Transparent Interconnection of Lots of Links (TRILL): Appointed Forwarders
RFC 8139

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

• Versions
• 00
• 01
• 02
• 03
• 04
• 05

Internet Engineering Task Force (IETF)                   D. Eastlake 3rd
Request for Comments: 8139                                         Y. Li
Obsoletes: 6439                                                   Huawei
Updates: 6325, 7177                                             M. Umair
Category: Standards Track                                    IP Infusion
ISSN: 2070-1721                                              A. Banerjee
                                                                   Cisco
                                                                   F. Hu
                                                                     ZTE
                                                               June 2017

         Transparent Interconnection of Lots of Links (TRILL):
                          Appointed Forwarders

Abstract

   TRILL (Transparent Interconnection of Lots of Links) supports multi-
   access LAN (Local Area Network) links where a single link can have
   multiple end stations and TRILL switches attached.  Where multiple
   TRILL switches are attached to a link, native traffic to and from end
   stations on that link is handled by a subset of those TRILL switches
   called "Appointed Forwarders" as originally specified in RFC 6325,
   with the intent that native traffic in each VLAN be handled by at
   most one TRILL switch.  This document clarifies and updates the
   Appointed Forwarder mechanism.  It updates RFCs 6325 and 7177 and
   obsoletes RFC 6439.

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 7841.

   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/rfc8139.

Eastlake, et al.             Standards Track                    [Page 1]
RFC 8139               TRILL: Appointed Forwarders             June 2017

Copyright Notice

   Copyright (c) 2017 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.

Eastlake, et al.             Standards Track                    [Page 2]
RFC 8139               TRILL: Appointed Forwarders             June 2017

Table of Contents

   1. Introduction ....................................................4
      1.1. Appointed Forwarders and Active-Active .....................5
      1.2. Terminology and Abbreviations ..............................6
   2. Appointed Forwarders and Their Appointment ......................7
      2.1. The Appointment Databases and DRB Actions ..................8
      2.2. Appointment Effects of DRB Elections ......................10
           2.2.1. Processing Forwarder Appointments in Hellos ........11
           2.2.2. Frequency of Hello Appointments ....................13
           2.2.3. Appointed Forwarders Hello Limit ...................13
      2.3. Effects of Local Configuration Actions on Appointments ....14
      2.4. Overload and Appointed Forwarders .........................14
      2.5. VLAN Mapping within a Link ................................15
   3. The Inhibition Mechanism .......................................15
      3.1. Inhibited Appointed Forwarder Behavior ....................18
      3.2. Root Bridge Change Inhibition Optimizations ...............18
           3.2.1. Optimization for Change to Lower Priority ..........19
           3.2.2. Optimization for Change to Priority Only ...........19
           3.2.3. Optimizing the Detection of Completed Settling .....19
   4. Optional TRILL Hello Reduction .................................20
   5. Multiple Ports on the Same Link ................................22
   6. Port-Shutdown Messages .........................................23
      6.1. Planned Shutdown and Hellos ...............................23
      6.2. Port-Shutdown Message Structure ...........................23
      6.3. Port-Shutdown Message Transmission ........................24
      6.4. Port-Shutdown Message Reception ...........................25
      6.5. Port-Shutdown Message Security ............................25