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Versions: (draft-tseng-ips-isns) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 RFC 4171

   IPS                                                 Kevin Gibbons
   Internet Draft                                         Josh Tseng
   <draft-ietf-ips-isns-05.txt>                              Fa Yoeu
   Standards Track                                     Charles Monia
   Expires May 2002                                   Nishan Systems

                                                   Franco Travostino
                                                     Nortel Networks

                                                       Tom McSweeney
                                                       Curt Du Laney
                                                          John Dowdy
                                                                 IBM

                                                        Chad Gregory
                                                               Intel

                                                          Ken Hirata
                                                   Vixel Corporation

                                                         Howard Hall
                                                      Pirus Networks

                                                       November 2001


                    Internet Storage Name Service (iSNS)

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026 [1].

   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.

Acknowledgements

   Numerous individuals contributed to the creation of this draft
   through their careful review and submissions of comments and


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   recommendations.  We acknowledge the following persons for their
   technical contributions to this document:  John Hufferd (IBM),
   Julian Satran (IBM), Kaladhar Voruganti(IBM), Joe Czap (IBM), Jim
   Hafner (IBM), Yaron Klein (Sanrad), Larry Lamers (SAN Valley), Jack
   Harwood (EMC), David Black (EMC), David Robinson (Sun), and Marjorie
   Krueger (HP).

Comments

   Comments should be sent to the IPS mailing list (ips@ece.cmu.edu) or
   to the authors.












































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                             Table of Contents

Status of this Memo...................................................1
Acknowledgements......................................................1
Comments..............................................................2
1.Abstract...........................................................6
2.Conventions used in this document..................................6
3.iSNS Overview......................................................6
3.1 iSNS Architectural Components....................................6
3.1.1 iSNS Protocol (iSNSP)..........................................6
3.1.2 iSNS Client....................................................7
3.1.3 iSNS Server....................................................7
3.1.4 iSNS Database..................................................7
3.1.5 iSCSI..........................................................7
3.1.6 iFCP...........................................................7
3.2 iSNS Functional Overview.........................................7
3.2.1 Name Registration Service......................................8
3.2.2 Discovery Domain and Login Control Service.....................8
3.2.3 State Change Notification Service..............................9
3.2.4 Open Mapping Between Fibre Channel and iSCSI Devices..........10
3.3 iSNS and Domain Name System (DNS)...............................10
3.4 iSNS and LDAP...................................................10
3.5 iSNS Server Discovery...........................................11
3.6 iSNS and NAT....................................................11
3.7 Interactions Between iSNS Infrastructures.......................12
3.8 Deployment Architecture Diagram.................................14
4.iSNS Object Model.................................................14
4.1 NETWORK ENTITY Object...........................................15
4.2 PORTAL Object...................................................15
4.3 STORAGE NODE Object.............................................15
4.4 FC DEVICE Object (iFCP Only)....................................15
4.5 DISCOVERY DOMAIN Object.........................................15
4.6 DISCOVERY DOMAIN SET Object.....................................16
4.7 iSNS Database Model.............................................16
5.iSNS Implementation Requirements..................................16
5.1 iSCSI Requirements..............................................16
5.1.1 Required Attributes for Support of iSCSI......................16
5.1.2 Example iSCSI Object Model Diagrams...........................17
5.1.3 Required Commands and Response Messages for Support of iSCSI..19
5.2 iFCP Requirements...............................................20
5.2.1 Required Attributes for Support of iFCP.......................21
5.2.2 iFCP Attribute Requirements...................................22
5.2.3 Example iFCP Object Model Diagram.............................23
5.2.4 Required Commands and Response Messages for Support of iFCP...24
5.3 Attribute Descriptions for Discovery Domain Registration........25
5.4 Use of TCP For iSNS Communication...............................26
5.5 Use of UDP For iSNS Communication...............................27
6.iSNS Message Attributes...........................................27
6.1 iSNS Attribute Summary..........................................27
6.2 Entity Identifier-Keyed Attributes..............................30
6.2.1 Entity Identifier (EID).......................................30
6.2.2 Entity Protocol...............................................30
6.2.3 Management IP Address.........................................31
6.2.4 Entity Registration Timestamp.................................31

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6.2.5 Protocol Version Range........................................31
6.2.6 Registration Period...........................................31
6.2.7 Entity Index..................................................32
6.2.8 ISAKMP Phase-1 Proposals......................................32
6.2.9 Entity Certificate............................................32
6.3 Portal-Keyed Attributes.........................................32
6.3.1 Portal IP-Address.............................................32
6.3.2 Portal TCP/UDP Port...........................................33
6.3.3 Portal Symbolic Name..........................................33
6.3.4 Entity Status Inquiry Interval................................33
6.3.5 ESI/SCN UDP Port..............................................34
6.3.6 Portal Group..................................................34
6.3.7 Portal Index..................................................34
6.3.8 Portal Certificate............................................34
6.4 iSCSI Node-Keyed Attributes.....................................35
6.4.1 iSCSI Name....................................................35
6.4.2 iSCSI Node Type...............................................35
6.4.3 iSCSI Node Alias..............................................36
6.4.4 iSCSI Node SCN Bitmap.........................................36
6.4.5 iSCSI Node Index..............................................36
6.4.6 iSCSI Security Bitmap.........................................36
6.4.7 iSCSI ISAKMP Phase-2 Proposals................................37
6.4.8 iSCSI Node Pre-Shared Key.....................................37
6.4.9 iSCSI Node Certificate........................................37
6.5 iFCP Node-Keyed Attributes......................................37
6.5.1 iFCP Node Port Name (WWPN)....................................37
6.5.2 Port ID.......................................................38
6.5.3 Port Type.....................................................38
6.5.4 iFCP Node Port Symbolic Name..................................38
6.5.5 iFCP Node Fabric Port Name (FWWN).............................38
6.5.6 FC Hard Address...............................................39
6.5.7 FC Port IP Address............................................39
6.5.8 FC Class of Service (COS).....................................39
6.5.9 FC FC-4 Types.................................................39
6.5.10 FC FC-4 Descriptor...........................................39
6.5.11 FC FC-4 Features.............................................39
6.5.12 iFCP Node SCN Bitmap.........................................40
6.5.13 iFCP Node Type...............................................40
6.5.14 iFCP Security Bitmap.........................................41
6.5.15 iFCP ISAKMP Phase-2 Proposals................................41
6.5.16 iFCP Node Pre-Shared Key.....................................41
6.5.17 iFCP Node Certificate........................................41
6.6 iFCP FC Device Node-Keyed Attributes............................42
6.6.1 iFCP FC Device Node Name (WWNN)...............................42
6.6.2 iFCP FC Device Symbolic Name..................................42
6.6.3 FC Device IP Address..........................................42
6.6.4 FC Device IPA.................................................42
6.6.5 FC Device Certificate.........................................42
6.7 Other Attributes................................................42
6.7.1 FC-4 Type Code................................................43
6.7.2 Preferred ID..................................................43
6.7.3 Assigned ID...................................................43
6.7.4 Space_Identifier..............................................43
6.7.5 Server-Specific Attributes....................................43

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6.8 Discovery Domain Registration Attributes........................43
6.8.1 iSNS Discovery Domain Attribute Summary.......................44
6.8.2 DD Set ID Keyed Attributes....................................44
6.8.3 DD ID Keyed Attributes........................................45
6.9 Vendor-Specific Attributes......................................46
6.10 Company OUI....................................................47
6.11 Standards-Based Extensions.....................................47
7.iSNSP Message Format..............................................47
7.1 iSNSP PDU Header................................................47
7.1.1 iSNSP Version.................................................47
7.1.2 iSNSP Function ID.............................................47
7.1.3 iSNSP PDU Length..............................................48
7.1.4 iSNSP Flags...................................................48
7.1.5 iSNSP Transaction ID..........................................48
7.1.6 iSNSP Sequence ID.............................................48
7.2 iSNSP Message Segmentation and Reassembly.......................48
7.3 iSNSP Message Payload...........................................49
7.3.1 Attribute Value 4-Byte Alignment..............................49
7.4 iSNSP Response Error Codes......................................49
7.5 Registration and Query Messages.................................50
7.5.1 Source Attribute..............................................51
7.5.2 Key Attributes................................................51
7.5.3 Delimiter Attribute...........................................52
7.5.4 Operating Attributes..........................................52
7.5.5 Registration and Query Message Types..........................52
7.6 Response Messages...............................................63
7.6.1 Error Code....................................................63
7.6.2 Key Attributes in Response....................................63
7.6.3 Delimiter Attribute in Response...............................63
7.6.4 Operating Attributes in Response..............................64
7.6.5 Registration and Query Message Types..........................64
7.7 Vendor Specific Messages........................................67
8.Security Considerations...........................................68
8.1 Security Requirements...........................................68
8.2 Resource Issues.................................................68
8.3 iSNS Interaction with IKE and IPSec.............................68
8.4 Implementation Requirements.....................................69
9.References........................................................70
10.Author's Addresses...............................................71
Full Copyright Statement.............................................72
Appendix A -- iSNS Examples..........................................73
A.1 iSCSI Initialization Example....................................73
A.1.1  Simple iSCSI Target Registration.............................73
A.1.2  Target Registration and DD Configuration.....................75
A.1.3  Initiator Registration and Target Discovery..................77










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1.       Abstract

   This document provides a generic framework centering around use of
   the iSNS for discovery and management of iSCSI and Fibre Channel
   (FCP) storage devices in an enterprise-scale IP storage network.
   iSNS is an application that stores iSCSI and FC device attributes
   and monitors their availability and reachability in an integrated IP
   storage network.  Due to its role as a consolidated information
   repository, iSNS provides for more efficient and scalable management
   of storage devices in an IP network.

2.       Conventions used in this document

   iSNS refers to the framework consisting of the storage network model
   and associated services.

   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 [2].

   All frame formats are in big endian network byte order.

3.       iSNS Overview

   The objective of iSNS is to facilitate scalable configuration and
   management of iSCSI and Fibre Channel (FCP) storage devices in an IP
   network.  iSNS allows the administrator to go beyond a simple
   device-by-device management model, where each storage device is
   manually and individually configured with its own list of known
   initiators and targets.  Using the iSNS, each storage device
   subordinates its discovery and management responsibilities to the
   iSNS server.  The iSNS server thereby serves as the consolidated
   management contact through which administrator workstations can
   configure and manage the entire storage network.

   iSNS can be implemented to support iSCSI and/or iFCP protocols as
   needed; an iSNS implementation MAY provide support for one or both
   of these protocols as desired by the implementer.  Implementation
   requirements within each of these protocols is further discussed in
   section 5.  Use of iSNS is OPTIONAL for iSCSI, and REQUIRED for
   iFCP.

   When used to support both iSCSI and iFCP protocols, iSNS can be
   implemented to facilitate the discovery and management of both iSCSI
   and FC devices in an integrated IP/Fibre Channel environment.

3.1      iSNS Architectural Components

3.1.1   iSNS Protocol (iSNSP)

   The iSNS Protocol (iSNSP) is a flexible and lightweight protocol
   that specifies how iSNS clients and servers communicate.  It is


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   suitable for various platforms, including switches and targets as
   well as server hosts.



3.1.2   iSNS Client

   iSNS clients initiate transactions with the iSNS server using the
   iSNSP.  iSNS clients are applications that are co-resident in the
   storage device, and can register deviceÆs attribute information,
   download information about other registered clients in a common
   Discovery Domain (DD), and receive asynchronous notification of
   topology events that occur in their DD(s). Management stations are a
   special type of iSNS client that have access to all DDs stored in
   the iSNS.



3.1.3   iSNS Server

   The iSNS server responds to iSNS protocol queries and requests, and
   initiates iSNS protocol State Change Notifications.  Properly
   authenticated information submitted by a registration request is
   stored in an internal or external iSNS database.

3.1.4   iSNS Database

   The iSNS database is the information repository for the iSNS
   server(s).  It maintains information about iSNS client attributes.
   A directory-enabled implementation of iSNS may store client
   attributes in an LDAP directory infrastructure.

3.1.5   iSCSI

   iSCSI (Internet SCSI) is an encapsulation of SCSI for a new
   generation of storage devices interconnected with TCP/IP.

3.1.6   iFCP

   iFCP (Internet FCP) is a gateway-to-gateway protocol designed to
   interconnect existing Fibre Channel and SCSI devices using TCP/IP.
   iFCP maps the existing FCP standard and associated Fibre Channel
   services to TCP/IP.

3.2      iSNS Functional Overview

   iSNS Protocol registration and query messages are sent by iSNS
   clients to servers, while notification messages are sent by iSNS
   servers to clients.  Messages originating at the client are sent to
   the iSNS server at the well-known iSNS TCP or UDP port number.
   Notification messages are sent by the iSNS server to any of the
   registered portals (specified by IP address and TCP or UDP port
   number) of the iSNS client's network entity.


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   There are four main functions of the iSNS:

   1)  A Name Service Providing Storage Resource Discovery

   2)  Discovery Domain (DD) and Login Control Service

   3)  State Change Notification Service

   4)  Open Mapping of Fibre Channel and iSCSI Devices

3.2.1   Name Registration Service

   The iSNS provides a registration function to allow all entities in a
   storage network to register and query the iSNS database.  Both
   targets and initiators can register in the iSNS database, as well as
   query for information about other initiators and targets.  This
   allows, for example, a client initiator to obtain information about
   target devices from the iSNS server. This service is modeled on the
   Fibre Channel Generic Services Name Server described in FC-GS-3,
   with extensions, operating within the context of an IP network.

   The naming registration service also provides the ability to obtain
   a network unique Domain ID for iFCP gateways when required.

3.2.2   Discovery Domain and Login Control Service

   The Discovery Domain (DD) Service facilitates the partitioning of
   iSNS client devices into more manageable groupings for
   administrative and login control purposes. This allows the
   administrator to limit the login process to the more appropriate
   subset of targets registered in the iSNS.  iSNS clients must be in
   at least one common DD in order to obtain information about each
   other.  iSNS clients can be a member of multiple DD's
   simultaneously.

   The DD information stored in the iSNS can be used by various
   enforcement points in the network to configure security and access
   control policy.  For example, a DD-aware switch can block storage
   initiators from accessing targets that are not in the same DD, even
   if the initiator somehow obtained address information for a target
   outside of its DD.  This functionality is the equivalent of the
   ôHard Zoningö functionality in a Fibre Channel network.

   Login Control allows targets to subordinate their access control
   policy to the iSNS.  The target node or device downloads the list of
   authorized initiator nodes or devices from the iSNS.  Each node or
   device is uniquely identified by an iSCSI Name or Port Name (iFCP).
   Only initiator nodes or devices that match the required
   identification and authenticating information provided by the iSNS
   will be allowed access by that target node or device during session
   establishment.  If spoofing of initiator identities is a concern,
   the target may use the public key certificate of the authorized
   initiator, obtained from the iSNS server, to authenticate the
   initiator.

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   DD's can be managed offline by a separate management workstation,
   through the iSNSP or through SNMP.  If the target opts to use the
   Login Control feature of the iSNS, the target subordinates
   management of access control policy (i.e., the list of initiators
   allowed to login to that target) to the management workstations that
   are manipulating information in the iSNS database.

   If administratively authorized, a target can upload its own Login
   Control list.  This is accomplished using the DDReg message and
   listing the iSCSI Name of each initiator to be registered in the
   Target's DD.

   Depending on the implementation, newly registered devices that have
   not explicitly been placed into a DD by the management station MAY
   be placed into a "default DD" where they are visible to other
   devices in that DD.  Other implementations MAY decide that they are
   registered with no DD, making them inaccessible to source-scoped
   iSNSP messages.

   The iSNS server MUST use every iSNSP message containing the SOURCE
   field  to determine the source of the request and scope the
   operation to the set of Discovery Domains that the iSNS client is a
   member of.   In addition, the SOURCE field MAY also be used to
   determine whether the specified node is authorized to perform the
   specified iSNS operation.  For example, an iSNS server
   implementation may decide that only CONTROL nodes (identified by the
   iFCP or iSCSI Node Type bitmap) are authorized to create or delete
   discovery domains.

   Valid and active Discovery Domains (DD's) belong to at least one
   active Discovery Domain Sets (DDS's).  Discovery Domains that do not
   belong to an activated DDS are not enabled.

3.2.3   State Change Notification Service

   The State Change Notification (SCN) service allows the iSNS to issue
   notifications about network events that affect the operational state
   of iSNS clients. The iSNS client has the ability to register for
   these notifications of events detected by the iSNS.  The types of
   events for which SCNs can be sent include change in Discovery Domain
   (DD) membership and device registration updates.

   The State Change Notification service utilizes the Discovery Domain
   Service to control the distribution of notification messages.
   Notifications about changes within a DD are limited to members of
   that DD.

   If the iSNS is unable to service an SCN registration it SHALL reject
   the SCN registration request, returning a SCN Registration Rejected
   error code.  The rejection might occur in situations where the
   network size, or current level of SCN registrations, has passed an
   implementation-specific threshold.  A client not allowed to register
   for SCNs SHOULD monitor its sessions with other storage devices
   directly.

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   The specific notification mechanism by which the iSNS learns of the
   events is implementation-specific, but can include examples such as
   explicit notification messages from an iSNS client to the iSNS
   server, or a hardware interrupt to a switch-hosted iSNS as a result
   of link failure.  The iSNS is equivalent to the Fibre Channel State
   Change Notification service, with extensions, operating within the
   context of an IP network.

3.2.4   Open Mapping Between Fibre Channel and iSCSI Devices

   The iSNS database stores naming and discovery information about both
   Fibre Channel and iSCSI devices.  This allows the iSNS to store
   mappings of Fibre Channel devices to a proxy iSCSI device "image" in
   the IP network.  Fibre Channel-aware management stations that
   interact with the iSNS server can use this information to manage
   Fibre Channel devices as well as iSCSI devices.  This allows
   Discovery Domain and State Change Notification functionality to be
   seamlessly applied for both iSCSI and Fibre Channel devices.

3.3      iSNS and Domain Name System (DNS)

   A directory-enabled iSNS implementation may use LDAP to store iSNS
   client attributes.  If this is the case, then LDAP can be used to
   support both the iSNS and DNS server infrastructures, maintaining
   consistency in Domain Name-to-IP address mappings used by DNS and
   iSNS.

   A detailed description of the Domain Name System (DNS) protocol is
   found in [RFC 1035], and is beyond the scope of this document. If a
   common LDAP information base is used to support both DNS and iSNS
   servers, then Domain-Name-to-IP address mappings for storage devices
   can be obtained from either DNS servers or the iSNS.

3.4      iSNS and LDAP

   LDAP is a generic protocol to access directory services through the
   network.  It is a passive service designed to deliver scalable
   directory services using a get/set model.  Applications designed and
   tailored to specific user requirements interact with LDAP for their
   generic directory service needs.  On the other hand, iSNS is an
   application that goes beyond the simple get/set model, and provides
   specific capabilities needed to monitor and manage an enterprise-
   scale storage network.  iSNS is one example of an application that
   can leverage the services of LDAP.  By layering iSNS on top of LDAP,
   the capabilities of both iSNS and LDAP can be leveraged to manage
   and scale the enterprise IP storage network.

   The iSNS application provides capabilities that LDAP alone is not
   designed to achieve.  This includes the following:

   1)  Client Attribute Awareness - The iSNS server application
       interprets attribute values submitted by clients in registration
       messages, and can take appropriate action based upon specific


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       registered attribute values.  The iSNS server is conscious of
       the state of each client.

   2)  State Change Notification - An iSNS server may initiate
       notification messages to clients in the event of a change in the
       network, such as the non-availability or reachability of a
       storage device, or a specific change in the value of a client
       attribute.

   3)  Monitoring of Clients - iSNS provides a Entity Status Inquiry
       message to verify the availability and reachability of storage
       devices.

   4)  Lightweight - iSNSP is a simple and lightweight protocol
       suitable for implementation on embedded devices such as switches
       and targets.  There are no unused or "wasted" features that may
       bog down the performance of the host device.

3.5      iSNS Server Discovery

   The Service Location Protocol (SLP) provides a flexible and scalable
   framework for providing hosts with access to information about the
   existence, location, and configuration of networked services,
   including the iSNS server.  SLP MAY be used by iSNS clients to
   discover the IP address of the iSNS server.  To implement discovery
   through SLP, a Service Agent (SA) should be cohosted in the iSNS
   server, and a User Agent (UA) should be in each iSNS client. Each
   client multicasts a discovery message requesting the IP address of
   the iSNS server(s).  The SA responds to this request.  Optionally,
   the location of the iSNS can be stored in the SLP Directory Agent
   (DA).

   Note that a complete description and specification of SLP can be
   found in [RFC2608], and is beyond the scope of this document.
   Additional details on use of SLP to discover iSNS can be found in
   the document draft-bakke-iscsi-slp-00.txt.

   If SLP is not used, then the IP address of the iSNS server can be
   stored in a DHCP server to be downloaded using a DHCP option, such
   as any of the reserved site-specific option codes (from 128 to 255).
   Another approach is to configure each iSNS client to listen to the
   iSNS Name Service Heartbeat message.  A final approach would be to
   manually configure the IP address of the iSNS server in each iSNS
   client.

3.6      iSNS and NAT

   The existence of NAT will have an impact upon information retrieved
   from the iSNS.  If the iSNS client exists in a different addressing
   domain than the iSNS server, then IP address information stored in
   the iSNS server may not be correct when interpreted in the domain of
   the iSNS client.



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   There are several possible approaches to allow operation of iSNS
   within a NAT network.  The first approach is to require use of the
   canonical TCP port number by both targets and initiators when
   addressing targets across a NAT boundary, and for the iSNS client to
   not query for nominal IP addresses.  Rather, the iSNS client
   initiator queries for the DNS Fully Qualified Domain Name stored in
   the Entity Identifier field, when seeking addressing information.
   Once retrieved, the DNS name can be interpreted in each address
   domain and mapped to the appropriate IP address by local DNS
   servers.

   A second approach is to deploy a distributed network of iSNS
   servers.  Local iSNS servers are deployed inside and outside NAT
   boundaries, with each local server storing relevant IP addresses for
   their respective NAT domains.  Updates among the network of
   decentralized, local iSNS servers are handled using LDAP and using
   appropriate NAT translation rules implemented within the update
   mechanism in each server.

   The final alternative is to simply disallow use of NAT in between
   communication between the iSNS server and any iSNS client.

3.7      Interactions Between iSNS Infrastructures

   Each individual iSNS deployment is designed to be operated in
   networks under the control of a single administrative authority.
   This administrative authority facilitates a seamless, integrated
   policy for iSNS usage, including security, naming and registration
   of storage assets, and management of Discovery Domains.  Through
   leverage of an Internet-based database framework such as LDAP, the
   iSNS not only scales to large storage networks, but also to support
   interactions among multiple independently managed storage
   infrastructures, each managed by its own administrative authority.

   The information registered in the iSNS can be shared with other iSNS
   servers managed by other administrative authorities through out-of-
   band, non-iSNS protocols.  By importing registration information
   from a remote iSNS server, storage connectivity can be established
   to devices managed by that server.

   The following examples illustrate possible methods to transfer iSNS
   records of devices between autonomous, independently-administered
   iSNS servers.  In the first example, a back-end LDAP information
   base is used to support the iSNS server.  The following diagram
   illustrates use of the LDAP protocol to import iSNS registration
   information from one iSNS server to another.  Once the record
   transfer of the remote device is completed, it becomes visible and
   accessible to local devices on the local iSNS server.  This allows
   local devices to establish sessions with remote devices (provided
   firewall boundaries can be negotiated).





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   +-------------------------+           +-------------------------+
   |+------+ iSNSP           |           |           iSNSP +-----+ |
   ||dev A |<----->+------+  |           |  +------+<----->|dev C| |
   |+------+       |      |  |           |  |      |       +-----+ |
   |+------+ iSNSP |local |  |           |  |remote| iSNSP +-----+ |
   ||dev B |<----->| iSNS |  |           |  | iSNS |<----->|dev D| |
   |+------+       |      |  |           |  |      |       +-----+ |
   |........       +--+---+  |   WAN     |  +---+--+               |
   |.dev C'.          |      |   Link    |      |                  |
   |........          |      =============      |                  |
   |                  |      |           |      |                  |
   |               +--+---+  |           |  +---+--+               |
   |               | local|<--- <--- <--- <-|remote|               |
   |               | LDAP |  |  LDAP:    |  | LDAP |               |
   |               +------+  Xfer "dev C"|  +------+               |
   +-------------------------+           +-------------------------+
          Enterprise                           Enterprise
          Network A                            Network B

   In the above diagram, two business partners wish to share storage
   "dev C". Using LDAP, the record for "dev C" can be transfered from
   Network B to Network A.  Once accessible to the local iSNS in
   Network A, local devices A and B can now discover and connect to
   "dev C".

   +-------------------------+           +-------------------------+
   |+------+ iSNSP           |           |           iSNSP +-----+ |
   ||dev A |<----->+------+  |           |  +------+<----->|dev C| |
   |+------+       |      |  |           |  |      |       +-----+ |
   |+------+ iSNSP |local |  |           |  |remote| iSNSP +-----+ |
   ||dev B |<----->| iSNS |  |           |  | iSNS |<----->|dev D| |
   |+------+       |      |  |           |  |      |       +-----+ |
   |........       +------+  |   WAN     |  +---+--+               |
   |.dev C'.          ^      |   Link    |      |                  |
   |........          |      =============      v                  |
   |                  |      |           |      |SNMP              |
   |                  |      |           |      |                  |
   |               +--+----+ |           |      v                  |
   |               | SNMP  |<--- <--- <--- <----                   |
   |               | Mgmt  | |  SNMP: Xfer "dev C"                 |
   |               |Station| |           |                         |
   |               +-------+ |           |                         |
   +-------------------------+           +-------------------------+
          Enterprise                           Enterprise
          Network A                            Network B


   The above diagram illustrates a second example of how iSNS records
   can be shared.  In this case, the iSNS servers are not using LDAP to
   store records.  This method uses an SNMP-based management station to
   manually download the desired record for "dev C", and then directly
   upload it to the local iSNS. Once the record is transfered to the
   local iSNS in Network A, "dev C" becomes visible and accessible


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   (provided firewall boundaries can be negotiated) to other devices in
   Network A.

   Other methods, including proprietary protocols, can be used to
   transfer device records between independently-administered iSNS
   servers.  Further discussion and explanation of these methodologies
   is beyond the scope of this document.

3.8      Deployment Architecture Diagram

   The following diagram displays examples of where and how iSNS can be
   deployed, and of the various IP-based storage entities that it can
   support.

    +------------+          +-----------+          +-----------+
    |            |   LDAP   | Directory |   LDAP   |   iSNS    |
    | DNS Server |<-------->|  Database |<-------->|  Server   |
    |            |          |           |          |           |
    +------+-----+          +-----+-----+          +-----+-----+
           |                      |                      |
           | DNS                  | LDAP           iSNSP |
           |Queries               |                      |
    +------+----------------------+----------------------+---------+
    |                                                              |
    |                         IP Network                           |
    |                                                              |
    +----+-----------+----------+---------------+------------------+
         |           |          |               |
         |           |    +-----+-----+  +------+-----+
         |           |    |iSCSI-/    |  |iFCP   /    |
         |           |    | FC  /iSNS |  |Switch/iSNS |
         |           |    |Gtwy/Server|  |     /Server|
         |           |    +----+------+  +-+-------+--+
         |           |         |           |       |
    +----+----+ +----+---+ +---+----+ +----+-+ +---+----+
    |  iSCSI  | |  iSCSI | | Fibre  | |  FC  | | Fibre  |
    |Initiator| | Target | |Channel | |Device| |Channel |
    +---------+ +--------+ |Network | +------+ |Network |
                           +--------+          +--------+

4.       iSNS Object Model

   iSNS provides the framework for the registration, discovery, and
   management of iSCSI devices and Fibre Channel-based devices (using
   iFCP).  This architecture defines common objects that can be used to
   represent components referenced by each of these protocols.

   This architecture framework provides elements needed to describe
   various storage device objects and attributes that may exist on an
   IP storage network.  Objects defined in this architecture framework
   include SAN, NETWORK ENTITY, PORTAL, STORAGE NODE, STORAGE DEVICE
   DISCOVERY DOMAIN, and DISCOVERY DOMAIN SET.  Each of these objects
   are described in greater detail in the following sections.


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4.1      NETWORK ENTITY Object

   The NETWORK ENTITY object is a container of STORAGE NODE objects and
   PORTAL objects.  It represents a logical device or gateway that is
   accessible from the IP network.  All STORAGE NODEs and PORTALs
   contained within a single NETWORK ENTITY object operate in a
   coordinated manner.

   Note that it is possible for a single physical device or gateway to
   be represented by more than one logical Network Entity in the iSNS
   database.  For example, one of the storage nodes on a physical
   device may be accessible from only a subset of the network
   interfaces (i.e., portals) available on that device.  In this case,
   a logical network entity (i.e., a "shadow entity") is created and
   used to contain the portals and storage nodes that can operate
   cooperatively.  No object (portals, storage nodes, etc...) can be
   contained by more than one logical Network Entity.

4.2      PORTAL Object

   The PORTAL object is an IP interface through which access to any
   STORAGE NODE within the NETWORK ENTITY can be obtained.  A NETWORK
   ENTITY should have one or more PORTALs, each of which is usable by
   STORAGE NODEs contained in that NETWORK ENTITY to gain access to, or
   be accessible from, the IP network.

4.3      STORAGE NODE Object

   The STORAGE NODE object is the logical endpoint of an iSCSI or iFCP
   connection session. In iFCP, the session endpoint is represented by
   the World Wide Port Name (WWPN).  In iSCSI, the session endpoint is
   represented by the iSCSI Name of the device.

4.4      FC DEVICE Object (iFCP Only)

   The FC DEVICE represents the Fibre Channel end node.  Although
   mostly unused in support of the iFCP storage connection, this object
   contains information that may be useful in the management of the
   Fibre Channel device.

4.5      DISCOVERY DOMAIN Object

   DISCOVERY DOMAINS (DD) are a security and management mechanism used
   to partition storage resources.  Discovery Domains limit the
   discovery process to the administrator-configured subset of relevant
   storage devices, preventing initiators from inappropriately
   attempting login to devices that they shouldnÆt have access to.
   When queried, the iSNS server will provide information only for
   storage entities that share at least one common DD.  Initiators will
   not be able to "see" devices with which they do not have at least
   one common DD.




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4.6      DISCOVERY DOMAIN SET Object

   The DISCOVERY DOMAIN SET (DDS) is a container object for DDÆs.
   DDSÆs may contain one or more DDÆs.  Similarly, each DD can be a
   member of one or more DDSÆs.  DDSÆs are a mechanism to store
   coordinated sets of DD mappings in the iSNS.

4.7      iSNS Database Model

   The following shows the the various objects described above and
   their relationship to each other.

                    +--------------+    +-----------+
                    |    NETWORK   |1  *|           |
                    |    ENTITY    |----|  PORTAL   |
                    |              |    |           |
                    +--------------+    +-----------+
                            | 1
                            |
                            |
                            | *
   +-----------+    +--------------+    +-----------+    +-----------+
   |    FC     |1  *|   STORAGE    |*  *| DISCOVERY |*  *| DISCOVERY |
   |  DEVICE   |----|    NODE      |----|  DOMAIN   |----|  DOMAIN   |
   |(iFCP Only)|    |              |    |           |    |    SET    |
   +-----------+    +--------------+    +-----------+    +-----------+

                * represents 0 to many possible relationships


5.       iSNS Implementation Requirements

   iSNS can be implemented with features to support iSCSI and/or iFCP.
   Implementation of support for either or both of these protocols is
   OPTIONAL. IF iSNS is implemented to support a particular protocol,
   then a minimum set of attributes and iSNSP commands is REQUIRED for
   support of that protocol. This section details specific requirements
   for support of each of these IP storage protocols.

5.1      iSCSI Requirements

   Use of iSNS in support of iSCSI is OPTIONAL.  iSCSI devices MAY be
   manually configured with the iSCSI Name and IP address of peer
   devices, without the aid or intervention of iSNS.  iSCSI devices
   also MAY use SLP [RFC 2608] to discover peer iSCSI devices.
   However, for scaling a storage network to a larger number of iSCSI
   devices, use of iSNS is RECOMMENDED.

5.1.1   Required Attributes for Support of iSCSI

   The following attributes are available to support iSCSI.  Attributes
   indicated in the REQUIRED TO IMPLEMENT column MUST be supported by
   an iSNS server used to support iSCSI.  Attributes indicated in the


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   REQUIRED TO USE column MUST be supported by an iSCSI device that
   elects to use the iSNS.

                                               REQUIRED     REQUIRED
   Object                Attribute           to Implement   to Use
   ------                ---------           ------------   --------
   NETWORK ENTITY     Entity Identifier            *           *
                      Entity Protocol              *           *
                      Management IP Address
                      Timestamp                    *
                      Protocol Version Range       *
                      Entity Certificate
                      IKE Phase-1 Proposal

   PORTAL             IP Address                   *           *
                      TCP/UDP Port                 *           *
                      Portal Symbolic Name         *
                      ESI Interval                 *
                      ESI Port                     *
                      Portal Group                 *
                      Portal Certificate

   STORAGE NODE       iSCSI Name                   *           *
                      Node Type                    *           *
                      Alias/Symbolic Node Name     *
                      SCN Event Bitmap             *
                      iSCSI Security Bitmap        *
                      ISAKMP Phase-2 Proposal
                      Pre-Shared Key
                      Node Certificate


   DISCOVERY DOMAIN   DD_ID                        *           *
                      DD_Symbolic Name             *

   DISCOVERY DOMAIN   DDS Identifier               *
   SET                DDS Symbolic Name            *
                      Status                       *


   All iSCSI user-specified and vendor-specified attributes are
   optional to implement and use.

5.1.2   Example iSCSI Object Model Diagrams

   The following diagram models how a simple iSCSI-based initiator and
   target is represented using database objects stored in the iSNS.  In
   this implementation, each target and initiator is attached to a
   single PORTAL.






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   +----------------------------------------------------------------+
   |                         IP Network                             |
   +------------+--------------------------------------+------------+
                |                                      |
                |                                      |
   +-----+------+------+-----+            +-----+------+------+-----+
   |     | PORTAL      |     |            |     | PORTAL      |     |
   |     | -IP Addr 1  |     |            |     | -IP Addr 2  |     |
   |     | -TCP Port 1 |     |            |     | -TCP Port 2 |     |
   |     +-----+ +-----+     |            |     +-----+ +-----+     |
   |           | |           |            |           | |           |
   |           | |           |            |           | |           |
   |  +--------+ +--------+  |            |   +-------+ +--------+  |
   |  |                   |  |            |   |                  |  |
   |  |  STORAGE NODE     |  |            |   |  STORAGE NODE    |  |
   |  |  -iSCSI Name      |  |            |   |   -iSCSI Name    |  |
   |  |  -Alias: "server1"|  |            |   |   -Alias: "disk1"|  |
   |  |  -Type: initiator |  |            |   |   -Type: target  |  |
   |  |                   |  |            |   |                  |  |
   |  +-------------------+  |            |   +------------------+  |
   |                         |            |                         |
   |    NETWORK ENTITY       |            |    NETWORK ENTITY       |
   |   -Entity ID (FQDN):    |            |   -Entity ID (FQDN):    |
   |    "strg1.foo.com"      |            |    "strg2.bar.com"      |
   |   -Protocol: iSCSI      |            |   -Protocol: iSCSI      |
   |                         |            |                         |
   +-------------------------+            +-------------------------+

   The object model can be expanded to describe more complex devices,
   such as an iSCSI device with more than one storage controller, each
   controller accessible through any of multiple PORTAL interfaces.
   The storage controllers on this device which can be accessed through
   alternate PORTAL interfaces, if any original interface should fail.
   The following diagram describes such a device:





















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   +---------------------------------------------------------------+
   |                         IP Network                            |
   +-------------------+-----------------------+-------------------+
                       |                       |
                       |                       |
   +------------+------+------+---------+------+------+------------+
   |            | PORTAL      |         | PORTAL      |            |
   |            | -IP Addr 1  |         | -IP Addr 2  |            |
   |            | -TCP Port 1 |         | -TCP Port 2 |            |
   |            +-----+ +-----+         +-----+ +-----+            |
   |                  | |                     | |                  |
   |  +---------------+ +---------------------+ +---------------+  |
   |  +-------+ +----------------+ +-------------------+ +------+  |
   |          | |                | |                   | |         |
   |  +-------+ +-------+ +------+ +--------+ +--------+ +------+  |
   |  |                 | |                 | |                 |  |
   |  | STORAGE NODE    | | STORAGE NODE    | | STORAGE NODE    |  |
   |  |  -iSCSI Name 1  | |  -iSCSI Name 2  | |  -iSCSI Name 3  |  |
   |  |  -Alias: "disk1"| |  -Alias: "disk2"| |  -Alias: "disk3"|  |
   |  |  -Type: target  | |  -Type: target  | |  -Type: target  |  |
   |  |                 | |                 | |                 |  |
   |  +-----------------+ +-----------------+ +-----------------+  |
   |                                                               |
   |                         NETWORK ENTITY                        |
   |                    -Entity ID (FQDN): "dev1.foo.com"          |
   |                    -Protocol: iSCSI                           |
   |                                                               |
   +---------------------------------------------------------------+


5.1.3   Required Commands and Response Messages for Support of iSCSI

   The following are iSNSP messages and responses are available in
   support of iSCSI.  Messages indicated in the REQUIRED TO IMPLEMENT
   column MUST be implemented in iSNS servers used for iSCSI devices.
   Messages indicated in the REQUIRED TO USE column must be implemented
   in iSCSI devices that elect to use the iSNS.


















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                                                     REQUIRED TO:
      Message Description    Abbreviation  Func ID  Implement  Use
      -------------------    ------------  -------  ---------  ---
   Register Dev Attr Req     RegDevAttr    0x0001       *       *
   Dev Attr Query Request    DevAttrQry    0x0002       *       *
   Dev Get Next Request      DevGetNext    0x0003       *
   Deregister Dev Request    DeregDev      0x0004       *       *
   SCN Register Request      SCNReg        0x0005       *
   SCN Deregister Request    SCNDereg      0x0006       *
   SCN Event                 SCNEvent      0x0007       *
   State Change Notification SCN           0x0008       *
   DD Register               DDReg         0x0009       *       *
   DD Deregister             DDDereg       0x000A       *       *
   DDS Register              DDSReg        0x000B       *       *
   DDS Deregister            DDSDereg      0x000C       *       *
   Entity Status Inquiry     ESI           0x000D       *
   Name Service Heartbeat    Heartbeat     0x000E
   NOT USED                                0x000F-0x0013
   RESERVED                                0x0014-0x00FF
   Vendor Specific                         0x0100-0x01FF
   RESERVED                                0x0200-0x8000


   The following are iSNSP response messages used in support of iSCSI:

                                                     REQUIRED TO:
   Response Message Desc     Abbreviation  Func_ID  Implement  Use
   ---------------------     ------------  -------  ---------  ---
   Register Dev Attr Rsp     RegDevRsp     0x8001       *       *
   Dev Attr Query Rsp        DevAttrQryRsp 0x8002       *       *
   Dev Get Next Rsp          DevGetNextRsp 0x8003       *
   Deregister Dev Rsp        DeregDevRsp   0x8004       *       *
   SCN Register Rsp          SCNRegRsp     0x8005       *
   SCN Deregister Rsp        SCNDeregRsp   0x8006       *
   SCN Event Rsp             SCNEventRsp   0x8007       *
   SCN Response              SCNRsp        0x8008       *
   DD Register Rsp           DDRegRsp      0x8009       *       *
   DD Deregister Rsp         DDDeregRsp    0x800A       *       *
   DDS Register Rsp          DDSRegRsp     0x800B       *       *
   DDS Deregister Rsp        DDSDeregRsp   0x800C       *       *
   Entity Stat Inquiry Rsp   ESIRsp        0x800D       *
   NOT USED                                0x800E-0x8013
   RESERVED                                0x8014-0x80FF
   Vendor Specific                         0x8100-0x81FF
   RESERVED                                0x8200-0xFFFF


5.2      iFCP Requirements

   In iFCP, use of iSNS is REQUIRED.  No alternatives exist for support
   of iFCP Naming & Discovery functions.  iSNS is integral to the
   operation of iFCP, in order to allow iFCP gateways to execute Fibre
   Channel S_ID and D_ID address mappings to remote gateways.


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5.2.1   Required Attributes for Support of iFCP

   The following table displays attributes that are used by iSNS to
   support iFCP.  Attributes indicated in the REQUIRED TO IMPLEMENT
   column MUST be supported by the iSNS server that supports iFCP.
   Attributes indicated in the REQUIRED TO USE column MUST be supported
   by iFCP gateways.














































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                                               REQUIRED     REQUIRED
   Object                Attribute           to Implement    to Use
   ------                ---------           ------------   --------
   NETWORK ENTITY     Entity Identifier            *           *
                      Entity Protocol              *           *
                      Management IP Address
                      Timestamp                    *
                      Protocol Version Range       *
                      Entity Certificate
                      IKE Phase-1 Proposal

   PORTAL             IP Address                   *           *
                      TCP/UDP Port                 *           *
                      Portal Symbolic Name         *
                      ESI Interval                 *
                      ESI Port                     *
                      Portal Group                 *
                      Portal Certificate

   STORAGE NODE       Port Name (WWPN)             *           *
                      Port_ID                      *           *
                      Port Type                    *           *
                      Port Symbolic Name           *
                      FC Fabric Port Name (FWWN)   *
                      FC Hard Address              *
                      FC Port IP Address           *
                      FC Class of Service          *
                      FC FC-4 Types                *
                      FC FC-4 Descriptors          *
                      FC FC-4 Features             *
                      SCN Event Bitmap             *
                      iFCP Security Bitmap         *
                      IKE Phase-2 Proposal
                      Pre-Shared Key
                      Node Certificate

   FC DEVICE          Port Name (WWPN)             *           *
                      Node Type                    *           *
                      Alias/Node Symbolic Name     *
                      FC Node IP Address           *
                      FC Node IPA                  *

   DISCOVERY DOMAIN   DD_ID                        *           *
                      DD_Symbolic Name             *

   DISCOVERY DOMAIN   DDS Identifier               *
   SET                DDS Symbolic Name            *
                      Status                       *


5.2.2   iFCP Attribute Requirements

5.2.2.1  Port_ID


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   Port_ID assignments for each STORAGE NODE object within a single
   NETWORK ENTITY SHALL be unique.  For each NETWORK ENTITY (i.e., iFCP
   gateway), no more than one STORAGE NODE can be assigned a given
   PORT_ID value.

5.2.3   Example iFCP Object Model Diagram

   The iFCP protocol allows native Fibre Channel devices, or Fibre
   Channel fabrics connected to an iFCP gateway, to be directly
   internetworked using IP.

   When supporting iFCP, the iSNS stores Fibre Channel device
   attributes, iFCP gateway attributes, and Fibre Channel fabric switch
   attributes that might also be stored in an FC name server.

   The following diagram shows a representation of a gateway supporting
   multiple Fibre Channel devices behind it.  The two PORTAL objects
   represent IP interfaces on the iFCP gateway that can be used to
   access any of the three STORAGE NODE objects behind it.  Note that
   the FC DEVICE object is not contained in the NETWORK ENTITY object.
   However, each FC DEVICE has a relationship to one or more STORAGE
   NODE objects.

   +--------------------------------------------------------+
   |                         IP Network                     |
   +--------+-----------------+-----------------------------+
            |                 |
   +-+------+------+---+------+------+----------------------+
   | | PORTAL      |   | PORTAL      |    NETWORK ENTITY    |
   | | -IP Addr 1  |   | -IP Addr 2  |   -Entity ID (FQDN): |
   | | -TCP Port 1 |   | -TCP Port 2 |    ôgtwy1.foo.comö   |
   | +-----+ +-----+   +-----+ +-----+   -Protocol: iFCP    |
   |       | |               | |                            |
   | +-----+ +---------------+ +----------------------+     |
   | +-----+ +---------------+ +-------------+ +------+     |
   |       | |               | |             | |            |
   | +-----+ +-----+    +----+ +------+ +----+ +------+     |
   | |STORAGE NODE |    |STORAGE NODE | |STORAGE NODE |     |
   | | -WWPN 1     |    | -WWPN 2     | | -WWPN 3     |     |
   | | -Port ID 1  |    | -Port ID 2  | | -Port ID 3  |     |
   | | -FWWN 1     |    | -FWWN 2     | | -FWWN 3     |     |
   | | -FC COS     |    | -FC COS     | | -FC COS     |     |
   | +------+------+    +-------+-----+ +----+--------+     |
   +--------|-------------------|------------|--------------+
            |                   |            |
     +------+------+        +---+------------+---+
     | FC DEVICE   |        |    FC DEVICE       |
     | -WWNN 1     |        |   -WWNN 2          |
     |             |        |                    |
     +-------------+        +--------------------+



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5.2.4   Required Commands and Response Messages for Support of iFCP

   The iSNSP messages and responses displayed in the following tables
   are available to support iFCP gateways.  Messages indicated in the
   REQUIRED TO IMPLEMENT column MUST be supported by the iSNS server
   used by iFCP gateways.  Messages indicated in the REQUIRED TO USE
   column MUST be supported by the iFCP gateways themselves.

                                                     REQUIRED TO:
      Message Description    Abbreviation  Func ID  Implement  Use
      -------------------    ------------  -------  ---------  ---
   Register Dev Attr Req     RegDevAttr    0x0001       *       *
   Dev Attr Query Request    DevAttrQry    0x0002       *       *
   Dev Get Next Request      DevGetNext    0x0003       *
   Deregister Dev Request    DeregDev      0x0004       *       *
   SCN Register Request      SCNReg        0x0005       *
   SCN Deregister Request    SCNDereg      0x0006       *
   SCN Event                 SCNEvent      0x0007       *
   State Change Notification SCN           0x0008       *
   DD Register               DDReg         0x0009       *       *
   DD Deregister             DDDereg       0x000A       *       *
   DDS Register              DDSReg        0x000B       *       *
   DDS Deregister            DDSDereg      0x000C       *       *
   Entity Status Inquiry     ESI           0x000D       *
   Name Service Heartbeat    Heartbeat     0x000E       *
   Reserved                  Reserved      0x000F-0x0010
   Request Switch ID         RqstSwId      0x0011
   Release Switch ID         RlseSwId      0x0012
   Get Switch IDs            GetSwIds      0x0013
   RESERVED                                0x0014-0x00FF
   Vendor Specific                         0x0100-0x01FF
   RESERVED                                0x0200-0x8000


   The following are iSNSP response messages in support of iFCP:




















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                                                     REQUIRED TO:
   Response Message Desc     Abbreviation  Func_ID  Implement  Use
   ---------------------     ------------  -------  ---------  ---
   Register Dev Attr Rsp     RegDevRsp     0x8001       *       *
   Dev Attr Query Resp       DevAttrQryRsp 0x8002       *       *
   Dev Get Next Resp         DevGetNextRsp 0x8003       *
   Deregister Dev Resp       DeregDevRsp   0x8004       *       *
   SCN Register Resp         SCNRegRsp     0x8005       *
   SCN Deregister Resp       SCNDeregRsp   0x8006       *
   SCN Event Resp            SCNEventRsp   0x8007       *
   SCN Response              SCNRsp        0x8008       *
   DD Register Rsp           DDRegRsp      0x8009       *       *
   DD Deregister Rsp         DDDeregRsp    0x800A       *       *
   DDS Register Rsp          DDSRegRsp     0x800B       *       *
   DDS Deregister Rsp        DDSDeregRsp   0x800C       *       *
   Entity Stat Inquiry Resp  ESIRsp        0x800D       *
   NOT USED                                0x800E
   RESERVED                                0x800F-0x8010
   Request Switch ID Resp    RqstSwIdRsp   0x8011
   Release Switch ID Resp    RlseSwIdRsp   0x8012
   Get Switch IDs            GetSwIdRsp    0x0013
   RESERVED                                0x8014-0x80FF
   Vendor Specific                         0x8100-0x81FF
   RESERVED                                0x8200-0xFFFF


5.3      Attribute Descriptions for Discovery Domain Registration

   Discovery Domains are logical groupings of initiators and targets
   that are used to limit the login process to the appropriate subset
   of devices registered in the iSNS.

   Support for Discovery Domains is required for all protocols.  The
   iSNS attributes for Discovery Domain, and Discovery Domain Set,
   registration are shown in the following figure:




















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   DISCOVERY DOMAIN SET
      |
      - DD Set_ID
      - DD Set_Symbolic Name
      - DD Set Enabled/Disabled

   DD SET_MEMBER
      |
      - DD Set_ID
      - DD_ID

   DISCOVERY DOMAIN
      |
      - DD_ID
      - DD_Symbolic Name
      - DD Features

   DD_MEMBER
      |
      - DD_ID
      - Entity Identifier, iSCSI Name, or WWPN


   Members of a Discovery Domain can be defined by registering one of
   the following storage entity attributes in a Discovery Domain:

        - iSCSI Name       : this places the individual iSCSI
                             storage node in the Discovery Domain
        - WWPN             : this places the iFCP Storage Node in the
                             Discovery Domain

5.4      Use of TCP For iSNS Communication

   TCP can be used for all iSNS communication.  The iSNS server SHALL
   accept TCP connections for client registrations.  The TCP port used
   by the iSNS server to receive TCP messages used SHALL be <<TBD>>.
   The client can also use multiple streams to register attributes and
   communicate with the server.

   To register for ESI monitoring using TCP, the client SHALL register
   the Portal ESI Interval using the TCP connection that will be used
   to receive ESI inquiry messages.

   To register for SCN notifications using TCP, the client SHALL
   register the iSCSI/iFCP SCN Bitmap using the TCP connection that
   SHALL be used to receive SCN notification messages.

   This allows the client to be flexible about how many and which
   connections will be used for each feature.  Using the above method,
   a client can optionally open one stream and use it for SCN, ESI, and
   iSNS queries.  A client may also open up 3 sessions: one for ESI,
   one for SCN, and another for iSNS queries.



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   If a TCP connection supporting ESI or SCN messages goes down, and
   the client creates a new connection for the ESI or SCN messages,
   then the client must reregister for ESI's and/or SCN's on the new
   connection.

5.5      Use of UDP For iSNS Communication

   The iSNS server MAY accept UDP messages for client registrations.
   The iSNS server SHALL accept registrations from clients requesting
   UDP-based ESI and SCN messages.  The UDP port used to receive
   messages SHALL be <<TBD>>.

   To register for UDP-based ESI monitoring messages, the client SHALL
   register the Portal ESI/SCN UDP Port to be used for communication of
   ESI messages from the server to the client.

   To register for UDP-based SCN notifications messages, the client
   SHALL register at least one Portal ESI/SCN UDP port to be used for
   communication of SCN messages from the server to the client.  If an
   entity has multiple Portals with registered ESI/SCN UDP Ports, then
   ESI and SCN messages SHALL be delivered to each Portal registered to
   receive such messages.

6.       iSNS Message Attributes

   When an iSNS client registers with the iSNS server, it provides
   attribute values to describe the entity characteristics and
   capabilities.  The iSNS server also returns the attributes in
   response to queries.

6.1      iSNS Attribute Summary

   The following table lists all iSNSP message attributes for device
   registration and queries:





















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   T Entity Attributes       Length  Tag  Reg Key Query Key
   - ----------------------- ------  ---  ------- -----------
     Delimiter               0-256   0    N/A     N/A
   ^ Entity Identifier (EID) 0-256   1    1|@     @|1|2|16,17|32|64
   & Entity Protocol         4       2    1       @|1|2|16,17|32|64
     Mgt IP Address          16      3    1       @|1|2|16,17|32|64
   = Timestamp               8       4    1       @|1|2|16,17|32|64
     Protocol Version Range  4       5    1       @|1|2|16,17|32|64
     Registration Period     4       6    1       @|1|2|16,17|32|64
     Entity Index            4       7    1       @|1|2|16,17|32|64
     ISAKMP Phase-1 Prop     var     11   1       @|1|2|16,17|32|64
   * Entity Certificate      var     12   1       @|1|2|16,17|32|64
   # Portal IP-Address       16      16   1       @|1|16,17|32|64
   $ Portal TCP/UDP Port     4       17   1       @|1|16,17|32|64
     Portal Symbolic Name    0-256   18   16,17   @|1|16,17|32|64
     ESI Interval            4       19   16,17   @|1|16,17|32|64
     ESI/SCN UDP Port        4       20   16,17   @|1|16,17|32|64
     Portal Group            4       21   16,17   @|1|16,17|32|64
     Portal Index            4       22   16,17   @|1|16,17|32|64
   * Portal Certificate      var     31   16,17   @|1|16,17|32|64
   # iSCSI Name              4-256   32   1%      @|1|16,17|32|33
   & iSCSI Node Type         4       33   32      @|1|16,17|32
     Alias                   0-256   34   32      @|1|16,17|32
     iSCSI SCN Bitmap        4       35   32      @|1|16,17|32
     iSCSI Node Index        4       36   32      @|1|16,17|32
     iSCSI Security Bitmap   4       40   32      @|1|16,17|32
     ISAKMP Phase-2 Proposal var     41   32      @|1|16,17|32
   * iSCSI Node PreShare Key var     42   32      @|1|16,17|32
   * iSCSI Node Certificate  var     43   32      @|1|16,17|32
   # iFCP Node WWPN          8       64   1%     @|1|16,17|64|66|96|128
     Port_ID                 4       65   64      @|1|16,17|64
     Port_Type               4       66   64      @|1|16,17|64
     Port_Symbolic Name      0-256   67   64      @|1|16,17|64
     FC Fabric Port Name     8       68   64      @|1|16,17|64
     FC Hard Address         4       69   64      @|1|16,17|64
     FC Port IP-Address      16      70   64      @|1|16,17|64
     FC Class of Service     4       71   64      @|1|16,17|64
     FC FC-4 Types           32      72   64      @|1|16,17|64
     FC FC-4 Descriptor      0-256   73   64      @|1|16,17|64
     FC FC-4 Features        128     74   64      @|1|16,17|64
     iFCP Node SCN bitmap    4       75   64      @|1|16,17|64
     iFCP Node Type          4       76   64      @|1|16,17|64
     iFCP Security Bitmap    4       80   64      @|1|16,17|64
   * ISAKMP Phase-2 Proposal var     81   64      @|1|16,17|64
   * iFCP Node PreShared Key var     82   64      @|1|16,17|64
   * iFCP Node Certificate   var     83   64      @|1|16,17|64
     FC-4 Type Code          4       95   Query Key only
   # FC Device WWNN          8       96   @       @|64|96
     FC Device Sym Node Name 0-256   97   96      @|64|96
     FC Device IP-Address    16      98   96      @|64|96
     FC Device IPA           8       99   96      @|64|96
   * FC Device Certificate   var    100   96      @|64|96
     Preferred ID            4      128   Switch ID msgs only
     Assigned ID             4      129   Switch ID msgs only

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     Space_Identifier        0-256  130   Switch ID msgs only
     RESERVED for iSNS server-specific    tags in range 132-255
     Company OUI             4      256
   * Vendor-Spec iSNS Srvr  var      -    tags in range 257-383
   * Vendor-Spec Entity     var      -    tags in range 384-511
   * Vendor-Spec Portal     var      -    tags in range 512-639
   * Vendor-Spec iSCSI Node var      -    tags in range 640-767
   * Vendor-Spec iFCP Node  var      -    tags in range 768-895
   * Vendor-Spec iFCP FC Node var    -    tags in range 896-1023
   * Vendor-Specific DD     var      -    tags in range 1024-1279
   * Other Vendor-Specific  var      -    tags in the range 1280-2047
     RESERVED                    2048-6000
     Standards-based Extensions  6001-12000
     RESERVED                   12001-65535


   The following is a description of the columns used in the above
   table:

   Attribute Type (T)
   --------------------------------------------------------------
   # : Required key for object registration.
   ^ : Required key for object registration, unique value is
       assigned by the iSNS if value not provided during initial
       registration.
   $ : Required as part of the key, and the canonical value is
       used if one is not registered.
   & : Attribute required during initial registration that is
       not a key.
   * : Optional to implement in the iSNS.
   = : Cannot be used as a query key or be explicitly registered.  The
       value is assigned by the iSNS at registration / update.
   @ : if no key is present then a new entry is created, or all
       entries of the operating attributes are returned.
   | : used to separate the different sets of possible keys in the
       table.
   % : If an iSCSI Name or iFCP Node WWPN is registered
       without an EID key, then an Entity will be created and an EID
       assigned.  The assigned EID will be returned in the response
       as an Operating attribute.

   Length - indicates the attribute length.  Variable-length
   identifiers are NULL character terminated, which is included in the
   length.

   Tag - the integer tag value used to identify the attribute.  All
   undefined tag values are reserved.

   Value û a description of the data.

   Implementation Notes:
   --------------------------------------------------------------



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   A well-formed registration contains the key of the object to
   register, or no key if it can be generated by the iSNS.  If an
   attribute is present as a key, then it cannot be an operating
   attribute.

   The registration response will contain the key for each object
   registered, including any key values that were assigned by the iSNS
   as part of the registration.  For example, if an entity, two
   portals, and one iFCP node was registered, then the response message
   key attributes section would contain the keys for each.  The key
   attributes, returned in the response, may be in a different order
   they appeared in the registration.

   iSNS client attributes are defined below.

6.2      Entity Identifier-Keyed Attributes

   The following attributes are registered in the iSNS using the Entity
   Identifier attribute as the key.

6.2.1   Entity Identifier (EID)

   The Entity Identifier is a variable length identifier that uniquely
   identifies each network entity registered in the iSNS.  The
   attribute length varies from 4 to 256 bytes, and is a unique value
   within the iSNS.

   If the iSNS client does not provide an EID during registration the
   iSNS shall generate one that is unique within the iSNS.  If an EID
   is to be generated, then the EID attribute value in the registration
   message shall be empty (0 length).  The generated EID shall be
   returned in the registration response.

   In environments where iSNS is integrated with a DNS infrastructure,
   the Entity Identifier may be used to store the Fully Qualified
   Domain Name (FQDN) of the iSCSI or iFCP device.

   If FQDN's are not used, the iSNS server can be used to generate
   EIDs.  By convention, EIDs generated by the iSNS server begin with
   the string ôiSNS:ö.  iSNS clients SHOULD NOT generate and register
   EIDs beginning with the string "iSNS:".

6.2.2   Entity Protocol

   Entity Protocol is a required 4-byte attribute that indicates the
   protocol of network entity that is being registered and is provided
   by the iSNS client.  The valid types are defined as below:

       Type Value      Entity Type
       ----------_     -----------
          1            iSCSI
          2            iFCP
       All Others      RESERVED


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6.2.3   Management IP Address

   This optional field is provided by the iSNS client.  It contains the
   IP Address used to manage the entity.  The Management IP Address is
   a 16-byte field that may contain either a 32-bit IPv4 or 128-bit
   IPv6 address.  When this field contains an IPv4 value, the most
   significant 12 bytes are set to 0x00.  If the network entity is
   capable of being managed and this field is not set, then in-band
   management is assumed.

6.2.4   Entity Registration Timestamp

   This field is updated by the iSNS.  It cannot be used as a query key
   or be explicitly registered.  It indicates the time the entity
   registration occurred, an associated object was updated, or the time
   of the most recent response from a message to the entity was
   received, whichever is later. The time format is, in seconds, the
   update period since the standard base time of 00:00:00 GMT on
   January 1, 1970.

6.2.5   Protocol Version Range

   This optional field is provided by the iSNS client.  This field
   contains the minimum and maximum version of the protocol supported
   by the entity.  The most significant two bytes contain the maximum
   version supported, and the least significant two bytes contain the
   minimum version supported.  If a range is not registered then the
   entity is assumed to support all versions of the protocol.

6.2.6   Registration Period

   This required field, provided by the iSNS client, indicates the
   maximum period, in seconds, that the entity registration will be
   maintained by the server without receipt of an iSNS message from the
   client.  If the Registration Period is set to 0, then the Entity
   SHALL NOT be deregistered due to no contact with the iSNS client.

   If ESI messages are not requested by an entity and the Registration
   Period is not set to 0, then the entity registration SHALL be
   removed if an iSNS Protocol message is not received from the iSNS
   client before the registration period has expired.  Receipt of any
   iSNS Protocol message from the iSNS client automatically refreshes
   the Entity Registration Period and Entity Registration Timestamp. To
   prevent a registration from expiring, the iSNS client should send an
   iSNS Protocol message to the iSNS server at intervals shorter than
   the registration period.  Such a message can be as simple as a query
   for one of its own attributes, using its associated iSCSI Name or
   iFCP Node Port Name, as the SOURCE attribute.

   For a multi-node entity, receipt of an iSNS message from any single
   node from that entity is sufficient to refresh the registration of
   all nodes of the entity.



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   Byte 0 and 1 represents the entity registration period, in seconds.
   Byte 2 and 3 are reserved.

   If ESI support is requested as part of a portal registration, the
   ESI Response message received by the server SHALL act as an
   alternative to a refresh of the entity registration.

6.2.7   Entity Index

   The Entity Index is a 4-byte integer value that uniquely identifies
   each network entity registered in the iSNS.  The Entity Index is
   assigned by iSNS server during the initial registration of an
   Entity.  The value MAY BE assigned using a monotonically increasing
   process.

   The Entity Index can be used to represent a registered entity in
   situations where the Entity Identifier is too long to be used.  An
   example of this is when SNMP tables are used to access the contents
   of the iSNS server.  In this case, the Entity Index may be used as
   the table index.

6.2.8   ISAKMP Phase-1 Proposals

   This field contains the IKE Phase-1 proposal listing in decreasing
   order of preference of the protection suites acceptable to protect
   all IKE Phase-2 messages sent and received by this Network Entity.
   This includes Phase-2 SA's to the iSNS server as well as peer iFCP
   and iSCSI devices.  The proposal contains the SA payload, proposal
   payload(s), and transform payload(s) in the ISAKMP format defined in
   [RFC2408].

6.2.9   Entity Certificate

   This attribute contains an X.509 certificate that is bound to the
   NETWORK ENTITY of the iSNS client. This certificate is uploaded and
   registered to the iSNS by clients wishing to allow other clients to
   authenticate themselves and access the services offered by that
   NETWORK ENTITY. The maximum size of this variable length field is
   implementation dependent.

6.3      Portal-Keyed Attributes

   The following portal attributes are registered in the iSNS using the
   combined Portal IP-Address and Portal TCP/UDP Port as the key.  Each
   portal is associated with one Entity Identifier object key.

6.3.1   Portal IP-Address

   The IP address of the PORTAL through which a STORAGE NODE can
   transmit and receive storage data.  This required field is provided
   by the iSNS client. When an IPv4 value is contained in this field,
   the most significant 12 bytes are set to 0x00.  The Portal IP
   Address along with the Portal TCP/UDP Port number uniquely
   identifies a Portal.

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6.3.2   Portal TCP/UDP Port

   The TCP/UDP port of the PORTAL through which a STORAGE NODE can
   transmit and receive storage data.  This required 4 byte field is
   provided by the iSNS client.  Bit 0 to 15 represents the TCP/UDP
   port number.  Bit 16 represents the port type.  If bit 16 is set the
   port type is UDP. Otherwise it is TCP.  Bits 17 to 31 are reserved.

   If the field value is 0, then the port number is the implied
   canonical port number and type of the protocol indicated by the
   associated Entity Protocol.

   The Portal IP-Address along with the Portal TCP/UDP Port number
   uniquely identifies a Portal.

6.3.3   Portal Symbolic Name

   This is an optional, variable-length text-based value from 0 to 256
   bytes.  The text field contains user-readable UTF-8 text, and is
   terminated with at least one NULL character. The Portal Symbolic
   Name is a user-readable description of the Portal entry in the iSNS.

6.3.4   Entity Status Inquiry Interval

   This optional field is provided by the iSNS client.  It indicates
   the requested time, in seconds, between Entity Status Inquiry (ESI)
   messages sent from the iSNS to this entity portal.  ESI messages can
   be used to verify that a Portal registration continues to be valid.
   To request monitoring by the iSNS, an iSNS client registers a non-
   zero value for this portal attribute using a RegDevAttr message.

   If the iSNS server does not receive an expected response to an ESI
   message, it shall attempt at least three re-transmissions of the ESI
   message.  All re-transmissions MUST be sent before twice the ESI
   Interval period has passed since the last ESI response was received
   from the client.  If no response is received from any of the ESI
   messages, then the Portal SHALL be deregistered.  If TCP was used to
   transport the ESI messages, then that TCP connection SHALL be
   closed.

   If all Portals associated with an entity that have registered for
   ESI messages are deregistered due to non-response, and no
   registrations have been received from the client for at least two
   ESI Interval periods, then the entity and all associated objects
   (including storage nodes) SHALL be deregistered.

   If the iSNS server is unable to support ESI messages or the ESI
   Interval requested, it SHALL reject the ESI request by returning an
   "ESI Not Available" error code.  The rejection might occur in
   situations where the resulting frequency of ESI messages being
   issued to clients would pass an implementation-specific threshold.

   If at any time an iSNS client that is registered for ESI messages
   has not received an ESI message to any of its portals as expected,

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   then the client MAY attempt to query the iSNS server using a
   DevAttrQry message using its Entity_ID as the key.  If the query
   result is the error "no such entry", then the client SHALL close all
   remaining TCP connections to the iSNS server and assume that it is
   no longer registered in the iSNS database.  Such a client MAY
   attempt re-registration.

6.3.5   ESI/SCN UDP Port

   This optional field is provided by the iSNS client.  If the client
   requires UDP based ESI monitoring or SCN notification, it SHALL
   register the UDP port to be used for communication from the server
   to a client Portal. Bit 0 to 15 represents the UDP port number.
   Bits 16 to 31 are reserved.

   If an entity node registers for SCN notifications with a UDP
   message, at least one entity portal shall have a registered ESI/SCN
   UDP port number.  The iSNS server will return an error for an SCN
   registration if no ESI/SCN port has been registered.  If multiple
   Portals have a registered ESI/SCN UDP port, then SCN data MAY be
   delivered to any of the available registered portals.

6.3.6   Portal Group

   This optional field is provided by the iSNS client.  The Portal
   Group is used to group portals into aggregation groups.  All entity
   portals that belong to the same Portal Group can provide connections
   to the same STORAGE NODE.  This allows multiple sessions to be
   established to a node through multiple portals. The least
   significant two bytes contain the Portal Group for the Portal.  The
   most significant two bytes are reserved.

6.3.7   Portal Index

   The Portal Index is a 4-byte integer value that uniquely identifies
   each portal registered in the iSNS.  The Portal Index is assigned by
   iSNS server during the initial registration of a portal.  The value
   MAY BE assigned using a monotonically increasing process.

   The Portal Index can be used to represent a registered portal in
   situations where the Portal IP-Address and Portal TCP/UDP Port is
   unwieldy to use.  An example of this is when SNMP tables are used to
   access the contents of the iSNS server.  In this case, the Portal
   Index may be used as the Registered Portal table index.

6.3.8   Portal Certificate

   This attribute contains an X.509 certificate that is bound to the
   PORTAL of the iSNS client.  This certificate is used to identify and
   authenticate communications to the IP address supported by the
   Portal.




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6.4      iSCSI Node-Keyed Attributes

   The following attributes are registered in the iSNS using the iSCSI
   Name attribute as the key.  Each set of Node-Keyed attributes is
   associated with one Entity Identifier object key.

   Although the iSCSI Name key is associated with one Entity
   Identifier, it is unique across the entire iSNS.

6.4.1   iSCSI Name

   This identifier uniquely defines an iSCSI STORAGE NODE, and is a
   variable-length text-based value from 0 to 256 bytes.  This field is
   required for iSCSI STORAGE NODEs, and is provided by the iSNS
   client.

   If an iSCSI Name is registered without an EID key, then an Entity
   will be created and an EID assigned.  The assigned EID will be
   returned in the registration response as an operating attribute.

6.4.2   iSCSI Node Type

   This required 32-bit field is a bitmap indicating the type of iSCSI
   STORAGE NODE.  The bit fields are defined below.  An enabled bit
   indicates the node has the corresponding characteristics.

       Bit Field       Node Type
       ---------       ---------
          0 (Lsb)      Target
          1            Initiator
          2            Control
       All Others      RESERVED

   If the 'Target' bit is set, then the node represents an iSCSI
   target.  Setting of the 'Target' bit MAY be performed by iSNS
   clients using the iSNSP.

   If the 'Initiator' bit is set, then the node represents an iSCSI
   initiator.  Setting of the 'Initiator' bit MAY be performed by iSNS
   clients using the iSNSP.

   If the control bit is set, then the node represents a gateway,
   management station, or other device which is not an initiator or
   target that requires the ability to send and receive iSNSP messages,
   including state change notifications.  Setting of the control bit is
   an administrative task that MUST be performed on the iSNS server;
   iSNS clients SHALL NOT be allowed to change this bit using the
   iSNSP.

   This field MAY be used by the iSNS server to distinguish among
   permissions by different iSCSI node types for accessing various iSNS
   functions.  For example, an iSNS server implementation may be
   administratively configured to allow only targets to receive ESI's,


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   or for only control nodes to have permission to add, modify, or
   delete discovery domains.

6.4.3   iSCSI Node Alias

   This is an optional, variable-length text-based value from 0 to 256
   bytes.  The text field contains user-readable UTF-8 text, and is
   terminated with at least one NULL character. The Alias is a user-
   readable description of the node entry in the iSNS.

6.4.4   iSCSI Node SCN Bitmap

   This field indicates the events that the iSCSI Node is interested
   in.  These events can cause a State Change Notification (SCN) to be
   generated.  SCNs provide information about objects that are updated,
   added or removed from Discovery Domains that the source and
   destination are a member of.  Detailed SCNs provide information
   about all changes to the network, and may be sent if requested and
   administratively allowed.

   Bit Field          Flag Description
   ---------          ----------------
       0              MEMBER ADDED (DETAILED SCN ONLY)
       1              MEMBER REMOVED (DETAILED SCN ONLY)
       2              OBJECT UPDATED
       3              OBJECT ADDED
       4              OBJECT REMOVED
       5              DETAILED SCN REQUESTED/SENT
   All others reserved.

6.4.5   iSCSI Node Index

   The iSCSI Node Index is a 4-byte integer value that uniquely
   identifies each iSCSI node registered in the iSNS.  The iSCSI Node
   Index is assigned by the iSNS server during the initial registration
   of an node.  The value MAY BE assigned using a monotonically
   increasing process.

   The iSCSI Node Index may be used to represent a registered node in
   situations where the iSCSI Name is too long to be used.  An example
   of this is when SNMP tables are used to access the contents of the
   iSNS server.  In this case, the iSCSI Node Index may be used as the
   registered iSCSI Node table index.

6.4.6   iSCSI Security Bitmap

   This field contains flags that indicate security attribute settings
   for the iSCSI Node.  Bit 0 of this field must be 1 (enabled) in
   order for this field to contain significant information.  If Bit 0
   is enabled, this signifies the iSNS server can be used to store and
   distribute security policies and settings for iSNS clients (i.e.,
   iSCSI devices).



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   Bit Field           Flag Description
   ---------           ----------------
       0               1 = Bitmap VALID; 0 = INVALID
       1               1 = IPSec Enabled; 0 = IPSec Disabled
       2               1 = IKE Enabled; 0 = IKE Disabled
       3               1 = Main Mode Enabled; 0 = MM Disabled
       4               1 = Aggressive Mode Enabled; 0 = Disabled
      5-9              RESERVED
      10               1 = PFS Enabled; 0 = PFS Disabled
      11               1 = Pre-shared Key Enabled; 0 = PSK Disabled
      12               1 = Certificate Support Enabled; 0 = Disabled
   All others reserved


6.4.7   iSCSI ISAKMP Phase-2 Proposals

   This field contains the IKE Phase-2 proposal, in ISAKMP format
   [RFC2408], listing in decreasing order of preference of the
   protection suites acceptable to protect traffic sent and received by
   the iSCSI Node. This field is used only if bits 0, 1 and 2 of the
   iSCSI Security Bitmap are enabled.

6.4.8   iSCSI Node Pre-Shared Key

   This field contains a pre-shared key used for IKE Aggressive Mode
   negotiation.  If this attribute is used to distribute the IKE pre-
   shared key, then IPSec confidentiality MUST be enabled for iSNS
   messages.  This field is used only if bits 0, 1, 2, and 11 of the
   iSCSI Security Bitmap are enabled.

6.4.9   iSCSI Node Certificate

   This optional attribute contains an X.509 certificate that is bound
   to the iSCSI STORAGE NODE of the iSNS client.  For example, this
   X.509 certificate may have the Node Identifier of the target device.
   This certificate is uploaded and registered to the iSNS by clients
   wishing to allow other clients to authenticate themselves and access
   the STORAGE NODE.  This field is used only if bits 0, 1, 2, and 12
   of the iSCSI Security Bitmap are enabled.

6.5      iFCP Node-Keyed Attributes

   The following attributes are registered in the iSNS using the iFCP
   Node World Wide Port Name (WWPN) attribute as the key.  Each set of
   iFCP Node-Keyed attributes is associated with one Entity Identifier
   object key.

   Although the iFCP Node WWPN is associated with one Entity
   Identifier, it is globally unique.

6.5.1   iFCP Node Port Name (WWPN)

   This 64-bit identifier uniquely defines the iFCP Node, and is the
   World Wide Port Name (WWPN) of the corresponding Fibre Channel

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   device.  This globally unique identifier is used during the device
   registration process, and uses a value conforming to IEEE Naming
   Assignment Authority (NAA) type 1, 2, 5, or 6.  This format is found
   in ANSI/IEEE Std 802-1990 [802-1990].

6.5.2   Port ID

   Along with the IP Address, this field uniquely identifies a native
   Fibre Channel device port in the network, and maps one-to-one to a
   specific Port Name (WWPN) entry.  The Port ID is used for iFCP based
   storage devices.

6.5.3   Port Type

   Indicates the type of iFCP node port.  This is provided by the iSNS
   client.  Encoded values for this field are listed in the following
   table:

   Type              Description
   ----              -----------
   0x0000           Unidentified/Null Entry
   0x0001           Fibre Channel N_Port
   0x0002           Fibre Channel NL_Port
   0x0003           Fibre Channel F/NL_Port
   0x0004-0080      RESERVED
   0x0081           Fibre Channel F_Port
   0x0082           Fibre Channel FL_Port
   0x0083           RESERVED
   0x0084           Fibre Channel E_Port
   0x0085-00FF      RESERVED
   0xFF11           mFCP Port
   0xFF12           iFCP Port
   0xFF13-FFFF      RESERVED


6.5.4   iFCP Node Port Symbolic Name

   A variable-length text-based description of up to 255 bytes, that is
   associated with the iSNS-registered iFCP Node in the network.  The
   text field contains user-readable UTF-8 text and is terminated with
   at least one NULL character.  This optional field is normally
   provided by the iSNS client during registration.  However, network
   management application can update this field as required.

6.5.5   iFCP Node Fabric Port Name (FWWN)

   This 64-bit identifier uniquely defines the fabric port.  If the
   iSNS client is attached to a Fibre Channel fabric port with a
   registered Port Name, then that fabric Port Name shall be indicated
   in this field.  This field is included in the iSNSP for
   compatibility with Fibre Channel fabric devices and topologies.

   The Fabric Port may itself be registered as a port in the iSNS.  In
   that case, the Fabric Port Name (FWWN) attribute of fabric attached

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   ports will match the Port Name (WWPN) of the Fabric Port
   registration.

6.5.6   FC Hard Address

   This optional field is the requested hard address 24-bit NL Port
   Identifier, included in the iSNSP for compatibility with Fibre
   Channel Arbitrated Loop devices and topologies.

6.5.7   FC Port IP Address

   The Fibre Channel IP address associated with the iFCP Node.  This
   optional field is included for compatibility with Fibre Channel.
   When an IPv4 value is contained in this field, the most significant
   12 bytes are set to 0x00.  This value is provided by the iSNS
   client.

6.5.8   FC Class of Service (COS)

   This 32-bit bit-map field indicates the Fibre Channel COS types that
   are supported by the registered port.  This field is provided by a
   Fibre Channel-based iSNS client.  The COS values are equivalent to
   Fibre Channel COS values.  The valid COS types, and associated bit-
   map, are listed in the following table:

   Class of Service   Description                         Bit-Map
   ----------------   -----------                         ---------
         2            Delivery Confirmation Provided      bit 2 set
         3            Delivery Confirmation Not Provided  bit 3 set
                      RESERVED                            other


6.5.9   FC FC-4 Types

   This 32-byte field indicates the FC-4 protocol types supported by
   the associated port.  This field for iFCP Node is provided by the
   iSNS client.  This field can be used to support Fibre Channel
   devices and is consistent with FC-GS-4.

6.5.10  FC FC-4 Descriptor

   A variable-length text-based description of up to 256 bytes, that is
   associated with the iSNS-registered device port in the network.
   This optional field for iFCP ports is provided by the iSNS client.
   This field can be used to support Fibre Channel devices.  This field
   can be used to support Fibre Channel devices and is consistent with
   FC-GS-4.

6.5.11  FC FC-4 Features

   This is a 128-byte array, 4 bits per type, for the FC-4 protocol
   types supported by the associated port.  This optional field for
   iFCP ports is provided by the iSNS client.  This field can be used
   to support Fibre Channel devices and is consistent with FC-GS-4.

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6.5.12  iFCP Node SCN Bitmap

   This field indicates the events that the iFCP Node is interested in.
   These events can cause SCN to be generated.  SCNs provide
   information about objects that are updated, added or removed from
   Discovery Domains that the source and destination are a member of.
   Detailed SCNs provide information about all changes to the network,
   and may be sent if requested and administratively allowed

   Bit Field          Flag Description
   ---------          ----------------
       0              MEMBER ADDED (DETAILED SCN ONLY)
       1              MEMBER REMOVED (DETAILED SCN ONLY)
       2              OBJECT UPDATED
       3              OBJECT ADDED
       4              OBJECT REMOVED
       5              DETAILED SCN REQUESTED/SENT
   All others reserved.


6.5.13  iFCP Node Type

   This required 32-bit field is a bitmap indicating the type of iFCP
   STORAGE NODE.  The bit fields are defined below.  An enabled bit
   indicates the node has the corresponding characteristics.

       Bit Field       Node Type
       ---------       ---------
          0 (Lsb)      Target
          1            Initiator
          2            Control
       All Others      RESERVED


   If the 'Target' bit is set, then the node represents an FC target.
   Setting of the 'Target' bit MAY be performed by iSNS clients using
   the iSNSP.

   If the 'Initiator' bit is set, then the node represents an FC
   initiator. Setting of the 'Initiator' bit MAY be performed by iSNS
   clients using the iSNSP.

   If the control bit is set, then the node represents a gateway,
   management station, or other device which is not an initiator or
   target that requires the ability to send and receive iSNSP messages,
   including state change notifications.  Setting of the control bit is
   an administrative task that MUST be performed on the iSNS server;
   iSNS clients SHALL NOT be allowed to change this bit using the
   iSNSP.

   This field MAY be used by the iSNS server to distinguish among
   permissions by different iSCSI node types for accessing various iSNS
   functions.  For example, an iSNS server implementation may be
   administratively configured to allow only targets to receive ESI's,

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   or for only control nodes to have permission to add, modify, or
   delete discovery domains.

6.5.14  iFCP Security Bitmap

   This field contains flags that indicate security attribute settings
   for the iFCP Node.  Bit 0 of this field must be 1 (enabled) in order
   for this field to contain significant information.  If Bit 0 is
   enabled, this signifies the iSNS server can be used to store and
   distribute security policies and settings for iSNS clients (i.e.,
   iFCP gateways).

   Bit Field           Flag Description
   ---------           ----------------
       0               1 = Bitmap VALID; 0 = INVALID
       1               1 = IPSec Enabled; 0 = IPSec Disabled
       2               1 = IKE Enabled; 0 = IKE Disabled
       3               1 = Main Mode Enabled; 0 = MM Disabled
       4               1 = Aggressive Mode Enabled; 0 = Disabled
      5-9              RESERVED
      10               1 = PFS Enabled; 0 = PFS Disabled
      11               1 = Pre-shared Key Enabled; 0 = PSK Disabled
      12               1 = Certificate Support Enabled; 0 = Disabled
   All others reserved


6.5.15  iFCP ISAKMP Phase-2 Proposals

   This field contains the IKE Phase-2 proposal, in ISAKMP format
   [RFC2408], listing in decreasing order of preference of the
   protection suites acceptable to protect traffic sent and received by
   the iFCP Node.  This field is used only if bits 0, 1 and 2 of the
   iFCP Security Bitmap are enabled.

6.5.16  iFCP Node Pre-Shared Key

   This field contains a pre-shared key used for IKE Aggressive Mode
   negotiation.  If this attribute is used to distribute the IKE pre-
   shared key, then IPSec confidentiality MUST be enabled for iSNS
   messages.  This field is used only if bits 0, 1, 2, and 11 of the
   iFCP Security Bitmap are enabled.

6.5.17  iFCP Node Certificate

   This optional attribute contains an X.509 certificate that is bound
   to the iFCP STORAGE NODE of the iSNS client.  For example, this
   X.509 certificate may have the Node Identifier of the target device.
   This certificate is uploaded and registered to the iSNS by clients
   wishing to allow other clients to authenticate themselves and access
   the STORAGE NODE. This field is used only if bits 0, 1, 2, and 12 of
   the iFCP Security Bitmap are enabled.




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6.6      iFCP FC Device Node-Keyed Attributes

   The following attributes are registered in the iSNS using the iFCP
   FC Node World Wide Node Name (WWNN) attribute as the key.  Each set
   of iFCP FC Node-Keyed attributes represents a single device, and can
   be associated with many iFCP Node Ports.

   The iFCP Node WWNN is unique across the entire iSNS.

6.6.1   iFCP FC Device Node Name (WWNN)

   Node Name is a 64-bit identifier that uniquely identifies the iFCP
   FC device node in the network, and is the World Wide Node Name
   (WWNN) of the corresponding Fibre Channel device. This globally
   unique identifier is used during the device registration process,
   and uses a value conforming to IEEE Naming Assignment Authority
   (NAA) type 1, 2, 5, or 6.  This format is found in ANSI/IEEE Std
   802-1990 [802-1990].

6.6.2   iFCP FC Device Symbolic Name

   A variable-length text-based description of up to 256 bytes, that is
   associated with the iSNS-registered FC Device in the network.  The
   text field contains user-readable UTF-8 text and is terminated with
   at least one NULL character.  This optional field is normally
   provided by the iSNS client during registration.  However, network
   management application can update this field as required.

6.6.3   FC Device IP Address

   This optional IP address is associated with the device node in the
   network.  This field is included for compatibility with Fibre
   Channel.  When an IPv4 value is contained in this field, the most
   significant 12 bytes are set to 0x00.  This value is provided by the
   iSNS client.

6.6.4   FC Device IPA

   This optional 8 byte Fibre Channel Initial Process Associator (IPA)
   is associated with the device node in the network.  This field is
   included for compatibility with Fibre Channel, and is provided by a
   Fibre Channel-based iSNS client entity.  The initial process
   associator can be used for communication between Fibre Channel
   devices.

6.6.5   FC Device Certificate

   This optional attribute contains an X.509 certificate that is bound
   to the FC DEVICE of the iSNS client.

6.7      Other Attributes

   The following are not attributes of the previously-defined objects.


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6.7.1   FC-4 Type Code

   This is a 4-byte field, and is used to provide a FC-4 type during a
   FC-4 Type query.  The FC-4 types are consistent with the FC-4 Types
   as defined in FC-PH.  Byte 0 contains the FC-4 type.  All other
   bytes are reserved.

6.7.2   Preferred ID

   This is a 4-byte unsigned integer field, and is the requested value
   that the iSNS client wishes to use for the SWITCH_ID.  The iSNS
   server SHALL grant the iSNS client the use of the requested value as
   the SWITCH_ID, if the requested value has not been already
   allocated.  If the requested value is not available, the iSNS server
   SHALL return a different value that has not been allocated.

6.7.3   Assigned ID

   This is a 4-byte unsigned integer field that is used to support iFCP
   Transparent Mode.  When operating in iFCP Transparent Mode, the
   RqstSwId message SHALL be used by each iFCP gateway to reserve its
   own unique SWITCH_ID value from the range 1 to 239.  When a Switch
   ID is no longer required, it SHALL be released by the iFCP gateway
   using the RlseSwId message.  The iSNS MAY use the Entity Status
   Inquiry message to determine if an iFCP gateway is still present on
   the network.

6.7.4   Space_Identifier

   This is a UTF-8 encoded string.  The Space_Identifier string is used
   as a key attribute to identify a range of non-overlapping SWITCH_ID
   values to be allocated using RqstSwId.  Each Space_Identifier string
   submitted by iSNS clients shall have its own range of non-
   overlapping SWITCH_ID values to be allocated to iSNS clients.

6.7.5   Server-Specific Attributes

   Attributes with tags in the range 131 to 255 are server-specific and
   vendor-specific (see section 6.9).  These attributes are unique for
   each logical iSNS server instance.  Query and registration messages
   for these attributes SHALL NOT contain a key attribute.

6.8      Discovery Domain Registration Attributes

   iSNS STORAGE NODE objects can be placed into Discovery Domains.
   Only objects that share the same enabled Discovery Domain can query
   for information about each other.  Discovery Domains can overlap, so
   an iSCSI node may be a member of many DDÆs.

   Enabled Discovery Domains are members of one or more enabled
   Discovery Domain Sets (DDS).  Discovery Domains that are not members
   of at least one enabled DDS are disabled. Therefore, Discovery
   Domains are not directly enabled, but rather are enabled through
   their association with one or more enabled Discovery Domain Sets

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   (DDS). Discovery Domain Sets are enabled by setting bit 0 in the DDS
   Status field.

6.8.1   iSNS Discovery Domain Attribute Summary

   The following table lists the iSNSP DD attributes:

   Attribute Name     Size(bytes)    ID      Reg Key     Query Key
   --------------     -----------    --      -------     ---------
   DD_Set ID               4        101         @      1,32,64,101,104
   DD_Set Sym Name        4-256     102        101          101
   DD_Set Status           4        103        101          101
   DD_ID                   4        104       @|101*   1,32,64,101,104
   DD_Symbolic Name       4-256     105        104          104
   DD_iSCSI Node Index     4        106        104          104
   DD_iSCSI Node Member   0-256     107        104          104
   DD_iFCP Member (WWPN)   8        108        104          104
   DD_Features             4        109        104          104


   @ = no key required during registration
   | = either key can be used during registration
   * = When a DD ID is placed into a DD Set by using the DDS ID
       as a key


   All undefined tag values are reserved.

6.8.2   DD Set ID Keyed Attributes

6.8.2.1  Discovery Domain Set ID (DDS ID)

   The DDS ID is a unique unsigned integer identifier used in the iSNS
   directory database to indicate a Discovery Domain Set.  A DDS is a
   collection of Discovery Domains that can be enabled or disabled by a
   management station.  This value is used as a key for DDS attribute
   queries.  When a Discovery Domain is registered it is initially not
   in any DDS.

   If the iSNS client does not provide a DDS_ID in a DDS registration
   request message, the iSNS shall generate a DDS_ID value that is
   unique within the iSNS database for that new DDS.  The created DDS
   ID shall be returned in the response message.  The DDS ID value of 0
   is reserved.

6.8.2.2  Discovery Domain Set Symbolic Name

   The DDS_Symbolic Name is a UTF-8, variable-length, NULL-terminated
   string.  This is an user-readable field used to assist a network
   administrator in tracking the DDS function.  When registered by a
   client, the DDS symbolic name SHALL be verified unique by the iSNS.
   If the DDS symbolic name is not unique, then the DDS registration
   SHALL be rejected with an ôInvalid Registrationö error code.  The


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   invalid attribute(s), in this case the DDS symbolic name, SHALL be
   included in the response.

6.8.2.3  Discovery Domain Set Status

   The DDS_Status field is a 32-bit bitmap indicating the status of the
   DDS.  Bit 0 of the bitmap indicates whether the DDS is Enabled (1)
   or Disabled (0).  The default value for the DDS Enabled flag is
   Disabled (0).

       Bit Field       DDS Status
       ---------       ---------
          0 (Lsb)      DDS Enabled (1) / DDS Disabled (0)
       All Others      RESERVED


6.8.2.4  Discovery Domain Set Member

   The Discovery Domain Set Member is a DD ID for a previously
   registered Discovery Domain.  The DD ID tag value is used to
   represents membership.

6.8.3   DD ID Keyed Attributes

6.8.3.1  Discovery Domain ID (DD ID)

   The DD ID is a unique unsigned integer identifier used in the iSNS
   directory database to indicate the DD.  This value is used as the
   key for any DD attribute query. If the iSNS client does not provide
   a DD_ID in a DD registration request message, the iSNS shall
   generate a DD_ID value that is unique within the iSNS database for
   that new DD (i.e., the iSNS client will be registered in a new DD).
   The created DD ID shall be returned in the response message.  The DD
   ID value of 0 is reserved.

6.8.3.2  Discovery Domain Symbolic Name

   The DD_Symbolic Name is a UTF-8 encoded, variable-length, NULL-
   terminated string.  When registered by a client, the DD symbolic
   name SHALL be verified unique by the iSNS.  If the DD symbolic name
   is not unique, then the DD registration SHALL be rejected with an
   ôInvalid Registrationö error code.  The invalid attribute(s), in
   this case the DD symbolic name, SHALL be included in the response.

6.8.3.3  Discovery Domain iSCSI Node Index

   This is the iSCSI Node Index of an iSNS client that is a member of
   the DD.  The DD may have a list of 0 to n members.  The iSCSI Node
   Index is one alternate representation of membership in a Discovery
   Domain, the other alternative being the iSCSI Node Name.  The
   Discovery Domain iSCSI Node Index is a 4-byte integer value.

   The iSCSI Node Index can be used to represent a DD member in
   situations where the iSCSI Name is too long to be used.  An example

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   of this is when SNMP tables are used to access the contents of the
   iSNS server.

   The iSCSI Node Index and iSCSI Node Name registered as a member in a
   DD SHALL be consistent with the iSCSI Node Index and iSCSI Node Name
   used for the registered node in the iSNS.

   Both the iSCSI Name and iSCSI Node Index of a member are registered
   in the DD in order to maintain the unique 1:1 mapping between the
   two attributes for the member over multiple registration /
   deregistrations of the same member in the iSNS.

6.8.3.4  Discovery Domain iSCSI Node Member

   The iSCSI Name of an iSNS client that is a member of the DD.  The DD
   may have a list of 0 to n members.  The iSCSI Name of the iSNS
   client represents membership.

6.8.3.5  Discovery Domain iFCP Node Member

   The iFCP Node Port Name of an iSNS client that is a member of the
   DD.  The DD may have a list of 0 to n members.  Membership is
   represented by the iFCP Node Port Name (WWPN) of the iSNS client
   being listed.

6.8.3.6  Discovery Domain Features

   The Discovery Domain Features is a bitmap indicating the features of
   this DD.  The bit fields are defined below.  An enabled bit
   indicates the DD has the corresponding characteristics.

       Bit Field       DD Feature
       ---------       ----------
          0 (Lsb)      Boot List
       All Others      RESERVED

   Boot List: this feature indicates that the targets in this DD
   provide boot capabilities for the member initiators.

6.9      Vendor-Specific Attributes

   Specific iSNS implementations MAY define vendor-specific attributes
   for private use.  The tag values reserved for vendor-specific and
   user-specific use are defined in section 6.1.  To avoid
   misinterpreting proprietary attributes, it is RECOMMENDED that the
   vendor's own OUI (Organizationally Unique Identifier) be placed in
   the upper three bytes of the attribute field itself.  If the OUI is
   not used, then some other unique marker recognizable by the vendor
   SHOULD be used.  The OUI is defined in IEEE Std 802-1990, and is the
   same constant used to generate 48 bit Universal LAN MAC addresses.
   A vendor's own iSNS implementation will then be able to recognize
   the OUI in the vendor-specific or user-specific attribute field, and
   be able to execute vendor-specific handling of the attribute.


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6.10     Company OUI

   This attribute is the OUI (Organizationally Unique Identifier)
   identifying the specific vendor implementing the iSNS.  It is used
   to identify the original creator of a vendor-specific iSNSP message.

6.11     Standards-Based Extensions

   These attributes are reserved for future work by other standards
   bodies.

7.       iSNSP Message Format

   The iSNSP message format is similar to the format of other common
   protocols such as DHCP, DNS and BOOTP.  An iSNSP message may be sent
   in one or more iSNS Protocol Data Units (PDU).  Each PDU is 4 byte
   aligned.  The following describes the format of the iSNSP PDU:

   Byte   MSb                                        LSb
   Offset 31                                           0
          +---------------------+----------------------+
        0 |   iSNSP VERSION     |    FUNCTION ID       | 4 Bytes
          +---------------------+----------------------+
        4 |     PDU LENGTH      |       FLAGS          | 4 Bytes
          +---------------------+----------------------+
        8 |   TRANSACTION ID    |    SEQUENCE ID       | 4 Bytes
          +---------------------+----------------------+
       12 |                                            |
          |                PDU PAYLOAD                 | N Bytes
          |                    ...                     |
          +--------------------------------------------+
   Total Length = 12

7.1      iSNSP PDU Header

   The iSNSP header contains the iSNSP VERSION, FUNCTION ID, PDU
   LENGTH, FLAGS, TRANSACTIONID, and SEQUENCE ID fields as defined
   below.

7.1.1   iSNSP Version

   The iSNSP version is currently 0x0001.

7.1.2   iSNSP Function ID

   The FUNCTION ID defines the type of iSNS message and the function
   the message is supporting.  See section 5 under the appropriate
   protocol (i.e., iSCSI or iFCP) for a mapping of the FUNCTION_ID
   value to the iSNSP Command or Response message.  All PDU's
   comprising an iSNSP message must have the same FUNCTION_ID and
   TRANSACTION ID value.




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7.1.3   iSNSP PDU Length

   The iSNS PDU LENGTH specifies the length of the PDU PAYLOAD field in
   bytes. The payload contains the data/attribute values for the
   operation.

7.1.4   iSNSP Flags

   The FLAGS field indicates additional information about the message
   and the type of iSNS entity that generated the message.  The
   following table displays the valid flags:

   Bit Field            Enabled Means:
   ---------            -------------
     0-9                RESERVED
      10                First PDU of the iSNS message
      11                Last PDU of the iSNS message
      12                Replace Flag (used only for registrations)
      13                RESERVED
      14                Sender is the iSNS server
      15                Sender is the iSNS client


7.1.5   iSNSP Transaction ID

   The TRANSACTION ID is set to a unique random value for each request
   message.  Replies MUST use the same TRANSACTION ID value as the
   associated iSNS request message.  If a message is retransmitted, the
   same TRANSACTION ID value MUST be used.

7.1.6   iSNSP Sequence ID

   The SEQUENCE ID is set to a unique value for each PDU within a
   single transaction.  Each SEQUENCE_ID value in each PDU SHALL be
   numbered sequentially in the order that the PDU's are transmitted.
   If a message is retransmitted, then the same SEQUENCE_ID value MUST
   be used for all PDU's in the message.

7.2      iSNSP Message Segmentation and Reassembly

   iSNS messages may be carried in one or more iSNS PDU's.  If only one
   iSNS PDU is used to carry the iSNS message, then bit 10 (First PDU)
   and bit 11 in the FLAGS field (Last PDU) SHALL both be enabled.  If
   multiple PDUs are used to carry the iSNS message, then bit 10 SHALL
   be enabled in the first PDU of the message, and bit 11 SHALL be
   enabled in the last PDU.

   All PDU's comprising the same iSNSP message SHALL have the same
   FUNCTION_ID and TRANSACTION_ID values.  Each PDU comprising an iSNSP
   message SHALL have a unique SEQUENCE_ID value.

   The authentication operation described in section 7.5 SHALL be
   performed on a per-PDU basis.


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7.3      iSNSP Message Payload

   The MESSAGE PAYLOAD is variable length and contains attributes used
   for registration and query operations.  The attribute data items use
   a format similar to other protocols, such as DHCP (RFC 2131)
   options.  Each iSNS attribute is specified in the iSNSP message
   payload using Tag-Length-Value (TLV) data format, as shown below:

   Byte   MSb                                        LSb
   Offset 31                                           0
          +--------------------------------------------+
        0 |               Attribute Tag                | 4 Bytes
          +--------------------------------------------+
        4 |            Attribute Length (N)            | 4 Bytes
          +--------------------------------------------+
        8 |                                            |
          |              Attribute Value               | N Bytes
          |                                            |
          +--------------------------------------------+
                      Total Length = 8 + N


   Attribute Tag - a 4-byte tag field that identifies the attribute as
   defined in section 6.1.  This field contains the ID of the indicated
   attribute.

   Attribute Length - a 4-byte field that indicates the length, in
   bytes, of the attribute value to follow.

   Attribute Value - a variable-length field containing the attribute
   value.

   The above format is used to identify each attribute in the iSNS
   message payload.  Each iSNSP request message contains several
   attributes in the above format to identify the requesting iSNS
   client and register or query for attribute values in the iSNS
   server.

7.3.1   Attribute Value 4-Byte Alignment

   All attribute values are aligned at 4 byte boundaries.  For variable
   length attributes, the value length is increased to the next 4-byte
   boundary and the value is NULL padded.

7.4      iSNSP Response Error Codes

   All iSNSP response messages contain a 4-byte ERROR CODE field as the
   first field in the iSNSP PAYLOAD. If the original iSNSP request
   message was processed normally by the iSNS server, or the iSNS
   client for ESI and SCN messages, the field SHALL contain 0x00000000
   (NO ERROR).




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        Error Code       Error Description
        ----------       -----------------
           0             No Error
           1             Unknown Error
           2             Message Format Error
           3             Invalid Registration
           4             Requested ESI Period Too Short
           5             Invalid Query
           6             Authentication Unknown
           7             Authentication Absent
           8             Authentication Failed
           9             No Such Entry
          10             Version Not Supported
          11             Internal Bus Error
          12             Busy Now
          13             Option Not Understood
          14             Invalid Update
          15             Message Not Supported
          16             SCN Event Rejected
          17             SCN Registration Rejected
          18             Attribute not Implemented
          19             SWITCH_ID not available
          20             SWITCH_ID not allocated
          21             ESI Not Available
          22 And Above   RESERVED
   All undefined Error Code values are RESERVED.

7.5      Registration and Query Messages

   The iSNSP registration and query message payloads contain a list of
   attributes, and have the following format:
























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             MSb                                    LSb
             31                                       0
             +----------------------------------------+
             |         Source Attribute (Query Only)  |
             +----------------------------------------+
             |         Key Attribute[1] (if present)  |
             +----------------------------------------+
             |         Key Attribute[2] (if present)  |
             +----------------------------------------+
             |         Key Attribute[3] (if present)  |
             +----------------------------------------+
             |                 . . .                  |
             +----------------------------------------+
             |       - Delimiter Attribute -          |
             +----------------------------------------+
             |   Operating Attribute[1]               |
             +----------------------------------------+
             |   Operating Attribute[2] (if present)  |
             +----------------------------------------+
             |   Operating Attribute[3] (if present)  |
             +----------------------------------------+
             |                 . . .                  |
             +----------------------------------------+

   iSNS Registration and Query messages, sent by iSNS Clients, are sent
   to the iSNS IP-Address and TCP/UDP Port.  The iSNS Responses will be
   sent to the iSNS Client IP-Address and the originating TCP/UDP Port
   used for the associated registration and query message.

7.5.1   Source Attribute

   The source attribute is used o identify the iSNS client to the iSNS
   server for queries and other messages that require source
   identification.  The source attribute uniquely identifies the source
   of the message.  Valid source attribute types are shown below.

           Valid Source Attributes
           -----------------------
           iSCSI Name (iSCSI only)
           iFCP Node Port WWN (iFCP only)

   For a query operation, the source attribute is used to limit the
   scope of the specified operation to the Discovery Domains of which
   the source is a member.  Special control nodes, identified by the
   SOURCE attribute, may be administratively configured to perform the
   specified operation on all objects in the iSNS database without
   scoping to Discovery Domains.

7.5.2   Key Attributes

   Key attributes are used to identify the object (or objects) in the
   iSNS server that the registration or query operation will be
   performed on.  The number of Key Attributes depends on the specific
   iSNSP request or query operation being performed.

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7.5.3   Delimiter Attribute

   The Delimiter Attribute separates the key attributes from the
   operating attributes in a message payload.  The Delimiter Attribute
   has a tag value of 0 and a length value of 0.  The Delimiter
   Attribute is effectively 8 Bytes long, a 4 Byte tag containing
   0x00000000, and a 4 Byte length field containing 0x00000000.

7.5.4   Operating Attributes

   The Operating Attributes are a list of one or more attributes
   related to the actual iSNS registration or query operation being
   performed.  In a registration, operating attributes represent values
   to be registered by the iSNS client performing the registration.  In
   a query, operating attributes represent values being requested by
   the iSNS client.

   The number of possible Operating Attributes depends on the specific
   iSNSP request or query.  For example, the Operating Attributes in a
   Device Attribute Query message are the set of attributes to be
   returned in the associated Device Attribute Query Response message
   that match the Key Attributes of the query.

   Some iSNSP messages do not require any Operating Attributes.

7.5.4.1  Operating Attributes for Query and Get Next Requests

   In Query and Get Next request messages, TLV attributes with length
   value of 0 are used to indicate what operating attributes are to be
   returned in the corresponding response. Operating Attribute values
   which match the TLV attributes in the original message are returned
   in the response message.

7.5.5   Registration and Query Message Types

   The following describes each query and message type.

7.5.5.1  Register Device Attribute Request (RegDevAttr)

   The RegDevAttr message type is 0x0001. The RegDevAttr message
   provides an iSNS client with the means to register network entities.
   The iSNS client formulates a RegDevAttr by specifying Key
   Attribute(s) and list of Operating Attributes to register.  All
   values are in Tag Length Value (TLV) format.

   Attributes following the Delimiter Attribute are Operating
   Attributes.  Depending on the setting of the Replace bit in the
   FLAGS field, the Operating attribute values in the RegDevAttr
   message will either replace existing attributes(s), or be added to
   existing attributes(s).  See section 7.5.5.1.1 below for a complete
   description of the Replace Flag.

   The operating attributes are the elements that will be registered.
   Multiple attributes can be registered in one RegDevAttr.  The

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   ordering of the operating attributes indicates the associations to
   be created in the iSNS.  For example, Portal attributes following
   Entity attributes SHALL create a link between the registered entity
   and portal.  Similarly, node attributes following entity attributes
   will create an association.

   A RegDevAttr message with no key attribute results in creation of a
   new entity (EID).  If the EID attribute (with non-zero length) is
   included among the operating attributes in the RegDevAttr message,
   then the new entity SHALL be assigned the value contained in that
   EID attribute.  Otherwise, if the EID attribute is not contained
   among the operating attributes of the RegDevAttr message, or if the
   EID is an operating attribute with TLV length of 0, then the iSNS
   SHALL assign the EID value that is returned in the RegDevAttr
   Response message.

   One RegDevAttr message can contain attributes for Entity, Portal,
   and Node objects if each of these attributes are contained in the
   same Entity.  When the registration contains attributes for the
   Entity, Portal, and Node objects together in the same message, then
   the appropriate Portal, and Node key attributes must be registered
   as part of the operating attributes.

   Ordering of the attributes is important in multi-object
   registrations.  For example, Node Attributes follow a valid Node
   key.

7.5.5.1.1          Replace Flag

   The Replace Flag, contained in the message header FLAGS field,
   indicates whether the registration is a replacement of, or update
   to, an existing entry.  If the Replace bit in the FLAGS field is
   enabled then a new object entry SHALL be created, replacing the
   existing object if one exists.

   If the key attributes of the registration do not match an existing
   object then the Replace flag has no effect.

   If the key attributes match an existing object in the iSNS, and the
   Replace flag is enabled, then the registration will replace the
   existing entry in the iSNS. The existing object(s) specified in the
   RegDevAttr message shall be de-registered.  A new registration shall
   be created with the new attribute value(s) in the registration
   request.  Existing associations between objects will be updated to
   reflect the new information.  For example, an existing Node object
   may be de-registered and reregistered with a different Entity object
   as part of a registration.

   If the key attributes match an existing object in the iSNS, and the
   Replace flag is not enabled, then the new attribute value(s) in the
   registration request SHALL update existing values and may add new,
   additional attributes for the key entry.  Only non-key attributes
   can be updated.  Existing associations between objects will be
   maintained.  If a registration update of the existing object would

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   cause a change in associations, then the error ôInvalid Updateô
   SHALL be returned.  For example, if a RegDevAttr message with an
   Entity Identifier key for one entity contains a Node attribute
   associated with another entity, then an error shall be returned.

7.5.5.2  Device Attribute Query Request (DevAttrQry)

   The DevAttrQry message type is 0x0002.  The DevAttrQry message
   provides an iSNS client with the means to query the iSNS server for
   network entity attributes.  The source is used to scope the query to
   the Discovery Domains that the source attribute is a member of.

   The Key Attribute(s) follow the source attribute in the message
   payload.  The attributes returned by the query will be from objects
   WHERE the Key Attribute(s) match the object.  The Key Attributes map
   to a type of object.

   The DevAttrQry message shall support the following minimum set of
   Key Attributes:

          Valid Key Attributes for Queries
          --------------------------------
           Entity Identifier
           Entity Protocol
           Portal IP-Address
           Portal IP-Address, Portal TCP/UDP Port
           iSCSI Node Type
           iSCSI Identifier
           iFCP Node Port WWN
           iFCP Node Port Type
           iFCP Node Port FC-4 Type

   If the network entities matching key attributes are not in the same
   Discovery Domain as the Source Attribute, then the results for the
   network entity will not be included in the response message.

   The Operating Attributes are the attributes whose values are being
   queried.

7.5.5.3  Device Get Next Request (DevGetNext)

   The DevGetNext message type is 0x0003. This message provides the
   iSNS client with the means to sequentially retrieve Entity, Portal,
   iSCSI Node, iFCP Node, or FC Node attributes from DD's to which the
   client has access. The source is used to scope the Get Next process
   to the Discovery Domains that the source attribute is a member of.

   The Key Attribute follows the source attribute in the message
   payload.  The Key Attribute may be an Entity Identifier, iSCSI Name,
   Portal IP Address and TCP/UDP Port, FC Device WWNN, or iFCP Node
   WWPN.  If the key TLV length value entered is zero, signifying an
   empty key value field, then the first accessible Entity Identifier,
   iSCSI Name, Portal IP Address and TCP/UDP Port, FC Device, or iFCP
   Node instance shall be returned to the client.  DevGetNext SHALL

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   return the object that is stored sequentially after the object
   matching the key provided.  If the key provided matches the last
   object instance, then the Error Code of "No Such Entry" SHALL be
   returned in the response.

   The values of the matching Operating Attributes listed in the
   original DevGetNext message SHALL be returned in the DevGetNext
   response.

7.5.5.4  Deregister Device Request (DeregDev)

   The DeregDev message type is 0x0004.  An iSNS client port or device
   is removed from the iSNS directory database by using DeregDev.  Upon
   receiving the DeregDev, the iSNS server removes all object
   registrations associated with the Key Attribute in the payload.

   The DeregDev request message payload contains a Source Attribute and
   Key Attribute(s). Valid Key Attributes are shown below:

          Valid Key Attributes for DeregDev
          ---------------------------------
           Entity Identifier
           Portal IP-Address
           Portal IP-Address, Portal TCP/UDP Port
           iSCSI Name
           iFCP Node Port WWN
           iFCP Device Node WWN

   The removal of the object will initiate an SCN message to registered
   iSNS clients that are in the same DD as the removed device or port.
   After removing the port or device, the iSNS server sends back an
   acknowledgement to the iSNS client.

   If all nodes associated with an entity are deregistered from that
   entity, then the entity SHALL also be removed UNLESS the entity
   (through one or more Portals) is responding to ESI's.

   If all Portals associated with an entity are deregistered from that
   entity, then that entity SHALL be removed from the iSNS database.

7.5.5.5  SCN Register Request (SCNReg)

   The SCNReg message type is 0x0005.  The State Change Notification
   Registration Request (SCNReg) message allows an iSNS client to
   register a STORAGE NODE to receive State Change Notification (SCN)
   messages.  SCN messages allow an iSNS client to be notified of
   changes within the DD or network (if administratively allowed) that
   the device is a member of.

   The SCNReg request message payload contains a Source Attribute, a
   Key Attribute(s), and an Operating Attribute. Valid Key Attributes
   for an SCNReg are shown below:



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          Valid Key Attributes for SCNReg
          -------------------------------
           iSCSI Name (iSCSI Only)
           Port WWN (iFCP Only)

   The iSCSI nodes or iFCP nodes matching the Key Attributes are
   registered to receive SCNs.

   The Operating Attribute is the SCN Bitmap attribute for the protocol
   type.  The bitmap indicates those INTERESTED EVENT TYPES the node or
   entity is registering for.

7.5.5.6  SCN Deregister Request (SCNDereg)

   The SCNDereg message type is 0x0006. The SCNDereg message allows an
   iSNS client to disable  State Change Notification (SCN) messages.

   The SCNDereg request message payload contains a Source Attribute and
   Key Attribute(s). Valid Key Attributes for an SCNDereg are shown
   below:

          Valid Key Attributes for SCNDereg
          ---------------------------------
           iSCSI Name (iSCSI only)
           Port WWN (iFCP only)

   The network entities matching the Key Attributes are deregistered
   for SCNs.

   There are no Delimiter or Operating Attributes in the SCNDereg
   message.

7.5.5.7  SCN Event (SCNEvent)

   The SCNEvent message type is 0x0007. The SCNEvent is a message
   generated by an iSNS client.  The SCNEvent allows the client to
   request generation of a State Change Notification (SCN) message by
   the iSNS server.  The SCN, sent by the iSNS server, then notifies
   other registered network nodes or entities within a DD or network
   (if administratively allowed) of the change indicated in the
   SCNEvent.

   Most SCNs are automatically generated by the iSNS when network nodes
   or entities are registered or deregistered from the directory
   database.  SCNs are also be generated when a network management
   application makes changes to the DD membership in the iSNS.
   However, a network entity can trigger a SCN by using SCNEvent.

   The SCNEvent message payload contains a Source Attribute, Key
   Attribute, and Operating Attribute. Valid Key Attributes for an
   SCNEvent are shown below:




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          Valid Key Attributes for SCNEvent
          ---------------------------------
           iSCSI Name (iSCSI Only)
           Port WWN (iFCP Only)

   The Operating Attributes section SHALL contain the SCN Event Bitmap
   attribute.  The bitmap indicates the event that caused the SCNEvent
   to be generated.

7.5.5.8  State Change Notification (SCN)

   The SCN message type is 0x0008. The SCN is a message generated by
   the iSNS server which allows a registered network node or entity to
   be notified of changes within a DD, network (if administratively
   allowed), or about device registration parameter updates in the iSNS
   directory database.

   The types of events that a network node or entity will be notified
   about are based on the value of the SCN Event Bitmap for the node or
   entity.

   The format of the SCN payload is shown below:

             +----------------------------------------+
             |         Destination Attribute          |
             +----------------------------------------+
             |               Timestamp                |
             +----------------------------------------+
             |          Source SCN Bitmap 1           |
             +----------------------------------------+
             |          Source Attribute [1]          |
             +----------------------------------------+
             |    Source Attribute [2](if present)    |
             +----------------------------------------+
             |    Source Attribute [3](if present)    |
             +----------------------------------------+
             |    Source Attribute [n](if present)    |
             +----------------------------------------+
             |    Source SCN Bitmap 2 (if present)    |
             +----------------------------------------+
             |                 . . .                  |
             +----------------------------------------+

   All payload attributes are in TLV format.

   The Destination Attribute is the node or entity identifier that is
   receiving the SCN.  The Destination Attribute can be an Entity
   Identifier, iSCSI Name, or iFCP Port Name.

   The Timestamp field, using the Timestamp TLV format, indicates the
   time the SCN was generated.

   The Source Attributes describe the object that caused the SCN to be
   generated.  The Source Attributes can be an Entity Identifier, iSCSI

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   Name, DD ID, DDS ID, or iFCP Port Name, and possibly include other
   attributes to describe the change that occurred.  The additional
   attributes are included to provide additional information about the
   source to minimize the possibility that the destination object needs
   to query the server for additional information.

   The Source SCN Bitmap indicates the event that caused the SCN to be
   generated. The SCN Bitmap is the delimiter between information about
   multiple objects if a single SCN message is providing information
   for multiple notifications.

   The SCN Bitmap is a 32 bit field, with the following definitions:

   Bit Field          Flag Description
   ---------          ----------------
       0              MEMBER ADDED (DETAILED SCN ONLY)
       1              MEMBER REMOVED (DETAILED SCN ONLY)
       2              OBJECT UPDATED
       3              OBJECT ADDED
       4              OBJECT REMOVED
       5              DETAILED SCN REQUESTED/SENT
    All Others        Reserved

7.5.5.9  DD Register (DDReg)

   The DDReg message type is 0x0009.  This message is used to create a
   new Discovery Domain (DD), update an existing DD Symbolic Name,
   and/or add DD members.

   DDs are uniquely defined using DD_IDs.  DD registration attributes
   are described in section 6.8.

   The DDReg message payload contains the Source Attribute, and
   optionally Key and Operating Attributes.

   A DDReg message with no key attribute results in creation of a new
   Discovery Domain (DD).  If the DD_ID attribute (with non-zero
   length) is included among the operating attributes in the DDReg
   message, then the new Discovery Domain SHALL be assigned the value
   contained in that DD_ID attribute.  Otherwise, if the DD_ID
   attribute is not contained among the operating attributes of the
   DDReg message, or if the DD_ID is an operating attribute with TLV
   length of 0, then the iSNS SHALL assign the DD_ID value that is
   returned in the DDReg Response message.

   The Operating Attributes can contain the iSCSI Node Identifier or
   iFCP WWPN of iSNS clients to be added to the DD.  It may also
   contain the DD_Symbolic_Name of the DD.

   This message shall add any DD members listed as operating attributes
   to the Discovery Domain specified by the DD_ID.  In addition, if the
   DD_Symbolic_Name is an operating attribute, then it will be stored
   in the iSNS as the DD_Symbolic_Name for the specified Discovery
   Domain.

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7.5.5.10 DD Deregister (DDDereg)

   The DDDereg message type is 0x000A.  This message allows an iSNS
   client to deregister an existing Discovery Domain (DD) or remove
   members from an existing DD.

   DDs are uniquely defined using DD_IDs.  DD registration attributes
   are described in section 6.8.

   The DDDereg message payload contains a Source Attribute, Key
   Attribute, and Operating Attributes.

   The Key Attribute for a DDDereg message is the DD ID for the domain
   being removed, or having members removed.  If the DD ID matches an
   existing DD, and there are no operating attributes, then the DD will
   be removed and a success error code returned.  If the key attribute
   does not match an existing DD then the error code ôNo Such Entryö
   will be returned.

   If the DD ID matches an existing DD, and there are operating
   attributes matching DD members, then the DD members identified by
   the operating attributes SHALL be removed from the DD and a success
   error code returned.  If any of the operating attributes do not
   match existing DD members, then the error code ôNo Such Entryö will
   be returned, and no DD members shall be removed.

7.5.5.11 7.5.5.11 DDS Register (DDSReg)

   The DDSReg message type is 0x000B.  This message allows an iSNS
   client to create a new Discovery Domain Set (DDS), update an
   existing DDS Symbolic Name, or add DDS members.

   DDSÆs are uniquely defined using DDS_IDÆs.  DDS registration
   attributes are described in section 6.8.

   The DDSReg message payload contains the Source Attribute, and
   optionally Key and Operating Attributes.

   A DDSReg message with no key attribute results in creation of a new
   Discovery Domain Set (DDS).  If the DDS_ID attribute (with non-zero
   length) is included among the operating attributes in the DDSReg
   message, then the new Discovery Domain Set SHALL be assigned the
   value contained in that DDS_ID attribute.  Otherwise, if the DDS_ID
   attribute is not contained among the operating attributes of the
   DDSReg message, or if the DDS_ID is an operating attribute with TLV
   length of 0, then the iSNS SHALL assign the DDS_ID value that is
   returned in the DDSReg Response message.

   The Operating Attributes can contain the DDS_Symbolic_Name and the
   DD_IDÆs of Discovery Domains to be added to the DDS.

   This message shall add any DDS members listed as operating
   attributes to the Discovery Domain Set specified by the DDS_ID key
   attribute.  In addition, if the DDS_Symbolic_Name is an operating

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   attribute, then it will be stored in the iSNS as the
   DDS_Symbolic_Name for the specified Discovery Domain Set.

7.5.5.12 DDS Deregister (DDSDereg)

   The DDSDereg message type is 0x000C. This message allows an iSNS
   client to deregister an existing Discovery Domain Set (DDS) or
   remove some DDÆs from an existing DDS.

   DDSs are uniquely defined using DDS_IDs.  DDS registration
   attributes are described in section 6.8.

   The DDSDereg message payload contains a Source Attribute, Key
   Attribute, and Operating Attributes.

   The Key Attribute for a DDSDereg message is the DDS ID for the set
   being removed, or having members removed.  If the DDS ID matches an
   existing DDS, and there are no operating attributes, then the DDS
   will be removed and a success error code returned.  If the key
   attribute does not match an existing DDS then the error code ôNo
   Such Entryö will be returned.

   If the DDS ID matches an existing DDS, and there are operating
   attributes matching DDS members, then the DDS members will be
   removed from the DDS and a success error code returned.  If any of
   the operating attributes do not match existing DDS members, then the
   error code ôNo Such Entryö will be returned and no DDS members shall
   be removed.

7.5.5.13 Entity Status Inquiry (ESI)

   The ESI message type is 0x000D. This message is sent by the iSNS
   server, and is used to verify that an iSNS client portal is
   reachable and available. The ESI message is sent to the ESI UDP port
   provided during registration, or the TCP connection used for ESI
   registration, depending on which communication type that is being
   used.

   The ESI message payload contains several attributes in TLV format,
   including the current iSNS timestamp, the EID, the Portal IP
   Address, and Portal TCP/UDP Port.

   The ESI response message payload contains the Attributes from the
   original ESI message.

   If the iSNS client portal fails to respond to three consecutive ESI
   messages, then the iSNS SHALL remove that client portal from the
   iSNS database. If there are no other remaining ESI monitored portals
   for the associated entity, then the entity SHALL also be removed.
   The appropriate State Change Notifications, if any, SHALL be
   triggered.




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7.5.5.14 Name Service Heartbeat (Heartbeat)

   This optional message can be regularly issued by the iSNS server to
   a broadcast or multicast address at an administratively-configured
   time interval.  The payload of this message is shown below:

             MSb                                    LSb
             31                                       0
             +----------------------------------------+
             |                                        |
             |              IP-Address                |
             |                                        |
             |                                        |
             +----------------------------------------+
             |  iSNS TCP Port   |    iSNS UDP Port    |
             +----------------------------------------+
             |               Interval                 |
             +----------------------------------------+
             |               Counter                  |
             +----------------------------------------+


   The heartbeat payload contains:

   IP-Address : the IP_Address of the server in IPv6 format
   TCP Port : the TCP Port of the server currently in use
   UDP Port : the UDP Port of the server currently in use, otherwise 0
   Interval : the interval, in seconds, of the heartbeat
   Counter : a monotonically incrementing count of heartbeats sent

   This information is NOT in TLV format.

   The content of the remainder of this message is vendor-specific.
   Vendors may use additional fields to coordinate between multiple
   iSNS servers to identify vendor specific features.

   This message allows iSNS clients listening to the broadcast or
   multicast address to discover the IP address of the iSNS server.  It
   may also be used by backup iSNS servers to monitor the health and
   status of the primary iSNS server.

   There is no response message to the Name Service Heartbeat.

7.5.5.15 Request Switch ID (RqstSwId)

   The RqstSwId message type is 0x0011. This optional message is used
   for iFCP Transparent Mode to allocate non-overlapping SWITCH_ID
   values between 1 and 239. The iSNS server becomes the address
   assignment authority for the entire iFCP fabric.  To obtain multiple
   SWITCH_ID values, this request must be repeated multiple times to
   the iSNS server.

   The RqstSwId payload contains three TLV attributes in the following
   order: the requesting entity EID as the source attribute, the Space

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   Identifier as the key attribute, and Preferred ID as the operating
   attribute. The Space Identifier is a string identifying the domain
   space for which the iSNS server shall allocate non-overlapping
   integer SWITCH_ID values between 1 and 239.  The Preferred_ID is the
   nominal SWITCH_ID value requested by the iSNS client.  If the
   Preferred_ID value is available and has not been already allocated
   for the Space_Identifier specified in the message, the iSNS server
   shall return the requested Preferred_ID value as the Assigned_ID to
   the requesting client.

   The RqstSwId response contains an Error Code, and the TLV attribute
   Assigned ID, which contains the integer value in the space
   requested. If no further unallocated values are available from this
   space, the iSNS server SHALL respond with the error code 18
   "SWITCH_ID not available".

   Once a SWITCH_ID value has been allocated to an iSNS client by the
   iSNS server for a given Space_Identifier, that SWITCH_ID value shall
   not be reused until it has been deallocated, or the ESI message
   detects that the iSNS client no longer exists on the network.

   The iSNS server and client SHALL use TCP to transmit and receive
   RqstSwId, RqstSwIdRsp, RlseSwId, and RlseSwIdRsp messages.

7.5.5.16 Release Switch ID (RlseSwId)

   The RlseSwId message type is 0x0012. This optional message may be
   used by iFCP Transparent Mode to release integer identifier values
   used to assign 3-byte Fibre Channel PORT_ID values.

   The RlseSwId message contains three TLV attributes in the following
   order:  the requesting entity EID as the source attribute, the
   Space_Identifier as the key attribute, and Assigned_ID as the
   operating attribute.  Upon receiving the RlseSwId message, the iSNS
   server shall deallocate the SWITCH_ID value contained in the
   Assigned_ID attribute for the Space_Identifier attribute specified.
   Upon deallocation, that SWITCH_ID value can now be requested by, and
   assigned to, a different iSNS client.

   The iSNS server and client SHALL use TCP to transmit and receive
   RqstSwId, RqstSwIdRsp, RlseSwId, and RlseSwIdRsp messages.

7.5.5.17 Get Switch IDs (GetSwIds)

   The GetSwIds message type is 0x0013. This optional message is used
   to learn the currently-allocated SWITCH_ID values for a given
   Space_Identifier.

   The GetSwIds message payload contains a Source Attribute and Key
   Attribute.

   The Key Attribute for the GetSwIds message is the Space_Identifier.
   The response to this message returns all of the SWITCH_ID values
   that have been allocated for the Space_Identifier specified.

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7.6      Response Messages

   The iSNSP response message payloads contain an Error Code, followed
   by a list of attributes, and have the following format:

             MSb                                    LSb
             31                                       0
             +----------------------------------------+
             |          4-byte ERROR CODE             |
             +----------------------------------------+
             |      Key Attribute[1] (if present)     |
             +----------------------------------------+
             |      Key Attribute[2] (if present)     |
             +----------------------------------------+
             |      Key Attribute[3] (if present)     |
             +----------------------------------------+
             |                 . . .                  |
             +----------------------------------------+
             |  - Delimiter Attribute - (if present)  |
             +----------------------------------------+
             |   Operating Attribute[1] (if present)  |
             +----------------------------------------+
             |   Operating Attribute[2] (if present)  |
             +----------------------------------------+
             |   Operating Attribute[3] (if present)  |
             +----------------------------------------+
             |                 . . .                  |
             +----------------------------------------+

   The iSNS Response messages will be sent to the iSNS Client IP
   Address and the originating TCP/UDP Port that was used for the
   associated registration and query message.

7.6.1   Error Code

   The first field in an iSNSP response message payload is the Error
   Code for the operation that was performed.  The Error Code format is
   defined in section 7.4.

7.6.2   Key Attributes in Response

   Depending on the specific iSNSP request, the response message will
   contain Key Attributes.  For example, a Register Device Attribute
   Response message will contain the Key Attributes used in the Device
   Attribute Registration with the assigned values, if they were
   assigned by the iSNS.

7.6.3   Delimiter Attribute in Response

   The Delimiter Attribute separates the key and operating attributes
   in a response message, if they exist.  The Delimiter Attribute has a
   tag value of 0 and a length value of 0.  The Delimiter Attribute is
   effectively 8 Bytes long, a 4 Byte tag containing 0x00000000, and a
   4 Byte length field containing 0x00000000.

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7.6.4   Operating Attributes in Response

   The Operating Attributes in a response are the results related to
   the iSNS registration or query operation being performed.

   The number of Operating Attributes in the response depends on the
   specific iSNSP request or query response.  For example, the
   Operating Attributes in a Device Attribute Query Response message
   are the set of Operating Attributes from network entity entries that
   matched the Key Attributes in the associated Device Attribute Query
   message.

7.6.5   Registration and Query Message Types

   The following describes each query and message type.

7.6.5.1  Register Device Attribute Response (RegDevRsp)

   The RegDevRsp message type is 0x8001.  The RegDevRsp message
   contains the results for the RegDevAttr message with the same
   TRANSACTION ID.

   The Error Code contains the operation results.  If the registration
   completed successfully the code of ôNo Errorö is returned.  If an
   error occurred then the appropriate code will be returned.

   The Key Attributes contain the set of keys for the objects
   registered by the Register Device Attribute message.  If the iSNS
   assigned a unique Entity Identifier for a network entity, then the
   key attribute field shall contain the assigned Entity Identifier.

   There are no Operating Attributes in the RegDevRsp message.

7.6.5.2  Device Attribute Query Response (DevAttrQryRsp)

   The DevAttrQryRsp message type is 0x8002.  The DevAttrQryRsp message
   contains the results for the DevAttrQry message with the same
   TRANSACTION ID.

   The Error Code contains the operation results.  If the query
   completed successfully the code of ôNo Errorö is returned.  If an
   error occurred then the appropriate code will be returned.

   For a successful query result, the DevAttrQryRsp Operating
   Attributes will contain the results of the original DevAttrQry
   message.

7.6.5.3  Device Get Next Response (DevGetNextRsp)

   The DevGetNextRsp message type is 0x8003. The DevGetNextRsp message
   contains the results for the DevGetNext message with the same
   TRANSACTION ID.



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   The Error Code contains the operation results.  If the operation
   completed successfully the code of ôNo Errorö is returned.  If an
   error occurred then the appropriate code will be returned.

   The Key Attribute field contains the next key, in sequential order,
   after the Key Attribute used in the DevGetNext message.

   The Operating Attribute field contains the same attributes as in the
   DevGetNext message.  The values of the Operating Attributes are the
   attribute values associated with the key returned.

7.6.5.4  Deregister Device Response (DeregDevRsp)

   The DeregDevRsp message type is 0x8004. If the DeregDe operation
   completed successfully then the code of ôNo Errorö is returned.  If
   an error occurred then the appropriate code will be returned.

   The DeregDevRsp message does not contain any key or operating
   attributes.

7.6.5.5  SCN Register Response (SCNRegRsp)

   The SCNRegRsp message type is 0x8005. If the SCReg operation
   completed successfully then the code of ôNo Errorö is returned.  If
   an error occurred then the appropriate code will be returned.

   The SCNRegRsp message does not contain any key or operating
   attributes.

7.6.5.6  SCN Deregister Response (SCNDeregRsp)

   The SCNDeregRsp message type is 0x8006. If the SCNDereg operation
   completed successfully then the code of ôNo Errorö is returned.  If
   an error occurred then the appropriate code will be returned.

   The SCNDeregRsp message does not contain any key or operating
   attributes.

7.6.5.7  SCN Event Response (SCNEventRsp)

   The SCNEventRsp message type is 0x8007. If the SCNEvent operation
   completed successfully then the Error Code of ôNo Errorö is
   returned.  If an error occurred then the appropriate code will be
   returned.

   The SCNEventRsp message does not contain any key or operating
   attributes.

7.6.5.8  SCN Response (SCNRsp)

   The SCNRsp message type is 0x8008. This message is sent by an iSNS
   client, and provides confirmation that the SCN message was received
   and processed.


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   If the SCN operation completed successfully, then the Error Code of
   ôNo Errorö is returned by the iSNS client.  If an error occurred
   then the appropriate code will be returned.

   The SCNRsp response message payload also contains the SCN
   Destination Attribute representing the node or entity identifier
   that received the SCN.

7.6.5.9  DD Register Response (DDRegRsp)

   The DDRegRsp message type is 0x8009. If the DDReg operation
   completed successfully then the code of ôNo Errorö is returned.  If
   an error occurred then the appropriate code will be returned.

   If successful, the DD ID of the DD created or updated during the
   DDReg operation will be returned as an operating attribute of the
   message.

7.6.5.10 DD Deregister Response (DDDeregRsp)

   The DDDeregRsp message type is 0x800A.  If the DDDereg operation
   completed successfully then the code of ôNo Errorö is returned.  If
   an error occurred then the appropriate code will be returned.

   The DDDeregRsp message does not contain any key or operating
   attributes.

7.6.5.11 DDS Register Response (DDSRegRsp)

   The DDSRegRsp message type is 0x800B. If the DDSRegRsp operation
   completed successfully then the code of ôNo Errorö is returned.  If
   an error occurred then the appropriate code will be returned.

   If successful, the DDS ID of the DDS created or updated during the
   DDSReg operation will be returned as an operating attribute of the
   message.

7.6.5.12 DDS Deregister Response (DDSDeregRsp)

   The DDSDeregRsp message type is 0x800C. If the DDSDeregRsp operation
   completed successfully then the code of ôNo Errorö is returned.  If
   an error occurred then the appropriate code will be returned.

   The DDSDeregRsp message does not contain any key or operating
   attributes.

7.6.5.13 Entity Status Inquiry Response (ESIRsp)

   The ESIRsp message type is 0x800D. This message is sent by an iSNS
   client, and provides confirmation that the ESI message was received
   and processed.

   The ESIRsp response message payload contains the attributes from the
   original ESI message.  These attributes represent the iSNS client

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   portal that is responding to the ESI. The ESIRsp Attributes are in
   the order they were provided in the original ESI message.  An error
   code of "No Error" is returned.

   Upon receiving the ESIRsp from the iSNS client, the iSNS server
   SHALL update the timestamp attribute for that client entity and
   portal.

7.6.5.14 Request Switch ID Response (RqstSwIdRsp)

   The RqstSwIdRsp message type is 0x8011.  This message provides the
   response for RqstSwId.

   The RqstSwId response contains an Error Code and the TLV attribute
   Assigned ID, which contains the integer value in the space
   requested. If no further unallocated values are available from this
   space, the iSNS server SHALL respond with the error code 19
   "SWITCH_ID not available".

   Once a SWITCH_ID value is allocated by the iSNS server, it shall not
   be reused until it has been deallocated by the iSNS client to which
   the value was assigned, or the ESI message detects that the iSNS
   client no longer exists on the network.

   The iSNS server and client SHALL use TCP to transmit and receive
   RqstSwId, RqstSwIdRsp, RlseSwId, and RlseSwIdRsp messages.

7.6.5.15 Release Switch ID Response (RlseSwIdRsp)

   The RlseSwIdRsp message type is 0x8012. This message provides the
   response for RlseSwId.  The response contains an Error indicating if
   the request was successful or not.  If the Assigned_ID value in the
   original RlseSwId message is not allocated, then the iSNS server
   SHALL respond with this message using the error code 20 ôSWITCH_ID
   not allocatedö.

   The iSNS server and client SHALL use TCP to transmit and receive
   RqstSwId, RqstSwIdRsp, RlseSwId, and RlseSwIdRsp messages.

7.6.5.16 Get Switch IDs Response (GetSwIdRsp)

   The GetSwIdsResp message type is 0x8013. This optional message is
   used determine which SWITCH_ID values have been allocated for the
   Space_Identifier specified in the original GetSwId request message.

   The GetSwIds response message payload contains an error code
   indicating if the request was successful, and a list of the Assigned
   IDs from the space requested.  The Assigned_ID attributes are listed
   in TLV format.

7.7      Vendor Specific Messages

   Vendor-specific iSNSP messages have a functional ID of between
   0x0100 and 0x01FF, while vendor-specific responses have a functional

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   ID of between 0x8100 and 0x81FF.  The first key attribute in a
   vendor-specific message SHALL be the company OUI (tag=256)
   identifying original creator of the proprietary iSNSP message.  The
   contents of the remainder of the message is vendor-specific.

8.       Security Considerations

8.1      Security Requirements

   The iSNS Protocol is used to transfer naming, discovery, and
   management information between iSCSI devices, iFCP gateways,
   management stations, and the iSNS server.  Such information contains
   data that would assist an attack on storage assets.

   To address this threat, the iSNS security protocol MUST provide
   confidentiality, data origin authentication, integrity, and replay
   protection on a per-datagram basis.  It MUST provide a scalable
   approach to key management.  Confidentiality MUST be supported since
   iSNS traffic may traverse insecure public networks.  Furthermore,
   bi-directional authentication of the communication endpoints MUST be
   provided, since authentication of both iSNS client and server is
   important.

   There is no requirement that the identities used in authentication
   be kept confidential.  Specifically, the identity and location of
   the iSNS server shall not be considered confidential.  Therefore,
   broadcast or multicast name service heartbeat messages sent by the
   iSNS server do not need to be authenticated or encrypted.

8.2      Resource Issues

   The iSNS protocol is lightweight, and will not generate a
   significant amount of traffic.  iSNS traffic is characterized by
   occassional registration, notification, and update messages that do
   not consume measurable amounts of bandwidth.  Even software-based
   IPSec implementations should not have a problem handling the traffic
   loads generated by iSNS.

   To fulfill iSNS security requirements, the only additional resources
   needed beyond what is already required for iSCSI and iFCP involves
   the iSNS server.  Since iSCSI and iFCP end nodes are already
   required to implement IKE and IPSec, these existing requirements can
   also be used to fulfill IKE and IPSec requirements for iSNS clients.

8.3      iSNS Interaction with IKE and IPSec

   When IPSec security is enabled, each iSNS client that is registered
   in the iSNS database shall maintain at least one phase-1 and one
   phase-2 security association with the iSNS server.  All iSNS
   Protocol messages sent between the iSNS client and server shall be
   protected by a phase-2 security association.

   When the iSNS client is removed from the iSNS database, its phase-1
   and phase-2 SA's SHALL be torn down by the iSNS server.

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8.4      Implementation Requirements

   All iSNS security compliant implementations MUST support the ESP
   protocol to protect all iSNS protocol messages.  When supporting
   iSCSI devices, conformant iSNS server implementations MUST support
   ESP in transport mode.  When supporting iFCP gateways, conformant
   iSNS server implementations MUST support ESP in tunnel mode.
   Furthermore, all replay protection mechanisms of IPSec MUST be
   supported.

   To provide confidentiality with ESP, 3DES in CBC mode MUST be
   supported, and AES in Counter mode, as described in [AES], SHOULD be
   supported.  To provide data origin authentication and integrity with
   ESP, HMAC-SHA1 MUST be supported, and AES in CBC MAC mode with XCBC
   extensions [AES-CBC] SHOULD be supported.  DES in CBC mode SHOULD
   NOT be used due to its inherent weakness.  If confidentiality is not
   required but data origin authentication and integrity is enabled,
   ESP with NULL Encryption MUST be used.

   Conformant iSNS security implementations MUST support IKE for peer
   authentication, negotiation of security associations, and key
   management, using the IPSec DOI [RFC2407].  Manual keying SHOULD NOT
   be used since it does not provide the necessary rekeying support.
   Conformant iSNS security implementations MUST support peer
   authentication using a pre-shared key, and MAY support certificate-
   based peer authentication using digital signatures.  Peer
   authentication using the public key encryption methods outlined in
   IKE's sections 5.2 and 5.3 [RFC2409] SHOULD NOT be supported.

   When pre-shared keys are used for authentication, IKE Aggressive
   Mode SHOULD be used, and the IKE Main Mode SHOULD NOT be used.  When
   digital signatures are used for authentication, either IKE Main Mode
   or IKE Aggressive Mode MAY be used.  In all cases, access to locally
   stored secret information (pre-shared key or private key for digital
   signing) MUST be suitably restricted, since compromise of the secret
   information nullifies the security properties of the IKE/IPSec
   protocols.

   When digital signatures are used to achieve authentiation, an IKE
   negotiator SHOULD use IKE Certificate Request Payload(s) to specify
   the certificate authority (or authorities) that are trusted in
   accordance with its local policy.  IKE negotiators SHOULD check the
   pertinent Certificate Revocation List (CRL) before accepting a PKI
   certificate for use in IKE's authentication procedures.











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9.       References

   [RFC1035]      Domain Implementation and Specification
   [RFC1305]      Network Time Protocol (Version 3)
   [STD0035]      Domain Name System
   [RFC2065]      Domain Name System Security Extensions
   [RFC2608]      Service Location Protocol, Version 2
   [FC-GS-2]      Fibre Channel Generic Services-2, ANSI NCITS 288
   [FC-GS-3]      Fibre Channel Generic Services-3, NCITS Working
                  Draft Rev 7.01, November 28, 2000
   [RFC2609]      Service Templates and Service
   [IEEE802.1Q]   Standard for Virtual Bridged Local Area Networks
   [RFC1510]      The Kerberos Network Authentication Service
   [DSS]          FIPS PUB 186-2, National Institute of Standards and
                  Technology, Digital Signature Standard(DSS),
                  Technical Report
   [802-1990]     ANSI/IEEE Std 802-1990, Name: IEEE Standards for
                  Local and Metropolitan Area Networks: Overview and
                  Architecture
   [SPC]          SCSI-3 Primary Commands, ANSI NCITS 995D, Revision
                  11a
   [iSCSI-SLP]    Finding iSCSI Targets and Name Servers Using SLP,
                  draft-bakke-iscsi-slp-00.txt
   [iSCSI-NDR]    iSCSI Naming and Discovery Requirements,
                  draft-ietf-ips-iscsi-name-disc-00.txt
   [RFC2407]      The Internet IP Security Domain of Interpretation of
                  ISAKMP
   [RFC2408]      Internet Security Association and Key Management
                  Protocol (ISAKMP)
   [RFC2409]      The Internet Key Exchange
   [AES-CTR]      The AES128 CTR Mode of Operation and Its Use with
                  IPSec, draft-moskowitz-aes128-ctr-00.txt
   [AES-CBC]      The AES Cipher Algorithm and Its Use with IPSec,
                  draft-ietf-ipsec-ciph-aes-cbc-01.txt

   1  Bradner, S., "The Internet Standards Process -- Revision 3", BCP
      9, RFC 2026, October 1996.



   2  Bradner, S., "Key words for use in RFCs to Indicate Requirement
      Levels", BCP 14, RFC 2119, March 1997













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10.      Author's Addresses

   Josh Tseng
   Kevin Gibbons
   Fa Yoeu
   Nishan Systems
   3850 North First Street
   San Jose, CA 95134-1702
   Phone: (408) 519-3749
   Email: jtseng@nishansystems.com

   Franco Travostino
   Nortel Networks
   3 Federal Street
   Billerica, MA  01821
   Phone:  978-288-7708
   Email:  travos@nortelnetworks.com

   Kenneth Hirata
   Vixel Corporation
   Irvine, CA 92618
   Phone: (949) 450-6100
   Email: khirata@vixel.com

   Tom McSweeney
   Curt Du Laney
   John Dowdy
   IBM
   4205 South Miami Blvd
   Research Triangle Park, NC 27709
   Email:  jdowdy@us.ibm.com
   Phone: (919) 254-5632

   Chad Gregory
   505 E. Huntland Drive, Suite 550
   Austin, TX 78752
   Email: chad.gregory@intel.com
   Phone: (512) 407-2137

   Howard Hall
   Pirus Networks
   43 Nagog Park
   Acton, MA 01720
   Email:  howard@pirus.com
   Phone:  978-206-9103










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Full Copyright Statement

   "Copyright (C) The Internet Society (date). 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 implementation 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."




























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                      Appendix A  -- iSNS Examples

A.1 iSCSI Initialization Example

   This example assumes an SLP Service Agent (SA) has been implemented
   on the iSNS host, and an SLP User Agent (UA) has been implemented on
   the iSNS initiator.  See [RFC2608] for further details on SA's and
   UA's.  This example also assumes the target is configured to use the
   iSNS, and have its access control policy subordinated to the iSNS.

A.1.1    Simple iSCSI Target Registration

   In this example, a simple target with a single iSCSI name registers
   with the iSNS.  The target has not been assigned a Fully Qualified
   Domain Name (FQDN) by the administrator.








































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   +--------------------------+------------------+-------------------+
   |    iSCSI Target Device   |    iSNS          |Management Station |
   +--------------------------+------------------+-------------------+
   |Discover iSNS--SLP------->|                  |/*mgmt station is  |
   |                          |<--SLP--iSNS Here:| administratively  |
   |                          |      192.36.53.1 | authorized to view|
   |                          |                  | all DD's.  Device |
   |                          |                  | NAMEabcd has been |
   |      RegDevAttr--------->|                  | previously placed |
   |Oper Attrs:               |                  | into DDabcd******/|
   |tag=1: NULL               |                  |                   |
   |tag=2: "iSCSI"            |                  |                   |
   |tag=16: "192.36.4.5"      |                  |                   |
   |tag=17: "5001"            |                  |                   |
   |tag=19: 0                 |                  |                   |
   |tag=32: "NAMEabcd"        |                  |                   |
   |tag=33: "target"          |                  |                   |
   |tag=34: "disk 1"          |                  |                   |
   |                          |<---RegDevAttrRsp |                   |
   |                          |SUCCESS           |                   |
   |                          |tag=1: "iSNS:0001"|                   |
   |                          |tag=16: "192.36.4.5"                  |
   |                          |tag=17: "5001"    |                   |
   |                          |tag=32: "NAMEabcd"|                   |
   |                          |                  |                   |
   |      DevAttrQry--------->|      SCN-------->|                   |
   |Src:(tag=32) "NAMEabcd"   |(or SNMP trap)    |                   |
   |Key:(tag=2) "iSCSI"       |tag=1: "iSNS:0001"                    |
   |Key:(tag=33) "initiator"  |dest: "mgmt.foo.com"                  |
   |Oper Attrs:               |CHANGE IN NETWORK |                   |
   |tag=16:  NULL             |                  |                   |
   |tag=17:  NULL             |                  |<-------SCNRsp     |
   |tag=32:  NULL             |                  |                   |
   |/*Query asks for all iSCSI|                  |                   |
   |devices' IP address, port |<---DevAttrQryRsp |                   |
   |number, and Name*/        |SUCCESS           |                   |
   |                          |tag=16:"192.36.4.1"                   |
   |                          |tag=17:"50000"    |                   |
   |                          |tag=32:"devpdq"   |                   |
   |                          |tag=16:"192.1.3.2"|<-----DevAttrQry   |
   |                          |tag=17:"50000"    |src: ôMGMTname1ö   |
   |                          |tag=32:"devrst"   |key:(tag=1)iSNS:0001
   |                          |                  |Op Attrs:          |
   |/*************************|                  |tag=16:  NULL      |
   |Our target "iSNS:0001"    |                  |tag=17:  NULL      |
   |discovers two initiators  |                  |tag=32:  NULL      |
   |in the same DD.  It will  |                  |                   |
   |accept iSCSI logins from  |                  |                   |
   |these two identified      |                  |                   |
   |initiators presented by   |                  |                   |
   |iSNS*********************/| DevAttrQryRsp--->|                   |
   |                          |SUCCESS           |                   |
   |                          |tag=16: 192.36.4.5|                   |
   |                          |tag=17: 5001      |                   |

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   |                          |tag=32: NAMEabcd  |                   |
   +--------------------------+------------------+-------------------+


A.1.2    Target Registration and DD Configuration

   In this example, a more complex target registers with the iSNS.
   This target has been configured with a Fully Qualified Domain Name
   (FQDN) in the DNS servers, and the user wishes to use this
   identifier for the device.  Also, the user wishes to use public key
   certificates in the iSCSI login authentication.












































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   +--------------------------+------------------+-------------------+
   |    iSCSI Target Device   |    iSNS          |Management Station |
   +--------------------------+------------------+-------------------+
   |Discover iSNS--SLP-->     |                  |/*mgmt station is  |
   |                          |<--SLP--iSNS Here:| administratively  |
   |                          |      192.36.53.1 | authorized to view|
   |      RegDevAttr-->       |                  | all DD's ********/|
   |Oper Attrs:               |                  |                   |
   |tag=1: "jbod1.foo.com"    |                  |                   |
   |tag=2: "iSCSI"            |                  |                   |
   |tag=16: "192.36.34.4"     |                  |                   |
   |tag=17: "5001"            |                  |                   |
   |tag=19: "5 seconds"       |                  |                   |
   |tag=16: "192.36.53.5"     |                  |                   |
   |tag=17: "5001"            |                  |                   |
   |tag=32: "NAMEabcd"        |                  |                   |
   |tag=33: "Target"          |/*****************|                   |
   |tag=34: "Volume 1"        |jbod1.foo.com is  |                   |
   |tag=40: X.509 cert blob 1 |now registered in |                   |
   |tag=32: "NAMEefgh"        |iSNS, but is not  |                   |
   |tag=33: "Target"          |in any DD. Therefore,                 |
   |tag=34: "Volume 2"        |no other devices  |                   |
   |tag=40: X.509 cert blob 2 |can "see" it.     |                   |
   |                          |*****************/|                   |
   |                          |<--RegDevAttrRsp  |                   |
   |                          |SUCCESS           |                   |
   |                          |tag=1: "jbod1.foo.com"                |
   |                          |tag=16: "192.36.34.4"                 |
   |                          |tag=17: "5001"    |                   |
   |                          |tag=16: "192.36.53.5"                 |
   |                          |tag=17: "5001"    |                   |
   |                          |tag=32: "NAMEabcd"|                   |
   |                          |tag=32: "NAMEefgh"|                   |
   |                          |                  |                   |
   |                          |       SCN------> |                   |
   |                          |  (or SNMP trap)  |                   |
   |                          |tag=1: jbod1.foo.com                  |
   |                          |dest: mgmt.foo.com|                   |
   |                          |CHANGE IN NETWORK |                   |
   |                          |                  |                   |
   |                          |                  |<--SCNRsp          |
   |                          |                  |<--DevAttrQry      |
   |                          |                  |src: mgmt.foo.com  |
   |                          |                  |key:  (tag=1)      |
   |                          |                  |  jbod1.foo.com    |
   |                          |                  |Op Attr: (tag=2)   |
   |                          |                  |Op Attr: (tag=16)  |
   |                          |                  |Op Attr: (tag=17)  |
   |                          |                  |Op Attr: (tag=32)  |
   |                          |                  |                   |
   |                          | DevAttrQryRsp--> |                   |
   |                          |SUCCESS           |                   |
   |                          |tag=2:  "iSCSI"   |                   |
   |                          |tag=16: 192.36.34.4                   |

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   |                          |tag=17: 5001      |                   |
   |                          |tag=16: 192.36.53.5                   |
   |                          |tag=17: 5001      |/**Mgmt Station ***|
   |                          |tag=32:"NAMEabcd" |displays device,   |
   |                          |tag=32:"NAMEefgh" |the operator decides
   |                          |                  |to place "NAMEabcd"|
   |                          |                  |into Domain "DDxyz"|
   |/*************************|                  |******************/|
   |Target is now registered  |                  |                   |
   |in iSNS.  It has been placed                 |<--DDReg           |
   |in DDxyz by management    |                  |src: "mgmt.foo.com"|
   |station.                  |                  |key: "DDxyz ID"    |
   |*************************/|                  |Op Attr:           |
   |                          |                  |tag=32: "NAMEabcd" |
   |                          |    DDRegRsp----->|                   |
   |                          |    SUCCESS       |                   |
   +--------------------------+------------------+-------------------+


A.1.3    Initiator Registration and Target Discovery

   The following example illustrates a new initiator registering with
   the iSNS, and discovering the target NAMEabcd from the example in
   A.1.2.































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   +--------------------------+------------------+-------------------+
   |    iSCSI Initiator       |    iSNS          |Management Station |
   +--------------------------+------------------+-------------------+
   |Discover iSNS--SLP-->     |                  |/*mgmt station is  |
   |                          |<--SLP--iSNS Here:| administratively  |
   |                          |      192.36.53.1 | authorized to view|
   |RegDevAttr-->             |                  | all DD's ********/|
   |Oper Attrs:               |                  |                   |
   |tag=1: "svr1.foo.com"     |                  |                   |
   |tag=2: "iSCSI"            |                  |                   |
   |tag=16: "192.20.3.1"      |/*****************|                   |
   |tag=17: "5001"            |Device not in any |                   |
   |tag=19: 5 seconds         |DD, so it is      |                   |
   |tag=32: "NAMEijkl"        |inaccessible by   |                   |
   |tag=33: "Initiator"       |other devices     |                   |
   |tag=34: "Server1"         |*****************/|                   |
   |tag=39: X.509 cert blob 3 |                  |                   |
   |                          |<--RegDevAttrRsp  |                   |
   |                          |SUCCESS           |                   |
   |                          |tag=1: "svr1.foo.com"                 |
   |                          |tag=16: "192.20.3.1"                  |
   |                          |tag=17: "5001"    |                   |
   |                          |tag=32: "NAMEijkl"|                   |
   |                          |                  |                   |
   |                          |       SCN------> |                   |
   |                          |  (or SNMP trap)  |                   |
   |                          |tag=1: svr1.foo.com                   |
   |                          |dest: mgmt.foo.com|                   |
   |                          |CHANGE IN NETWORK |                   |
   |                          |                  |                   |
   |                          |                  |<------SCNRsp      |
   |                          |                  |<----DevAttrQry    |
   |                          |                  |src: mgmt.foo.com  |
   |                          |                  |key:  (tag=1)      |
   |                          |                  |  svr1.foo.com     |
   |                          |                  |Op Attr: (tag=2)   |
   |                          |                  |Op Attr: (tag=16)  |
   |                          |                  |Op Attr: (tag=17)  |
   |                          |                  |Op Attr: (tag=32)  |
   |                          | DevAttrQryRsp--> |                   |
   |                          |SUCCESS           |                   |
   |                          |tag=2:  "iSCSI"   |                   |
   |                          |tag=16:192.20.3.1 |                   |
   |                          |tag=17: "5001"    |                   |
   |                          |tag=32:"NAMEijkl" |                   |
   |                          |                  |/**Mgmt Station ***|
   |                          |                  |displays device,   |
   |                          |                  |the operator decides
   |                          |                  |to place "NAMEijkl"|
   |                          |                  |into Domain "DDxyz"|
   |                          |                  |with device NAMEabcd
   |                          |                  |******************/|
   |                          |                  |<--DDReg           |
   |                          |                  |src: (tag=1)       |

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   |                          |                  |  "mgmt.foo.com"   |
   |                          |                  |key: "DDxyz ID"    |
   |                          |                  |tag=32: "NAMEijkl  |
   |                          |                  |                   |
   |                          |     DDRegRsp---->|/******************|
   |                          |     SUCCESS      |"NAMEijkl" has been|
   |                          |                  |moved to "DDxyz"   |
   |                          |                  |******************/|
   |                          |<-----SCN         |                   |
   |                          |tag=32: "NAMEijkl"|                   |
   |                          |CHANGE IN DD MEMBERSHIP               |
   |    DevAttrQry----------->|                  |                   |
   |src: "NAMEabcd"           |/*****************|                   |
   |key:(tag=2) "iSCSI"       |Note that NAMEabcd|                   |
   |key:(tag=33) "Target"     |also receives an  |                   |
   |Op Attr: (tag=16)         |SCN that NAMEijkl |                   |
   |Op Attr: (tag=17)         |is in the same DD |                   |
   |Op Attr: (tag=32)         |*****************/|                   |
   |Op Attr: (tag=34)         |                  |                   |
   |Op Attr: (tag=40)         |<-----AttrQryRsp  |                   |
   |                          |SUCCESS           |                   |
   |                          |tag=16: 192.36.34.4                   |
   |                          |tag=17: 5001      |                   |
   |                          |tag=16: 192.36.53.5                   |
   |                          |tag=17: 5001      |                   |
   |                          |tag=32: NAMEabcd  |                   |
   |                          |tag=34: Volume 1  |                   |
   |                          |tag=40: X.509 cert blob 2             |
   |                          |                  |                   |
   |/***The initiator has discovered             |                   |
   |the target, and has everything               |                   |
   |needed to complete iSCSI login               |                   |
   |The same process occurs on the               |                   |
   |target side; the SCN prompts the             |                   |
   |target to download the list of               |                   |
   |authorized initiators from the               |                   |
   |iSNS (i.e., those initiators in the          |                   |
   |same DD as the target.************/          |                   |
   +--------------------------+------------------+-------------------+
















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