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Internet Engineering Task Force (IETF)                             D. LiRequest for Comments: 6898                                        HuaweiUpdates:4204,4207,4209,5818                            D. CeccarelliCategory: Standards Track                                       EricssonISSN: 2070-1721                                                L. Berger                                                                    LabN                                                              March 2013Link Management Protocol Behavior Negotiation andConfiguration ModificationsAbstract   The Link Management Protocol (LMP) is used to coordinate the   properties, use, and faults of data links in networks controlled by   Generalized Multiprotocol Label Switching (GMPLS).  This document   defines an extension to LMP to negotiate capabilities and indicate   support for LMP extensions.  The defined extension is compatible with   non-supporting implementations.   This document updatesRFC 4204,RFC 4207,RFC 4209, andRFC 5818.Status of This Memo   This is an Internet Standards Track document.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   Internet Standards is available inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc6898.Li, et al.                   Standards Track                    [Page 1]

RFC 6898                LMP Behavior Negotiation              March 2013Copyright Notice   Copyright (c) 2013 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (http://trustee.ietf.org/license-info) in effect on the date of   publication of this document.  Please review these documents   carefully, as they describe your rights and restrictions with respect   to this document.  Code Components extracted from this document must   include Simplified BSD License text as described in Section 4.e of   the Trust Legal Provisions and are provided without warranty as   described in the Simplified BSD License.Table of Contents1. Introduction ....................................................31.1. Conventions Used in This Document ..........................42. LMP Message Modifications .......................................42.1. Modified Message Formats ...................................42.2. Processing .................................................53. LMP Behavior Negotiation ........................................63.1. BehaviorConfig C-Type Format ...............................63.2. Processing .................................................74. Backward Compatibility ..........................................75. Security Considerations .........................................86. IANA Considerations .............................................96.1. New LMP Class Type .........................................96.2. New Capabilities Registry ..................................97. Normative References ...........................................108. Acknowledgments ................................................109. Contributors ...................................................10Li, et al.                   Standards Track                    [Page 2]

RFC 6898                LMP Behavior Negotiation              March 20131.  Introduction   The Link Management Protocol (LMP) [RFC4204] has been successfully   deployed in networks controlled by Generalized Multiprotocol Label   Switching (GMPLS).   New LMP behaviors and protocol extensions have been introduced in a   number of IETF documents, as set out later in this section.  It is   likely that future extensions will be made to support additional   functions.   In a network, if one LMP-capable node supports a new behavior or   protocol extension but its adjacent node does not, it is beneficial   to have a protocol mechanism to discover the capabilities of peer   nodes so that the right protocol extensions can be selected and the   correct features can be enabled.  There are no such procedures   defined in the base LMP specification [RFC4204]. [RFC4209] defined a   specific mechanism to identify support for the functions specified in   that document.  This document defines an LMP extension to support the   identification of supported LMP functions in a generic fashion, as   well as how a node supporting these extensions would communicate with   legacy nodes.   In [RFC4204], the basic behaviors have been defined around the use of   the standard LMP messages, which include Config, Hello, Verify, Test,   LinkSummary, and ChannelStatus.  Per [RFC4204], these behaviors MUST   be supported when LMP is implemented, and the message types from 1 to   20 have been assigned by IANA for these messages.  Support for all   functions required by [RFC4204] is assumed by this document.   In [RFC4207], the SONET/SDH technology-specific behavior and   information for LMP is defined.  The Trace behavior is added to LMP,   and the message types from 21 to 31 have been assigned by IANA for   the messages that provide the Trace function.   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 subobject class name have been extended to   support Dense Wavelength Division Multiplexing (DWDM) behavior.   In [RFC5818], the data channel consistency check behavior is defined,   and the message types from 32 to 34 have been assigned by IANA for   messages that provide this behavior.   It is likely that future extensions to LMP for other functions or   technologies will require the definition of further LMP messages.Li, et al.                   Standards Track                    [Page 3]

RFC 6898                LMP Behavior Negotiation              March 2013   This document describes an LMP extension, referred to as behavior   negotiation, that enables the nodes at the ends of a link to identify   the LMP messages and functions supported by the adjacent node.  The   extension makes use of a new CONFIG object.  The use of this new   object does not preclude the use of existing or yet to be defined   CONFIG objects.   This document also modifies the format of messages that carry the   CONFIG object to allow for multiple objects.  Multiple CONFIG objects   allow behavior negotiation concurrent with existing usage of the   CONFIG object, i.e., HelloConfig C-Type defined in [RFC4204] and   LMP-WDM_CONFIG C-Type defined in [RFC4209].  This document modifies   the ConfigAck message to include CONFIG objects so that acceptable   parameters are explicitly identified.  It also describes how a node   that supports the extensions defined in this document interacts with   a legacy LMP-capable node.1.1.  Conventions Used in This Document   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this   document are to be interpreted as described in [RFC2119].2.  LMP Message Modifications   LMP Config, ConfigNack, and ConfigAck messages are modified by this   document to allow for the inclusion of multiple CONFIG objects.  The   Config and ConfigNack messages were only defined to carry one CONFIG   object in [RFC4204].  The ConfigAck message, which was defined   without carrying any CONFIG objects in [RFC4204], is modified to   enable explicit identification of negotiated configuration   parameters.  The inclusion of CONFIG objects in ConfigAck messages is   triggered by the use of the BehaviorConfig object (defined below) in   a received Config message.   The message formats in the sections that follow use Backus-Naur Form   (BNF) encoding as defined in [RFC5511].2.1.  Modified Message Formats   The format of the Config message as updated by this document is as   follows:    <Config Message> ::= <Common Header> <LOCAL_CCID> <MESSAGE_ID>                         <LOCAL_NODE_ID> <CONFIG> [ <CONFIG> ... ]Li, et al.                   Standards Track                    [Page 4]

RFC 6898                LMP Behavior Negotiation              March 2013   The format of the ConfigAck message as updated by this document is as   follows:    <ConfigAck Message> ::= <Common Header> <LOCAL_CCID> <LOCAL_NODE_ID>                            <REMOTE_CCID> <MESSAGE_ID_ACK>                            <REMOTE_NODE_ID>[ <CONFIG> ... ]   The format of the ConfigNack message as updated by this document is   as follows:    <ConfigNack Message> ::= <Common Header> <LOCAL_CCID>                             <LOCAL_NODE_ID>  <REMOTE_CCID>                             <MESSAGE_ID_ACK> <REMOTE_NODE_ID>                             <CONFIG> [ <CONFIG> ... ]2.2.  Processing   Nodes that support the extensions defined in this document MAY   include multiple CONFIG objects when sending a Config, ConfigAck, and   ConfigNack message.  A maximum of a single object of any particular   C-type SHALL be included.  A node that receives a message with   multiple CONFIG objects of the same C-type SHALL process the first   object of a particular C-type and ignore any subsequent CONFIG   objects of the same C-type.  Unless specified as part of the CONFIG   object definition, ordering of CONFIG objects with different C-type   values is not significant.   Nodes that support the extensions defined in this document MUST   include a BehaviorConfig type object when sending a Config message to   a neighbor whose support for the extensions is either known or   unknown.  When the neighbor is known to not support the extensions,   the object MUST NOT be sent.  Inclusion of other CONFIG objects in a   Config message is at the discretion of the message sender and is   based on the rules defined as part of CONFIG object definition.   Nodes MAY include HelloConfig, LMP-WDM_CONFIG, BehaviorConfig object   types in a single message.   Inclusion of multiple CONFIG objects in a ConfigNack message is based   on the processing of a received Config message.  Per [RFC4204],   "Parameters where agreement was reached MUST NOT be included in the   ConfigNack Message."  As such, a ConfigNack message MUST NOT include   CONFIG objects that are acceptable and MUST include any CONFIG   objects which are not acceptable.  When a CONFIG object is included   in a ConfigNack message, per [RFC4204], the object is to include   "acceptable alternate values for negotiable parameters".Li, et al.                   Standards Track                    [Page 5]

RFC 6898                LMP Behavior Negotiation              March 2013   When sending a ConfigAck message, nodes supporting the extensions   defined in this document MUST include all CONFIG objects received in   the corresponding Config message when that message includes a CONFIG   object of type BehaviorConfig.3.  LMP Behavior Negotiation   The Config message is used in the control channel negotiation phase   of LMP [RFC4204].  The LMP behavior negotiation procedure is defined   in this document as an addition to this phase.   The Config message is defined inSection 12.3.1 of [RFC4204] and   carries the CONFIG object (class name 6) as defined inSection 13.6   of [RFC4204].   Two class types have been defined:   - C-Type = 1, HelloConfig, defined in [RFC4204]   - C-Type = 2, LMP-WDM_CONFIG, defined in [RFC4209]   This document defines a third C-Type to report and negotiate LMP   mechanisms and behaviors.  Its usage indicates support for the   extensions defined in this document.3.1.  BehaviorConfig C-Type Format   Class = 6   - C-Type = 3, BehaviorConfig       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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |S|D|C|                   Must Be Zero (MBZ)                    |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   Flags:     S: 1 bit      This bit indicates support for the Trace behavior of SONET/SDH      technology-specific defined in [RFC4207].     D: 1 bit      This bit indicates support for the DWDM behavior defined in      [RFC4209].Li, et al.                   Standards Track                    [Page 6]

RFC 6898                LMP Behavior Negotiation              March 2013     C: 1 bit      This bit indicates support for the data channel consistency check      behavior defined in [RFC5818].     Must Be Zero (MBZ): Variable length      The remaining bits in the flags field MUST be set to zero (0).      This field MUST be sized to ensure 32-bit alignment of the object.      Other bits may be defined in future documents, in which case the      number of bits in the MBZ field is expected to change.3.2.  Processing   The inclusion of a BehaviorConfig type object in a message is   discussed above inSection 2.2.   When sending a BehaviorConfig type object, the N-bit (negotiable) in   the LMP object header MUST be set (N=1) in the LMP object header.   When sending a BehaviorConfig type object in Config and ConfigNack   messages, the flags field SHOULD be set based on the supported   capabilities of the sending node.  When sending a ConfigAck message,   the flags field MUST be set to the value received in the   corresponding Config message.   When receiving a BehaviorConfig type object, the node compares the   flags field against its capacities.  Any bit set in the MBZ portion   of the flags field MUST be interpreted as unacceptable.  Processing   related to unacceptable values in CONFIG objects is defined in   [RFC4204] and is not modified by this document.4.  Backward Compatibility   The required use of the BehaviorConfig type CONFIG object enables   nodes that support the extensions defined in this document to   explicitly identify when a neighboring node does not.  When a non-   supporting node receives a Config message with the BehaviorConfig   type CONFIG object or multiple CONFIG objects, its behavior is to be   one of the following behaviors:   a) Reject the Config message because of the unknown BehaviorConfig      object type and send a ConfigNack message which includes the      unsupported C-type.Li, et al.                   Standards Track                    [Page 7]

RFC 6898                LMP Behavior Negotiation              March 2013   b) Reject the message because of multiple CONFIG objects and send a      ConfigNack message which includes all but one of the CONFIG      objects.   c) Silently ignore the one or more of the CONFIG object, and respond      with a ConfigAck message that does not include any CONFIG objects.   d) Treat the message as malformed, and discard it without any      response.   Behaviors (a) and (b) result in ConfigNack messages with a   BehaviorConfig type object whose contents are identical to what was   sent in the Config message.  Behavior (c) results in a ConfigAck   message without a BehaviorConfig type CONFIG object.  In each of   these cases, the node SHOULD explicitly identify that the LMP   neighbor does not support the extensions defined in this document.   Behavior (d) results in no response at all.  When the node reaches   the "retry limit", defined in [RFC4204], the node SHOULD infer that   the LMP neighbor does not support the extensions defined in this   document.   Once a node identifies a neighbor as not supporting the extensions   defined in this document, the node SHOULD follow previously defined   Config message usage.5.  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.   Alone, the procedures described in this document do not 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.   Note, however, that [RFC4204] references for security have been   updated with [RFC4301], and the current reference for IKEv2 is   [RFC5996].Li, et al.                   Standards Track                    [Page 8]

RFC 6898                LMP Behavior Negotiation              March 20136.  IANA Considerations6.1.  New LMP Class Type   IANA maintains the "Link Management Protocol (LMP) Parameters"   registry, which has a subregistry called "LMP Object Class name space   and Class type (C-Type)".   IANA has made an assignment from this registry as follows:      6   CONFIG                              [RFC4204]   CONFIG Object Class type name space:      C-Type        Description            Reference      ------------  ---------------------  ---------      3             BehaviorConfigRFC 68986.2.  New Capabilities Registry   IANA has created a new subregistry of the "Link Management Protocol   (LMP) Parameters" registry to track the Behavior Configuration bits   defined inSection 2 of this document.  This registry is called "LMP   Behavior Configuration Flags".   Allocations from this registry are by Standards Action.   Bits in this registry are numbered from zero as the most significant   bit (transmitted first).  The number of bits that can be present is   limited by the length field of the CONFIG object, which gives rise to   (255 x 32)-8 = 8152.  IANA is strongly recommended to allocate new   bits with the lowest available unused number.   The registry is initially populated as follows:      Bit    | Bit  | Meaning                                | Reference      Number | Name |                                        |      -------+------+----------------------------------------+----------        0    |   S  | SONET/SDH Test support                 |RFC 6898        1    |   D  | DWDM support                           |RFC 6898        2    |   C  | Data Channel consistency check support |RFC 6898Li, et al.                   Standards Track                    [Page 9]

RFC 6898                LMP Behavior Negotiation              March 20137.  Normative References   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate              Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the              Internet Protocol",RFC 4301, December 2005.   [RFC5996]  Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,              "Internet Key Exchange Protocol Version 2 (IKEv2)",RFC5996, September 2010.   [RFC4204]  Lang, J., Ed., "Link Management Protocol (LMP)",RFC 4204,              October 2005.   [RFC4207]  Lang, J. and D. Papadimitriou, "Synchronous Optical              Network (SONET)/Synchronous Digital Hierarchy (SDH)              Encoding for Link Management Protocol (LMP) Test              Messages",RFC 4207, October 2005.   [RFC4209]  Fredette, A., Ed., and J. Lang, Ed., "Link Management              Protocol (LMP) for Dense Wavelength Division Multiplexing              (DWDM) Optical Line Systems",RFC 4209, October 2005.   [RFC5818]  Li, D., Xu, H., Bardalai, S., Meuric, J., and D. Caviglia,              "Data Channel Status Confirmation Extensions for the Link              Management Protocol",RFC 5818, April 2010.   [RFC5511]  Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax              Used to Form Encoding Rules in Various Routing Protocol              Specifications",RFC 5511, April 2009.8.  Acknowledgments   Thanks to Adrian Farrel and Richard Graveman for their useful   comments.9.  Contributors   Diego Caviglia   Ericsson   Via E. Melen, 77   Genova - Erzelli   Italy   Phone: +39 010 600 3736   EMail: diego.caviglia@ericsson.comLi, et al.                   Standards Track                   [Page 10]

RFC 6898                LMP Behavior Negotiation              March 2013Authors' Addresses   Dan Li   Huawei Technologies   F3-5-B R&D Center, Huawei Industrial Base,   Shenzhen 518129   China   Phone: +86 755-289-70230   EMail: huawei.danli@huawei.com   Daniele Ceccarelli   Ericsson   Via E. Melen, 77   Genova - Erzelli   Italy   EMail: daniele.ceccarelli@ericsson.com   Lou Berger   LabN Consulting, L.L.C.   EMail: lberger@labn.netLi, et al.                   Standards Track                   [Page 11]