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A Framework for Inter-Domain Route Aggregation (RFC2519)

IP.com Disclosure Number: IPCOM000003103D
Original Publication Date: 1999-Feb-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 10 page(s) / 23K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

E. Chen: AUTHOR [+2]

Abstract

This document presents a framework for inter-domain route aggregation and shows an example router configuration which 'implements' this framework. This framework is flexible and scales well as it emphasizes the philosophy of aggregation by the source, both within routing domains as well as towards upstream providers, and it also strongly encourages the use of the 'no-export' BGP community to balance the provider-subscriber need for more granular routing information with the Internet's need for scalable inter-domain routing.

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This is the abbreviated version, containing approximately 12% of the total text.

Network Working Group E. Chen

Request for Comments: 2519 Cisco

Category: Informational J. Stewart

Juniper

February 1999

A Framework for Inter-Domain Route Aggregation

Status of this Memo

This memo provides information for the Internet community. It does

not specify an Internet standard of any kind. Distribution of this

memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1999). All Rights Reserved.

Abstract

This document presents a framework for inter-domain route aggregation

and shows an example router configuration which 'implements' this

framework. This framework is flexible and scales well as it

emphasizes the philosophy of aggregation by the source, both within

routing domains as well as towards upstream providers, and it also

strongly encourages the use of the 'no-export' BGP community to

balance the provider-subscriber need for more granular routing

information with the Internet's need for scalable inter-domain

routing.

1. Introduction

The need for route aggregation has long been recognized. Route

aggregation is good as it reduces the size, and slows the growth, of

the Internet routing table. Thus, the amount of resources (e.g., CPU

and memory) required to process routing information is reduced and

route calculation is sped up. Another benefit of route aggregation

is that route flaps are limited in number, frequency and scope, which

saves resources and makes the global Internet routing system more

stable.

Since CIDR (Classless Inter-Domain Routing) [2] was introduced,

significant progress has been made on route aggregation, particularly

in the following two areas:

- Formulation and implementation of IP address allocation policies

by the top registries that conform to the CIDR principles [1].

This policy work is the cornerstone which makes efficient route

aggregation technically possible.

- Route aggregation by large (especially "Tier 1") providers. To

date, the largest reductions in the size of the routing table

have resulted from efficient aggregation by large providers.

However, the ability of various levels of the global routing system

to implement efficient aggregation schemes varies widely. As a

result, the size and growth rate of the Internet routing table, as

well as the associated route computation required, remain majo...