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Versions: (draft-martini-pwe3-iccp) 00 01 02 03 04 05 06 07 08 09 11 12 13 14 15 16 RFC 7275

Internet Engineering Task Force                             Luca Martini
Internet Draft                                               Samer Salam
Intended status: Standards Track                             Ali Sajassi
Expires: August 7, 2012                                            Cisco

Matthew Bocci                                          Satoru Matsushima
Alcatel-Lucent                                                  Softbank

Thomas Nadeau
CA Technologies
                                                        February 7, 2012


      Inter-Chassis Communication Protocol for L2VPN PE Redundancy


                      draft-ietf-pwe3-iccp-07.txt

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   The list of Internet-Draft Shadow Directories can be accessed at
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   This Internet-Draft will expire on August 7, 2012

Abstract

   This document specifies an inter-chassis communication protocol
   (ICCP) that enables Provider Edge (PE) device redundancy for Virtual
   Private Wire Service (VPWS) and Virtual Private LAN Service (VPLS)
   applications. The protocol runs within a set of two or more PEs,
   forming a redundancy group, for the purpose of synchronizing data



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   amongst the systems. It accommodates multi-chassis attachment circuit
   as well as pseudowire redundancy mechanisms.

















































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Table of Contents

    1        Specification of Requirements  ........................   5
    2        Introduction  .........................................   5
    3        ICCP Overview  ........................................   5
    3.1      Redundancy Model & Topology  ..........................   5
    3.2      ICCP Interconnect Scenarios  ..........................   7
    3.2.1    Co-located Dedicated Interconnect  ....................   7
    3.2.2    Co-located Shared Interconnect  .......................   8
    3.2.3    Geo-redundant Dedicated Interconnect  .................   8
    3.2.4    Geo-redundant Shared Interconnect  ....................   9
    3.3      ICCP Requirements  ....................................  10
    4        ICC LDP Protocol Extension Specification  .............  12
    4.1      LDP ICCP Capability Advertisement  ....................  12
    4.2      RG Membership Management  .............................  13
    4.2.1    ICCP Connection State Machine  ........................  13
    4.3      Redundant Object Identification  ......................  16
    4.4      Application Connection Management  ....................  16
    4.4.1    Application Versioning  ...............................  17
    4.4.2    Application Connection State Machine  .................  18
    4.5      Application Data Transfer  ............................  21
    4.6      Dedicated Redundancy Group LDP session  ...............  21
    5        ICCP PE Node Failure Detection Mechanism  .............  22
    6        ICCP Message Formats  .................................  22
    6.1      Encoding ICC into LDP Messages   ......................  23
    6.1.1    ICC Header  ...........................................  23
    6.1.2    Message Encoding  .....................................  25
    6.1.3    ROID Encoding  ........................................  26
    6.2      RG Connect Message  ...................................  26
    6.2.1    ICC Sender Name TLV  ..................................  27
    6.3      RG Disconnect Message  ................................  28
    6.4      RG Notification Message  ..............................  30
    6.4.1    Notification Message TLVs  ............................  31
    6.5      RG Application Data Message  ..........................  34
    7        Application TLVs  .....................................  34
    7.1      Pseudowire Redundancy (PW-RED) Application TLVs  ......  34
    7.1.1    PW-RED Connect TLV  ...................................  34
    7.1.2    PW-RED Disconnect TLV  ................................  36
    7.1.2.1  PW-RED Disconnect Cause TLV  ..........................  36
    7.1.3    PW-RED Config TLV  ....................................  37
    7.1.3.1  Service Name TLV  .....................................  39
    7.1.3.2  PW ID TLV  ............................................  39
    7.1.3.3  Generalized PW ID TLV  ................................  40
    7.1.4    PW-RED State TLV  .....................................  41
    7.1.5    PW-RED Synchronization Request TLV  ...................  43
    7.1.6    PW-RED Synchronization Data TLV  ......................  44



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    7.2      Multi-chassis LACP (mLACP) Application TLVs  ..........  45
    7.2.1    mLACP Connect TLV  ....................................  46
    7.2.2    mLACP Disconnect TLV  .................................  47
    7.2.2.1  mLACP Disconnect Cause TLV  ...........................  47
    7.2.3    mLACP System Config TLV  ..............................  48
    7.2.4    mLACP Aggregator Config TLV  ..........................  49
    7.2.5    mLACP Port Config TLV  ................................  51
    7.2.6    mLACP Port Priority TLV  ..............................  53
    7.2.7    mLACP Port State TLV  .................................  55
    7.2.8    mLACP Aggregator State TLV  ...........................  57
    7.2.9    mLACP Synchronization Request TLV  ....................  59
    7.2.10   mLACP Synchronization Data TLV  .......................  61
    8        LDP Capability Negotiation  ...........................  62
    9        Client Applications  ..................................  63
    9.1      Pseudowire Redundancy Application Procedures  .........  63
    9.1.1    Initial Setup  ........................................  64
    9.1.2    Pseudowire Configuration Synchronization  .............  64
    9.1.3    Pseudowire Status Synchronization  ....................  65
    9.1.4    PE Node Failure  ......................................  66
    9.2      Attachment Circuit Redundancy Application Procedures  .  66
    9.2.1    Common AC Procedures  .................................  66
    9.2.2    AC Failure  ...........................................  67
    9.2.3    PE Node Failure  ......................................  67
    9.2.4    PE Isolation  .........................................  67
    9.2.5    Ethernet AC Procedures  ...............................  67
    9.2.6    Multi-chassis LACP (mLACP) Application Procedures  ....  67
    9.2.6.1  Initial Setup  ........................................  67
    9.2.6.2  mLACP Aggregator and Port Configuration  ..............  69
    9.2.6.3  mLACP Aggregator and Port Status Synchronization  .....  70
    9.2.6.4  Failure and Recovery  .................................  72
   10        Security Considerations  ..............................  73
   11        IANA Considerations  ..................................  73
   11.1      MESSAGE TYPE NAME SPACE  ..............................  73
   11.2      TLV TYPE NAME SPACE  ..................................  74
   11.3      ICC RG Parameter Type Space  ..........................  74
   11.4      STATUS CODE NAME SPACE  ...............................  75
   12        Acknowledgments  ......................................  75
   13        Normative References  .................................  76
   14        Informative References  ...............................  76
   15        Author's Addresses  ...................................  76











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1. Specification of Requirements

   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. Introduction

   Network availability is a critical metric for service providers as it
   has a direct bearing on their profitability. Outages translate not
   only to lost revenue but also to potential penalties mandated by
   contractual agreements with customers running mission-critical
   applications that require tight SLAs. This is true for any carrier
   network, and networks employing Layer 2 Virtual Private Network
   (L2VPN) technology are no exception.  Network high-availability can
   be achieved by employing intra and inter-chassis redundancy
   mechanisms. The focus of this document is on the latter. The document
   defines an Inter-Chassis Communication Protocol (ICCP) that allows
   synchronization of state and configuration data between a set of two
   or more PEs forming a Redundancy Group (RG). The protocol supports
   multi-chassis redundancy mechanisms that can be employed on either
   the attachment circuit or pseudowire front.


3. ICCP Overview

3.1. Redundancy Model & Topology

   The focus of this document is on PE node redundancy. It is assumed
   that a set of two or more PE nodes are designated by the operator to
   form a Redundancy Group (RG). Members of a Redundancy Group fall
   under a single administration (e.g. service provider) and employ a
   common redundancy mechanism towards the access (attachment circuits
   or access pseudowires) and/or towards the core (pseudowires) for any
   given service instance. It is possible, however, for members of an RG
   to make use of disparate redundancy mechanisms for disjoint services.
   The PE devices may be offering any type of L2VPN service, i.e. VPWS
   or VPLS. As a matter of fact, the use of ICCP may even be applicable
   for Layer 3 service redundancy, but this is considered to be outside
   the scope of this document.

   The PEs in an RG offer multi-homed connectivity to either individual
   devices (e.g. CE, DSLAM, etc...) or entire networks (e.g. access
   network). Figure 1 below depicts the model.






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                                    +=================+
                                    |                 |
   Mutli-homed         +----+       |  +-----+        |
   Node  ------------> | CE |-------|--| PE1 ||<------|---Pseudowire-->|
                       |    |--+   -|--|     ||<------|---Pseudowire-->|
                       +----+  |  / |  +-----+        |
                               | /  |     ||          |
                               |/   |     || ICCP     |--> Towards Core
              +-------------+  /    |     ||          |
              |             | /|    |  +-----+        |
              |    Access   |/ +----|--| PE2 ||<------|---Pseudowire-->|
              |   Network   |-------|--|     ||<------|---Pseudowire-->|
              |             |       |  +-----+        |
              |             |       |                 |
              +-------------+       |   Redundancy    |
                ^                   |     Group       |
                |                   +=================+
                |
         Multi-homed Network

                 Figure 1: Generic Multi-chassis Redundancy Model


   In the topology of Figure 1, the redundancy mechanism employed
   towards the access node/network can be one of a multitude of
   technologies, e.g. it could be IEEE 802.1AX Link Aggregation Groups
   with Link Aggregation Control Protocol (LACP), or SONET APS. The
   specifics of the mechanism are out of the scope of this document.
   However, it is assumed that the PEs in the RG are required to
   communicate amongst each other in order for the access redundancy
   mechanism to operate correctly. As such, it is required to run an
   inter-chassis communication protocol among the PEs in the RG in order
   to synchronize configuration and/or running state data.

   Furthermore, the presence of the inter-chassis communication channel
   allows simplification of the pseudowire redundancy mechanism. This is
   primarily because it allows the PEs within an RG to run some
   arbitration algorithm to elect which pseudowire(s) should be in
   active or standby mode for a given service instance. The PEs can then
   advertise the outcome of the arbitration to the remote-end PE(s), as
   opposed to having to embed a hand-shake procedure into the pseudowire
   redundancy status communication mechanism, and every other possible
   Layer 2 status communication mechanism.








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3.2. ICCP Interconnect Scenarios

   When referring to 'interconnect' in this section, we are concerned
   with the links or networks over which Inter-Chassis Communication
   Protocol messages are transported, and not normal data traffic
   between PEs. The PEs which are members of an RG may be either
   physically co-located or geo-redundant.  Furthermore, the physical
   interconnect between the PEs over which ICCP is to run may comprise
   of either dedicated back-to-back links or a shared connection through
   the packet switched network (PSN); for e.g., MPLS core network. This
   gives rise to a matrix of four interconnect scenarios, described
   next.


3.2.1. Co-located Dedicated Interconnect

   In this scenario, the PEs within an RG are co-located in the same
   physical location (POP, CO). Furthermore, dedicated links provide the
   interconnect for ICCP among the PEs.

           +=================+     +-----------------+
           |CO               |     |                 |
           |  +-----+        |     |                 |
           |  | PE1 |________|_____|                 |
           |  |     |        |     |                 |
           |  +-----+        |     |                 |
           |     ||          |     |                 |
           |     || ICCP     |     |       Core      |
           |     ||          |     |      Network    |
           |  +-----+        |     |                 |
           |  | PE2 |________|_____|                 |
           |  |     |        |     |                 |
           |  +-----+        |     |                 |
           |                 |     |                 |
           +=================+     +-----------------+

   Figure 2: ICCP Co-located PEs Dedicated Interconnect Scenario



   Given that the PEs are connected back-to-back in this case, it is
   possible to rely on Layer 2 redundancy mechanisms to guarantee the
   robustness of the ICCP interconnect. For example, if the interconnect
   comprises of IEEE 802.3 Ethernet links, it is possible to provide
   link redundancy by means of IEEE 802.1AX Link Aggregation Groups.






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3.2.2. Co-located Shared Interconnect

   In this scenario, the PEs within an RG are co-located in the same
   physical location (POP, CO). However, unlike the previous scenario,
   there are no dedicated links between the PEs. The interconnect for
   ICCP is provided through the core network to which the PEs are
   connected. Figure 3 depicts this model.

           +=================+     +-----------------+
           |CO               |     |                 |
           |  +-----+        |     |                 |
           |  | PE1 |________|_____|                 |
           |  |     |<=================+             |
           |  +-----+   ICCP |     |  ||             |
           |                 |     |  ||             |
           |                 |     |  ||   Core      |
           |                 |     |  ||  Network    |
           |  +-----+        |     |  ||             |
           |  | PE2 |________|_____|  ||             |
           |  |     |<=================+             |
           |  +-----+        |     |                 |
           |                 |     |                 |
           +=================+     +-----------------+

   Figure 3: ICCP Co-located PEs Shared Interconnect Scenario


   Given that the PEs in the RG are connected over the packet switched
   network (PSN), then PSN Layer mechanisms can be leveraged to ensure
   the resiliency of the interconnect against connectivity failures. For
   example, it is possible to employ RSVP LSPs with Fast Re-Route (FRR)
   and/or end-to-end backup LSPs.


3.2.3. Geo-redundant Dedicated Interconnect

   In this variation, the PEs within a Redundancy Group are located in
   different physical locations to provide geographic redundancy. This
   may be desirable, for example, to protect against natural disasters
   or the like. A dedicated interconnect is provided to link the PEs,
   which is a costly option, especially when considering the possibility
   of providing multiple such links for interconnect robustness. The
   resiliency mechanisms for the interconnect are similar to those
   highlighted in the co-located interconnect counterpart.







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           +=================+     +-----------------+
           |CO 1             |     |                 |
           |  +-----+        |     |                 |
           |  | PE1 |________|_____|                 |
           |  |     |        |     |                 |
           |  +-----+        |     |                 |
           +=====||==========+     |                 |
                 || ICCP           |       Core      |
           +=====||==========+     |      Network    |
           |  +-----+        |     |                 |
           |  | PE2 |________|_____|                 |
           |  |     |        |     |                 |
           |  +-----+        |     |                 |
           |CO 2             |     |                 |
           +=================+     +-----------------+

   Figure 4: ICCP Geo-redundant PEs Dedicated Interconnect Scenario



3.2.4. Geo-redundant Shared Interconnect

   In this scenario, the PEs of an RG are located in different physical
   locations and the interconnect for ICCP is provided over the PSN
   network to which the PEs are connected. This interconnect option is
   more likely to be the one used for geo-redundancy as it is more
   economically appealing compared to the geo-redundant dedicated
   interconnect. The resiliency mechanisms that can be employed to
   guarantee the robustness of the ICCP transport are PSN Layer
   mechanisms as has been described in the "Co-located Shared
   Interconnect" section above.




















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           +=================+     +-----------------+
           |CO 1             |     |                 |
           |  +-----+        |     |                 |
           |  | PE1 |________|_____|                 |
           |  |     |<=================+             |
           |  +-----+   ICCP |     |  ||             |
           +=================+     |  ||             |
                                   |  ||   Core      |
           +=================+     |  ||  Network    |
           |  +-----+        |     |  ||             |
           |  | PE2 |________|_____|  ||             |
           |  |     |<=================+             |
           |  +-----+        |     |                 |
           |CO 2             |     |                 |
           +=================+     +-----------------+

   Figure 5: ICCP Geo-redundant PEs Shared Interconnect Scenario



3.3. ICCP Requirements

   The Inter-chassis Communication Protocol SHOULD satisfy the following
   requirements:

        -i. Provide a control channel for communication between PEs in a
            Redundancy Group (RG). Nodes may be co-located or remote
            (refer to "Interconnect Scenarios" section above). It is
            expected that client applications which make use of ICCP
            services will only use this channel to communicate control
            information and not data-traffic. As such the protocol
            should cater for relatively low bandwidth, low-delay and
            highly reliable message transfer.

       -ii. Accommodate multiple client applications (e.g. multi-chassis
            LACP, PW redundancy, SONET APS, etc...). This implies that
            the messages should be extensible (e.g. TLV-based) and the
            protocol should provide a robust application registration
            and versioning scheme.

      -iii. Provide reliable message transport and in-order delivery
            between nodes in a RG with secure authentication mechanisms
            built into the protocol. The redundancy applications that
            are clients of ICCP expect reliable message transfer, and as
            such will assume that the protocol takes care of flow-
            control and retransmissions. Furthermore, given that the
            applications will rely on ICCP to communicate data used to
            synchronize state-machines on disparate nodes, it is



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            critical that ICCP guarantees in-order message delivery.
            Loss of messages or out-of-sequence messages would have
            adverse side-effects to the operation of the client
            applications.

       -iv. Provide a common mechanism to actively monitor the health of
            PEs in an RG.  This mechanism will be used to detect PE node
            failure and inform the client applications. The applications
            require this to trigger failover according to the procedures
            of the employed redundancy protocol on the AC and PW. It is
            desired to achieve sub-second detection of loss of remote
            node (~ 50 - 150 msec) in order to give the client
            applications (redundancy mechanisms) enough reaction time to
            achieve sub-second service restoration time.

        -v. Provide asynchronous event-driven state update, independent
            of periodic messages, for immediate notification of client
            applications' state changes.  In other words, the
            transmission of messages carrying application data should be
            on-demand rather than timer-based to minimize inter-chassis
            state synchronization delay.

       -vi. Accommodate multi-link and multi-hop interconnect between
            nodes. When the devices within an RG are located in
            different physical locations, the physical interconnect
            between them will comprise of a network rather than a link.
            As such, ICCP should accommodate the case where the
            interconnect involves multiple hops. Furthermore, it is
            possible to have multiple (redundant) paths or interconnects
            between a given pair of devices. This is true for both the
            co-located and geo-redundant scenarios. ICCP should handle
            this as well.

      -vii. Ensure transport security between devices in an RG. This is
            especially important in the scenario where the members of an
            RG are located in different physical locations and connected
            over a shared network (e.g. PSN).

     -viii. Must allow operator to statically configure members of RG.
            Auto-discovery may be considered in the future.

       -ix. Allow for flexible RG membership. It is expected that only
            two nodes per an RG will cover most of the redundancy
            applications for common deployments.  ICCP should not
            preclude supporting more than two nodes in an RG by virtue
            of design. Furthermore, it is required to allow a single
            node to be member of multiple RGs simultaneously.




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4. ICC LDP Protocol Extension Specification

   To address the requirements identified in the previous section, ICCP
   is modeled to comprise of three layers:

        -i. Application Layer: This provides the interface to the
            various redundancy applications that make use of the
            services of ICCP. ICCP is concerned with defining common
            connection management procedures and the formats of the
            messages exchanged at this layer; however, beyond that, it
            does not impose any restrictions on the procedures or
            state-machines of the clients, as these are deemed
            application-specific and lie outside the scope of ICCP.
            This guarantees implementation inter-operability without
            placing any unnecessary constraints on internal design
            specifics.

       -ii. Inter Chassis Communication (ICC) Layer: This layer
            implements the common set of services which ICCP offers to
            the client applications. It handles protocol versioning, RG
            membership, Redundant Object identification, PE node
            identification and ICCP connection management.

      -iii. Transport Layer: This layer provides the actual ICCP message
            transport. It is responsible for addressing, route
            resolution, flow-control, reliable and in-order message
            delivery, connectivity resiliency/redundancy and finally PE
            node failure detection. The Transport layer may differ
            depending on the Physical Layer of the inter-connect.


4.1. LDP ICCP Capability Advertisement

   When an RG is enabled on a particular PE, the capability of
   supporting ICCP must be advertised to all LDP peers in that RG. This
   is achieved by using the methods in [RFC5561] and advertising the
   ICCP LDP capability TLV. If an LDP peer supports the dynamic
   capability advertisement, this can be done by sending a new
   capability message with the S bit set for the ICCP capability TLV
   when the first RG is enabled on the PE. If the peer does not support
   dynamic capability advertisement, then the ICCP TLV MUST be included
   in the LDP initialization procedures in the capability parameter
   [RFC5561].








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4.2. RG Membership Management

   ICCP defines a mechanism that enables PE nodes to manage their RG
   membership. When a PE is configured to be a member of an RG, it will
   first advertise the ICCP capability to its peers. Subsequently, the
   PE sends an RG Connect message to the peers that have also advertised
   ICCP capability. The PE then waits for the peers to send their own RG
   Connect messages, if they haven't done so already. For a given RG,
   the ICCP connection between two devices is considered to be
   operational only when both have sent and received ICCP RG Connect
   messages for that RG.

   If a PE that has sent a particular RG Connect message doesn't receive
   a corresponding RG Connect (or a Notification message with NAK) from
   a destination, it will remain in a state expecting the corresponding
   RG Connect message (or Notification message). The RG will not become
   operational until the corresponding RG Connect Message has been
   received. If a PE that has sent an RG Connect message receives a
   Notification message with a NAK, it will stop attempting to bring up
   the ICCP connection immediately. The PE MUST resume bringing up the
   connection after it receives an RG Connect message from the peer PE
   for the RG in question. This is achieved by responding to the
   incoming RG Connect message with an appropriate RG Connect.

   A device MUST send a NAK for an RG Connect message if at least one of
   the following conditions is satisfied:

        -i. the PE is not a member of the RG;

       -ii. the maximum number of simultaneous ICCP connections that the
            PE can handle is exceeded.

   A PE sends an RG Disconnect message to tear down the ICCP connection
   for a given RG. This is a unilateral operation and doesn't require
   any acknowledgement from the other PEs. Note that the ICCP connection
   for an RG MUST be operational before any client application can make
   use of ICCP services in that RG.


4.2.1. ICCP Connection State Machine

   The ICCP Connection state machine is defined to have six states as
   depicted in the state transition table and state transition diagram
   that follow.

   ICCP Connection State Transition Table





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   STATE         EVENT                                    NEW STATE

   NON EXISTENT  LDP session established                  INITIALIZED

   INITIALIZED   Transmit LDP ICCP Capability             CAPSENT

                 Receive LDP ICCP Capability              CAPREC
                    Action: Transmit LDP ICCP Capability

                 LDP session torn down                    NON EXISTENT

   CAPSENT       Receive LDP ICCP Capability              CAPREC

                 LDP session torn down                    NON EXISTENT

   CAPREC        Transmit RG Connect Message              CONNECTING

                 Receive acceptable RG Connect Message    OPERATIONAL
                    Action: Transmit RG Connect Message

                 Receive any other ICCP Message           CAPREC
                    Action: Transmit NAK in RG
                            Notification Message

                 LDP session torn down                    NON EXISTENT

   CONNECTING    Receive acceptable RG Connect Message    OPERATIONAL

                 Receive any other ICCP Message           CAPREC
                    Action: Transmit NAK in RG
                            Notification Message

                 LDP session torn down                    NON EXISTENT

   OPERATIONAL   Receive acceptable RG Disconnect Message CAPREC

                 Transmit RG Disconnect Message           CAPREC

                 LDP session torn down                    NON EXISTENT


   ICCP Connection State Transition Diagram









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                                +------------+
                                |            |
          +------------------>|NON EXISTENT|    LDP session torn down
          |                   |            |<--------------------------+
          |                   +------------+                           |
          |         LDP session  |    ^ LDP session                    |
          |         established  |    | torn down                      |
          |                      V    |                                |
          |                  +-----------+                             |
   LDP    |                  |           |  Tx LDP ICCP                |
   session|                  |INITIALIZED|    capability               |
   torn   |              +---|           |---------------+             |
   down   |  Rx other    |   +-----------+               |             |
          |  ICCP msg/   |Rx LDP ICCP                    |             |
          |   Tx NAK     |  capability/                  |             |
          |      +---+   |Tx LDP ICCP capability         |             |
          |      |   |   |                               |             |
          |      V   |   V                               V             |
          |   +-----------+   Rx LDP ICCP         +--------+           |
          +---|           |     capability        |        |           |
              |CAPREC     |<----------------------|CAPSENT |---------->+
          +---|           |-------------------+   |        |           |
          |   +-----------+                   |   +--------+           |
          |       ^    ^                      |                        |
   Tx     |       |    |                      |                        |
   RG     |       |    |Rx RG Disconnect msg  |                        |
   Connect|       |    | or                   |Rx RG Connect msg /     |
   Msg    |       |    |Tx RG Disconnect msg  | Tx RG Connect msg      |
          |       |    |                      V                        |
          |       |    |                    +------------+             |
          |       |    +--------------------|            |             |
          |       |                         |OPERATIONAL |------------>+
          |       |                         |            |             |
          |       |Rx other ICCP msg/       +------------+             |
          |       | Tx NAK                        ^                    |
          |       |                               |                    |
          |      +----------+  Rx RG Connect msg  |                    |
          |      |          |---------------------+                    |
          +----->|CONNECTING|                                          |
                 |          |----------------------------------------->+
                 +----------+










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4.3. Redundant Object Identification

   ICCP offers its client applications a uniform mechanism for
   identifying links, ports, forwarding constructs and more generally
   objects (e.g.  interfaces, pseudowires, VLANs, etc...) that are being
   protected in a redundant setup. These are referred to as Redundant
   Objects (RO). An example of an RO is a multi-chassis link-aggregation
   group that spans two PEs. ICCP introduces a 64-bit opaque identifier
   to uniquely identify ROs in an RG.  This identifier, referred to as
   Redundant Object ID (ROID), MUST match between RG members for the
   protected object in question. That allows separate systems in an RG
   to use a common handle to reference the protected entity irrespective
   of its nature (e.g. physical or virtual) and in a manner that is
   agnostic to implementation specifics. Client applications that need
   to synchronize state pertaining to a particular RO SHOULD embed the
   corresponding ROID in their TLVs.



4.4. Application Connection Management

   ICCP provides a common set of procedures by which applications on one
   PE can connect to their counterparts on another PE, for purpose of
   inter-chassis communication in the context of a given RG. The
   prerequisite for establishing an application connection is to have an
   operational ICCP RG connection between the two endpoints. It is
   assumed that the association of applications with RGs is known a
   priori, e.g. by means of device configuration. ICCP then sends an
   Application-specific Connect TLV (carried in RG Connect message), on
   behalf of each client application, to each remote PE within the RG.
   The client may piggyback application-specific information in that
   Connect TLV, which for example can be used to negotiate parameters or
   attributes prior to bringing up the actual application connection.
   The procedures for bringing up the application connection are similar
   to those of the ICCP connection: An application connection between
   two nodes is up only when both nodes have sent and received RG
   Connect Messages with the proper Application-specific Connect TLVs. A
   PE MUST send a Notification Message to NAK an application connection
   request if one of the following conditions is encountered:

        -i. the application doesn't exist or is not configured for that
            RG;

       -ii. the application connection count exceeds the PE's
            capabilities.

   When a PE receives such a NAK notification, it MUST stop attempting
   to bring up the application connection until it receives a new



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   application connection request from the remote PE. This is done by
   responding to the incoming RG Connect message (carrying an
   Application-specific Connect TLV) with an appropriate RG Connect
   message (carrying a corresponding Application-specific Connect TLV).

   When an application is stopped on a device or it is no longer
   associated with an RG, it MUST signal ICCP to trigger sending an
   Application-specific Disconnect TLV (in the RG Disconnect message).
   This is a unilateral notification to the other PEs within an RG, and
   as such doesn't trigger any response.


4.4.1. Application Versioning

   During application connection setup time, a given application on one
   PE can negotiate with its counterpart on a peer PE the proper
   application version to use for communication. If no common version is
   agreed upon, then the application connection is not brought up. This
   is achieved through the following set of rules:

     - If an application receives an Application-specific Connect TLV
       with a version number that is higher than its own, it MUST send a
       Notification message with a NAK TLV indicating status code
       "Incompatible Protocol Version" and supplying the version that is
       locally supported by the PE.

     - If an application receives an Application-specific Connect TLV
       with a version number that is lower than its own, it MAY respond
       with an RG Connect that has an Application-specific Connect TLV
       using the same version that was received. Alternatively, the
       application MAY respond with a Notification message to NAK the
       request using the "Incompatible Protocol Version" code, and
       supplying the version that is supported. The above allows an
       application to operate in either backwards compatible or
       incompatible mode.

     - If an application receives an Application-specific Connect TLV
       with a version that is equal to its own, then the application
       MUST honor or reject the request based on whether the application
       is configured for the RG in question, and whether or not the
       application connection count has been exceeded.










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4.4.2. Application Connection State Machine

   The Application Connection state machine has six states as described
   in the state transition table and diagram that follow.

   ICCP Application Connection State Transition Table













































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   STATE          EVENT                                  NEW STATE

   NON EXISTENT   ICCP connection established            RESET

   RESET          ICCP connection torn down              NON EXISTENT

                  Transmit Application Connect TLV       CONNSENT

                  Receive Application Connect TLV        CONNREC

                  Receive any other Application TLV      RESET
                    Action: Transmit NAK TLV

   CONNSENT       Receive NAK TLV                        RESET

                  Receive Application Connect TLV        OPERATIONAL
                  with A-bit=1
                    Action: Transmit Application Connect
                    TLV with A-bit=1

                  Receive any other Application TLV      RESET
                    Action: Transmit NAK TLV

                  ICCP connection torn down              NON EXISTENT

   CONNREC        Transmit NAK TLV                       RESET

                  Transmit Application Connect TLV       CONNECTING
                  with A-bit=1

                  Receive any Application TLV except     RESET
                  Connect
                    Action: Transmit NAK TLV

                  ICCP connection torn down              NON EXISTENT

   CONNECTING     Receive Application Connect TLV        OPERATIONAL
                  with A-bit=1

                  Receive any other Application TLV      RESET
                    Action: Transmit NAK TLV

                  ICCP connection torn down              NON EXISTENT

   OPERATIONAL    Receive Application Disconnect TLV     RESET

                  Transmit Applicaton Disconnect TLV     RESET




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                  ICCP connection torn down              NON EXISTENT


   ICCP Application Connection State Transition Diagram
                            +------------+
                            |            |
          +---------------->|NON EXISTENT|  ICCP connection torn down
          |                 |            |<--------------------------+
          |                 +------------+                           |
          |     ICCP connection|    ^ ICCP connection                |
          |       established  |    | torn down                      |
          |                    |    |                                |
          |                    V    |          Rx other App TLV/     |
          |                +-----------+<-----+  Tx NAK              |
   ICCP   |    Rx App      |           |      |                      |
   connect|    Connect TLV |   RESET   |------+                      |
   torn   |  +-------------|           |---------------+             |
   down   |  |             +-----------+    Tx App     |             |
          |  |              ^  ^   ^  ^     Connect TLV|             |
          |  |      Tx NAK  |  |   |  |                |             |
          |  |      or      |  |   |  |                |             |
          |  |      Rx non  |  |   |  |                |             |
          |  |      Connect |  |   |  |                |             |
          |  V      TLV/Tx NAK |   |  |Rx NAK TLV      V             |
          | +-----------+   |  |   |  |or       +--------+           |
          +-|           |---+  |   |  +---------|        |           |
            |CONNREC    |      |   |   Rx other |CONNSENT|---------->+
          +-|           |      |   |   App TLV/ |        |           |
          | +-----------+      |   |     Tx NAK +--------+           |
          |                    |   |                 |Rx App Connect |
          |  Tx App Connect    |   |                 |TLV (A=1) /    |
          |  TLV (A=1)         |   |Rx App Disconn   | Tx App        |
          |                    |   |or               | Connect TLV   |
          |                    |   |Tx App Disconn   V (A=1)         |
          |                    |   |      +------------+             |
          |                    |   +------|            |             |
          |       Rx other App |          |OPERATIONAL |------------>+
          |       TLV / Tx NAK |          |            |             |
          |             +------+          +------------+             |
          |             |                       ^ Rx App Connect     |
          |    +----------+                     | TLV (A=1)          |
          |    |          |---------------------+                    |
          +--->|CONNECTING|                                          |
               |          |----------------------------------------->+
               +----------+






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4.5. Application Data Transfer

   When an application has information to transfer over ICCP it triggers
   the transmission of an Application Data message. ICCP guarantees in-
   order and loss-less delivery of data. An application may NAK a
   message or a set of one or more TLVs within a message by using the
   Notification Message with NAK TLV. Furthermore, an application may
   implement its own ACK mechanism, if deemed required, by defining an
   application-specific TLV to be transported in an Application Data
   message.

   It is left up to the application to define the procedures to handle
   the situation where a PE receives a NAK in response to a transmitted
   Application Data message. Depending on the specifics of the
   application, it may be favorable to have the PE, which sent the NAK,
   explicitly request retransmission of data. On the other hand, for
   certain applications it may be more suitable to have the original
   sender of the Application Data message handle retransmissions in
   response to a NAK. ICCP supports both models.


4.6. Dedicated Redundancy Group LDP session

   For certain ICCP applications, it is required to exchange a fairly
   large amount of RG information in a very short period of time. In
   order to better distribute the load in a multiple processor system,
   and to avoid head of line blocking to other LDP applications, it may
   be required to initiate a separate TCP/IP session between the two LDP
   speakers.

   This procedure is OPTIONAL, and does not change the operation of LDP
   or ICCP.

   A PE that requires a separate LDP session will advertise a separate
   LDP adjacency with a non-zero label space identifier. This will cause
   the remote peer to open a separate LDP session for this label space.
   No labels need to be advertised in this label space, as it is only
   used for one or a set of ICCP RGs. All relevant LDP and ICCP
   procedures still apply as described in the relevant documents.












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5. ICCP PE Node Failure Detection Mechanism

   ICCP provides its client applications a notification when a remote PE
   that is member of the RG fails. This is used by the client
   applications to trigger failover according to the procedures of the
   employed redundancy protocol on the AC and PW. To that end, ICCP does
   not define its own KeepAlive mechanism for purpose of monitoring the
   health of remote PE nodes, but rather reuses existing fault detection
   mechanisms. The following mechanisms may be used by ICCP to detect PE
   node failure:

     - BFD

       Run a BFD session [RFC5880] between the PEs that are members of a
       given RG, and use that to detect PE node failure. This assumes
       that resiliency mechanisms are in place to protect connectivity
       to the remote PE nodes, and hence loss of BFD periodic messages
       from a given PE node can only mean that the node itself has
       failed.

     - IP Reachability Monitoring

       It is possible for a PE to monitor IP layer connectivity to other
       members of an RG that are participating in IGP/BGP. When
       connectivity to a given PE is lost, the local PE interprets that
       to mean loss of the remote PE node.  This assumes that resiliency
       mechanisms are in place to protect the route to the remote PE
       nodes, and hence loss of IP reachability to a given node can only
       mean that the node itself has failed.

   It is worth noting here that loss of the LDP session with a PE in an
   RG is not a reliable indicator that the remote PE itself is down. It
   is possible, for e.g. that the remote PE encounters a local event
   that leads to resetting the LDP session, while the PE node remains
   operational for purpose of traffic forwarding.


6. ICCP Message Formats

   This section defines the messages exchanged at the Application and
   ICC layers.










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6.1. Encoding ICC into LDP Messages

   ICCP requires reliable, in-order, state-full message delivery, as
   well as capability negotiation between PEs. The LDP protocol offers
   all these features, and is already in wide use in the applications
   that would also require the ICCP protocol extensions. For these
   reasons, ICCP takes advantage of the already defined LDP protocol
   infrastructure.

   [RFC5036] Section 3.5 defines a generic LDP message structure. A new
   set of LDP message types is defined to communicate the ICCP
   information. LDP message types in the range of 0x700 to 0x7ff will be
   used for ICCP.

   Message types are allocated by IANA, and requested in the IANA
   section below.


6.1.1. ICC Header

   Every ICCP message comprises of an ICC specific LDP Header followed
   by message data. The format of the ICC Header is 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|   Message Type              |      Message Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Message ID                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Type=0x0005 (ICC RG ID)     |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          ICC RG ID                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                     Mandatory Parameters                      |
   ~                                                               ~
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   +                                                               +
   |                     Optional Parameters                       |
   ~                                                               ~
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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     - U-bit

       Unknown message bit.  Upon receipt of an unknown message, if U is
       clear (=0), a notification is returned to the message originator;
       if U is set (=1), the unknown message is silently ignored.  The
       following sections which define messages specify a value for the
       U-bit.


     - Message Type

       Identifies the type of the ICCP message, must be in the range of
       0x0700 to 0x07ff.

     - Message Length

       Two octet integer specifying the total length of this message in
       octets, excluding the U-bit, Message Type and Length fields.

     - Message ID

       Four octet value used to identify this message.  Used by the
       sending PE to facilitate identifying RG Notification messages
       that may apply to this message.  A PE sending an RG Notification
       message in response to this message SHOULD include this Message
       ID in the "NAK TLV" of the RG Notification message; see Section
       "RG Notification Message".

     - ICC RG ID TLV

       A TLV of type 0x0005, length 4, containing 4 octets unsigned
       integer designating the Redundancy Group which the sending device
       is member of. RG ID value 0x00000000 is reserved by the protocol.

     - Mandatory Parameters

       Variable length set of required message parameters.  Some
       messages have no required parameters.

       For messages that have required parameters, the required
       parameters MUST appear in the order specified by the individual
       message specifications in the sections that follow.

     - Optional Parameters

       Variable length set of optional message parameters.  Many
       messages have no optional parameters.




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       For messages that have optional parameters, the optional
       parameters may appear in any order.


6.1.2. Message Encoding

   The generic format of an ICC parameter is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|       Type                |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   TLV(s)                                                      |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U-bit

       Unknown TLV bit. Upon receipt of an unknown TLV, if U is clear
       (=0), a notification MUST be returned to the message originator
       and the entire message MUST be ignored; if U is set (=1), the
       unknown TLV MUST be silently ignored and the rest of the message
       processed as if the unknown TLV did not exist. The sections
       following that define TLVs specify a value for the U-bit.

     - F-bit

       Forward unknown TLV bit. This bit applies only when the U-bit is
       set and the LDP message containing the unknown TLV is to be
       forwarded. If F is clear (=0), the unknown TLV is not forwarded
       with the containing message; if F is set (=1), the unknown TLV is
       forwarded with the containing message. The sections following
       that define TLVs specify a value for the F-bit. By setting both
       the U- and F-bits, a TLV can be propagated as opaque data through
       nodes that do not recognize the TLV.

     - Type

       Fourteen bits indicating the parameter type.

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.





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     - TLV(s):  A set of 0 or more TLVs, that vary according to the
       message type.


6.1.3. ROID Encoding

   The Redundant Object Identifier (ROID) is a generic opaque handle
   that uniquely identifies a Redundant Object (e.g. link, bundle, VLAN,
   etc...)  which is being protected in an RG. It is encoded 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ROID                             |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   where: ROID is an 8 octets field encoded as an unsigned integer. The
   ROID value of 0 is reserved.

   The ROID is carried within application specific TLVs.


6.2. RG Connect Message

   The RG Connect Message is used to establish the ICCP RG connection in
   addition to individual Application connections between PEs in an RG.
   An RG Connect message with no "Application-specific connect TLV"
   signals establishment of the ICCP RG connection. Whereas, an RG
   Connect message with a valid "Application-specific connect TLV"
   signals the establishment of an Application connection, in addition
   to the ICCP RG connection if the latter is not already established.

   An implementation MAY send a dedicated RG Connect message to set up
   the ICCP RG connection and a separate RG Connect message per client
   application. However, all implementations MUST support the receipt of
   an RG Connect message that triggers the setup of the ICCP RG
   connection as well as a single Application connection simultaneously.

   A PE sends an RG Connect Message to declare its membership in a
   Redundancy Group. One such message should be sent to each PE that is
   member of the same RG. The set of PEs to which RG Connect Messages
   should be transmitted is known via configuration or an auto-discovery
   mechanism that is outside the scope of this specification. If a
   device is member of multiple RGs, it MUST send separate RG Connect
   Messages for each RG even if the receiving device(s) happen to be the



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   same.

   The format of the RG Connect Message is as follows:

        -i. ICC header with Message type = "RG Connect Message" (0x0700)
       -ii. ICC Sender Name TLV
      -iii. Zero or one Application-specific connect TLV

   The currently defined Application-specific connect TLVs are:

     - PW Redundancy Connect TLV

     - mLACP Connect TLV

   The details of these TLVs are discussed in the "Application TLVs"
   section.

   The RG Connect message can contain zero or one Application-specific
   connect TLV, but no application connect TLV can be sent more than
   once.


6.2.1. ICC Sender Name TLV

   A TLV that carries the hostname of the sender encoded in UTF-8. This
   is used primarily for purpose of management of the RG and easing
   network operations.  The specific format is shown 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|       Type = 0x0001       |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Sender Name                                                  |
   +                                             +-+-+-+-+-+-+-+-+-+
   ~                                             ~
   |      ...                                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U=F=0

     - Type set to 0x0001 (from ICC parameter name space).

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.



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     - Sender Name

       Hostname of sending device encoded in UTF-8, and SHOULD NOT
       exceed 80 characters.


6.3. RG Disconnect Message

   The RG Disconnect Message serves dual-purpose: to signal that a
   particular Application connection is being closed within an RG, or
   that the ICCP RG connection itself is being disconnected because the
   PE wishes to leave the RG. The format of this message is:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|   Message Type=0x0701       |      Message Length           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Message ID                                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   Type=0x0005 (ICC RG ID)     |           Length=4            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     ICC RG ID                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Disconnect Code TLV                          |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Optional Application-specific Disconnect TLV        |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |              Optional Parameter TLVs                          |
   +                                                               +
   |                                                               |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U-bit

       U=0

     - Message Type

       The message type for RG Disconnect Message is set to (0x0701)






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     - Length

       Length of the TLV in octets excluding the U-bit, Message Type,
       and Message Length fields.

     - Message ID

       Defined in the "ICC Header" section above.

     - ICC RG ID

       Defined in the "ICC Header" section above.

     - Disconnect Code TLV

       The format of this TLV is 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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |U|F|         Type=0x0004       |    Length                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      ICCP Status Code                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U,F Bits

       both U and F are set to 0.

     - Type

       set to "Disconnect Code TLV" (0x0004)

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - ICCP Status Code

       A status code that reflects the reason for the disconnect
       message.  Allowed values are "ICCP RG Removed" and "ICCP
       Application Removed from RG".







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     - Optional Application-specific Disconnect TLV

       Zero or one Application-specific Disconnect TLVs which are
       defined later in the document.  If the RG Disconnect message has
       a status code of "RG Removed", then it MUST NOT contain any
       Application-specific Disconnect TLVs, as the sending PE is
       signaling that it has left the RG and, thus, is disconnecting the
       ICCP RG connection, with all associated client application
       connections. If the message has a status code of "Application
       Removed from RG", then it MUST contain exactly one Application-
       specific Disconnect TLV, as the sending PE is only tearing down
       the connection for the specified application. Other applications,
       and the ICCP RG connection are not to be affected.

     - Optional Parameter TLVs

       None are defined for this message in this document. This is
       specified to allow for future extensions.


6.4. RG Notification Message

   A PE sends an RG Notification Message to indicate one of the
   following: to reject an ICCP connection, to reject an application
   connection, to NAK an entire message or to NAK one or more TLV(s)
   within a message. The Notification message can only be sent to a PE
   that is already part of an RG.

   The RG Notification Message MUST NOT be used to NAK messages or TLVs
   corresponding to multiple ICCP applications simultaneously. In other
   words, there is a limit of at most a single ICCP application per RG
   Notification Message.

   The format of the RG Notification Message is:

        -i. ICC header with Message type = "RG Notification Message"
            (0x0702)
       -ii. Notification Message TLVs.

   The currently defined Notification message TLVs are:

        -i. ICC Sender Name TLV
       -ii. NAK TLV.








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6.4.1. Notification Message TLVs

   The ICC Sender Name TLV uses the same format as in the RG Connect
   message, and was described above.

   The NAK TLV 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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|         Type=0x0002       |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      ICCP Status Code                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Rejected Message ID                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Optional TLV(s)                              |
   +                                                               +
   |                                                               |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U,F Bits

       both U and F are set to 0.

     - Type

       set to "NAK TLV" (0x0002)

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - ICCP Status Code

       A status code that reflects the reason for the NAK TLV. Allowed
       values are:
            -i. Unknown RG (0x00010001)

                This code is used to reject a new incoming ICCP
                connection for an RG that is not configured on the local
                PE. When this code is used, the Rejected Message ID
                field MUST contain the message ID of the rejected "RG
                Connect" message.




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           -ii. ICCP Connection Count Exceeded (0x00010002)

                This is used to reject a new incoming ICCP connection
                that would cause the local PE's ICCP connection count to
                exceed its capabilities. When this code is used, the
                Rejected Message ID field MUST contain the message ID of
                the rejected "RG Connect" message.

          -iii. Application Connection Count Exceeded (0x00010003)

                This is used to reject a new incoming application
                connection that would cause the local PE's ICCP
                connection count to exceed its capabilities. When this
                code is used, the Rejected Message ID field MUST contain
                the message ID of the rejected "RG Connect" message and
                the corresponding Application Connect TLV MUST be
                included in the "Optional TLV".

           -iv. Application not in RG (0x00010004)

                This is used to reject a new incoming application
                connection when the local PE doesn't support the
                application, or the application is not configured in the
                RG. When this code is used, the Rejected Message ID
                field MUST contain the message ID of the rejected "RG
                Connect" message and the corresponding Application
                Connect TLV MUST be included in the "Optional TLV".

            -v. Incompatible Protocol Version (0x00010005)

                This is used to reject a new incoming application
                connection when the local PE has an incompatible version
                of the application. When this code is used, the Rejected
                Message ID field MUST contain the message ID of the
                rejected "RG Connect" message and the corresponding
                Application Connect TLV MUST be included in the
                "Optional TLV".

           -vi. Rejected Message (0x00010006)

                This is used to reject an RG Application Data message,
                or one or more TLV(s) within the message. When this code
                is used, the Rejected Message ID field MUST contain the
                message ID of the rejected "RG Application Data"
                message.






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          -vii. ICCP Administratively Disabled (0x00010007)

                This is used to reject any ICCP messages from a peer
                from which the PE is not allowed to exchange ICCP
                messages due to local administrative policy.

     - Rejected Message ID

       If non-zero, four octets value that identifies the peer message
       to which the NAK TLV refers. If zero, no specific peer message is
       being identified.

     - Optional TLV(s)

       A set of one or more optional TLVs. If the status code is
       "Rejected Message" then this field contains the TLV(s) that were
       rejected. If the entire message is rejected, all its TLVs MUST be
       present in this field; otherwise, the subset of TLVs that were
       rejected MUST be echoed in this field.

       If the status code is "Incompatible Protocol Version" then this
       field contains the original "Application Connect TLV" sent by the
       peer, in addition to the "Requested Protocol Version TLV" defined
       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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |U|F|   Type=0x0003             |    Length                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Connection Reference        |   Requested Version           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0003 for "Requested Protocol Version TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.





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     - Connection Reference

       This field is set to the Type field of the Application specific
       Connect TLV that was rejected because of incompatible version.

     - Requested Version

       The version of the application supported by the transmitting
       device. For this version of the protocol it is set to 0x0001.


6.5. RG Application Data Message

   The RG Application Data Message is used to transport application data
   between PEs within an RG. A single message can be used to carry data
   from only one application. Multiple application TLVs are allowed in a
   single message, as long as all of these TLVs belong to the same
   application. The format of the Application Data Message is:

        -i. ICC header with Message type = "RG Application Data Message"
            (0x703)
       -ii. "Application specific TLVs"

   The details of these TLVs are discussed in the "Application TLVs"
   section.  All application specific TLVs in one RG Application Data
   Message MUST belong to a single application but MAY reference
   different ROs.


7. Application TLVs

7.1. Pseudowire Redundancy (PW-RED) Application TLVs

   This section discusses the ICCP TLVs for the Pseudowire Redundancy
   application.


7.1.1. PW-RED Connect TLV

   This TLV is included in the RG Connect message to signal the
   establishment of PW-RED application connection.










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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0010             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Protocol Version         |A|         Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Optional Sub-TLVs                        |
   ~                                                               ~
   |                                                               |
   +                                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             ...                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0010 for "PW-RED Connect TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Protocol Version

       The version of this particular protocol for the purposes of ICCP.
       This is set to 0x0001.

     - A bit

       Acknowledgement Bit. Set to 1 if the sender has received a PW-RED
       Connect TLV from the recipient. Otherwise, set to 0.

     - Reserved

       Reserved for future use.

     - Optional Sub-TLVs

       There are no optional Sub-TLVs defined for this version of the
       protocol.





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7.1.2. PW-RED Disconnect TLV

   This TLV is used in an RG Disconnect Message to indicate that the
   connection for the PW-RED application is to be terminated.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0011             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Optional Sub-TLVs                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0011 for "PW-RED Disconnect TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Optional Sub-TLVs

       The only optional Sub-TLV defined for this version of the
       protocol is the "PW-RED Disconnect Cause" TLV defined next:


7.1.2.1. PW-RED Disconnect Cause TLV

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0019             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Disconnect Cause String                  |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+








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     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0019 for "PW-RED Disconnect Cause TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Disconnect Cause String

       Variable length string specifying the reason for the disconnect.
       Used for network management.


7.1.3. PW-RED Config TLV

   The PW-RED Config TLV is used in the RG Application Data message and
   has the following format:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type = 0x0012           |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ROID                             |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      PW Priority              |            Flags              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                  Service Name TLV                             |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            PW ID TLV or Generalized PW ID TLV                 |
   ~                                                               ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+









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     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0012 for "PW-RED Config TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - ROID

       As defined in the ROID section above.

     - PW Priority

       Two octets Pseudowire Priority. Used to indicate which PW has
       better priority to go into Active state. Numerically lower
       numbers are better priority. In case of a tie, the PE with the
       numerically lower identifier (i.e. IP Address) has better
       priority.

     - Flags

       Valid values are:


            -i. Synchronized (0x01)

                Indicates that the sender has concluded transmitting all
                pseudowire configuration for a given service.

           -ii. Purge Configuration (0x02)

                Indicates that the pseudowire is no longer configured
                for PW-RED operation.


     - Sub-TLVs

       The "PW-RED Config TLV" includes the following two sub-TLVs:







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            -i. Service Name TLV

           -ii.  PW ID TLV or Generalized PW ID TLV


       The format of the sub-TLVs is as follows:


7.1.3.1. Service Name TLV

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type                    |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Service Name                           |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0013 for "Service Name TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Service Name

       The name of the L2VPN service instance encoded in UTF-8 format
       and up to 80 character in length.


7.1.3.2. PW ID TLV

   This TLV is used to communicate the configuration of PWs for VPWS.









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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type                    |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Peer ID                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Group ID                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         PW ID                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0014 for "PW ID TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Peer ID

       Four octet LDP Router ID of the peer at the far end of the PW.

     - Group ID

       Same as Group ID in [RFC4447] section 5.2.

     - PW ID

       Same as PW ID in [RFC4447] section 5.2.


7.1.3.3. Generalized PW ID TLV

   This TLV is used to communicate the configuration of PWs for VPLS.









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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type = 0x0015           |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   AGI Type    |    Length     |      Value                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                    AGI  Value (contd.)                        ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   AII Type    |    Length     |      Value                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                   SAII  Value (contd.)                        ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   AII Type    |    Length     |      Value                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                   TAII Value (contd.)                         ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F bits

       both set to 0.

     - Type

       set to 0x0015

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - AGI, AII, SAII and TAII

       defined in [RFC4447] section 5.3.2.


7.1.4. PW-RED State TLV

   The PW-RED State TLV is used in the RG Application Data Message. This
   TLV is used by a device to report its PW status to other members in
   the RG.

   The format of this TLV is as follows:




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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0016             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ROID                             |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Local PW State                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Remote PW State                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0016 for PW-RED State TLV.

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - ROID

       As defined in the ROID section above.

     - Local PW State

       The status of the PW as determined by the sending PE, encoded in
       the same format as the "Status Code" field of the "PW Status TLV"
       defined in [RFC4447].

     - Remote PW State

       The status of the PW as determined by the remote peer of the
       sending PE. Encoded in the same format as the "Status Code" field
       of the "PW Status TLV" defined in [RFC4447]. The same code points
       listed above are used here as well.







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7.1.5. PW-RED Synchronization Request TLV

   The PW-RED Synchronization Request TLV is used in the RG Application
   Data message. This TLV is used by a device to request from its peer
   to retransmit configuration or operational state. The following
   information can be requested:

     - configuration and/or state for one or more pseudowires

     - configuration and/or state for all pseudowires

     - configuration and/or state for all pseudowires in a given service

       The format of the TLV is 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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |U|F|   Type=0x0017             |    Length                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Request Number           |C|S|    Request Type           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    Optional Sub-TLVs                          |
       ~                                                               ~
       |                                                               |
       +                                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |             ...                 |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0017 for "PW-RED Synchronization Request TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Request Number

       2 octets. Unsigned integer uniquely identifying the request. Used
       to match the request with a response. The value of 0 is reserved
       for unsolicited synchronization, and MUST NOT be used in the PW-



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       RED Synchronization Request TLV.

     - C Bit

       Set to 1 if request is for configuration data. Otherwise, set to
       0.

     - S Bit

       Set to 1 if request is for running state data. Otherwise, set to
       0.

     - Request Type

       14-bits specifying the request type, encoded as follows:

        0x00   Request Data for specified pseudowire(s)
        0x01   Request Data for all pseudowires in specified service(s)
        0x3FFF Request All Data


     - Optional Sub-TLVs

       A set of zero or more TLVs, as follows:

       If the Request Type field is set to (0x00), then this field
       contains one or more PW ID TLV(s) or Generalized PW ID TLV(s). If
       the Request Type field is set to (0x01), then this field contains
       one or more Service Name TLV(s). If the Request Type field is set
       to (0x3FFF), then this field MUST be empty.


7.1.6. PW-RED Synchronization Data TLV

   The PW-RED Synchronization Data TLV is used in the RG Application
   Data mesage. A pair of these TLVs is used by a device to delimit a
   set of TLVs that are sent in response to a PW-RED Synchronization
   Request TLV. The delimiting TLVs signal the start and end of the
   synchronization data, and associate the response with its
   corresponding request via the Request Number field.

   The PW-RED Synchronization Data TLVs are also used for unsolicited
   advertisements of complete PW-RED configuration and operational state
   data.  In this case, the Request Number field MUST be set to 0.

   This TLV has the following format:





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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0018             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Request Number            |     Flags                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0018 for "PW-RED Synchronization Data TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Request Number

       2 octets. Unsigned integer identifying the Request Number from
       the "PW-RED Synchronization Request TLV" which solicited this
       synchronization data response.

     - Flags

       2 octets, response flags encoded as follows:

           0x00 Synchronization Data Start
           0x01 Synchronization Data End



7.2. Multi-chassis LACP (mLACP) Application TLVs

   This section discusses the ICCP TLVs for Ethernet attachment circuit
   redundancy using the multi-chassis LACP (mLACP) application.










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7.2.1. mLACP Connect TLV

   This TLV is included in the RG Connect message to signal the
   establishment of mLACP application connection.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0030             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Protocol Version         |A|         Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Optional Sub-TLVs                          |
   ~                                                               ~
   |                                                               |
   +                                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             ...                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0030 for "mLACP Connect TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Protocol Version

       The version of this particular protocol for the purposes of ICCP.
       This is set to 0x0001.

     - A Bit

       Acknowledgement Bit. Set to 1 if the sender has received an mLACP
       Connect TLV from the recipient. Otherwise, set to 0.

     - Reserved

       Reserved for future use.





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     - Optional Sub-TLVs

       There are no optional Sub-TLVs defined for this version of the
       protocol.


7.2.2. mLACP Disconnect TLV

   This TLV is used in an RG Disconnect Message to indicate that the
   connection for the mLACP application is to be terminated.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0031             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Optional Sub-TLVs                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0031 for "mLACP Disconnect TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Optional Sub-TLVs

       The only optional Sub-TLV defined for this version of the
       protocol is the "mLACP Disconnect Cause" TLV defined next:


7.2.2.1. mLACP Disconnect Cause TLV

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x003A             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Disconnect Cause String                  |
   ~                                                               ~



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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x003A for "mLACP Disconnect Cause TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Disconnect Cause String

       Variable length string specifying the reason for the disconnect.
       Used for network management.


7.2.3. mLACP System Config TLV

   The mLACP System Config TLV is sent in the RG Application Data
   message. This TLV announces the local node's LACP System Parameters
   to the RG peers.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0032             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         System ID                             |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |         System Priority       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Node ID    |
   +-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.







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     - Type

       set to 0x0032 for "mLACP System Config TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - System ID

       6 octets field encoding the System ID used by LACP as specified
       in [IEEE-802.1AX] section 5.3.2.

     - System Priority

       2 octets encoding the LACP System Priority as defined in [IEEE-
       802.1AX] section 5.3.2.

     - Node ID

       One octet, LACP node ID. Used to ensure that the LACP Port
       Numbers are unique across all devices in an RG. Valid values are
       in the range 0 - 7.  Uniqueness of the LACP Port Numbers across
       RG members is ensured by encoding the Port Numbers as follows:

           - Most significant bit always set to 1
           - The next 3 most significant bits set to Node ID
           - Remaining 12 bits freely assigned by the system



7.2.4. mLACP Aggregator Config TLV

   The mLACP Aggregator Config TLV is sent in the RG Application Data
   message.  This TLV is used to notify RG peers about the local
   configuration state of an aggregator.














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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0036             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ROID                             |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Aggregator ID           |    MAC Address                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Actor Key               |    Member Ports Priority      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flags     | Agg Name Len  |    Aggregator Name            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   ~                                                               ~
   |                                        ...                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0036 for "mLACP Aggregator Config TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - ROID

       Defined in the 'ROID Encoding' section above.

     - Aggregator ID

       Two octets, LACP Aggregator Identifier as specified in [IEEE-
       802.1AX] section 5.4.6

     - MAC Address

       Six octets encoding the Aggregator MAC address.




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     - Actor Key

       Two octets, LACP Actor Key for the corresponding Aggregator, as
       specified in [IEEE-802.1AX] section 5.3.5.

     - Member Ports Priority

       Two octets, LACP administrative port priority associated with all
       interfaces bound to the Aggregator. This field is valid only when
       the "Flags" field has "Priority Set" asserted.

     - Flags

       Valid values are:

            -i. Synchronized (0x01)

                Indicates that the sender has concluded transmitting all
                Aggregator configuration information.

           -ii. Purge Configuration (0x02)

                Indicates that the Aggregator is no longer configured
                for mLACP operation.

          -iii. Priority Set (0x04)

                Indicates that the "Member Ports Priority" field is
                valid.

     - Agg Name Len

       One octet, length of the "Aggregator Name" field in octets.

     - Aggregator Name

       Aggregator name encoded in UTF-8 format, up to a maximum of 20
       characters.  Used for ease of management.


7.2.5. mLACP Port Config TLV

   The mLACP Port Config TLV is sent in the RG Application Data message.
   This TLV is used to notify RG peers about the local configuration
   state of a port.






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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0033             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Port Number             |    MAC Address                |
   +-------------------------------+                               +
   |                                                               |
   +---------------------------------------------------------------+
   |       Actor Key               |     Port Priority             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Port Speed                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flags     | Port Name Len |         Port Name             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
   ~                                                               ~
   |                                        ...                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0033 for "mLACP Port Config TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Port Number

       Two octets, LACP Port Number for the corresponding interface as
       specified in [IEEE-802.1AX] section 5.3.4. The Port Number MUST
       be encoded with the Node ID as was discussed above.

     - MAC Address

       Six octets encoding the port MAC address.

     - Actor Key

       Two octets, LACP Actor Key for the corresponding interface, as
       specified in [IEEE-802.1AX] section 5.3.5.




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     - Port Priority

       Two octets, LACP administrative port priority for the
       corresponding interface, as specified in [IEEE-802.1AX] section
       5.3.4. This field is valid only when the "Flags" field has
       "Priority Set" asserted.

     - Port Speed

       Four octets integer encoding the port's current bandwidth in
       units of 1,000,000 bits per second. This field corresponds to the
       ifHighSpeed object of IF-MIB [RFC2863].

     - Flags

       Valid values are:

            -i. Synchronized (0x01)

                Indicates that the sender has concluded transmitting all
                member link port configurations for a given Aggregator.

           -ii. Purge Configuration (0x02)

                Indicates that the port is no longer configured for
                mLACP operation.

          -iii. Priority Set (0x04)

                Indicates that the "Port Priority" field is valid.

     - Port Name Len

       One octet, length of the "Port Name" field in octets.

     - Port Name

       Port (interface) name encoded in UTF-8 format, up to a maximum of
       20 characters.


7.2.6. mLACP Port Priority TLV

   The mLACP Port Priority TLV is sent in the RG Application Data
   message. This TLV is used by a device to either advertise its
   operational Port Priority to other members in the RG, or to
   authoritatively request that a particular member of an RG change its
   port priority.



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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0034             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          OpCode               |          Port Number          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Aggregator ID         |    Last Port Priority         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Current Port Priority      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0034 for "mLACP Port Priority TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - OpCode

       Two octets identifying the operational code-point for the TLV,
       encoded as follows:

           0x00 Local Priority Change Notification
           0x01 Remote Request for Priority Change


     - Port Number

       2 octets field representing the LACP Port Number as specified in
       [IEEE-802.1AX] section 5.3.4. When the value of this field is 0,
       it denotes all ports bound to the Aggregator specified in the
       "Aggregator ID" field. When non-zero, the Port Number MUST be
       encoded with the Node ID as was discussed above.

     - Aggregator ID

       Two octets, LACP Aggregator Identifier as specified in [IEEE-
       802.1AX] section 5.4.6




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     - Last Port Priority

       Two octets, LACP port priority for the corresponding interface,
       as specified in [IEEE-802.1AX] section 5.3.4. For local ports,
       this field encodes the previous operational value of port
       priority. For remote ports, this field encodes the operational
       port priority last known to the PE via notifications received
       from its peers in the RG.

     - Current Port Priority

       Two octets, LACP port priority for the corresponding interface,
       as specified in [IEEE-802.1AX] section 5.3.4. For local ports,
       this field encodes the new operational value of port priority
       being advertised by the PE. For remote ports, this field
       specifies the new port priority being requested by the PE.


7.2.7. mLACP Port State TLV

   The mLACP Port State TLV is used in the RG Application Data message.
   This TLV is used by a device to report its LACP port status to other
   members in the RG.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0035             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Partner System ID                        |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |     Partner System Priority   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Partner Port Number       |     Partner Port Priority     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Partner Key             | Partner State |  Actor State  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Actor Port Number        |           Actor Key           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Selected     |  Port State   |        Aggregator ID          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.





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     - Type

       set to 0x0035 for "mLACP Port State TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Partner System ID

       6 octets, the LACP Partner System ID for the corresponding
       interface, encoded as a MAC address as specified in [IEEE-
       802.1AX] section 5.4.2.2 item r.

     - Partner System Priority

       2 octets field specifying the LACP Partner System Priority as
       specified in [IEEE-802.1AX] section 5.4.2.2 item q.

     - Partner Port Number

       2 octets encoding the LACP Partner Port Number as specified in
       [IEEE-802.1AX] section 5.4.2.2 item u. The Port Number MUST be
       encoded with the Node ID as was discussed above.

     - Partner Port Priority

       2 octets field encoding the LACP Partner Port Priority as
       specified in [IEEE-802.1AX] section 5.4.2.2 item t.

     - Partner Key

       2 octets field representing the LACP Partner Key as defined in
       [IEEE-802.1AX] section 5.4.2.2 item s.

     - Partner State

       1 octet field encoding the LACP Partner State Variable as defined
       in [IEEE-802.1AX] section 5.4.2.2 item v.

     - Actor State

       1 octet encoding the LACP Actor's State Variable for the port as
       specified in [IEEE-802.1AX] section 5.4.2.2 item m.






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     - Actor Port Number

       2 octets field representing the LACP Actor Port Number as
       specified in [IEEE-802.1AX] section 5.3.4. The Port Number MUST
       be encoded with the Node ID as was discussed above.

     - Actor Key

       2 octet field encoding the LACP Actor Operational Key as
       specified in [IEEE-802.1AX] section 5.3.5.

     - Selected

       1 octet encoding the LACP 'Selected' variable, defined in [IEEE-
       802.1AX] section 5.4.8, as follows:

           0x00 SELECTED
           0x01 UNSELECTED
           0x02 STANDBY


     - Port State

       1 octet encoding the operational state of the port as follows:
           0x00 Up
           0x01 Down
           0x02 Administrative Down
           0x03 Test (e.g. IEEE 802.3ah OAM Intrusive Loopback mode)


     - Aggregator ID

       Two octets, LACP Aggregator Identifier to which this port is
       bound based on the outcome of the LACP selection logic.


7.2.8. mLACP Aggregator State TLV

   The mLACP Aggregator State TLV is used in the RG Application Data
   message. This TLV is used by a device to report its Aggregator status
   to other members in the RG.










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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0037             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Partner System ID                        |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |     Partner System Priority   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Partner Key              |         Aggregator ID         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Actor Key                |   Agg State   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0037 for "mLACP Aggregator State TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Partner System ID

       6 octets, the LACP Partner System ID for the corresponding
       interface, encoded as a MAC address as specified in [IEEE-
       802.1AX] section 5.4.2.2 item r.

     - Partner System Priority

       2 octets field specifying the LACP Partner System Priority as
       specified in [IEEE-802.1AX] section 5.4.2.2 item q.

     - Partner Key

       2 octets field representing the LACP Partner Key as defined in
       [IEEE-802.1AX] section 5.4.2.2 item s.

     - Aggregator ID

       Two octets, LACP Aggregator Identifier as specified in [IEEE-
       802.1AX] section 5.4.6



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     - Actor Key

       2 octet field encoding the LACP Actor Operational Key as
       specified in [IEEE-802.1AX] section 5.3.5.

     - Agg State

       1 octet encoding the operational state of the Aggregator as
       follows:
           0x00 Up
           0x01 Down
           0x02 Administrative Down
           0x03 Test (e.g. IEEE 802.3ah OAM Intrusive Loopback mode)



7.2.9. mLACP Synchronization Request TLV

   The mLACP Synchronization Request TLV is used in the RG Application
   Data message. This TLV is used by a device to request from its peer
   to re-transmit configuration or operational state. The following
   information can be requested:

     - system configuration and/or state

     - configuration and/or state for a specific port

     - configuration and/or state for all ports with a specific LACP key

     - configuration and/or state for all mLACP ports

     - configuration and/or state for a specific aggregator

     - configuration and/or state for all aggregators with a specific
       LACP key

     - configuration and/or state for all mLACP aggregators

       The format of the TLV is as follows:












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        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |U|F|   Type=0x0038             |    Length                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Request Number           |C|S|    Request Type           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Port Number / Aggregator ID  |             Actor Key         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0038 for "mLACP Synchronization Request TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Request Number

       2 octets. Unsigned integer uniquely identifying the request. Used
       to match the request with a response. The value of 0 is reserved
       for unsolicited synchronization, and MUST NOT be used in the
       mLACP Synchronization Request TLV.

     - C Bit

       Set to 1 if request is for configuration data. Otherwise, set to
       0.

     - S Bit

       Set to 1 if request is for running state data. Otherwise, set to
       0.

     - Request Type

       14-bits specifying the request type, encoded as follows:







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           0x00   Request System Data
           0x01   Request Aggregator Data
           0x02   Request Port Data
           0x3FFF Request All Data


     - Port Number / Aggregator ID

       2 octets. When Request Type field is set to 'Request Port Data',
       this field encodes the LACP Port Number for the requested port.
       When the Request Type field is set to 'Request Aggregator Data',
       this field encodes the Aggregator ID of the requested Aggregator.
       When the value of this field is 0, it denotes that all ports (or
       Aggregators), whose LACP Key is specified in the "Actor Key"
       field, are being requested.

     - Actor Key

       Two octets, LACP Actor key for the corresponding port or
       Aggregator. When the value of this field is 0 (and the Port
       Number/Aggregator ID field is 0 as well), it denotes that
       information for all ports or Aggregators in the system is being
       requested.


7.2.10. mLACP Synchronization Data TLV

   The mLACP Synchronization Data TLV is used in the RG Application Data
   message. A pair of these TLVs is used by a device to delimit a set of
   TLVs that are being transmitted in response to an mLACP
   Synchronization Request TLV. The delimiting TLVs signal the start and
   end of the synchronization data, and associate the response with its
   corresponding request via the 'Request Number' field.

   The mLACP Synchronization Data TLVs are also used for unsolicited
   advertisements of complete mLACP configuration and operational state
   data. The 'Request Number' field MUST be set to 0 in this case. For
   such unsolicited synchronization, the PE MUST advertise all system,
   Aggregator and port information as done during the initialization
   sequence.

   This TLV has the following format:









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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F|   Type=0x0039             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Request Number            |     Flags                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     - U and F Bits

       Both are set to 0.

     - Type

       set to 0x0039 for "mLACP Synchronization Data TLV"

     - Length

       Length of the TLV in octets excluding the U-bit, F-bit, Type, and
       Length fields.

     - Request Number

       2 octets. Unsigned integer identifying the Request Number from
       the "mLACP Synchronization Request TLV" which solicited this
       synchronization data response.

     - Flags

       2 octets, response flags encoded as follows:

           0x00 Synchronization Data Start
           0x01 Synchronization Data End



8. LDP Capability Negotiation

   As requited in [RFC5561] the following TLV is defined to indicate the
   ICCP capability:
    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |U|F| TLV Code Point=0x700      |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |S| Reserved    |    Reserved   |  VER/Maj      |  Ver/Min      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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   where:

     - U-bit

       SHOULD be 1 (ignore if not understood).

     - F-bit

       SHOULD be 0 (don't forward if not understood).

     - TLV Code Point

       The TLV type, which identifies a specific capability. The ICCP
       code point is requested in the IANA allocation section below.

     - S-bit The State Bit indicates whether the sender is advertising
       or withdrawing the ICCP capability. The State bit is used as
       follows:
             1 - The TLV is advertising the capability specified by the
                 TLV Code Point.

             0 - The TLV is withdrawing the capability specified by the
                 TLV Code Point.

     - Ver/Maj

       The major version revision of the ICCP protocol, this document
       specifies 1.0. This field is then set to 1

     - Ver/Min

       The minor version revision of the ICCP protocol, this document
       specifies 1.0. This field is then set to 0

   ICCP capability is advertised to a LDP peer if there is at least one
   RG enabled on the local PE.


9. Client Applications

9.1. Pseudowire Redundancy Application Procedures

   This section defines the procedures for the Pseudowire Redundancy
   (PW-RED) Application.







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9.1.1. Initial Setup

   When an RG is configured on a system and multi-chassis pseudowire
   redundancy is enabled in that RG, the PW-RED application MUST send an
   "RG Connect" message with "PW-RED Connect TLV" to each PE that is a
   member of the same RG. The sending PE MUST set the A bit to 1 if it
   has already received a "PW-RED Connect TLV" from its peer; otherwise,
   the PE MUST set the A bit to 0. If a PE, that has sent the TLV with
   the A bit set to 0, receives a "PW-RED Connect TLV" from a peer, it
   MUST repeat its advertisement with the A bit set to 1. The PW-RED
   application connection is considered to be operational when both PEs
   have sent and received "PW-RED Connect TLVs" with the A bit set to 1.
   Once the application connection becomes operational, the two devices
   can start exchanging "RG Application Data" messages for the PW-RED
   application.

   If a system receives an "RG Connect" message with "PW-RED Connect
   TLV" that has a differing Protocol Version, it must follow the
   procedures outlined in the "Application Versioning" section above.

   When the PW-RED application is disabled on the device, or is
   unconfigured for the RG in question, the system MUST send an "RG
   Disconnect" message with "PW-RED Disconnect TLV".


9.1.2. Pseudowire Configuration Synchronization

   A system MUST advertise its local PW configuration to other PEs that
   are members of the same RG. This allows the PEs to build a view of
   the redundant nodes and pseudowires that are protecting the same
   service instances. The advertisement MUST be initiated when the PW-
   RED application connection first comes up. To that end, the system
   sends "RG Application Data" messages with "PW-RED Config TLVs" as
   part of an unsolicited synchronization. A PE MUST use a pair of "PW-
   RED Synchronization Data TLVs" to delimit the set of TLVs that are
   being sent as part of this unsolicited advertisement.

   In the case of a configuration change, a PE MUST re-advertise the
   most up to date information for the affected pseudowires.

   As part of the configuration synchronization, a PE advertizes the
   ROID associated with the pseudowire. This is used to correlate the
   pseudowires that are protecting each other on different PEs. A PE
   also advertizes a priority value that is used to determine the
   precedence of a given pseudowire to assume the Active role in a
   redundant setup. Furthermore, a PE advertizes a Service Name that is
   global in the context of an RG and is used to identify which
   pseudowires belong to the same service. Finally, a PE also advertizes



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   the pseudowire identifier as part of this synchronization.


9.1.3. Pseudowire Status Synchronization

   The mechanism for synchronizing pseudowire state depends on whether
   or not an AC redundancy mechanism is in use. If an AC mechanism is in
   use, then on a given PE, the forwarding status of the PW (Active or
   Standby) is derived from the state of the associated AC(s). This
   simplifies the operation of the multi-chassis redundancy solution
   (Figure 1) and eliminates the possibility of deadlock conditions
   between the AC and PW redundancy mechanisms. The rules by which the
   PW state is derived from the AC state are as follows:

     - VPWS

       For VPWS, there's a single AC per service instance.  If the AC is
       Active, then the PW status should be Active.  If the AC is
       Standby, then the PW status should be Standby.

     - VPLS

       For VPLS, there could be multiple ACs per service instance (i.e.
       VFI).  If AT LEAST ONE AC is Active, then the PW status should be
       Active.  If ALL ACs are Standby, then the PW status should be
       Standby.

   In this case, the PW-RED application does not synchronize PW status
   across chassis, per se. Rather, the AC Redundancy application should
   synchronize AC status between chassis, in order to determine which AC
   (and subsequently which PE) is Active or Standby for a given service.
   When that is determined, each PE will then adjust its local PWs state
   according to the rules described above.

   On the other hand, if an AC redundancy mechanism is not in use, then
   the PW-RED application is used to synchronize pseudowire state. This
   is done by sending the "PW-RED State TLV" whenever the pseudowire
   state changes on a PE.  This includes changes to the local end as
   well as the remote end of the pseudowire.

   A PE may request that its peer retransmit previously advertised PW-
   RED state. This is useful for instance when the PE is recovering from
   a soft failure. To request such retransmission, a PE MUST send a set
   of one or more "PW-RED Synchronization Request TLVs".

   A PE MUST respond to a "PW-RED Synchronization Request TLV" by
   sending the requested data in a set of one or more PW-RED TLVs
   delimited by a pair of "PW-RED Synchronization Data TLVs". The TLVs



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   comprising the response MUST be ordered such that the Synchronization
   Response TLV with the "Synchronization Data Start" flag precedes the
   various other PW-RED TLVs encoding the requested data. These, in
   turn, MUST precede the Synchronization Data TLV with the
   "Synchronization Data End" flag. It is worth noting that the response
   may span across multiple RG Application Data messages; however, the
   above TLV ordering MUST be retained across messages, and only a
   single pair of Synchronization Data TLVs must be used to delimit the
   response across all Application Data Messages.

   A PE MAY re-advertise its PW-RED state in an unsolicited manner. This
   is done by sending the appropriate config and state TLVs delimited by
   a pair of "PW-RED Synchronization Data TLVs" and using a 'Request
   Number' of 0.

   While a PE has a pending synchronization request for a pseudowire or
   a service, it SHOULD silently ignore all TLVs for said pseudowire or
   service that are received prior to the synchronization response and
   which carry the same type of information being requested. This saves
   the system from the burden of updating state that will ultimately be
   overwritten by the synchronization response. Note that TLVs
   pertaining to other pseudowires or services are to continue to be
   processed per normal in the interim.

   If a PE receives a synchronization request for a pseudowire or
   service that doesn't exist or is not known to the PE, then it MUST
   trigger an unsolicited synchronization of all pseudowire information
   (i.e. replay the initialization sequence).


9.1.4. PE Node Failure

   When a PE node detects that a remote PE, that is member of the same
   RG, has gone down, the local PE examines if it has redundant PWs for
   the affected services. If the local PE has the highest priority
   (after the failed PE) then it becomes the active node for the
   services in question, and subsequently activates its associated PWs.


9.2. Attachment Circuit Redundancy Application Procedures

9.2.1. Common AC Procedures

   This section describes generic procedures for AC Redundancy
   applications, independent of the type of the AC (ATM, FR or
   Ethernet).





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9.2.2. AC Failure

   When the AC Redundancy mechanism on the Active PE detects a failure
   of the AC, it should send an ICCP Application Data message to inform
   the redundant PEs of the need to take over.  The AC failures can be
   categorized into the following scenarios:

     - Failure of CE interface connecting to PE

     - Failure of CE uplink to PE

     - Failure of PE interface connecting to CE


9.2.3. PE Node Failure

   When a PE node detects that a remote PE, that is member of the same
   RG, has gone down, the local PE examines if it has redundant ACs for
   the affected services. If the local PE has the highest priority
   (after the failed PE) then it becomes the active node for the
   services in question, and subsequently activates its associated ACs.


9.2.4. PE Isolation

   When a PE node detects that is has been isolated from the core
   network (i.e. all core facing interfaces/links are not operational),
   then it should instruct its AC Redundancy mechanism to change the
   status of any active ACs to Standby. The AC Redundancy application
   should then send ICCP Application Data messages in order to trigger
   failover to a standby PE.


9.2.5. Ethernet AC Procedures

9.2.6. Multi-chassis LACP (mLACP) Application Procedures

   This section defines the procedures that are specific to the multi-
   chassis LACP (mLACP) application.


9.2.6.1. Initial Setup

   When an RG is configured on a system and mLACP is enabled in that RG,
   the mLACP application MUST send an "RG Connect" message with "mLACP
   Connect TLV" to each PE that is member of the same RG. The sending PE
   MUST set the A bit to 1 in the said TLV if it has received a
   corresponding "mLACP Connect TLV" from its peer PE; otherwise, the



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   sending PE MUST set the A bit to 0. If a PE receives an "mLACP
   Connect TLV" from its peer after sending the said TLV with the A bit
   set to 0, it MUST resend the TLV with the A bit set to 1. A system
   considers the mLACP application connection to be operational when it
   has sent and received "mLACP Connect TLVs" with the A bit set to 1.
   When the mLACP application connection between a pair of PEs is
   operational, the two devices can start exchanging "RG Application
   Data" messages for the mLACP application. This involves having each
   PE advertise its mLACP configuration and operational state in an
   unsolicited manner. A PE SHOULD subscribe to the following order when
   advertising its mLACP state upon initial application connection
   setup:

     - Advertise system configuration
     - Advertise Aggregator configuration
     - Advertise port configuration
     - Advertise Aggregator state
     - Advertise port state

   A PE MUST use a pair of "mLACP Synchronization Data TLVs" to delimit
   the entire set of TLVs that are being sent as part of this
   unsolicited advertisement.

   If a system receives an "RG Connect" message with "mLACP Connect TLV"
   that has a differing Protocol Version, it MUST follow the procedures
   outlined in the "Application Versioning" section above.

   After the mLACP application connection has been established, every PE
   MUST communicate its system level configuration to its peers via the
   use of "mLACP System Config TLV". This allows every PE to discover
   the Node ID and the locally configured System ID and System Priority
   values of its peers.

   If a PE receives an "mLACP System Config TLV" from a remote peer
   advertising the same Node ID value as the local system, then the PE
   MUST respond with an "RG Notification Message" to NAK the "mLACP
   System Config TLV". The PE MUST suspend the mLACP application until a
   satisfactory "mLACP System Config TLV" is received from the peer. It
   SHOULD also raise an alarm to alert the operator.  Furthermore, if a
   PE receives a NAK for an "mLACP System Config TLV" that it has
   advertised, the PE MUST suspend the mLACP application and SHOULD
   raise an alarm to alert the network operator of potential device
   mis-configuration.

   If a PE receives an "mLACP System Config TLV" from a new peer
   advertising the same Node ID value as another existing peer with
   which the local system has an established mLACP Application
   connection, then the PE MUST respond to the new peer with an "RG



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   Notification Message" to NAK the "mLACP System Config TLV" and MUST
   ignore the offending TLV.

   If the Node ID of a particular PE changes due to administrative
   configuration action, the PE MUST then inform its peers to purge the
   configuration of all previously advertised ports and/or aggregators,
   and MUST replay the initialization sequence by sending an unsolicited
   synchronization of: the system configuration, Aggregator
   configuration, port configuration, Aggregator state and port state.

   It is necessary for all PEs in an RG to agree upon the System ID and
   System Priority values to be used ubiquitously. To achieve this,
   every PE MUST use the values for the two parameters that are supplied
   by the PE with the numerically lowest value (among RG members) of
   System Aggregation Priority.  This guarantees that the PEs always
   agree on uniform values, which yield the highest System Priority.

   When the mLACP application is disabled on the device, or is
   unconfigured for the RG in question, the system MUST send an "RG
   Disconnect" message with "mLACP Disconnect TLV".


9.2.6.2. mLACP Aggregator and Port Configuration

   A system MUST synchronize the configuration of its mLACP enabled
   Aggregators and ports with other RG members. This is achieved via the
   use of "mLACP Aggregator Config TLVs" and "mLACP Port Config TLVs",
   respectively. An implementation MUST advertise the configuration of
   Aggregators prior to advertising the configuration of any of their
   associated member ports.

   The PEs in an RG MUST all agree on the MAC address to be associated
   with a given Aggregator. It is possible to achieve this via
   consistent configuration on member PEs. However, in order to protect
   against possible misconfiguration, a system MUST use, for any given
   Aggregator, the MAC address supplied by the PE with the numerically
   lowest System Aggregation Priority in the RG.

   A system that receives an "mLACP Aggregator Config TLV" with an ROID
   to Key association that is different from its local association MUST
   NAK the corresponding TLV and disable the Aggregator with the same
   ROID. Furthermore, it SHOULD raise an alarm to alert the operator.
   Similarly, a system that receives a NAK in response to a transmitted
   "mLACP Aggregator Config TLV" MUST disable the associated Aggregator
   and SHOULD raise an alarm to alert the network operator.

   A system MAY enforce a restriction that all ports that are to be
   bundled together on a given PE share the same Port Priority value. If



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   so, the system MUST advertise this common priority in the "mLACP
   Aggregator Config TLV" and assert the "Priority Set" flag in such
   TLV. Furthermore, the system in this case MUST NOT advertise
   individual Port Priority values in the associated "mLACP Port Config
   TLVs" (i.e. the "Priority Set" flag in these TLVs should be 0).

   A system MAY support individual Port Priority values to be configured
   on ports that are to be bundled together on a PE. If so, the system
   MUST advertise the individual Port Priority values in the appropriate
   "mLACP Port Config TLVs", and MUST NOT assert the "Priority Set" flag
   in the corresponding "mLACP Aggregator Config TLV".

   When the configurations of all ports for member links associated with
   a given Aggregator have been sent by a device, it asserts that fact
   by setting the "Synchronized" flag in the last port's "mLACP Port
   Config TLV". If an Aggregator doesn't have any candidate member ports
   configured, this is indicated by asserting the "Synchronized" flag in
   its "mLACP Aggregator Config TLV".

   Furthermore, for a given port/Aggregator, an implementation MUST
   advertise the port/Aggregator configuration prior to advertising its
   state (via the "mLACP Port State TLV" or "mLACP Aggregator State
   TLV"). If a PE receives an "mLACP Port State TLV" or "mLACP
   Aggregator State TLV" for a port or Aggregator that it had not
   learned of before via an appropriate Port or Aggregator Config TLV,
   then the PE MUST request synchronization of the configuration and
   state of all mLACP ports as well as all mLACP Aggregators from its
   respective peer. If during a synchronization (solicited or
   unsolicited), a PE receives a State TLV for a port or Aggregator that
   it has not learned of before, then the PE MUST send a NAK for the
   offending TLV. The PE MUST NOT request re-synchronization in this
   case.

   When mLACP is unconfigured on a port/Aggregator, a PE MUST send a
   "Port/Aggregator Config TLV" with the "Purge Configuration" flag
   asserted. This allows receiving PEs to purge any state maintained for
   the decommissioned port/Aggregator. If a PE receives a
   "Port/Aggregator Config TLV" with the "Purge Configuration" flag
   asserted, and the PE is not maintaining any state for that
   port/Aggregator, then it MUST silently discard the TLV.


9.2.6.3. mLACP Aggregator and Port Status Synchronization

   PEs within an RG need to synchronize their state-machines for proper
   mLACP operation with a multi-homed device. This is achieved by having
   each system advertise its Aggregators and ports running state in
   "mLACP Aggregator State TLVs" and "mLACP Port State TLVs",



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   respectively. Whenever any LACP parameter for an Aggregator or a
   port, whether on the Partner (i.e. multi-homed device) or the Actor
   (i.e. PE) side, is changed a system MUST transmit an updated TLV for
   the affected Aggregator and/or port. Moreover, when the
   administrative or operational state of an Aggregator or port changes,
   the system MUST transmit an updated Aggregator or port state TLV to
   its peers.

   If a PE receives an Aggregator or port state TLV where the 'Actor
   Key' doesn't match what was previously received in a corresponding
   Aggregator or port config TLV, the PE MUST then request
   synchronization of the configuration and state of the affected
   Aggregator or port. If such a mismatch occurs between the config and
   state TLVs as part of a synchronization (solicited or unsolicited),
   then the PE MUST send a NAK for the state TLV. Furthermore, if a PE
   receives a port state TLV with the 'Aggregator ID' set to a value
   that doesn't map to some Aggregator that the PE had learned of via a
   previous Aggregator config TLV, then the PE MUST request
   synchronization of the configuration and state of all Aggregators and
   ports. If the above anomaly occurs during a synchronization, then the
   PE MUST send a NAK for the offending port state TLV.

   A PE MAY request that its peer retransmit previously advertised
   state. This is useful for example when the PE is recovering from a
   soft failure and attempting to relearn state. To request such
   retransmissions, a PE MUST send a set of one or more "mLACP
   Synchronization Request TLVs".

   A PE MUST respond to an "mLACP Synchronization Request TLV" by
   sending the requested data in a set of one or more mLACP TLVs
   delimited by a pair of "mLACP Synchronization Data TLVs". The TLVs
   comprising the response MUST be ordered in the RG Application Data
   message(s) such that the Synchronization Response TLV with the
   "Synchronization Data Start" flag precedes the various other mLACP
   TLVs encoding the requested data. These, in turn, MUST precede the
   Synchronization Data TLV with the "Synchronization Data End" flag.
   Note that the response may span across multiple RG Application Data
   messages, for example when MTU limits are exceeded; however, the
   above ordering MUST be retained across messages, and only a single
   pair of Synchronization Data TLVs MUST be used to delimit the
   response across all Application Data Messages.

   A PE device MAY re-advertise its mLACP state in an unsolicited
   manner. This is done by sending the appropriate Config and State TLVs
   delimited by a pair of "mLACP Synchronization Data TLVs" and using a
   'Request Number' of 0.

   While a PE has a pending synchronization request for a system,



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   Aggregator or port, it SHOULD silently ignore all TLVs for said
   system, Aggregator or port that are received prior to the
   synchronization response and which carry the same type of information
   being requested.  This saves the system from the burden of updating
   state that will utlimately be overwritten by the synchronization
   response. Note that TLVs pertaining to other systems, Aggregators or
   ports are to continue to be processed per normal in this case.

   If a PE receives a synchronization request for an Aggregator, port or
   Key that doesn't exist or is not known to the PE, then it MUST
   trigger an unsolicited synchronization of all system, Aggregator and
   port information (i.e. replay the initialization sequence).

   If a PE learns, as part of a synchronization operation from its peer,
   that the latter is advertising a Node ID value which is different
   from the value previously advertised, then the PE MUST purge all
   port/aggregator data previously learnt from that peer prior to the
   last synchronization.


9.2.6.4. Failure and Recovery

   When a PE that is active for a multi-chassis link aggregation group
   encounters a fault, it SHOULD attempt to fail-over to a peer PE which
   hosts the same RO. To that effect, the faulty PE SHOULD lower its
   port priority (by using a larger numeric value) and advertise this
   change in the "mLACP Port Priority TLV". If the PE is not capable of
   lowering its own port priority any further, it SHOULD trigger a
   failover to the redundant PE by sending an "mLACP Port Priority TLV"
   in which it requests the redundant PE to raise the latter's port
   priority to the maximum permitted in [IEEE-802.1AX] (i.e. the
   smallest allowed numeric value) for the Aggregator in question.
   Furthermore, the PE SHOULD set its own port priority to the next
   smallest numeric value.

   Upon recovery from a previous fault, a PE MAY reclaim active role for
   a multi-chassis link aggregation group if configured for revertive
   protection.  Otherwise, the recovering PE may assume standby role
   when configured for non-revertive protection. In the revertive
   scenario, a PE SHOULD assume active role within the RG by sending an
   "mLACP Port Priority TLV" to the currently active PE, requesting that
   the latter change its port priority to a value that is lower (i.e.
   numerically larger) for the Aggregator in question.

   If a system is operating in a mode where different ports of a bundle
   are configured with different Port Priorities, then the system MUST
   NOT advertise or request change of Port Priority values for
   aggregated ports collectively (i.e. by using a 'Port Number' of 0 in



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   the "mLACP Port Priority TLV"). This is to avoid ambiguity in the
   interpretation of the 'Last Port Priority' field.

   If a PE receives an "mLACP Port Priority TLV" requesting a priority
   change for a port or Aggregator that is not local to the device, then
   the PE MUST re-advertise the local configuration of the system, as
   well as the configuration and state of all its mLACP ports and
   Aggregators.

   If a PE receives an "mLACP Port Priority TLV" in which the remote
   system is advertising priority change for a port or Aggregator that
   the local PE had not learned of before via an appropriate Port or
   Aggregator Config TLV, then the PE MUST request synchronization of
   the configuration and state of all mLACP ports as well as all mLACP
   Aggregators from its respective peer.


10. Security Considerations

   The security considerations described in [RFC5036] and [RFC4447] that
   apply to the base LDP specification, and to the PW LDP control
   protocol extensions apply to the capability mechanism described in
   this document.

   The ICCP protocol is not intended to be applicable when the
   redundancy group spans PE in different administrative domains.
   Furthermore, implementations SHOULD provide a mechanism to select to
   which LDP peers the ICCP capability will be advertised, and from
   which LDP peers the ICCP messages will be accepted.


11. IANA Considerations

11.1. MESSAGE TYPE NAME SPACE

   This document uses several new LDP message types, IANA already
   maintains a registry of name "MESSAGE TYPE NAME SPACE" defined by
   [RFC5036]. The following values are suggested for assignment:

     Message type  Description
        0x0700     RG Connect Message
        0x0701     RG Disconnect Message
        0x0702     RG Notification Message
        0x0703     RG Application Data Message







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11.2. TLV TYPE NAME SPACE

   This document use a new LDP TLV type, IANA already maintains a
   registry of name "TLV TYPE NAME SPACE" defined by [RFC5036]. The
   following value is suggested for assignment:
      TLV Type Description
       0x700       ICCP capability TLV.


11.3. ICC RG Parameter Type Space

   IANA needs to set up a registry of "ICC RG parameter type". These are
   14-bit values. Parameter Type values 1 through 0x000F are specified
   in this document, Parameter Type values 0x0010 through 0x1FFF are to
   be assigned by IANA, using the "Expert Review" policy defined in
   [RFC5226]. Parameter Type values 0x2000 through 0x2FFF, 0x3FFF, and 0
   are to be allocated using the IETF consensus policy defined in
   [RFC5226]. Parameter Type values 0x3000 through 0x3FFE are reserved
   for vendor proprietary extensions and are to be assigned by IANA,
   using the "First Come First Served" policy defined in [RFC5226]. A
   Parameter Type description is required for any assignment from this
   registry. Additionally, for the vendor proprietary extensions range a
   citation of a person or company name is also required. A document
   reference should also be provided.

   Initial ICC RG parameter type space value allocations are specified
   below:

   Parameter Type Description                            Reference
   -------------- ---------------------------------      ---------
   0x0001         ICC Sender Name                        [RFCxxxx]
   0x0002         NAK TLV                                [RFCxxxx]
   0x0003         Requested Protocol Version TLV         [RFCxxxx]
   0x0004         Disconnect Code TLV                    [RFCxxxx]
   0x0005         ICC RG ID TLV                          [RFCxxxx]

   0x0010         PW-RED Connect TLV                     [RFCxxxx]
   0x0011         PW-RED Disconnect TLV                  [RFCxxxx]
   0x0012         PW-RED Config TLV                      [RFCxxxx]
   0x0013         Service Name TLV                       [RFCxxxx]
   0x0014         PW ID TLV                              [RFCxxxx]
   0x0015         Generalized PW ID TLV                  [RFCxxxx]
   0x0016         PW-RED State TLV                       [RFCxxxx]
   0x0017         PW-RED Synchronization Request TLV     [RFCxxxx]
   0x0018         PW-RED Synchronization Data TLV        [RFCxxxx]
   0x0019         PW-RED Disconnect Cause TLV            [RFCxxxx]

   0x0030         mLACP Connect TLV                      [RFCxxxx]



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   0x0031         mLACP Disconnect TLV                   [RFCxxxx]
   0x0032         mLACP System Config TLV                [RFCxxxx]
   0x0033         mLACP Port Config TLV                  [RFCxxxx]
   0x0034         mLACP Port Priority TLV                [RFCxxxx]
   0x0035         mLACP Port State TLV                   [RFCxxxx]
   0x0036         mLACP Aggregator Config TLV            [RFCxxxx]
   0x0037         mLACP Aggregator State TLV             [RFCxxxx]
   0x0038         mLACP Synchronization Request TLV      [RFCxxxx]
   0x0039         mLACP Synchronization Data TLV         [RFCxxxx]
   0x003A         mLACP Disconnect Cause TLV             [RFCxxxx]




11.4. STATUS CODE NAME SPACE

   This document use several new Status codes, IANA already maintains a
   registry of name "STATUS CODE NAME SPACE" defined by [RFC5036]. The
   following values is suggested for assignment:  The "E" column is the
   required setting of the Status Code E-bit.
   Range/Value     E     Description                       Reference
   ------------- -----   ----------------------            ---------
   0x00010001      0     Unknown ICCP RG
   0x00010002      0     ICCP Connection Count Exceeded
   0x00010003      0     ICCP Application Connection
                         Count Exceeded
   0x00010004      0     ICCP Application not in RG
   0x00010005      0     Incompatible ICCP  Protocol Version
   0x00010006      0     ICCP Rejected Message
   0x00010007      0     ICCP Administratively Disabled
   0x00010010      0     ICCP RG Removed
   0x00010011      0     ICCP Application Removed from RG


12. Acknowledgments

   The authors wish to acknowledge the important contributions of Dennis
   Cai, Neil McGill, Amir Maleki, Dan Biagini, Robert Leger, Sami
   Boutros, Neil Ketley and Mark Christopher Sains.












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13. Normative References

   [RFC5036] L. Andersson et al, "LDP Specification", RFC 5036,
        October 2007.

   [RFC5561] "LDP Capabilities", RFC5561, July  2009.

   [RFC4447] "Transport of Layer 2 Frames Over MPLS", Martini, L.,
         et al., rfc4447 April 2006.

   [IEEE-802.1AX] IEEE Std. 802.1AX-2008, "IEEE Standard for Local and
        metropolitan area networks- Link Aggregation",
        IEEE Computer Society, November 2008.

   [RFC2863] K. McCloghrie, F. Kastenholz, "The Interfaces Group MIB",
        rfc2863, June 2000.


14. Informative References

   [RFC5880] D. Katz, D. Ward, "Bidirectional Forwarding Detection",
        RFC5880, June 2010

   [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
        IANA Considerations section in RFCs", BCP 26, RFC 5226, May 2008


15. Author's Addresses


   Luca Martini
   Cisco Systems, Inc.
   9155 East Nichols Avenue, Suite 400
   Englewood, CO, 80112
   e-mail: lmartini@cisco.com


   Samer Salam
   Cisco Systems, Inc.
   595 Burrard Street, Suite 2123
   Vancouver, BC V7X 1J1
   Canada
   e-mail: ssalam@cisco.com








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   Ali Sajassi
   Cisco Systems, Inc.
   170 West Tasman Drive
   San Jose, CA 95134
   e-mail: sajassi@cisco.com


   Matthew Bocci
   Alcatel-Lucent
   Grove House, Waltham Road Rd
   White Waltham, Berks, UK. SL6 3TN
   e-mail: matthew.bocci@alcatel-lucent.co.uk


   Satoru Matsushima
   Softbank Telecom
   1-9-1, Higashi-Shinbashi, Minato-ku
   Tokyo 105-7313, JAPAN
   e-mail: satoru.matsushima@tm.softbank.co.jp


   Thomas Nadeau
   CA Technologies
   273 Corporate Dr.
   Portsmouth, NH 03801
   USA
   e-mail: Thomas.Nadeau@ca.com



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   10, 2008. The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
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