RFC 3527 (rfc3527) - Page 1 of 9


Link Selection sub-option for the Relay Agent Information Option for DHCPv4



Alternative Format: Original Text Document



Network Working Group                                         K. Kinnear
Request for Comments: 3527                                      M. Stapp
Category: Standards Track                                     R. Johnson
                                                           J. Kumarasamy
                                                           Cisco Systems
                                                              April 2003


                       Link Selection sub-option
           for the Relay Agent Information Option for DHCPv4

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document describes the link selection sub-option of the relay-
   agent-information option for the Dynamic Host Configuration Protocol
   (DHCPv4).  The giaddr specifies an IP address which determines both a
   subnet, and thereby a link on which a Dynamic Host Configuration
   Protocol (DHCP) client resides as well as an IP address that can be
   used to communicate with the relay agent.  The subnet-selection
   option allows the functions of the giaddr to be split so that when
   one entity is performing as a DHCP proxy, it can specify the
   subnet/link from which to allocate an IP address, which is different
   from the IP address with which it desires to communicate with the
   DHCP server.  Analogous situations exist where the relay agent needs
   to specify the subnet/link on which a DHCP client resides, which is
   different from an IP address that can be used to communicate with the
   relay agent.

1.  Introduction

   In RFC 2131, the giaddr specifies an IP address which determines a
   subnet (and from there a link) on which a DHCP client resides as well
   as an IP address which can be used to communicate with the relay
   agent.  The subnet-selection option [RFC 3011] allows these functions
   of the giaddr to be split, so that when one entity is performing as a




Kinnear, et al.             Standards Track