Generalized Source UDP Port of DHCP Relay
draft-ietf-dhc-relay-port-00

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Document Type Active Internet-Draft (dhc WG)
Last updated 2016-12-09 (latest revision 2016-10-27)
Replaces draft-shen-dhc-client-port
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Networking Working Group                                         N. Shen
Internet-Draft                                                   E. Chen
Intended status: Standards Track                           Cisco Systems
Expires: April 30, 2017                                 October 27, 2016

               Generalized Source UDP Port of DHCP Relay
                      draft-ietf-dhc-relay-port-00

Abstract

   This document extends the DHCP and DHCPv6 protocols for the UDP
   transport from relay agent to server and allows the port to be any
   valid number on the DHCP relay system.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
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   This Internet-Draft will expire on April 30, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Changes to DHCP and DHCPv6 Specifications . . . . . . . . . .   3
     2.1.  Changes to DHCP in RFC 2131 . . . . . . . . . . . . . . .   3
     2.2.  Changes to DHCPv6 in RFC 3315 . . . . . . . . . . . . . .   3
   3.  Relay Agent Source Port Sub-option and Option . . . . . . . .   4
     3.1.  DHCP Relay Agent Source Port Sub-option . . . . . . . . .   4
     3.2.  DHCPv6 Relay Agent Source Port Option . . . . . . . . . .   4
   4.  Compatibility . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  Document Change Log . . . . . . . . . . . . . . . . . . . . .   6
     8.1.  Changes to draft-ietf-dhc-relay-port-00 . . . . . . . . .   6
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   RFC 2131 [RFC2131] and RFC 3315 [RFC3315] specify the DHCP transport
   protocol as UDP.  They also define both the server side and client
   side port numbers.  The DHCP server port is UDP number (67) and the
   client port is UDP number (68); for DHCPv6 the server port is (546)
   and the client port is (547).

   This fixed client port number of DHCP protocol scheme creates
   problems in certain DHCP relay operations and environments.  For
   instance, in a large scale DHCP relay implementation on a single
   switch node, the DHCP relay functionality may be partitioned among
   multiple relay processes running under different CPUs.  All those
   DHCP relay processes may share the same IP address of the switch
   node.  If the UDP source port has to be a fixed number, the transport
   socket operation of DHCP packets needs to go through a central
   location or process which defeats the purpose of distributed DHCP
   relay functionality.

   In some of the scalable operational environment, the decision to
   split functionality into multiple processes on a node may not be
   purely based on DHCP relay load.  But DHCP relay is one of the
   functions in the multiple process implementation.

   Although assigning the different source IP/IPv6 address for each DHCP
   relay process can be a solution, it requires operational and network
   management involvement.  It needs to be sure, at least for DHCP, the
   address space among the relay and server is in private IPv4 address
   domain.

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