Generalized UDP Source Port for DHCP Relay
RFC 8357
Document | Type | RFC - Proposed Standard (March 2018; Errata) | |
---|---|---|---|
Authors | Naiming Shen , Enke Chen | ||
Last updated | 2020-03-07 | ||
Replaces | draft-shen-dhc-client-port | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Tomek Mrugalski | ||
Shepherd write-up | Show (last changed 2017-06-23) | ||
IESG | IESG state | RFC 8357 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Suresh Krishnan | ||
Send notices to | "Tomek Mrugalski" <tomasz.mrugalski@gmail.com> | ||
IANA | IANA review state | Version Changed - Review Needed | |
IANA action state | RFC-Ed-Ack |
Internet Engineering Task Force (IETF) N. Shen Request for Comments: 8357 E. Chen Category: Standards Track Cisco Systems ISSN: 2070-1721 March 2018 Generalized UDP Source Port for DHCP Relay Abstract This document defines an extension to the DHCP protocols that allows a relay agent to use any available source port for upstream communications. The extension also allows inclusion of a DHCP option that can be used to statelessly route responses back to the appropriate source port on downstream communications. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8357. Copyright Notice Copyright (c) 2018 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 Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Shen & Chen Standards Track [Page 1] RFC 8357 DHCP Relay Source Port March 2018 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 2.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3 3. Changes to DHCP Specifications . . . . . . . . . . . . . . . 4 3.1. Additions to DHCPv4 in RFC 2131 . . . . . . . . . . . . . 4 3.2. Additions to DHCPv6 in RFC 3315 . . . . . . . . . . . . . 4 4. Relay Source Port Sub-option and Option . . . . . . . . . . . 4 4.1. Source Port Sub-option for DHCPv4 . . . . . . . . . . . . 5 4.2. Relay Source Port Option for DHCPv6 . . . . . . . . . . . 5 5. Relay Agent and Server Behavior . . . . . . . . . . . . . . . 6 5.1. DHCPv4 . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.2. DHCPv6 . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.3. Compatibility . . . . . . . . . . . . . . . . . . . . . . 7 5.4. Deployment Considerations . . . . . . . . . . . . . . . . 7 6. Example of an IPv6-Cascaded Relay . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 9. Normative References . . . . . . . . . . . . . . . . . . . . 9 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction RFC 2131 [RFC2131] and RFC 3315 [RFC3315] specify the use of UDP as the transport protocol for DHCP. They also define both the server- and client-side port numbers. The IPv4 server port is UDP number (67) and the client port is UDP number (68); for IPv6, the server port is (547) and the client port is (546). The fixed UDP port combinations for the 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 of 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 would need to go through a central entity or process, which would defeat the purpose of distributing DHCP relay functionality. In some large-scale deployments, the decision to split the DHCP functionality into multiple processes on a node may not be purely based on DHCP relay computational load. Rather, DHCP relay could just be one of the functions in a multi-process implementation. Shen & Chen Standards Track [Page 2]Show full document text