS3)", revision 7.01, NCITS Project 1356-D, November, 2000
     
        [FC-FLA] TR-20-199X, "Fibre Channel Fabric Loop Attachment (FC-
           FLA)", revision 2.7, NCITS Project 1235-D, August, 1997
     
     
     
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     iFCP Revision 3                                         July 2001
     
     
     
        [Kembel] Kembel, R., "Fibre Channel, A Comprehensive Introduction",
           Northwest Learning Associates Inc., 2000, ISBN 0-931836-84-0
     
         Kembel, R., "The Fibre Channel Consultant, Arbitrated Loop", Robert
         W. Kembel, Northwest Learning Associates, 2000, ISBN 0-931836-84-0
     
        [ENCAP] Weber, et-al., "FC Frame Encapsulation", draft-ietf-ips-
           fcencapsulation-01.txt, May, 2001
     
        [RFC2030] Mills, D., RFC 2030, "Simple Network Time Protocol (SNTP)"
           Version 4, October, 1996
     
        [RFC791] Postel, J., RFC 791, "The Internet Protocol", September,
           1981
     
        [00-603] Stephens, G., Warden, G. T11/00-603, "Fractional Bandwidth,
           Class 2, Class 3", October, 2000
     
        [RFC768] Postel, J., RFC 768, "User Datagram Protocol", August, 1980
     
        [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
     
        [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
     
        [RFC2460] Deering, S., Hinden, R., RFC 2460 "Internet Protocol,
           Version 6 (IPv6) Specification", December 1998
     
        [RFC2625] Rajagopal, M, et.al., RFC 2625, "IP and ARP over Fibre
           Channel", June 1999
     
        [RFC826] Plummer, D.C., RFC 826 "Ethernet Address Resolution
           Protocol: Or converting network protocol addresses to 48.bit
           Ethernet address for transmission on Ethernet hardware",
           November, 1982.
     
     
     
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        [Padhye] Padhye, J, Firoiu, D, Kurose, J., "Modeling TCP Reno
           Performance: A Simple Model and its Empirical Validation." J.
           Padhye, V. Firoiu, D. Towsley and J. Kurose, IEEE/ACM
           Transactions on Networking, April 2000.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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