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STP Application of ICCP
draft-ietf-pwe3-iccp-stp-01

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 7727.
Authors Mingui Zhang , Huafeng Wen , Jie Hu
Last updated 2014-07-25 (Latest revision 2014-04-23)
Replaces draft-zhang-pwe3-iccp-stp
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draft-ietf-pwe3-iccp-stp-01
INTERNET-DRAFT                                              Mingui Zhang
Intended Status: Proposed Standard                           Huafeng Wen
Expires: October 25, 2014                                         Huawei
                                                                  Jie Hu
                                                           China Telecom
                                                          April 23, 2014

                        STP Application of ICCP
                    draft-ietf-pwe3-iccp-stp-01.txt

Abstract

   Inter-Chassis Communication Protocol (ICCP) supports the inter-
   chassis redundancy mechanism which achieves high network
   availability.

   In this document, the PEs in a Redundant Group (RG) running ICCP are
   used to offer multi-homed connectivity to Spanning Tree Protocol
   (STP) networks. The ICCP TLVs for the STP application are defined,
   therefore PEs from the RG can make use of these TLVs to synchronize
   the state and configuration data of the STP network.

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
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html

Copyright and License Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors. All rights reserved.
 

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document. Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1. Conventions used in this document . . . . . . . . . . . . .  3
     1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. The Use Case Scenario . . . . . . . . . . . . . . . . . . . . .  3
     2.1. STP as an Application of ICCP . . . . . . . . . . . . . . .  4
     2.2. A Private Solution: The BPDU Tunneling Model  . . . . . . .  4
   3. Spanning Tree Protocol Application TLVs . . . . . . . . . . . .  6
     3.1. STP Connect TLV . . . . . . . . . . . . . . . . . . . . . .  6
     3.2. STP Disconnect TLV  . . . . . . . . . . . . . . . . . . . .  7
       3.2.1. STP Disconnect Cause TLV  . . . . . . . . . . . . . . .  8
     3.3. STP Config TLVs . . . . . . . . . . . . . . . . . . . . . .  8
       3.3.1. STP System Config . . . . . . . . . . . . . . . . . . .  8
       3.3.2. STP Topology Changed Instances  . . . . . . . . . . . .  9
       3.3.3. STP CIST Root Time  . . . . . . . . . . . . . . . . . . 10
       3.3.4. STP MSTI Root Time  . . . . . . . . . . . . . . . . . . 11
       3.3.5. STP Region Name . . . . . . . . . . . . . . . . . . . . 12
       3.3.6. STP Revision Level  . . . . . . . . . . . . . . . . . . 12
       3.3.7. STP Instance Priority . . . . . . . . . . . . . . . . . 13
       3.3.8. STP Configuration Digest  . . . . . . . . . . . . . . . 14
     3.4. STP Synchronization Request TLV . . . . . . . . . . . . . . 14
     3.5. STP Synchronization Data TLV  . . . . . . . . . . . . . . . 16
   4. Security Considerations . . . . . . . . . . . . . . . . . . . . 17
   5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 17
   Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 18
   6. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     6.1. Normative References  . . . . . . . . . . . . . . . . . . . 18
     6.2. Informative References  . . . . . . . . . . . . . . . . . . 18
   Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19

 

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1. Introduction

   Inter-Chassis Communication Protocol (ICCP) specifies a multi-chassis
   redundant mechanism, which enables PEs located in multi-chassis to
   act as a single Redundant Group (RG). 

   This document introduces Spanning Tree Protocol (STP) as a new
   application of ICCP. When a bridge network running STP is connected
   to an RG, the RG members pretend to be a single root bridge to
   participate the operations of the STP. STP relevant information need
   be exchanged and synchronized among the RG members. ICCP TLVs for the
   STP application are specified for this purpose. 

1.1. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

1.2. Terminology

   ICCP: Inter-Chassis Communication Protocol
   STP: Spanning Tree Protocol
   MSTP: Multiple Spanning Tree Protocol
   DSLAM: Digital Subscriber Line Access Multiplexer
   MST: Multiple Spanning Trees
   CIST: Common and Internal Spanning Tree
   MSTI: Multiple Spanning Tree Instance 
   BPDU: Bridge Protocol Data Unit

   In this document, unless otherwise explicitly noted, when the term
   STP is used, it also covers MSTP.

2. The Use Case Scenario

   In customers' broadband networks, bridged DSLAMs are usually
   geographically dispersed. It is a common case these DSLAMs are
   connected to carriers' L2VPN network at multiple points for the sake
   of reliability. Requirements from customers for this use case are
   listed as follows.

   o  These DSLAMs are running STP. 

   o  These DSLAMs are not geographically close to each other. Multiple
      DSLAMs are connected to the carrier network at different
      locations.

   o  When one connection to the carrier network fails, customers wish a
 

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      connection in another location can continue to work after the re-
      convergence of the STP rather than compromising the whole STP
      network. The failure of the connection may be due to the failure
      of the PE, the AC or even the CE (a DSLAM) itself. 

   o  Customers want to balance the load among those connections,
      therefore all those connections need be active. 

   In order to meet these requirements, the 'ICCP-STP' model is proposed
   in Section 2.1. It introduces STP as a new application of ICCP. A
   private implementation is depicted in Section 2.2 to serve as a
   contrast. Its issues are analyzed.

2.1. STP as an Application of ICCP

             +--------------+       +=============+
             |              |       |             |
             |              |       |             |
             |       +---+  |       |  +-----+    |
             |   +---+CE1+<6>-------<5>+ PE1 |    |
             |  <1>  +---+  |       |  +-----+    |
             | +-+-+        |       |     ||      |
             | |CE3|        |       |     || ICCP |
             | +-+-+        |       |     ||      |
             |  <2>  +---+  |       |  +-----+    |
             |   +---+CE2+<3>-------<4>+ PE2 |    |
             |       +---+  |       |  +-----+    |
             |              |       |             |
             | Multi-homed  |       |             |
             | STP Network  |       |             |
             +--------------+       +=============+

    Figure 2.1: A STP network is multi-homed to an RG running ICCP.

   Figure 2.1 shows an example topology of this model. With ICCP, the
   whole RG will be virtualized to be a single bridge. The RG pretends
   that the ports connected to the STP network (port <4>, <5>) are from
   the same bridge. All these ports emit configuration BPDU with the
   highest root priority to trigger the construction of the spanning
   tree. In this way, the STP will always break a loop within the multi-
   homed STP network.

   Each RG member has its BridgeIdentifier (the MAC address). The least
   significant one is elected as the BridgeIdentifier of the 'vitualized
   root bridge'.

2.2. A Private Solution: The BPDU Tunneling Model
 

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             +--------------+       +=============+
             |              |       |             |
             |              |       |             |
             |       +---+  |       |  +-----+    |
             |   +---+CE1+<6>-------<5>+ PE1 |    |
             |  <1>  +---+  |       |  +-----+    |
             | +-+-+        |       |     ||BPDU  |
             | |CE3|        |       |     ||tunnel|
             | +-+-+        |       |     ||      |
             |  <2>  +---+  |       |  +-----+    |
             |   +---+CE2+<3>-------<4>+ PE2 |    |
             |       +---+  |       |  +-----+    |
             |              |       |             |
             | Multi-homed  |       |             |
             | STP Network  |       |             |
             +--------------+       +=============+

                  Figure 2.2: The BPDU Tunneling Model

   Figure 2.2 shows an example network of the 'BPDU tunneling' model.
   Two PEs tunnel BPDUs of the STP network over a PW. The OAM designed
   in [RFC7023] can be adopted for the interworking between MPLS and
   Ethernet.

   In this model, the ports connected to the STP network at the PEs'
   side are non-bridge ports (e.g., port <4>, <5>). The tunnel between
   PE1 and PE2 is a transparent tunnel of BPDUs. For CE1 and CE2, they
   regard that there is a direct link between them. Issues of this model
   are listed as follows.

   o  Assume port <1> was blocked according to the STP calculation. Now,
      suppose link CE3-CE2 fails, port <2> is blocked while port <1> is
      unblocked. Since the BPDUs is just tunneled, PE2 is unaware of
      this change. It may continue to send traffic to CE3 via CE2 where
      a black-hole happens. 

      In order to handle this issue, PEs have to snoop the Topology
      Change (TC) message of the STP network so the tunnel is not
      "transparent" to BPDUs anymore. When the TC event is sensed, these
      PEs should withdraw MAC addresses of those instances affected by
      the TC event across the carrier's network.

   o  When port <4> fails, CE1 is unaware. Suppose CE2 is the root
      bridge, port <6> has to wait for 3 STP HELLO Intervals (3*2s) and
      2 Forwarding Delays (2*15s). The STP network takes at least 36
      seconds to complete the convergence. The convergence process of
      the STP network is greatly slowed down. This actually changes the
      behavior of customers' STP networks.
 

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      In order to speed up the convergence, CE1 has to sense the state
      of the link between CE2 and PE2. The interworking PEs and CEs have
      to cope with various combinations of failures. There is no
      standard solution yet.

   o  RFC 7023 is scoped to only single segment PWs [RFC6310][RFC 7023].
      When the STP network is attached to more than two PEs, a full mesh
      PWs have to be set up. It's not clear yet what behaviors these PEs
      should have.

   Compared with this 'BPDU tunneling' model, the advantage point of the
   "ICCP-STP" model is that PEs "participate" in the STP calculation,
   therefore we need not design the complex interworking mechanism.

3. Spanning Tree Protocol Application TLVs

   This section specifies the ICCP TLVs for the STP application. As an
   AC Redundancy application of ICCP, operations specified in Section
   9.2 of [ICCP] should be referred. 

3.1. STP Connect TLV

   This TLV is included in the RG Connect message to signal the
   establishment of STP 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=0x0040             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Protocol Version         |A|         Reserved            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Optional Sub-TLVs                        |
   ~                                                               ~
   |                                                               |
   +                                 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             ...                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x0040 for "STP Connect TLV"

      - Length
 

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        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 STP
        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.

3.2. STP Disconnect TLV

   This TLV is used in an RG Disconnect Message to indicate that the
   connection for the STP 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=0x0041             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Optional Sub-TLVs                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x0041 for "STP Disconnect TLV"

      - Length

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

 

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      - Optional Sub-TLVs

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

3.2.1. STP 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=0x004C             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Disconnect Cause String                  |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x004C for "STP 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.

3.3. STP Config TLVs

   The STP Config TLVs are sent in the RG Application Data message. When
   a STP Config TLV is received by a peering RB member, it SHOULD
   synchronize the configuration information contained in the TLV. TLVs
   specified from section 3.3.1 through section 3.3.8 contains such kind
   of configuration information. 

3.3.1. STP System Config

   This TLV announces the local node's STP System Parameters to the RG
   peers.

 

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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=0x0042             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              ROID                             |
   +                                                               +
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         MAC Address                           |
   +                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x0042 for "STP System Config"

      - Length

        Length of the MAC address, which is 6 octets.

      -ROID

        As defined in Section 6.1.3 of [ICCP].

      - MAC Address

        The MAC address of the sender. This MAC address is set to the
        BridgeIdentifier of the sender, as defined in [802.1q] section
        13.23.2. The the least significant unsigned BridgeIdentifier is
        used as the MAC address of the Virtual Root Bridge mentioned in
        Section 2.1.

3.3.2. STP Topology Changed Instances

   This TLV is used to report the Topology Changed Instances to other
   members in the RG. The receiver RG member SHOULD enforce the Topology
   Change to its port connected to the STP network, including the flush
   out of MAC addresses relevant to the instances listed in this TLV.

 

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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=0x0043             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       InstanceID List                         |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x0043 for "STP Topology Changed Instances"

      - Length

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

      - InstanceID List

        The list of the instances whose topology is changed as indicated
        by the Topology Change Notification (TCN) Messages as specified
        in [802.1q] section 13.14. 

3.3.3. STP CIST Root Time

   This TLV is used to report the Value of CIST Root Time 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=0x0044             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    MaxAge     |   MessageAge  |    FwdDelay   |   HelloTime   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | RemainingHops |
   +-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type
 

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        set to 0x0044 for "STP CIST Root Time"

      - Length

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

      - MaxAge

        The Maximum Age of this TLV.

      - MessageAge

        The actual age of this TLV.

      - FwdDelay

        The delay before the port enters the forwarding status.

      - HelloTime

        The interval between two continuous configuration BPDUs.

      - RemainingHops

        The remaining hops of this TLV

3.3.4. STP MSTI Root Time

   This TLV is used to report the Value of MSTI Root Time 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=0x0045             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         InstanceID            | RemainingHops |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x0045 for "STP MSTI Root Time"

 

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      - Length

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

      - InstanceID

        The instance identification number of the MSTI.

      - remainingHops

        The remaining hops of this TLV

3.3.5. STP Region Name

   This TLV is used to report the Value of Region Name 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=0x0046             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Region Name                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x0046 for "STP Region Name"

      - Length

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

      - Region Name

        The Name of the MST Region.

3.3.6. STP Revision Level

   This TLV is used to report the Value of Revision Level 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=0x0047             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       Revision Level          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x0047 for "STP Revision Level"

      - Length

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

      - Revision Level

        The Revision Level as specified in [802.1q] section 3.21;

3.3.7. STP Instance Priority

   This TLV is used to report the Value of Instance Priority 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=0x0048             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  Pri  |      InstanceID       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x0048 for "STP Instance Priority"

      - Length

 

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

      - Pri

        The Instance Priority

      - InstanceID

        The instance identification number of the MSTI.

3.3.8. STP Configuration Digest

   This TLV is used to report the Value of STP VLAN Instance Mapping 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=0x0049             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Configuration Digest                       |
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x0049 for "STP Configuration Digest"

      - Length

        Length of the STP Configuration Digest which is 16 octets. 

      - Configuration Digest

        As specified in [802.1q] section 13.7.

3.4. STP Synchronization Request TLV

   The STP 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:

 

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     - system configuration and/or state
     - configuration and/or state for a specific port
      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=0x004A             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Request Number           |C|S|    Request Type           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Port Number              |             Actor Key         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

        set to 0x004A for "STP 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 STP 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 Port Data
           0x3FFF Request All Data

      - Port Number

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

      - Actor Key

        2 octets. STP Actor key for the corresponding port. When the
        value of this field is 0 (and the Port Number field is 0 as
        well), it denotes that information for all ports in the system
        is being requested.

3.5. STP Synchronization Data TLV

   The STP 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 STP 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 STP Synchronization Data TLVs are also used for unsolicited
   advertisements of complete STP configuration and operational state
   data. The 'Request Number' field MUST be set to 0 in this case. 

   This TLV 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=0x004B             |    Length                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Request Number            |     Flags                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      - U and F Bits

        Both are set to 0.

      - Type

 

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        set to 0x004B for "STP 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 "STP 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

4. Security Considerations

   As an application running on the channel provided by ICCP, security
   considerations of [ICCP] should be referred.

5. IANA Considerations

   The ICC RG parameter types used by the application TLVs defined in
   Section 3 of this document should be assigned. ICC RG parameter types
   are 14-bit values. Parameter Type values 1 through 0x003A are
   specified in [ICCP]. This document adds the specification of values
   0x003B through 0x004C. Parameter Type values 0x004D through 0x1FFF
   are to be assigned by IANA, using the "Expert Review" policy defined
   in [RFC5226]. Suggested parameter type space value allocations for
   the STP application are specified below:

      Parameter Type Description
      -------------- ---------------------------------
      0x003B-0x003F  Reserved
      0x0040         STP Connect TLV
      0x0041         STP Disconnect TLV
      0x0042         STP System Config TLV
      0x0043         STP Topology Changed Instances TLV
      0x0044         STP STP CIST Root Time TLV
      0x0045         STP MSTI Root Time TLV
      0x0046         STP Region Name TLV
      0x0047         STP Revision Level TLV
      0x0048         STP Instance Priority TLV
 

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      0x0049         STP Configuration Digest TLV
      0x004A         STP Synchronization Request TLV
      0x004B         STP Synchronization Data TLV
      0x004C         STP Disconnect Cause TLV

Acknowledgements

   Authors would like to thank the comments and suggestions from Gregory
   Mirsky.

6. References 

6.1. Normative References

   [ICCP] L. Martini, S. Salam, et al, "Inter-Chassis Communication
         Protocol for L2VPN PE Redundancy", draft-ietf-pwe3-iccp-16.txt,
         in RFC Ed Queue.

   [802.1q] "IEEE Standard for Local and Metropolitan Area Networks---
         Virtual Bridged Local Area Networks.". IEEE Std 802.1 Q-2005,
         May 19, 2006.

6.2. Informative References

   [RFC7023] D. Mohan, Ed., N. Bitar, Ed., A. Sajassi, Ed., S. DeLord,
         P. Niger, R. Qiu., "MPLS and Ethernet Operations,
         Administration, and Maintenance (OAM) Interworking", RFC 7023,
         October 2013.

   [RFC6310] Aissaoui, M., Busschbach, P., Martini, L., Morrow, M.,
         Nadeau, T., and Y(J). Stein, "Pseudowire (PW) Operations,
         Administration, and Maintenance (OAM) Message Mapping", RFC
         6310, July 2011.

 

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Author's Addresses

   Mingui Zhang
   Huawei
        
   EMail: zhangmingui@huawei.com

   Huafeng Wen
   Huawei

   EMail: wenhuafeng@huawei.com

   Jie Hu
   China Telecom

   EMail: hujie@ctbri.com.cn    

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