Network Working Group                                          A. Takacs
Internet-Draft                                                   B. Gero
Intended status: Standards Track                                Ericsson
Expires: January 13, July 28, 2011                                          D. Fedyk
                                                          Alcatel-Lucent
                                                                 H. Long
                                                                  Huawei
                                                                D. Mohan
                                                           July 12, 2010
                                                        January 24, 2011

        GMPLS RSVP-TE Extensions for Ethernet OAM Configuration
                draft-ietf-ccamp-rsvp-te-eth-oam-ext-03
                draft-ietf-ccamp-rsvp-te-eth-oam-ext-04

Abstract

   The GMPLS controlled Ethernet Label Switching (GELS) work is
   extending GMPLS RSVP-TE to support the establishment of Ethernet
   LSPs.  IEEE Ethernet Connectivity Fault Management (CFM) specifies an
   adjunct OAM flow to check connectivity in Ethernet networks.  CFM can
   be also used with Ethernet LSPs for fault detection and triggering
   recovery mechanisms.  The ITU-T Y.1731 specification builds on CFM
   and specifies additional OAM mechanisms, including Performance
   Monitoring, for Ethernet networks.  This document specifies
   extensions of GMPLS RSVP-TE to support the setup of the associated
   Ethernet OAM (CFM and Y.1731) entities adding a technology specific
   TLV to [OAM-CONF-FWK].

Requirements Language

   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

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Table of Contents

   1.  Background . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Overview of Ethernet OAM operation . . . . . . . . . . . . . .  5
   3.  GMPLS RSVP-TE Extensions . . . . . . . . . . . . . . . . . . .  7
     3.1.  Operation overview . . . . . . . . . . . . . . . . . . . .  7
     3.2.  OAM Configuration TLV  . . . . . . . . . . . . . . . . . .  9
     3.3.  Ethernet OAM Configuration TLV . . . . . . . . . . . . . .  9
       3.3.1.  MD Name Sub-TLV  . . . . . . . . . . . . . . . . . . . 10
       3.3.2.  Short MA Name Sub-TLV  . . . . . . . . . . . . . . . . 11
       3.3.3.  MEP ID Sub-TLV . . . . . . . . . . . . . . . . . . . . 12
       3.3.4.  Continuity Check (CC) Sub-TLV  . . . . . . . . . . . . 12
     3.4.  Pro-active Performance Monitoring  . . . . . . . . . . . . 13
     3.5.  Ethernet OAM configuration errors  . . . . . . . . . . . . 13
   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
   7.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19

1.  Background

   Provider Backbone Bridging - Traffic Engineering (PBB-TE)
   [IEEE-PBBTE] decouples the Ethernet data and control planes by
   explicitly supporting external control/management mechanisms to
   configure static filtering entries in bridges and create explicitly
   routed Ethernet connections.  In addition PBB-TE defines mechanisms
   for 1:1 protection switching of bidirectional Ethernet connections.

   Ethernet Connectivity Fault Management (CFM) defines an adjunct
   connectivity monitoring OAM flow to check the liveliness of Ethernet
   networks [IEEE-CFM].  With PBB-TE Ethernet networks will support
   explicitly-routed Ethernet connections.  CFM can be used to track the
   liveliness of PBB-TE and point-to-point VLAN connections and detect
   data plane failures.

   In IETF the GMPLS controlled Ethernet Label Switching (GELS)
   [GELS-Framework] work is extending the GMPLS control plane to support
   the establishment of PBB-TE and point-to-point VLAN data plane
   connections.  We refer to GMPLS established Ethernet connections as
   Ethernet LSPs.  GELS enables the application of MPLS-TE and GMPLS
   provisioning and recovery features in Ethernet networks.

2.  Overview of Ethernet OAM operation

   For the purposes of this document, we only discuss Ethernet OAM
   [IEEE-CFM] aspects that are relevant for the connectivity monitoring
   of PBB-TE and point-to-point VLAN connections.

   PBB-TE [IEEE-PBBTE] defines point-to-point Ethernet Switched Paths
   (ESPs) as a provisioned traffic engineered unidirectional
   connectivity, identified by the 3-tuple [ESP-MAC DA, ESP-MAC SA, ESP-
   VID] where the ESP-MAC DA is the destination address of the ESP, the
   ESP-MAC SA is the source address of the ESP, and the ESP-VID is a
   VLAN identifier allocated for explicitly routed connections.  To form
   a bidirectional PBB-TE connection two co-routed point-to-point ESPs
   are combined.  The combined ESPs must have the same ESP-MAC addresses
   but may have different ESP-VIDs.

   Note that although it would be possible to use GMPLS to setup a
   single unidirectional ESP, the Ethernet OAM mechanisms are only full
   functional when bidirectional connections are established with co-
   routed ESPs.  Hence, we focus on bidirectional point-to-point PBB-TE
   connections.

   At both ends of the bidirectional point-to-point PBB-TE connection
   one Maintenance Endpoint (MEP) is configured.  The MEPs monitoring a
   PBB-TE connection must be configured with the same Maintenance Domain
   Level (MD Level) and Maintenance Association Identifier (MAID).  Each
   MEP has a unique identifier, the MEP ID.  Besides these identifiers a
   MEP monitoring a PBB-TE connection must be provisioned with the
   3-tuples [ESP-MAC DA, ESP-MAC SA, ESP-VID] of the two ESPs.

   In the case of point-to-point VLAN connections, the connection is
   identified with a single VLAN forwarding traffic in both directions
   or with two VLANs each forwarding traffic in a single direction.
   Hence instead of the 3-tuples of the PBB-TE case MEPs must be
   provisioned with the proper VLAN information, otherwise the same MD
   Level, MAID, MEP ID configuration is required in this case as well.

   MEPs exchange Connectivity Check Messages (CCMs) periodically with
   fixed intervals.  Eight distinct intervals are defined in [IEEE-CFM]:

                +---+--------------------+----------------+
                | # | CCM Interval (CCI) | 3 bit encoding |
                +---+--------------------+----------------+
                | 0 |      Reserved      |       000      |
                |   |                    |                |
                | 1 |      3 1/3 ms      |       001      |
                |   |                    |                |
                | 2 |        10 ms       |       010      |
                |   |                    |                |
                | 3 |       100 ms       |       011      |
                |   |                    |                |
                | 4 |         1 s        |       100      |
                |   |                    |                |
                | 5 |        10 s        |       101      |
                |   |                    |                |
                | 6 |        1 min       |       110      |
                |   |                    |                |
                | 7 |       10 min       |       111      |
                +---+--------------------+----------------+

                      Table 1: CCM Interval encoding

   If 3 consecutive CCM messages are not received by one of the MEPs it
   declares a connectivity failure and signals the failure in subsequent
   CCM messages, by setting the Remote Defect Indicator (RDI) bit, to
   the remote MEP.  If a MEP receives a CCM message with RDI set it
   immediately declares failure.  The detection of a failure may trigger
   protection switching mechanisms or may be signaled to a management
   system.  However, what happens once a failure is detected is out of
   the scope of this document.

   At each transit node Maintenance Intermediate Points (MIPs) can be
   established to help failure localization by supporting link trace and
   loop back functions.  MIPs need to be provisioned with a subset of
   MEP identification parameters described above.

3.  GMPLS RSVP-TE Extensions

3.1.  Operation overview

   To simplify the configuration of connectivity monitoring, when an
   Ethernet LSP is signaled the associated MEPs should be automatically
   established.  To monitor an Ethernet LSP a set of parameters must be
   provided to setup a Maintenance Association and related MEPs.
   Optionally, MIPs may be created at the transit nodes of the Ethernet
   LSP.  The LSP Attributes Flags: "OAM MEP entities desired" and "OAM
   MIP entities desired", described in [OAM-CONF-FWK] are used to signal
   that the respective OAM entities must be established.  Subsequently,
   an OAM Configuration TLV is added to the LSP_ATTRIBUTES Object
   specifying that Ethernet OAM is to be setup for the LSP.  The below
   detailed Ethernet OAM specific information is carried in a new sub-
   TLV.

   o  A unique MAID must be allocated for the PBB-TE connection and both
      MEPs must be configured with the same information.  The MAID
      consists of an optional Maintenance Domain Name (MD Name) and a
      mandatory Short Maintenance Association Name (Short MA Name).
      Various formatting rules for these names have been defined by
      [IEEE-CFM].  Since these information is also carried in all CCM
      messages, the combined length of the Names is limited to 44 bytes.
      How these parameters are determined is out of scope of this
      document.

   o  Each MEP must be provisioned with a MEP ID.  The MEP ID uniquely
      identifies a given MEP within a Maintenance Association.  That is,
      the combination of MAID and MEP ID must uniquely identify a MEP.
      How the value of the MEP ID is determined is out of scope of this
      document.

   o  The Maintenance Domain Level (MD Level) allows hierarchical
      separation of monitoring entities.  [IEEE-CFM] allows
      differentiation of 8 levels.  How the value of the MD Level is
      determined is out of scope of this document.  Note that most
      probably for all Ethernet LSPs a single (default) MD Level will be
      used in a network domain.

   o  The desired CCM Interval must be specified by the management
      system based on service requirements or operator policy.  The same
      CCM Interval must be set in each of the MEPs monitoring a given
      Ethernet LSP.  How the value of the CCM Interval is determined is
      out of scope of this document.

   o  The desired CCM priority to be set by MEPs for the CCM frames can
      be specified.  The same CCM priority must be set in each of the
      MEPs monitoring a given Ethernet LSP.  How CCM priority is
      determined is out of scope of this document.  Note that the
      highest priority is used as the default CCM priority.

   o  MEPs must be aware of their own and the reachability parameters of
      the remote MEP.  In the case of bidirectional point-to-point
      PBB-TE connections this requires that the 3-tuples [ESP-MAC A,
      ESP-MAC B, ESP-VID1] and [ESP-MAC B, ESP-MAC A, ESP-VID2] are
      configured in each MEP, where the ESP-MAC A is the same as the
      local MEP's MAC and ESP-MAC B is the same as remote MEP's MAC.
      The GMPLS Ethernet Label for forwarding, as defined in
      [GELS-PBBTE], consists of the ESP-MAC DA and ESP-VID.  Hence the
      necessary reachability parameters for the MEPs can be obtained
      from Ethernet Labels (i.e., carried in the "downstream" and
      upstream labels).  In the case of point-to-point VLAN connections,
      MEPs need to be provisioned with the VLAN identifiers, which in
      this case are derived similarly from the Ethernet Label.

   Assuming the procedures described in [GELS-PBBTE] for bidirectional
   PBB-TE Ethernet LSP establishment the MEP configuration should be as
   follows.  When the RSVP-TE signaling is initiated for the
   bidirectional Ethernet LSP the local node generates a Path message
   and:

   o  Allocates an Upstream Label from its MAC address (ESP-MAC A) and
      locally selected VID (ESP-VID1), that it would like to use to
      receive traffic;

   o  Inserts an Ethernet OAM Configuration TLV in the LSP_ATTRIBUTES
      object, specifying the CCM Interval and MD Level;

   o  Adds an MD Name Sub-TLV (optional) and a Short MA Name Sub-TLV to
      the Ethernet OAM Configuration TLV, that will unambiguously
      identify a Maintenance Association for this specific PBB-TE
      connection.  Note that values for these parameters may be derived
      from the GMPLS LSP identification parameters;

   o  Adds a MEP ID Sub-TLV to the Ethernet OAM Configuration TLV.  It
      selects two distinct integer values to identify the local and
      remote MEPs within the Maintenance Association created for
      monitoring of the point-to-point PBB-TE connection.

   Once the remote node receives the Path message it can use the
   UPSTREAM_LABEL to extract the reachability information of the
   initiator.  Then it allocates a LABEL by selecting the MAC address
   (ESP-MAC B) and VID (ESP-VID2) it would like to use to receive
   traffic.  These parameters determine the reachability information of
   the local MEP.  That is, the 3-tuples [ESP-MAC A, ESP-MAC B, ESP-
   VID1] and [ESP-MAC B, ESP-MAC A, ESP-VID2] are derived from the
   Ethernet Labels.  In addition the information received in the
   Ethernet OAM Configuration TLV is used to configure the local MEP.

   Once the Resv message successfully arrives to the initiator it can
   extract the remote side's reachability information from the LABEL
   object whereby this node has also obtained all the information needed
   to establish its local MEP.

   Once the MEPs are established the monitoring of the LSP is
   operational.  In certain situations, e.g., maintenance, re-
   optimization of LSPs, it is desirable to explicitly enable or disable
   the monitoring of LSPs (i.e., start/stop exchanging CC messages).  To
   allow administrative control of LSP monitoring the "Monitoring
   Disabled" (M) bit in the ADMIN_STATUS Object is used [OAM-CONF-FWK].

3.2.  OAM Configuration TLV

   This TLV is specified in [OAM-CONF-FWK] and is used to select which
   OAM technology/method should be used for the LSP.  In this document a
   new OAM Type: Ethernet OAM is defined.

       OAM Type           Description
     ------------      ------------------
         0                Reserved
         1                Ethernet OAM
       2-256              Reserved

   The receiving node when the Ethernet OAM Type is requested should
   look for the corresponding technology specific Ethernet OAM
   configuration TLV.

3.3.  Ethernet OAM Configuration TLV

   The Ethernet OAM Configuration TLV (depicted below) is defined for
   Ethernet OAM specific configuration parameters.  The Ethernet OAM
   Configuration TLV is carried in the LSP_ATTRIBUTES object in Path
   messages.  This new TLV accommodates generic Ethernet OAM information
   and carries sub-TLVs.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type (3) (IANA)     |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Version |MD L.|           Reserved (set to all 0s)            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                           sub TLVs                            ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type: indicates a new type: the Ethernet OAM Configuration TLV (3)
   (IANA to define).

   Length: indicates the total length including sub-TLVs.

   Version: identifies the CFM protocol version according to [IEEE-CFM].
   If a node does not support a specific CFM version an error must be
   generated: "OAM Problem/Unsupported OAM Version"

   MD L. (MD Level): indicates the desired MD Level.  The values are
   according to [IEEE-CFM].  If a node does not support a specific MD
   Level an error must be generated: "OAM Problem/Unsupported OAM
   Level".

3.3.1.  MD Name Sub-TLV

   The optional MD Name sub-TLV is depicted below.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type (1) (IANA)     |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Format     |  Name Length  |   Reserved (set to all 0s)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                            MD Name                            ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type: 1, MD Name Sub-TLV (IANA).

   Length: indicates the total length of the TLV including padding.

   Format: according to [IEEE-CFM].

   Name Length: the length of the MD Name field in bytes.  This is
   necessary to allow non 4 byte padded MD Name lengths.

   MD Name: variable length field, formatted according to the format
   specified in the Format field.

   If an undefined Format is specified an error must be generated: "OAM
   Problem/Unknown MD Name Format".  Also the combined length of MD Name
   and Short MA Name must be less or equal to 44bytes, if this is
   violated an error must be generated: "OAM Problem/Name Length
   Problem".  Note that it is allowed to have no MD Name, as such the MD
   Name sub-TLV is optional.  In this case the MA Name must uniquely
   identify a Maintenance Association.

3.3.2.  Short MA Name Sub-TLV

   The Short MA Name sub-TLV is depicted below.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type (2) (IANA)     |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Format     |  Name Length  |   Reserved (set to all 0s)    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                       Short MA Name                           ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type: 2, Short MA Name Sub-TLV (IANA)

   Length: indicates the total length of the TLV including padding.

   Format: according to [IEEE-CFM].

   Name Length: the length of the MA Name field in bytes.  This is
   necessary to allow non 4 byte padded MA Name lengths.

   Short MA Name: variable length field formatted according to the
   format specified in the Format field.

   If an undefined Format is specified an error must be generated: "OAM
   Problem/Unknown MA Name Format".  Also the combined length of MD Name
   and Short MA Name must be less or equal to 44bytes, if this is
   violated an error must be generated: "OAM Problem/Name Length
   Problem".  Note that it is allowed to have no MD Name, in this case
   the MA Name must uniquely identify a Maintenance Association.

3.3.3.  MEP ID Sub-TLV

   The MEP ID Sub-TLV is depicted below.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type (3) (IANA)     |           Length (4)          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Local MEP ID           |T|R|      Reserved             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Remote MEP ID          |T|R|      Reserved             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type: 3, MEP ID Sub-TLV (IANA)

   Length: indicates the total length of the TLV including padding.

   Local MEP ID: a 16 bit integer value in the range 1-8191 of the MEP
   ID on the initiator side.

   Remote MEP ID: a 16 bit integer value in the range 1-8191 of the MEP
   ID to be set for the MEP established at the receiving side.  This
   value is determined by the initiator node.  This is possible, since a
   new MAID is assigned to each PBB-TE connection, and MEP IDs must be
   only unique within the scope of the MAID.

   Two flags are defined Transmit (T) and Receive (R).  When T is set
   the corresponding MEP must send OAM packets.  When R is set the
   corresponding MEP must expect to receive OAM packets.  These flags
   are used to configure the role of MEPs.

3.3.4.  Continuity Check (CC) Sub-TLV

   The Continuity Check (CC) sub-TLV is depicted below.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type (4) (IANA)     |           Length              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Prio  | CCM I |           Reserved (set to all 0s)            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Prio: Indicates the priority to be set for CCM frames.  In Ethernet 3
   bits carried in VLAN TAGs identify priority information.

   CCM I (CCM Interval): CCM Interval, according to the 3 bit encoding
   [IEEE-CFM] shown in Table 1.  If a node does not support the
   requested CCM Interval an error must be generated: "OAM Problem/
   Unsupported CC Interval".

3.4.  Pro-active Performance Monitoring

   Ethernet OAM functions for Performance Monitoring (PM) allow
   measurements of different performance parameters including Frame Loss
   Ratio, Frame Delay and Frame Delay variation as defined in the ITU-T
   Y.1731 recommendation.  Only a subset of PM functions are operated in
   a pro-active fashion to monitor the performance of the connection
   continuously.  Pro-active PM supports Fault Management functions, by
   providing an indication of decreased service performance and as such
   may provide triggers to initiate recovery procedures.

   While on demand PM functions are always initiated by management
   commands, for pro-active PM it may be desirable to utilize the
   control plane for configuration and activation together with Fault
   Management functions such as Continuity Check.

   ITU-T Y.1731 defines dual-ended Loss Measurement as pro-active OAM
   for performance monitoring and as a PM function applicable to fault
   management.  For dual-ended Loss Measurement each MEP piggy-backs
   transmitted and received frame counters on CC messages; to support
   and synchronize bidirectional Loss Measurements at the MEPs.  Dual-
   ended Loss Measurement is invoked by setting the Performance
   Monitoring/Loss OAM Function flag in the OAM Configuration TLV
   [OAM-CONF-FWK].  Besides configuring the Continuity Check
   functionality, no additional configuration is required for this type
   of Loss Measurement.

3.5.  Ethernet OAM configuration errors

   In addition to error values specified in [OAM-CONF-FWK] this document
   defines the following values for the "OAM Problem" Error Code.

   o  If a node does not support a specific CFM version an error must be
      generated: "OAM Problem/Unsupported OAM Version".

   o  If a node does not support a specific MD Level an error must be
      generated: "OAM Problem/Unsupported OAM Level".

   o  If an undefined MD name format is specified an error must be
      generated: "OAM Problem/Unknown MD Name Format".

   o  If an undefined MA name format is specified an error must be
      generated: "OAM Problem/Unknown MA Name Format".

   o  If the combined length of MD Name and Short MA Name must be less
      or equal to 44bytes, if this is violated an error must be
      generated: "OAM Problem/Name Length Problem".

   o  If a node does not support the requested CCM Interval an error
      must be generated: "OAM Problem/Unsupported CC Interval".

4.  IANA Considerations

   This document specifies a new Ethernet OAM Configuration TLV to be
   carried in the OAM Configuration TLV in LSP_ATTRIBUTES and
   LSP_REQUIRED_ATTRIBUTES objects in Path messages.

   The following values need to be assigned under the Error Code: "OAM
   Problem": "Unsupported OAM Version", "Unsupported OAM Level",
   "Unknown MD Name Format", "Unknown MA Name Format", "Name Length
   Problem", "Unsupported CC Interval".

5.  Security Considerations

   The signaling of OAM related parameters and the automatic
   establishment of OAM entities introduces additional security
   considerations to those discussed in [RFC3473].  In particular, a
   network element could be overloaded, if an attacker would request
   liveliness monitoring, with frequent periodic messages, for a high
   number of LSPs, targeting a single network element.

   Security aspects will be covered in more detailed in subsequent
   versions of this document.

6.  Acknowledgements

   The authors would like to thank Francesco Fondelli, Adrian Farrel,
   Loa Andersson, Eric Gray and Dimitri Papadimitriou for their useful
   comments.

7.  References

   [GELS-Framework]
              "GMPLS Ethernet Label Switching Architecture and
              Framework", Internet Draft, work in progress.

   [GELS-PBBTE]
              "GMPLS control of Ethernet PBB-TE", Internet Draft, work
              in progress.

   [GMPLS-OAM]
              "OAM Requirements for Generalized Multi-Protocol Label
              Switching (GMPLS) Networks", Internet Draft, work in
              progress.

   [IEEE-CFM]
              "IEEE 802.1ag, Draft Standard for Connectivity Fault
              Management",  work in progress.

   [IEEE-PBBTE]
              "IEEE 802.1Qay Draft Standard for Provider Backbone
              Bridging Traffic Engineering",  work in progress.

   [OAM-CONF-FWK]
              "OAM Configuration Framework for GMPLS RSVP-TE", Internet
              Draft, work in progress.

   [RFC3469]  "Framework for Multi-Protocol Label Switching (MPLS)-based
              Recovery", RFC 3469, February 2003.

   [RFC3471]  "Generalized Multi-Protocol Label Switching (GMPLS)
              Signaling Functional Description", RFC 3471, January 2003.

   [RFC3473]  "Generalized Multi-Protocol Label Switching (GMPLS)
              Signaling Resource ReserVation Protocol-Traffic
              Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.

   [RFC4377]  "Operations and Management (OAM) Requirements for Multi-
              Protocol Label Switched (MPLS) Networks", RFC 4377,
              February 2006.

   [RFC4420]  "Encoding of Attributes for Multiprotocol Label Switching
              (MPLS) Label Switched Path (LSP) Establishment Using
              Resource ReserVation Protocol-Traffic Engineering
              (RSVP-TE)", RFC 4420, February 2006.

Authors' Addresses

   Attila Takacs
   Ericsson
   Laborc u. 1.
   Budapest,   1037
   Hungary

   Email: attila.takacs@ericsson.com

   Balazs Gero
   Ericsson
   Laborc u. 1.
   Budapest,   1037
   Hungary

   Email: balazs.gero@ericsson.com

   Don Fedyk
   Alcatel-Lucent
   Groton, MA  01450
   USA

   Email: donald.fedyk@alcatel-lucent.com

   Hao Long
   Huawei

   Email: lonho@huawei.com

   Dinesh Mohan