Generalized UDP Source Port for DHCP Relay
draft-ietf-dhc-relay-port-04

Document Type Active Internet-Draft (dhc WG)
Last updated 2017-04-18
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: October 20, 2017                                 April 18, 2017

               Generalized UDP Source Port for DHCP Relay
                      draft-ietf-dhc-relay-port-04

Abstract

   This document proposes an extension to the DHCP and DHCPv6 protocols
   that allows any valid number to be used as the relay agent's UDP
   source port for DHCP packets.

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
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   This Internet-Draft will expire on October 20, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Shen & Chen             Expires October 20, 2017                [Page 1]
Internet-Draft           DHCP Relay Source Port               April 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Changes to DHCP and DHCPv6 Specifications . . . . . . . . . .   3
     3.1.  Changes to DHCP in RFC 2131 . . . . . . . . . . . . . . .   4
     3.2.  Changes to DHCPv6 in RFC 3315 . . . . . . . . . . . . . .   4
   4.  Relay Source Port Sub-option and Option . . . . . . . . . . .   4
     4.1.  Source Port Sub-option for DHCP . . . . . . . . . . . . .   5
     4.2.  Relay Source Port Option for DHCPv6 . . . . . . . . . . .   5
   5.  Relay Agent and Server Behavior . . . . . . . . . . . . . . .   6
     5.1.  DHCP  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     5.2.  DHCPv6  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     5.3.  Compatibility . . . . . . . . . . . . . . . . . . . . . .   7
   6.  A DHCPv6 Cascaded Relay Example . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   8
   10. Document Change Log . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Changes to draft-ietf-dhc-relay-port-04  . . . . . . . .   9
     10.2.  Changes to draft-ietf-dhc-relay-port-03  . . . . . . . .   9
     10.3.  Changes to draft-ietf-dhc-relay-port-02  . . . . . . . .   9
     10.4.  Changes to draft-ietf-dhc-relay-port-01  . . . . . . . .   9
     10.5.  Changes to draft-ietf-dhc-relay-port-00  . . . . . . . .   9
   11. Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   RFC 2131 [RFC2131] and RFC 3315 [RFC3315] specify the use of UDP as
   the transport protocol for DHCP and DHCPv6.  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 UDP port of DHCP protocol scheme creates challenges in
   certain DHCP relay operations.  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.  All
   these DHCP relay processes may share the same IP address of the
   switch node.  If the UDP source port has to be a fixed number as
   currently specified, the transport socket operation of DHCP packets
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