Network Working Group A. Csaszar (Ed.)
Internet Draft G. Enyedi
Intended status: Standards Track J. Tantsura
Expires: August 25, 2013 S. Kini
Ericsson
J. Sucec
S. Das
Telcordia
February 25, 2013
IP Fast Re-Route with Fast Notification
draft-csaszar-rtgwg-ipfrr-fn-01.txt
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Csaszar et al. Expires August 25, 2013 [Page 1]
Internet-Draft IPFRR-FN February 2013
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Abstract
This document describes the benefits and main applications of sending
explicit fast notification (FN) packets to routers in an area. FN
packets are generated and processed in the dataplane, and a single FN
service can substitute existing OAM methods for remote failure
detection, such as a full mesh of multi-hop BFD session. The FN
service, therefore, decreases network overhead considerable. The main
application is fast reroute in pure IP and in IP/LDP-MPLS networks
called IPFRR-FN. The detour paths used when IPFRR-FN is active are in
most cases identical to those used after Interior Gateway Protocol
(IGP) convergence. The proposed mechanism can address all single
link, node, and SRLG failures in an area; moreover it is an efficient
solution to protect against BGP ASBR failures as well as VPN PE
router failures. IPFRR-FN can be a supplemental tool to provide FRR
when LFA cannot repair a failure case, while it can be a replacement
of existing ASBR/PE protection mechanisms by overcoming their
scalability and complexity issues.
Table of Contents
1. Introduction...................................................3
2. Overview of current IPFRR Proposals based on Local Repair......6
3. Requirements of an Explicit Failure Signaling Mechanism........7
4. Conceptual Operation of IPFRR relying on Fast Notification.....8
4.1. Preparation Phase.........................................8
4.2. Failure Reaction Phase....................................9
4.2.1. Activating Failure Specific Backups.................10
4.2.2. SRLG Handling.......................................11
4.3. Example and Timing.......................................12
4.4. Scoping FN Messages with TTL.............................13
5. Operation Details.............................................14
5.1. Transport of Fast Notification Messages..................14
5.2. Message Handling and Encoding............................16
5.2.1. Failure Identification Message for OSPF.............17
5.2.2. Failure Identification Message for ISISError! Bookmark
not defined.
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5.3. Protecting External Prefixes.............................18
5.3.1. Failure on the Intra-Area Path Leading to the ASBR..18
5.3.2. Protecting ASBR Failures: BGP-FRR...................19
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