BGP Prefix Independent Convergence
draft-ietf-rtgwg-bgp-pic-12
Network Working Group A. Bashandy, Ed.
Internet Draft Individual Contributor
Intended status: Informational C. Filsfils
Expires: February 2021 Cisco Systems
P. Mohapatra
Sproute Networks
August 11, 2020
BGP Prefix Independent Convergence
draft-ietf-rtgwg-bgp-pic-12.txt
Abstract
In the network comprising thousands of iBGP peers exchanging millions
of routes, many routes are reachable via more than one next-hop.
Given the large scaling targets, it is desirable to restore traffic
after failure in a time period that does not depend on the number of
BGP prefixes. In this document we proposed an architecture by which
traffic can be re-routed to ECMP or pre-calculated backup paths in a
timeframe that does not depend on the number of BGP prefixes. The
objective is achieved through organizing the forwarding data
structures in a hierarchical manner and sharing forwarding elements
among the maximum possible number of routes. The proposed technique
achieves prefix independent convergence while ensuring incremental
deployment, complete automation, and zero management and provisioning
effort. It is noteworthy to mention that the benefits of BGP-PIC are
hinged on the existence of more than one path whether as ECMP or
primary-backup.
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Internet-Draft BGP Prefix Independent Convergence August 2020
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Table of Contents
1. Introduction...................................................3
1.1. Terminology...............................................3
2. Overview.......................................................5
2.1. Dependency................................................6
2.1.1. Hierarchical Hardware FIB............................6
2.1.2. Availability of more than one BGP next-hops..........6
2.2. BGP-PIC Illustration......................................7
3. Constructing the Shared Hierarchical Forwarding Chain..........9
3.1. Constructing the BGP-PIC forwarding Chain.................9
3.2. Example: Primary-Backup Path Scenario....................10
4. Forwarding Behavior...........................................11
5. Handling Platforms with Limited Levels of Hierarchy...........12
5.1. Flattening the Forwarding Chain..........................12
5.2. Example: Flattening a forwarding chain...................14
6. Forwarding Chain Adjustment at a Failure......................21
6.1. BGP-PIC core.............................................22
6.2. BGP-PIC edge.............................................23
6.2.1. Adjusting forwarding Chain in egress node failure...23
6.2.2. Adjusting Forwarding Chain on PE-CE link Failure....23
6.3. Handling Failures for Flattened Forwarding Chains........24
7. Properties....................................................25
7.1. Coverage.................................................25
7.1.1. A remote failure on the path to a BGP next-hop......25
7.1.2. A local failure on the path to a BGP next-hop.......25
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