Network Working Group                                          Dan Li
Internet Draft                                                 Huawei
Updates: RFC4204                                        D. Ceccarelli
Category: Standards Track                                    Ericsson

Expires: November 2010                                   May 28, 2010

             Behavior Negotiation in Link Management Protocol


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   Section 4.e of the Trust Legal Provisions and are provided without
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   The Link Management Protocol (LMP) is used to coordinate the
   properties, use, and faults of data links in Generalized
   Multiprotocol Label Switching (GMPLS) networks. Various proposals
   have been advanced to provide extensions to the base LMP
   specification. This document provides a generic procedure for LMP
   implementations that do not recognize or do not support any one of
   these extensions.

Conventions used in this document

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

Table of Contents

   1. Introduction.................................................2
   2. LMP Behavior Negotiation Procedure...........................3
   3. Security Considerations......................................6
   4. IANA Considerations..........................................6
   5. Contributors.................................................6
   6. Acknowledgments..............................................7
   7. References...................................................7
      7.1. Normative References....................................7
      7.2. Informative References..................................7
   8. Authors' Address.............................................8

1. Introduction

   The Link Management Protocol (LMP) [RFC4204] is being successfully
   deployed in Generalized Multiprotocol Label Switching (GMPLS)
   networks in the field. New LMP behaviors and protocol extensions are
   being introduced in a number of IETF documents.

   In the network, if one GMPLS Label Switching Router (LSR) supports a
   new behavior or protocol extension, but its peer LSR does not, it is
   necessary to have a protocol mechanism for resolving issues that may
   arise. It is also beneficial to have a protocol mechanism to
   discover the capabilities of peer LSRs. There is no such procedure
   defined in the base LMP specification [RFC4204], so this document

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   defines how to handle LMP extensions both at legacy LSRs and at
   upgraded LSRs that communicate with legacy LSRs.

   In [RFC4204], the basic behaviors have been defined around the use
   of the standard LMP message, which includes Config, Hello, Verify,
   Test, LinkSummary, ChannelStatus. Per [RCF4204], these behaviors
   MUST be supported when the LMP is implemented, and the message types
   from 1 to 20 are used for these behaviors.

   In [RFC4207], the SONET/SDH technology-specific information for LMP
   is defined. The TRACE behavior is added to LMP, and the message
   types from 21 to 31 were defined for the TRACE function. The TRACE
   function has been extended for the support of OTNs (Optical
   Transport Networks) in [LMP TEST].

   In [RFC4209], extensions to LMP are defined to allow it to be used
   between a peer node and an adjacent optical line system (OLS). The
   LMP object class type and sub-object class name have been extended
   to support DWDM behavior.

   In [RFC5818], the data channel consistency check behavior is defined,
   the message types from 32 to 34 are used for this behavior.

   This document describes the behavior negotiation procedure to make
   sure both LSRs of each link understand the LMP messages being
   exchanged between peers.

2. LMP Behavior Negotiation Procedure

   The Config message is used in the control channel negotiation phase
   of LMP [RC4204]. The LMP behavior negotiation procedure is defined
   in this document as an addition at this phase.

   The Config message is defined in Section 12.3.1 of [RFC4204] and
   carries the <CONFIG> object (class name 6) as defined in Section
   13.6 of [RFC4204]. Multiple <CONFIG> objects (each with a different
   Class Type) MAY be present on a Config message in which case all of
   the objects MUST be processed.

   Two class types have been defined:

   - C-Type = 1, HelloConfig, defined in [RFC4204]

   - C-Type = 2, LMP_WDM_CONFIG, defined in [RFC4209]

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   This document defines a third C-Type with value 3 (TBD by IANA) to
   report and negotiate new and future LMP extensions and behaviors.


   Two different types of flag are defined in this object: Architecture
   Flags and Capability Flags. The first set of flags indicates the
   network architecture supported by the node (e.g. OTN, SDH/SONET,
   DWDM), while the second one all the optional capabilities supported
   by the protocol implementation (e.g. Link Verification, Fault
   Management). The existing RFCs define the following capabilities:

   - Control Channel Management (Mandatory)

   - Link Property Correlation (Mandatory)

   - Link Verification (Optional)

   - Fault Management (Optional)

   - Trace Monitoring (Optional)

   - Data Channel Status Confirmation (Optional)

   Due to the fact that Control Channel Management and Link Property
   Correlation are mandatory capabilities, no capability flag is
   defined for their configuration. When an architecture flag is set,
   automatically these two capabilities are implicitly supported. With
   respect to the other ones, a flag for each of them is defined.

   The format of the new type of CONFIG Class is defined as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   |       Reserved        |M|O|W|S|        Reserved       |D|T|F|V|
   |<----- Architecture Flags ---->|<-----  Capability Flags ----->|

   Architecture Flags:

   S: 1 bit

   This bit indicates support for the SONET/SDH.

   W: 1 bit

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   This bit indicates support for WDM.

   O: 1 bit

   This bit indicates support for OTN.

   M: 1 bit

   This bit indicates support for MPLS-TP

   Capability Flags:

   V: 1 bit

   This bit indicates support for the Link Verification capability
   defined in [RFC4204].

   F: 1 bit

   This bit indicates support for the Fault Management capability
   defined in [RFC4204].

   T: 1 bit

   This bit indicates support for the Trace Monitoring defined in
   [RFC4204], [RFC4207] and [LMP TEST].

   D: 1 bit

   This bit indicates support for the Data Channel Status Confirmation
   messages defined in [RFC5818].

   Further bits may be defined in future documents.

   The Reserved field MUST be sent as zero and MUST NOT be ignored on
   receipt. This allows the detection of supported/unsupported LMP

   Upon receiving a bit set related to a non supported behavior, a
   ConfigNack message MUST be sent with a <CONFIG> object representing
   the supported LMP behaviors.

   An LSR that receives a Config message containing a <CONFIG> object
   with a C-Type that it does not recognize MUST respond with a
   ConfigNack message as described in [RFC4204]. Thus, legacy LMP nodes
   that do not support the ENHANCED_BEHAVIOR_CONFIG C-Type defined in
   this document will respond with a ConfigNack message.

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3. Security Considerations

   [RFC4204] describes how LMP messages between peers can be secured,
   and these measures are equally applicable to messages carrying the
   new <CONFIG> object defined in this document.

   The operation of the procedures described in this document does not
   of itself constitute a security risk since they do not cause any
   change in network state. It would be possible, if the messages were
   intercepted or spoofed to cause bogus alerts in the management plane,
   or to cause LMP peers to consider that they could or could not
   operate protocol extensions, and so the use of the LMP security
   measures are RECOMMENDED.

4. IANA Considerations

   IANA maintains the "Link Management Protocol (LMP)" registry which
   has a subregistry called "LMP Object Class name space and Class type

   IANA is requested to make an assignment from this registry as

      6   CONFIG                              [RFC4204]

   CONFIG Object Class type name space:

   C-Type   Description                    Reference
   ------   ------------------------       ---------
        3   ENHANCED_BEHAVIOR_CONFIG       [This.I-D]

5. Contributors

   Diego Caviglia
   Via A. Negrone 1/A 16153
   Genoa Italy
   Phone: +39 010 600 3736

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6. Acknowledgments

   Thanks to Adrian Farrel and Lou Berger for their useful comments.

7. References

7.1. Normative References

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

   [RFC4204] J. Lang, Ed., "Link Management Protocol (LMP)", RFC 4204,
             October 2005.

   [RFC4207] J. Lang, Ed., "Synchronous Optical Network (SONET)/
             Synchronous Digital Hierarchy (SDH) Encoding for Link
             Management Protocol (LMP) Test Messages", RFC 4207,
             October 2005.

   [RFC4209] A. Fredette, Ed., "Link Management Protocol (LMP) for
             Dense Wavelength Division Multiplexing (DWDM) Optical Line
             Systems", RFC 4209, October 2005.

   [RFC5818] D. Li, Ed., "Data Channel Status Confirmation Extensions
             for the Link Management Protocol", RFC 5818, April 2010.

7.2. Informative References

   [LMP TEST] D. Ceccarelli, Ed., "Link Management Protocol (LMP) Test
             Messages Extensions for Evolutive Optical Transport
             Networks (OTN)" draft-ceccarelli-ccamp-gmpls-g709-lmp-
             test-02.txt, May, 2010.

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8. Authors' Address

      Dan Li
      Huawei Technologies
      F3-5-B R&D Center, Huawei Industrial Base,
      Shenzhen 518129 China
      Phone: +86 755-289-70230

      Daniele Ceccarelli
      Via A. Negrone 1/A
      Genova - Sestri Ponente

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