IDR Working Group                                                W. Hao
                                                            D. Eastlake
Internet Draft                                                   Huawei
Intended status: Standard Track                                S. Hares
                                                Hickory Hill Consulting
                                                            IP Infusion
                                                             M. Durrani
                                                                  Y. Li
Expires: February 2017                                  August 16, 2016

                Distribution of TRILL Link-State using BGP


   This draft describes a TRILL link state and MAC address reachability
   information distribution mechanism using a BGP LS extension.
   External components such as an SDN Controller can use the
   information for topology visibility, troubleshooting, network
   automation, etc.

Status of this Memo

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   provisions of BCP 78 and BCP 79.

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Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document. Please review these documents
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   warranty as described in the Simplified BSD License.

Table of Contents

   1. Introduction ................................................ 2
   2. Conventions used in this document............................ 4
   3. Carrying TRILL Link-State Information in BGP................. 4
      3.1. Node Descriptors........................................ 6
         3.1.1. IGP Router-ID...................................... 6
      3.2. MAC Address Descriptors................................. 6
         3.2.1. MAC-Reachability TLV............................... 7
      3.3. The BGP-LS Attribute.................................... 8
         3.3.1. Node Attribute TLVs................................ 8
   Node Flag Bits TLV............................ 8
   Opaque Node Attribute TLV..................... 8
         3.3.2. Link Attribute TLVs................................ 9
   4. Operational Considerations................................... 9
   5. Security Considerations..................................... 10
   6. IANA Considerations ........................................ 11
   7. References ................................................. 11
      7.1. Normative References................................... 11
      7.2. Informative References................................. 12
   8. Acknowledgments ............................................ 12

1. Introduction

   BGP has been extended to distribute IGP link-state and traffic
   engineering information to some external components [I-D.ietf-idr-
   ls-distribution], such as the PCE and ALTO servers. The information
   can be used by these external components to compute a MPLS-TE path
   across IGP areas, visualize and abstract network topology, and the

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   TRILL (Transparent Interconnection of Lots of Links) protocol
   [RFC6325] provides a solution for least cost transparent routing in
   multi-hop networks with arbitrary topologies and link technologies,
   using [IS-IS] [RFC7176] link-state routing and a hop count. TRILL
   switches are sometimes called RBridges (Routing Bridges).

   The TRILL protocol has been deployed in many data center networks.
   Data center automation is a vital step to increase the speed and
   agility of business. An SDN controller as an external component
   normally can be used to provide centralized control and automation
   for the data center network. Making a holistic view of whole network
   topology available to the SDN controller is an important part for
   data center network automation and troubleshooting.

                           |     SDN     |
                   --------|  Controller |--------
                   |       +-------------+       |
                   |                             |
                  + +                           + +
                   +        +-----------+        +
                            |           |
               +--------+   |IP Network |   +--------+
               |        | +----+     +----+ |        |
   +---+ +---+ |        | |    |     |    | |        | +---+ +---+
   |ES1|-|RB1|-| Area 1 |-|BRB1|     |BRB2|-| Area 2 |-|RB2|-|ES2|
   +---+ +---+ |        | +----+     +----+ |        | +---+ +---+
               |        |   |           |   |        |
               +--------+   +-----------+   +--------+

         |<----TRILL ------>|<IP tunnel>|<-----TRILL ----->|

                       Figure 1: TRILL interconnection

   In Data Center interconnection scenario illustrated in figure 1, a
   single SDN Controller or network management system (NMS) can be used
   for end-to-end network management. End-to-end topology visibility on
   the SDN controller or NMS is very useful for whole network
   automation and troubleshooting. BGP LS can be used by the external
   SDN controller to collect multiple TRILL domain's link-state.

   BGP LS also can be used for MAC address reachability information
   synchronization across multiple TRILL domains. The transported MAC
   reachability information and the like is for telemetry purposes and
   for use by SDN controller(s) where the coordination or protocol
   between the SDN controllers is out of scope.

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   This document describes the detailed BGP LS extension mechanisms for
   TRILL link state and MAC address reachability information

2. Conventions used in this document

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

   BGP - Border Gateway Protocol

   BGP-LS - BGP Link-State

   Data label - VLAN or FGL (Fine Grained Label [RFC7172])

   IS - Intermediate System (for this document, all relevant
   intermediate systems are RBridges)

   NLRI - Network Layer Reachability Information

   SDN - Software Defined Networking

   RBridge - A device implementing the TRILL protocol

   TRILL - Transparent Interconnection of Lots of Links

3. Carrying TRILL Link-State Information in BGP

   In [I-D.ietf-idr-ls-distribution], four NLRI types are defined as
   follows: Node NLRI, Link NLRI, IPv4 Topology Prefix NLRI and IPv6
   Topology Prefix NLRI. For TRILL link-state distribution, the Node
   NLRI and Link NLRI are extended to carry layer 3 gateway role and
   link MTU information. TRILL specific attributes are carried using
   opaque Node Attribute TLVs, such as nickname, distribution tree
   number and identifiers, interested VLANs/Fine Grained Label, and
   multicast group address, etc.

   To differentiate TRILL protocol from layer 3 IGP protocol, a new
   TRILL Protocol-ID is defined.

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   | Protocol-ID | NLRI information source protocol |
   | 1           | IS-IS Level 1                    |
   | 2           | IS-IS Level 2                    |
   | 3           | OSPFv2                           |
   | 4           | Direct                           |
   | 5           | Static configuration             |
   | 6           | OSPFv3                           |
   | TBD         | TRILL                            |
           Table 1: Protocol Identifiers

   ESADI (End Station Address Distribution Information) protocol
   [RFC7357] is a per data label control plane MAC learning solution.
   MAC address reachability information is carried in ESADI packets.
   Compared with data plane MAC learning solution, ESADI protocol has
   security and fast update advantage that are pointed out in [RFC7357].

   For an RBridge that is announcing participation in ESADI, the
   RBridge can distribute MAC address reachability information to
   external components using BGP. A new NLRI type of ''MAC Reachability
   NLRI'' is requested for the MAC address reachability distribution.

   | Type | NLRI Type                 |
   | 1    | Node NLRI                 |
   | 2    | Link NLRI                 |
   | 3    | IPv4 Topology Prefix NLRI |
   | 4    | IPv6 Topology Prefix NLRI |
   | TBD  | MAC Reachability NLRI     |
           Table 2: NLRI Types

   The MAC Reachability NLRI uses the format as shown in the following

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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
   |  Protocol-ID  |
   |  Identifier                                                   |
   |  (64 bits)                                                    |
   // Local Node Descriptor (variable) //
   // MAC Address Descriptors (variable) //
                Figure 2: The MAC Reachability NLRI format

3.1. Node Descriptors

   The Node Descriptor Sub-TLV types include Autonomous System and BGP-
   LS Identifier, IS-IS Area-ID and IGP Router-ID. TRILL uses a fixed
   zero Area Address as specified in [RFC6325], Section 4.2.3.  This is
   encoded in a 4-byte Area Address TLV (TLV #1) as follows:

      |   0x01, Area Address Type     |   (1 byte)
      |   0x02, Length of Value       |   (1 byte)
      |   0x01, Length of Address     |   (1 byte)
      |   0x00, zero Area Address     |   (1 byte)
         Figure 3: Area Address TLV

3.1.1. IGP Router-ID

   Similar to layer 3 IS-IS, TRILL protocol uses 7-octet "IS-IS ID" as
   the identity of an RBridge or a pseudonode, IGP Router ID sub-TLV in
   Node Descriptor TLVs contains the 7-octet "IS-IS ID". In TRILL
   network, each RBridge has a unique 48-bit (6-octet) IS-IS System ID.
   This ID may be derived from any of the RBridge's unique MAC
   addresses or configured. A pseudonode is assigned a 7-octet ID by
   the DRB (Designated RBridge) that created it, the DRB is similar to
   the "Designated Intermediate System" (DIS) corresponding to a LAN.

3.2. MAC Address Descriptors

   The ''MAC Address Descriptor'' field is a set of Type/Length/Value
   (TLV) triplets. ''MAC Address Descriptor'' TLVs uniquely identify an

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   MAC address reachable by a Node. The following attributes TLVs are

   | TLV Code     | Description           | Length   | Value defined   |
   | Point        |                       |          | in:             |
   |   1          | MAC-Reachability      | variable | section 3.2.1   |
                Table 3: MAC Address Descriptor TLVs

3.2.1. MAC-Reachability TLV

      | Type= MAC-RI  |                  (1 byte)
      |   Length      |                  (1 byte)
      |V|F|   RESV    |              Data Label            |  (4 bytes)
      |                          MAC (1)       (6 bytes)                 |
      |                      .................                           |
      |                          MAC (N)       (6 bytes)                 |
              Figure 4: MAC-Reachability TLV format

   Length is 4 plus a multiple of 6.

   The bits of 'V' and 'F' are used to identify Data Label type and are
   defined as follows:

   | Bit      | Description             |
   | 'V'      | VLAN                    |
   | 'F'      | Fine Grained Label      |
   Table 4: Data Label Type Bits Definitions

   Notes: If BGP LS is used for NVO3 network MAC address distribution
   between external SDN Controller and NVE, Data Label can be used to
   represent 24 bits VN ID.

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3.3. The BGP-LS Attribute

3.3.1. Node Attribute TLVs Node Flag Bits TLV

   A new Node Flag bit is added 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
      |             Type              |           Length              |
      |O|T|E|B|G| Reserved  |
              Figure 5: Node Flag Bits TLV format

   The new bit and remaining reserved bits are defined as follows:

   | Bit      |          Description       | Reference |
   | 'G'      | Layer 3 Gateway Bit        | [RFC7176] |
   | Reserved | Reserved for future use    |           |
     Table 5: Node Flag Bits Definitions Opaque Node Attribute TLV

   The Opaque Node Attribute TLV is used as the envelope to
   transparently carry TRILL specific information. In [RFC7176], there
   are the following Sub-TLVs in the Router Capability and MT-
   Capability TLVs and the Group Address (GADDR) TLV that need to be
   carried. Future possible TRILL TLVs/Sub-TLVs extension also can be
   carried using the Opaque Node Attribute TLV.

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   Descriptions       IS-IS TLV/Sub-TLV
   TRILL-VER             22/13
   NICKNAME              22/6
   TREES                 22/7
   TREE-RT-IDs           22/8
   TREE-USE-IDs          22/9
   INT-VLAN              22/10
   VLAN-GROUP            22/14
   INT-LABEL             22/15
   RBCHANNELS            22/16
   AFFINITY              22/17
   LABEL-GROUP           22/18
   GMAC-ADDR             142/1
   GIP-ADDR              142/2
   GIPV6-ADDR            142/3
   GLMAC-ADDR            142/4
   GLIP-ADDR             142/5
   GLIPV6-ADDR           142/6

   Table 6: TRILL TLVs/Sub-TLVs

3.3.2. Link Attribute TLVs

   Link attribute TLVs are TLVs that may be encoded in the BGP-LS
   attribute with a link NLRI. Besides the TLVs that has been defined
   in [I-D.ietf-idr-ls-distribution] section 3.3.2 table 9, the
   following 'Link Attribute' TLV is provided for TRILL.

   | TLV Code  | Description    | IS-IS TLV    | Defined in:      |
   | Point     |                | /Sub-TLV     |                  |
   | TBD       | Link MTU       |   22/28      | [RFC7176]/2.4    |
                       Table 7: Link Attribute TLVs

4. Operational Considerations

   This document does not require any MIB or Yang model to configure
   operational parameters.

   Any implementation of the protocol in this specification (i.e. that
   distributes TRILL Link-State information using BGP), MUST do the

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   malformed attribute checks below, and if it detects a malformed
   attribute, it should use the 'Attribute Discard' action per [I-
   D.ietf.idr-error-handling] section 2.

   An implementation MUST perform the following expanded [BGP-LS]
   syntactic check for determining if the message is malformed:

      o  Does the sum of all TLVs found in the BGP LS attribute
   correspond to the BGP LS path attribute length ?

      o  Does the sum of all TLVs found in the BGP MP_REACH_NLRI
   attribute correspond to the BGP MP_REACH_NLRI length ?

      o  Does the sum of all TLVs found in the BGP MP_UNREACH_NLRI
   attribute correspond to the BGP MP_UNREACH_NLRI length ?

      o  Does the sum of all TLVs found in a Node-, Link, prefix (IPv4
   or IPv6) NLRI attribute correspond to the Node-, Link- or Prefix
   Descriptors 'Total NLRI Length' field ?

      o  Does any fixed length TLV correspond to the TLV Length field
   in this document ?

      o Does the sum of MAC reachability TLVs equal the length of the

   In addition, the following checks need to be made for the fields
   specific to the BGP LS for TRILL:

           PROTOCOL ID is TRILL

           NLRI types are valid per table 2

           MAC Reachability NLRI has correct format including:

           o  Identifier (64 bits),

           o  local node descriptor with AREA address TLV has the form
             found in figure 2

           opaque TLV support the range of ISIS-TLV/SUB-TLV shown in
        table 3,  and link TLVs support the range in figure 8.

5. Security Considerations

   Procedures and protocol extensions defined in this document do not
   affect the BGP security model. See [RFC6952] for details.

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6. IANA Considerations

   For all of the following assignments, [this document] is the

   IANA is requested to assign one Protocol-ID for "TRILL" from the
   BGP-LS registry of Protocol-IDs.

   IANA is requested to assign one NLRI Type for "MAC Reachability"
   from the BGP-LS registry of NLRI Types.

   IANA is requested to assign one Node Flag bit for "Layer 3 Gateway"
   from the BGP-LS registry of BGP-LS Attribute TLVs.

   IANA is requested to assign one new TLV type for "Link MTU" from the
   BGP-LS registry of BGP-LS Attribute TLVs.

7. References

7.1. Normative References

[1]     [I-D.ietf-idr-ls-distribution] Gredler, H., Medved, J.,
      Previdi, S., Farrel, A., and S.Ray, "North-Bound Distribution of
      Link-State and TE Information using BGP", draft-ietf-idr-ls-
      distribution-10(work in progress), January 2015.

[2]     [I-D.ietf.idr-error-handling] Enke, C., John, S., Pradosh, M.,
      Keyur,P., "Revised Error Handling for BGP UPDATE Messages",
      draft-ietf-idr-error-handling-19(work in progress), April 2015.

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

[4]     [RFC6325] Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S.,and
      A. Ghanwani, "Routing Bridges (RBridges): Base Protocol
      Specification", RFC 6325, July 2011.

[5]     [RFC7172] Eastlake 3rd, D., Zhang, M., Agarwal, P., Perlman,
      R., and D. Dutt, "Transparent Interconnection of Lots of Links
      (TRILL): Fine-Grained Labeling", RFC 7172, DOI 10.17487/RFC7172,
      May 2014, <>.

[6]     [RFC7176] Eastlake, D., Senevirathne, T., Ghanwani, A., Dutt,
      D., Banerjee, A.," Transparent Interconnection of Lots of Links
      (TRILL) Use of IS-IS'', May 2014.

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[7]     [RFC7357] - Zhai, H., Hu, F., Perlman, R., Eastlake 3rd, D.,
      and O. Stokes, "Transparent Interconnection of Lots of Links
      (TRILL): End Station Address Distribution Information (ESADI)
      Protocol", RFC 7357, September 2014, <http://www.rfc->.

7.2. Informative References

8. Acknowledgments

   Authors like to thank Ross Callon, Andrew Qu, Jie Dong, Mingui Zhang,
   Qin Wu, Shunwan Zhuang, Zitao Wang, Lili Wang for their valuable

Authors' Addresses

   Weiguo Hao
   Huawei Technologies
   101 Software Avenue,
   Nanjing 210012

   Phone: +86-25-56623144

   Donald E. Eastlake
   Huawei Technologies
   155 Beaver Street
   Milford, MA 01757 USA

   Phone: +1-508-333-2270

  Susan K. Hares
   Hickory Hill Consulting
   7453 Hickory Hill
   Saline, MI  48176 USA


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   Sujay Gupta
   IP Infusion

   Muhammad Durrani
   Phone: +1-408-527-6921

   Yizhou Li
   Huawei Technologies
   101 Software Avenue,
   Nanjing 210012, China

   Phone: +86-25-56625375

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