draft-ietf-dhc-relay-port-05.txt   draft-ietf-dhc-relay-port-06.txt 
Networking Working Group N. Shen Networking Working Group N. Shen
Internet-Draft E. Chen Internet-Draft E. Chen
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: October 27, 2017 April 25, 2017 Expires: January 23, 2018 July 22, 2017
Generalized UDP Source Port for DHCP Relay Generalized UDP Source Port for DHCP Relay
draft-ietf-dhc-relay-port-05 draft-ietf-dhc-relay-port-05
Abstract Abstract
This document proposes an extension to the DHCP protocols that allows This document proposes an extension to the DHCP protocols that allows
a relay agent to receive packets from a server or an upstream relay a relay agent to receive packets from a server or an upstream relay
agent on any UDP port, not just the default port 67 for IPv4 or agent on any UDP port, not just the default port 67 for IPv4 or
default port 547 for IPv6. default port 547 for IPv6.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 27, 2017. This Internet-Draft will expire on January 23, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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paragraph. paragraph.
A DHCP relay agent can listen for DHCP messages from a server or A DHCP relay agent can listen for DHCP messages from a server or
another upstream relay agent device on any valid UDP port another upstream relay agent device on any valid UDP port
available in the relay system including the DHCP UDP port 547. available in the relay system including the DHCP UDP port 547.
The default UDP port is 547 if there is no explicit configuration The default UDP port is 547 if there is no explicit configuration
for the generalized UDP source port extension for DHCP relay. for the generalized UDP source port extension for DHCP relay.
4. Relay Source Port Sub-option and Option 4. Relay Source Port Sub-option and Option
Although a DHCP server can implicitly determine the UDP source port Relay agents do not maintain state. To return a message to its
when it receives a message from a relay agent, this sub-option makes source, the relay agent must include all the required information in
the request explicit for the server to use a non-DHCP UDP port in the the Relay-Forward message. When a relay in a sequence of cascaded
reply message. When IPv6 cascaded relay agents are involved, the relays does not use the standard source port, that source port must
downstream non-DHCP UDP port needs to be recorded using the option. be included along with the source address. This option allows the
relay agent to do so.
4.1. Source Port Sub-option for DHCPv4 4.1. Source Port Sub-option for DHCPv4
The Relay Agent "Source Port Sub-option" is a new option, and it is The Relay Agent "Source Port Sub-option" is a new option, and it is
part of the relay-agent-information option for DHCPv4 [RFC3046]. part of the relay-agent-information option for DHCPv4 [RFC3046].
The format of the "Source Port Sub-option" is shown below: The format of the "Source Port Sub-option" is shown below:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SubOpt Code | Len | | SubOpt Code | Len |
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