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Updated by: 7146 Errata Exist
Network Working Group                                        D. Peterson
Request for Comments: 3822             Computer Network Technology (CNT)
Category: Standards Track                                      July 2004

           Finding Fibre Channel over TCP/IP (FCIP) Entities
           Using Service Location Protocol version 2 (SLPv2)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2004).


   This document defines the use of Service Location Protocol version 2
   (SLPv2) by Fibre Channel over TCP/IP (FCIP) Entities.

1.  Introduction

   This document describes the use of the Service Location Protocol
   version 2 in performing dynamic discovery of participating Fibre
   Channel over TCP/IP (FCIP) Entities.  Implementation guidelines,
   service type templates, and security considerations are specified.

2.  Notation Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

3.  Terminology

   Here are some definitions that may aid readers that are unfamiliar
   with either SLP or FCIP.  Some of these definitions have been
   reproduced from [RFC2608] and [RFC3105].

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   User Agent (UA)            A process working on the client's behalf
                              to establish contact with some service.
                              The UA retrieves service information from
                              the Service Agents or Directory Agents.

   Service Agent (SA)         A process working on behalf of one or more
                              services to advertise the services and
                              their capabilities.

   Directory Agent (DA)       A process which collects service
                              advertisements.  There can only be one DA
                              present per given host.

   Scope                      A named set of services, typically making
                              up a logical administrative group.

   Service Advertisement      A URL, attributes, and a lifetime
                              (indicating how long the advertisement is
                              valid), providing service access
                              information and capabilities description
                              for a particular service.

   FCIP Entity                The principle FCIP interface point to the
                              IP network.

   FCIP Entity Name           The world wide name of the switch if the
                              FCIP Entity resides in a switch or the
                              world wide node name of the associated

   FCIP Discovery Domain      The FCIP Discovery Domain specifies which
                              FCIP Entities are allowed to discover each
                              other within the bounds of the scope.

4.  Using SLPv2 for FCIP Service Discovery

   At least two FCIP Entities must be involved in the entity discovery
   process.  The end result is that an FCIP Entity will discover one or
   more peer FCIP Entities.

4.1.  Discovering FCIP Entities using SLPv2

   Figure 1 shows the relationship between FCIP Entities and their
   associated SLPv2 agents.

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            |           FCIP Entity                |
            +----------------------------------+   |
            | FCIP Control and Services Module |   |
            +----------------+                 |   |
            |   SA  |   UA   |                 |   |
            +----------------+-----------------+   |
            |            TCP/UDP/IP            |   |
            +----------------+-----------------+   |
            |            Interface             |   |
            |              |   |
   +------------+            |
   |  SLPv2 DA  |----+  IP Network
   +------------+            |
            |            Interface             |   |
            |              |   |
            +----------------+-----------------+   |
            |            TCP/UDP/IP            |   |
            +----------------+-----------------+   |
            |   SA  |  UA    |                 |   |
            +----------------+                 |   |
            | FCIP Control and Services Module |   |
            +--------------------------------- +   |
            |           FCIP Entity                |

   Figure 1: FCIP Entity and SLPv2 Agent Relationship.

   As indicated in Figure 1, each FCIP Entity contains an FCIP Control
   and Services Module that interfaces to an SLPv2 SA and UA.

   The SA constructs a service advertisement of the type
   "service:fcip:entity" for each of the service URLs it wishes to
   register.  The service advertisement contains a lifetime, along with
   other attributes defined in the service template.

   The remainder of the discovery process is identical to that used by
   any client/server pair implementing SLPv2:

   1. If an SLPv2 DA is found [RFC2608], the SA contacts the DA and
      registers the service advertisement.  Whether or not one or more
      SLPv2 DAs are discovered, the SA maintains the service
      advertisement itself and answers multicast UA queries directly.

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   2. When the FCIP Entity requires contact information for a peer FCIP
      Entity, the UA either contacts the DA using unicast or the SA
      using multicast using an SLPv2 service request.  The UA service
      request includes a query, based on the attributes, to indicate the
      characteristics of the peer FCIP Entities it requires.

   3. Once the UA has the IP address and port number of a peer FCIP
      Entity, it may begin the normal connection procedure, as described
      in [RFC3821], to a peer FCIP Entity.

   The use of a DA is RECOMMENDED for SLPv2 operations in an FCIP

4.1.1.  FCIP Discovery Domains

   The concept of a discovery domain provides further granularity of
   control of allowed discovery between FCIP Entities within a specific
   SLPv2 scope.

   Figure 2 shows an example relationship between FCIP Entities and
   their associated discovery domains within a specified SLPv2 scope.

   =                                                          =
   =  *************************purple***********************  =
   =  *                                                    *  =
   =  *  #####orange######################                 *  =
   =  *  # ------------  //////blue//////+///////////////  *  =
   =  *  # | FCIP     |  /               #              /  *  =
   =  *  # | Entity A |  /               #              /  *  =
   =  *  # ------------  /               # ------------ /  *  =
   =  *  #               /               # | FCIP     | /  *  =
   =  *  #               /               # | Entity C | /  *  =
   =  *  #               /  ------------ # ------------ /  *  =
   =  *  #               /  | FCIP     | #              /  *  =
   =  *  #               /  | Entity B | #              /  *  =
   =  *  #               /  ------------ #              /  *  =
   =  *  ################+################              /  *  =
   =  *                  ////////////////////////////////  *  =
   =  *                                                    *  =
   =  ******************************************************  =
   =                                                          =

   Figure 2: FCIP Entity and Discovery Domain Example.

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   Within the specified scope "fcip", the administrator has defined a
   discovery domain "purple", allowing FCIP Entities A, B, and C to
   discover each other.  This discovery domain is illustrated using the
   "*" character.

   Within the specified scope "fcip", the administrator has defined a
   discovery domain "orange", allowing FCIP Entity A to discover FCIP
   Entity B, but not FCIP Entity  C.  This discovery domain is
   illustrated using the "#" character.

   Within the specified scope "fcip", the administrator has defined a
   discovery domain "blue", allowing FCIP Entity C to discover FCIP
   Entity B, but not FCIP Entity A.  This discovery domain is
   illustrated using the "/" character.

   For the example relationship shown in Figure 2, the value of the
   fcip-discovery-domain attribute for each FCIP Entity is as follows:

   FCIP Entity A = orange,purple

   FCIP Entity B = orange,blue,purple

   FCIP Entity C = blue,purple

5.  FCIP SLPv2 Templates

   Two templates are provided: an FCIP Entity template, and an abstract
   template to provide a means of adding other FCIP related templates in
   the future.

5.1.  The FCIP Abstract Service Type Template

   This template defines the abstract service "service:fcip".  It is
   used as a top-level service to encapsulate all other FCIP related

   Name of submitter: David Peterson
   Language of service template: en
   Security Considerations: see section 6.

   Template Text:
   -------------------------template begins here-----------------------


      This is an abstract service type.  The purpose of the fcip service

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      type is to encompass all of the services used to support the FCIP

   template-url-syntax =

      url-path=  ; Depends on the concrete service type.

   --------------------------template ends here------------------------

5.2.  The FCIP Entity Concrete Service Type Template

   This template defines the service "service:fcip:entity".  A device
   containing FCIP Entities that wishes to have them discovered via
   SLPv2 would register each of them with each of their addresses, as
   this service type.

   FCIP Entities wishing to discover other FCIP Entities in this manner
   will generally use one of the following example query strings:

   1. Find a specific FCIP Entity, given its FCIP Entity Name:

      Service:  service:fcip:entity
      Scope:    fcip-entity-scope-list
      Query:    (fcip-entity-name=\ff\10\00\00\60\69\20\34\0C)

   2. Find all of the FCIP Entities within a specified FCIP Discovery

      Service:  service:fcip:entity
      Scope:    fcip-entity-scope-list
      Query:    (fcip-discovery-domain=fcip-discovery-domain-name)

   3. In addition, a management application may wish to discover all
      FCIP Entities:

      Service:  service:fcip:entity
      Scope:    management-service-scope-list
      Query:    none

   Name of submitter: David Peterson
   Language of service template: en
   Security Considerations: see section 6.

   Template Text:
   -------------------------template begins here-----------------------


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     This is a concrete service type.  The fcip:entity service type is
     used to register individual FCIP Entity addresses to be discovered
     by others.  UAs will generally search for these by including one of
     the following:
     - the FCIP Entity Name for which an address is needed
     - the FCIP Discovery Domain Name for which addresses are requested
     - the service URL

   template-url-syntax =
     url-path = hostport
     hostport = host [ ":" port ]
     host = hostname / hostnumber
     hostname = *( domainlabel "." ) toplabel
     alphanum = ALPHA / DIGIT
     domainlabel = alphanum / alphanum * [alphanum / "-"] alphanum
     toplabel = ALPHA / ALPHA * [ alphanum / "-" ] alphanum
     hostnumber = ipv4-number
     ipv4-number = 1*3DIGIT 3("." 1*3DIGIT)
     port = 1*DIGIT

     ; A DNS host name should be used along with the well-known
     ; IANA FCIP port number for operation with NAT/NAPT devices.
     ; Examples:
     ; service:fcip:entity://host.example.com
     ; service:fcip:entity://

   fcip-entity-name = opaque L
   # If the FCIP Entity is a VE_Port/B_Access implementation [FC-BB-2]
   # residing in a switch, the fcip-entity-name is the Fibre Channel
   # Switch Name [FC-SW-3].  Otherwise, the fcip-entity-name is the
   # Fibre Channel Node Name [FC-FS] of the port (e.g., an Nx_Port)
   # associated with the FCIP Entity.
   # An entity representing multiple endpoints must register each of
   # the endpoints using SLPv2.

   transports = string M L
   # This is a list of transport protocols that the registered entity
   # supports.  FCIP is currently supported over TCP only.

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   mgmt-entity = string M O L
   # The URL's of the management interface(s) are appropriate for SNMP,
   # web-based, or telnet management of the FCIP Entity.
   # Examples:
   #  http://fcipentity.example.com:1080/
   #  telnet://fcipentity.example.com

   fcip-discovery-domain = string M L
   # The fcip-discovery-domain string contains the name(s) of the FCIP
   # discovery domain(s) to which this FCIP Entity belongs.

   --------------------------template ends here------------------------

6.  Security Considerations

   The SLPv2 security model as specified in [RFC2608] does not provide
   confidentiality, but does provide an authentication mechanism for UAs
   to assure that service advertisements only come from trusted SAs with
   the exception that it does not provide a mechanism for authenticating
   "zero-result responses".  See [RFC3723] for a discussion of the SLPv2
   [RFC2608] security model.

   Once an FCIP Entity is discovered, authentication and authorization
   are handled by the FCIP protocol.  It is the responsibility of the
   providers of these services to ensure that an inappropriately
   advertised or discovered service does not compromise their security.

   When no security is used for SLPv2, there is a risk of distribution
   of false discovery information.  The primary countermeasure for this
   risk is authentication.  When this risk is a significant concern,
   IPsec SAs SHOULD be used for FCIP traffic subject to this risk to
   ensure that FCIP traffic only flows between endpoints that have
   participated in IKE authentication.  For example, if an attacker
   distributes discovery information falsely claiming that it is an FCIP
   endpoint, it will lack the secret information necessary to
   successfully complete IKE authentication, and hence will be prevented
   from falsely sending or receiving FCIP traffic.

   There remains a risk of a denial of service attack based on repeated
   use of false discovery information that will cause the initiation of
   IKE negotiation.  The countermeasures for this are administrative
   configuration of each FCIP Entity to limit the peers that it is
   willing to communicate with (i.e., by IP address range and/or DNS
   domain), and maintenance of a negative authentication cache to avoid
   repeatedly contacting an FCIP Entity that fails to authenticate.
   These three measures (i.e., IP address range limits, DNS domain
   limits, negative authentication cache) MUST be implemented.

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6.1.  Security Implementation

   Security for SLPv2 in an IP storage environment is specified in
   [RFC3723].  IPsec is mandatory-to-implement for IPS clients and
   servers.  Thus, all IP storage clients, including those invoking SLP,
   can be assumed to support IPsec.  SLP servers, however, cannot be
   assumed to implement IPsec, since there is no such requirement in
   standard SLP.  In particular, SLP Directory Agents (DA) may be
   running on machines other than those running the IPS protocols.

   IPsec SHOULD be implemented for SLPv2 as specified in [RFC3723]; this
   includes ESP with a non-null transform to provide both authentication
   and confidentiality.

   Because the IP storage services have their own authentication
   capabilities when located, SLPv2 authentication is OPTIONAL to
   implement and use (as discussed in more detail in [RFC3723]).

7.  IANA Considerations

   This document describes two SLP Templates in Section 5.  They should
   be registered in the IANA "SVRLOC Templates" registry.  This process
   is described in the IANA Considerations section of [RFC2609].

8.  Internationalization Considerations

   SLP allows internationalized strings to be registered and retrieved.
   Attributes in the template that are not marked with an 'L' (literal)
   will be registered in a localized manner.  An "en" (English)
   localization MUST be registered, and others MAY be registered.

9.  Summary

   This document describes how SLPv2 can be used by FCIP Entities to
   find other FCIP Entities.  Service type templates for FCIP Entities
   are presented.

10.  Acknowledgements

   This document was produced by the FCIP discovery team, including Todd
   Sperry (Adaptec), Larry Lamars (SanValley), Robert Snively (Brocade),
   Ravi Natarajan (Lightsand), Anil Rijhsinghani (McData), and Venkat
   Rangan (Rhapsody Networks).  Thanks also to Mark Bakke (Cisco) for
   initial help and consultation, and David Black, Erik Guttman, and
   James Kempf for assistance during expert review.

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11.  References

11.1.  Normative References

   [RFC2608]   Guttman, E., Perkins, C., Veizades, J. and M. Day,
               "Service Location Protocol, Version 2", RFC 2608, June

   [RFC2609]   Guttman, E., Perkins, C. and J. Kempf, "Service Templates
               and Service: Schemes", RFC 2609, June 1999.

   [RFC2119]   Bradner, S., "Key Words for Use in RFCs to Indicate
               Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC3821]   Rajagopal, M., Bhagwat, R. and R. Weber, "Fibre Channel
               Over TCP/IP (FCIP)", RFC 3821, July 2004.

   [FC-SW-3]   Fibre Channel Switch Fabric - 3, ANSI INCITS 384-2004.

   [FC-BB-2]   Fibre Channel Backbone - 2, ANSI INCITS 372-2003.

   [FC-FS]     Fibre Channel Framing and Signaling, T11 Project 1331-D,
               Rev 1.90, April 9, 2003.

   [RFC3723]   Aboba, B., Tseng, J., Walker, J., Rangan, V. and F.
               Travostino, "Securing Block Storage Protocols over IP",
               RFC 3723, April 2004.

11.2.  Informative References

   [RFC3105]   Kempf, J. and G. Montenegro, "Finding an RSIP Server with
               SLP", RFC 3105, October 2001.

12.  Author's  Address

   David Peterson
   Computer Network Technology (CNT)
   6000 Nathan Lane North
   Minneapolis, MN 55442

   Phone: 763-268-6139
   EMail: dap@cnt.com

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13.  Full Copyright Statement

   Copyright (C) The Internet Society (2004).  This document is subject
   to the rights, licenses and restrictions contained in BCP 78, and
   except as set forth therein, the authors retain all their rights.

   This document and the information contained herein are provided on an

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   Internet Society.

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