Browse Prior Art Database

CIDR and Classful Routing (RFC1817)

IP.com Disclosure Number: IPCOM000004074D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2019-Feb-12
Document File: 2 page(s) / 3K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

Y. Rekhter: AUTHOR

Related Documents

10.17487/RFC1817: DOI

Abstract

This document represents the IAB's (Internet Architecture Board) evaluation of the current and near term implications of CIDR on organizations that use Classful routing technology. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 58% of the total text.

Network Working Group Y. Rekhter Request for Comments: 1817 cisco Systems Category: Informational August 1995

CIDR and Classful Routing

Status of this Memo

This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind. Distribution of this memo is unlimited.

Abstract

Classless Inter-Domain Routing (CIDR) is used in the Internet as the primary mechanism to improve scalability of the Internet routing system. This document represents the IAB’s (Internet Architecture Board) evaluation of the current and near term implications of CIDR on organizations that use Classful routing technology.

Background

Classless Inter-Domain Routing (CIDR) ([RFC1518], [RFC1519]) is deployed in the Internet as the primary mechanism to improve scaling property of the Internet routing system. Essential to CIDR is the generalization of the concept of variable length subnet masks (VLSM) and the elimination of classes of network numbers (A, B, and C). The interior (intra-domain) routing protocols that support CIDR are OSPF, RIP II, Integrated IS-IS, and E-IGRP. The exterior (inter-domain) routing protocol that supports CIDR is BGP-4. Protocols like RIP, BGP-3, EGP, and IGRP do not support CIDR.

Implications of CIDR

Deployment of CIDR has certain implications on the segments of the Internet that are still using routing technology that can not support CIDR. Existing sites that rely solely on a default route for their external connectivity may not require support of VLSM capable routing technology for their interior routing and CIDR for their exterior routing. All sites lacking support for VLSM and CIDR capable routing must rely on a default route, which consequently may result in...

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