Internet Engineering Task Force (IETF) R. Perlman
Request for Comments: 6439 Intel Labs
Updates: 6325 D. Eastlake 3rd
Category: Standards Track Y. Li
ISSN: 2070-1721 Huawei Technologies
A. Banerjee
Cisco Systems
F. Hu
ZTE Corporation
November 2011
Routing Bridges (RBridges): Appointed Forwarders
Abstract
The IETF TRILL (TRansparent Interconnection of Lots of Links)
protocol provides least cost pair-wise data forwarding without
configuration in multi-hop networks with arbitrary topology, 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 "RBridges" (Routing Bridges).
TRILL supports multi-access LAN (Local Area Network) links that can
have multiple end stations and RBridges attached. Where multiple
RBridges are attached to a link, native traffic to and from end
stations on that link is handled by a subset of those RBridges called
"Appointed Forwarders", with the intent that native traffic in each
VLAN (Virtual LAN) be handled by at most one RBridge. The purpose of
this document is to improve the documentation of the Appointed
Forwarder mechanism; thus, it updates RFC 6325.
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/rfc6439.
Perlman, et al. Standards Track [Page 1]
RFC 6439 RBridges: Appointed Forwarders November 2011
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Table of Contents
1. Introduction ....................................................2
1.1. Terminology and Acronyms ...................................3
2. Appointed Forwarders and Their Appointment ......................4
2.1. Appointment Effects of DRB Elections .......................5
2.2. Appointment and Removal by the DRB .........................5
2.2.1. Processing Forwarder Appointments ...................6
2.2.2. Frequency of Appointments ...........................7
2.2.3. Appointed Forwarders Limit ..........................8
2.3. Local Configuration Action Appointment Effects .............8
2.4. VLAN Mapping within a Link .................................9
3. The Inhibition Mechanism ........................................9
4. Inhibited Appointed Forwarder Behavior .........................11
5. Multiple Ports on the Same Link ................................12
6. Security Considerations ........................................12
7. Acknowledgements ...............................................13
8. References .....................................................13
8.1. Normative References ......................................13
8.2. Informative References ....................................13
Appendix. VLAN Inhibition Example .................................14
1. Introduction
The IETF TRILL (TRansparent Interconnection of Lots of Links)
datatracker.ietf.org