RFC 3568 (rfc3568) - Page 1 of 19


Known Content Network (CN) Request-Routing Mechanisms



Alternative Format: Original Text Document



Network Working Group                                          A. Barbir
Request for Comments: 3568                               Nortel Networks
Category: Informational                                          B. Cain
                                                        Storigen Systems
                                                                 R. Nair
                                                              Consultant
                                                           O. Spatscheck
                                                                    AT&T
                                                               July 2003


         Known Content Network (CN) Request-Routing Mechanisms

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 (2003).  All Rights Reserved.

Abstract

   This document presents a summary of Request-Routing techniques that
   are used to direct client requests to surrogates based on various
   policies and a possible set of metrics.  The document covers
   techniques that were commonly used in the industry on or before
   December 2000.  In this memo, the term Request-Routing represents
   techniques that is commonly called content routing or content
   redirection.  In principle, Request-Routing techniques can be
   classified under: DNS Request-Routing, Transport-layer
   Request-Routing, and Application-layer Request-Routing.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
   2.  DNS based Request-Routing Mechanisms . . . . . . . . . . . . 3
       2.1.  Single Reply . . . . . . . . . . . . . . . . . . . . . 3
       2.2.  Multiple Replies . . . . . . . . . . . . . . . . . . . 3
       2.3.  Multi-Level Resolution . . . . . . . . . . . . . . . . 4
             2.3.1.  NS Redirection . . . . . . . . . . . . . . . . 4
             2.3.2.  CNAME Redirection. . . . . . . . . . . . . . . 5
       2.4.  Anycast. . . . . . . . . . . . . . . . . . . . . . . . 5
       2.5.  Object Encoding. . . . . . . . . . . . . . . . . . . . 6
       2.6.  DNS Request-Routing Limitations. . . . . . . . . . . . 6
   3.  Transport-Layer Request-Routing  . . . . . . . . . . . . . . 7



Barbir, et al.               Informational