Generalized Source UDP Port of DHCP Relay
draft-ietf-dhc-relay-port-01

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Networking Working Group                                         N. Shen
Internet-Draft                                                   E. Chen
Intended status: Standards Track                           Cisco Systems
Expires: July 9, 2017                                    January 5, 2017

               Generalized Source UDP Port of DHCP Relay
                      draft-ietf-dhc-relay-port-01

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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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on July 9, 2017.

Copyright Notice

   Copyright (c) 2017 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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   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 . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  Document Change Log . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Changes to draft-ietf-dhc-relay-port-01 . . . . . . . . .   7
     8.2.  Changes to draft-ietf-dhc-relay-port-00 . . . . . . . . .   7
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   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 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

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