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Calculating Interior Gateway Protocol (IGP) Routes Over Traffic Engineering Tunnels (RFC3906)

IP.com Disclosure Number: IPCOM000031727D
Original Publication Date: 2004-Oct-01
Included in the Prior Art Database: 2004-Oct-07
Document File: 9 page(s) / 18K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

N. Shen: AUTHOR [+2]

Abstract

This document describes how conventional hop-by-hop link-state routing protocols interact with new Traffic Engineering capabilities to create Interior Gateway Protocol (IGP) shortcuts. In particular, this document describes how Dijkstra's Shortest Path First (SPF) algorithm can be adapted so that link-state IGPs will calculate IP routes to forward traffic over tunnels that are set up by Traffic Engineering.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 15% of the total text.

Network Working Group                                            N. Shen

Request for Comments: 3906                              Redback Networks

Category: Informational                                          H. Smit

                                                            October 2004

          Calculating Interior Gateway Protocol (IGP) Routes

                    Over Traffic Engineering Tunnels

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 (2004).

Abstract

   This document describes how conventional hop-by-hop link-state

   routing protocols interact with new Traffic Engineering capabilities

   to create Interior Gateway Protocol (IGP) shortcuts.  In particular,

   this document describes how Dijkstra's Shortest Path First (SPF)

   algorithm can be adapted so that link-state IGPs will calculate IP

   routes to forward traffic over tunnels that are set up by Traffic

   Engineering.

1.  Introduction

   Link-state protocols like integrated Intermediate System to

   Intermediate System (IS-IS) [1] and OSPF [2] use Dijkstra's SPF

   algorithm to compute a shortest path tree to all nodes in the

   network.  Routing tables are derived from this shortest path tree.

   The routing tables contain tuples of destination and first-hop

   information.  If a router does normal hop-by-hop routing, the first-

   hop will be a physical interface attached to the router.  New traffic

   engineering algorithms calculate explicit routes to one or more nodes

   in the network.  At the router that originates explicit routes, such

   routes can be viewed as logical interfaces which supply Label

   Switched Paths through the network.  In the context of this document,

   we refer to these Label Switched Paths as Traffic Engineering tunnels

   (TE-tunnels).  Such capabilities are specified in [3] and [4].

   The existence of TE-tunnels in the network and how the traffic in the

   network is switched over those tunnels are orthogonal issues.  A node

   may define static routes pointing to the TE-tunnels, it may match the

Shen & Smit                  Informational                      [Page 1]

RFC 3906              IGP ShortCut Over MPLS LSPs           October 2004

   recursive route next-hop with the TE-tunnel end-point address, or it

   may define local policy such as affinity based tunnel selection for

   switching certain traffic.  This document describes a mechanism

   utilizing link-state IGPs to dynamically install IGP routes over

   tho...