Routing Bridges (RBridges): Adjacency
RFC 6327

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 07

Internet Engineering Task Force (IETF)                   D. Eastlake 3rd
Request for Comments: 6327                                        Huawei
Updates: 6325                                                 R. Perlman
Category: Standards Track                                     Intel Labs
ISSN: 2070-1721                                              A. Ghanwani
                                                                 Brocade
                                                                 D. Dutt
                                                           Cisco Systems
                                                               V. Manral
                                                     Hewlett Packard Co.
                                                               July 2011

                 Routing Bridges (RBridges): Adjacency

Abstract

   The IETF TRILL (TRansparent Interconnection of Lots of Links)
   protocol provides optimal pair-wise data forwarding without
   configuration, safe forwarding even during periods of temporary
   loops, and support for multipathing of both unicast and multicast
   traffic.  TRILL accomplishes this by using IS-IS (Intermediate System
   to Intermediate System) link state routing and by encapsulating
   traffic using a header that includes a hop count.  Devices that
   implement TRILL are called Routing Bridges (RBridges).

   TRILL supports multi-access LAN (Local Area Network) links that can
   have multiple end stations and RBridges attached.  This document
   describes four aspects of the TRILL LAN Hello protocol used on such
   links, particularly adjacency, designated RBridge selection, and MTU
   (Maximum Transmission Unit) and pseudonode procedures, with state
   machines.  There is no change for IS-IS point-to-point Hellos used on
   links configured as point-to-point in TRILL.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6327.

Perlman, et al.              Standards Track                    [Page 1]
RFC 6327                   RBridges: Adjacency                 July 2011

Copyright Notice

   Copyright (c) 2011 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
   (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.

Perlman, et al.              Standards Track                    [Page 2]
RFC 6327                   RBridges: Adjacency                 July 2011

Table of Contents

   1. Introduction ....................................................4
      1.1. Content and Precedence .....................................4
      1.2. Terminology and Acronyms ...................................5
   2. The TRILL Hello Environment and Purposes ........................5
      2.1. Incrementally Replacing 802.1Q-2005 Bridges ................5
      2.2. Handling Native Frames .....................................6
      2.3. Zero or Minimal Configuration ..............................7
      2.4. MTU Robustness .............................................7
      2.5. Purposes of the TRILL Hello Protocol .......................8
   3. Adjacency State Machinery .......................................9
      3.1. TRILL LAN Hellos, MTU Test, and VLANs ......................9
      3.2. Adjacency Table Entries and States ........................10
      3.3. Adjacency and Hello Events ................................11
      3.4. Adjacency State Diagram and Table .........................13
      3.5. Multiple Parallel Links ...................................14
      3.6. Insufficient Space in Adjacency Table .....................15
   4. RBridge LAN Ports and DRB State ................................15
      4.1. Port Table Entries and DRB Election State .................16
      4.2. DRB Election Events .......................................16
           4.2.1. DRB Election Details ...............................17
           4.2.2. Change in DRB ......................................18