draft-ietf-dhc-relay-port-00.txt   draft-ietf-dhc-relay-port-01.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: April 30, 2017 October 27, 2016 Expires: July 9, 2017 January 5, 2017
Generalized Source UDP Port of DHCP Relay Generalized Source UDP Port of DHCP Relay
draft-ietf-dhc-relay-port-00 draft-ietf-dhc-relay-port-01
Abstract Abstract
This document extends the DHCP and DHCPv6 protocols for the UDP This document extends the DHCP and DHCPv6 protocols for the UDP
transport from relay agent to server and allows the port to be any transport from relay agent to server and allows the port to be any
valid number on the DHCP relay system. valid number on the DHCP relay system.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 1, line 32 skipping to change at page 1, line 32
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 April 30, 2017. This Internet-Draft will expire on July 9, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 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
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 2, line 15 skipping to change at page 2, line 15
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Changes to DHCP and DHCPv6 Specifications . . . . . . . . . . 3 2. Changes to DHCP and DHCPv6 Specifications . . . . . . . . . . 3
2.1. Changes to DHCP in RFC 2131 . . . . . . . . . . . . . . . 3 2.1. Changes to DHCP in RFC 2131 . . . . . . . . . . . . . . . 3
2.2. Changes to DHCPv6 in RFC 3315 . . . . . . . . . . . . . . 3 2.2. Changes to DHCPv6 in RFC 3315 . . . . . . . . . . . . . . 3
3. Relay Agent Source Port Sub-option and Option . . . . . . . . 4 3. Relay Agent Source Port Sub-option and Option . . . . . . . . 4
3.1. DHCP Relay Agent Source Port Sub-option . . . . . . . . . 4 3.1. DHCP Relay Agent Source Port Sub-option . . . . . . . . . 4
3.2. DHCPv6 Relay Agent Source Port Option . . . . . . . . . . 4 3.2. DHCPv6 Relay Agent Source Port Option . . . . . . . . . . 4
4. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
8. Document Change Log . . . . . . . . . . . . . . . . . . . . . 6 8. Document Change Log . . . . . . . . . . . . . . . . . . . . . 7
8.1. Changes to draft-ietf-dhc-relay-port-00 . . . . . . . . . 6 8.1. Changes to draft-ietf-dhc-relay-port-01 . . . . . . . . . 7
9. Normative References . . . . . . . . . . . . . . . . . . . . 6 8.2. Changes to draft-ietf-dhc-relay-port-00 . . . . . . . . . 7
9. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
RFC 2131 [RFC2131] and RFC 3315 [RFC3315] specify the DHCP transport RFC 2131 [RFC2131] and RFC 3315 [RFC3315] specify the DHCP transport
protocol as UDP. They also define both the server side and client 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 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) client port is UDP number (68); for DHCPv6 the server port is (546)
and the client port is (547). and the client port is (547).
This fixed client port number of DHCP protocol scheme creates This fixed port number of DHCP protocol scheme creates problems in
problems in certain DHCP relay operations and environments. For certain DHCP relay operations and environments. For instance, in a
instance, in a large scale DHCP relay implementation on a single large scale DHCP relay implementation on a single switch node, the
switch node, the DHCP relay functionality may be partitioned among DHCP relay functionality may be partitioned among multiple relay
multiple relay processes running under different CPUs. All those processes running under different CPUs. All those DHCP relay
DHCP relay processes may share the same IP address of the switch processes may share the same IP address of the switch node. If the
node. If the UDP source port has to be a fixed number, the transport UDP source port has to be a fixed number, the transport socket
socket operation of DHCP packets needs to go through a central operation of DHCP packets needs to go through a central location or
location or process which defeats the purpose of distributed DHCP process which defeats the purpose of distributed DHCP relay
relay functionality. functionality.
In some of the scalable operational environment, the decision to In some of the scalable operational environment, the decision to
split functionality into multiple processes on a node may not be split functionality into multiple processes on a node may not be
purely based on DHCP relay load. But DHCP relay is one of the purely based on DHCP relay load. But DHCP relay is one of the
functions in the multiple process implementation. functions in the multiple process implementation.
Although assigning the different source IP/IPv6 address for each DHCP Although assigning the different source IP/IPv6 address for each DHCP
relay process can be a solution, it requires operational and network relay process can be a solution, it requires operational and network
management involvement. It needs to be sure, at least for DHCP, the management involvement. It needs to be sure, at least for DHCP, the
address space among the relay and server is in private IPv4 address address space among the relay and server is in private IPv4 address
domain. domain.
This document proposes the option to relax the fixed source port This document proposes the option to relax the fixed source port
requirement for the DHCP relay agents. This extension requires the requirement for the DHCP relay agents. This extension requires the
DHCP server or relay agent, in the case of relay chaining [RFC3315], DHCP server or relay agent, in the case of relay chaining [RFC3315],
to remember the inbound packet's UDP port number along with the IP/ to remember the inbound packet's UDP port number along with the IP/
IPv6 address. The DHCP server MUST use the UDP port number that the IPv6 address. The DHCP server when sending back replies MUST use the
incoming relay agent uses instead of blindly setting the DHCP fixed UDP port number that the incoming relay agent uses instead of blindly
port number. setting the DHCP fixed port number.
1.1. Requirements Language 1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Changes to DHCP and DHCPv6 Specifications 2. Changes to DHCP and DHCPv6 Specifications
2.1. Changes to DHCP in RFC 2131 2.1. Changes to DHCP in RFC 2131
skipping to change at page 3, line 47 skipping to change at page 3, line 49
2.2. Changes to DHCPv6 in RFC 3315 2.2. Changes to DHCPv6 in RFC 3315
Section 5.2 of RFC 3315 [RFC3315] asserts that: Clients listen for Section 5.2 of RFC 3315 [RFC3315] asserts that: Clients listen for
DHCP messages on UDP port 546. Servers and relay agents listen for DHCP messages on UDP port 546. Servers and relay agents listen for
DHCP messages on UDP port 547. DHCP messages on UDP port 547.
This specification adds to the above paragraph in the paragraph This specification adds to the above paragraph in the paragraph
below. below.
DHCP relay agents can listen for DHCP messages from server or another DHCP relay agents can listen for DHCP messages from server or another
relay agent on any valid UDP port available on the relay system upstream relay agent on any valid UDP port available on the relay
including the DHCP UDP port 547. The default is port 547 if there is system including the DHCP UDP port 547. The default is port 547 if
no explicit configuration for generalized source UDP port extension there is no explicit configuration for generalized source UDP port
of DHCP relay. extension of DHCP relay.
3. Relay Agent Source Port Sub-option and Option 3. Relay Agent Source Port Sub-option and Option
Although the DHCP or DHCPv6 server can implicitly detect a source UDP Although the DHCP or DHCPv6 server can implicitly detect a source UDP
port that is different from the standard DHCP port number when it port that is different from the standard DHCP port number when it
receives an inbound message from relay agents, this sub-option makes receives an inbound message from relay agents, this sub-option makes
the request explicit for the server to use a non-DHCP UDP port in the the request explicit for the server to use a non-DHCP UDP port in the
reply message. reply message.
3.1. DHCP Relay Agent Source Port Sub-option 3.1. DHCP Relay Agent Source Port Sub-option
skipping to change at page 4, line 42 skipping to change at page 4, line 44
When a DHCP server receives a message from relay agent with this When a DHCP server receives a message from relay agent with this
Relay Source Port sub-option, it MUST remember the inbound message Relay Source Port sub-option, it MUST remember the inbound message
UDP source port from the relay agent and use the same port number for UDP source port from the relay agent and use the same port number for
the UDP destination port that sends the reply message to the same the UDP destination port that sends the reply message to the same
relay agent. relay agent.
3.2. DHCPv6 Relay Agent Source Port Option 3.2. DHCPv6 Relay Agent Source Port Option
The Relay Agent Source Port Option is a new DHCPv6 option. It SHOULD The Relay Agent Source Port Option is a new DHCPv6 option. It SHOULD
be used by the DHCPv6 relay agent that uses a non-DHCP UDP port be used either by a DHCPv6 relay agent that uses a non-DHCP UDP port
communicating with the DHCP server and upstream relay agent. communicating with the DHCP server and the upstream relay agent, or
by a DHCPv6 relay agent that detects the use of a non-DHCP UDP port
by a downstream relay agent.
The format of the DHCPv6 Relay Agent Source Port Option is shown The format of the DHCPv6 Relay Agent Source Port Option is shown
below: below:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Option-Code | Option-Len | | Option-Code | Option-Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| UDP Source Port | | Downstream UDP Source Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where: Where:
Option-Code: TBD. 16 bits value, to be assigned by IANA. Option-Code: TBD. 16 bits value, to be assigned by IANA.
Option-Len: 16 bits value to be set to 2. Option-Len: 16 bits value to be set to 2.
UDP Source Port: 16 bits value. To be set by the DHCPv6 relay to Downstream UDP Source Port: 16 bits value. To be set by the
the UDP source port used for the packet. DHCPv6 relay to the downstream relay agent's UDP source
port used for the UDP packet or to be set to zero.
The DHCPv6 relay agent SHOULD include this Relay Source Port Option
when it uses a non-DHCP UDP port to communicate to the DHCPv6 server
or an upstream DHCPv6 relay agent. Also when a DHCPv6 relay agent
detects that the downstream relay agent uses a non-DHCP UDP port in
the packet, it MUST record the port number in the Downstream UDP
Source Port field of this option. If this option is included to
indicate only the local non-DHCP UDP port usage and there is no
downstream relay agent's non-DHCP UDP port usage, the field
Downstream UDP Source Port MUST be set to zero.
When a DHCPv6 server receives the relayed DHCPv6 packet with this
Relay Source Port Option, it MUST copy and add the option when
constructing the Relay-Reply chain in response to the Relay-Forward
messages. This option MUST NOT appear in any message except a Relay-
Forward or Relay-Reply message.
With this Relay Source Port Option in the message, when a DHCPv6 With this Relay Source Port Option in the message, when a DHCPv6
server replies or a relay agent relays a message towards a downstream server replies the Relay-Reply message towards a relay agent, it MUST
relay agent, it MUST use the same port number for the UDP destination check and use the UDP source port from the UDP packet of the Relay-
to the previous hop relay agent. Forward message by the relay agent.
When a relay agent receives this Relay-Reply message with this option
from the server or from an upstream relay agent, and if the
Downstream UDP Source Port value is non-zero, it MUST use this UDP
port to relay the Relay-Reply message to the downstream relay agent.
4. Compatibility 4. Compatibility
With this extension of DHCP and DHCPv6 source port generalization, With this extension of DHCP and DHCPv6 source port generalization,
the server behavior is compatible with the relay agent that uses the the server behavior is compatible with the relay agent that uses the
DHCP fixed UDP port. The DHCP server will reflect back the UDP well- DHCP fixed UDP port. The DHCP server will reflect back the UDP well-
known port number (67/547) that the client uses when relaying back to known port number (67/547) that the client uses when relaying back to
the relay agent. It is recommended to upgrade the server side first. the relay agent. It is recommended to upgrade the server side first.
The implementation is advised to allow the configuration for The implementation is advised to allow the relay agent configuration
specifying a fixed DHCP relay port number. This is for the case for specifying a fixed DHCP relay port number. This is for the case
where the DHCP relay agent is upgraded with this extension before the where the DHCP relay agent is upgraded with this extension before the
server side upgrade. server side upgrade.
5. IANA Considerations 5. IANA Considerations
A new sub-option, DHCP Relay Agent Source Port, is defined in this A new sub-option, DHCP Relay Agent Source Port, is defined in this
document within the DHCPv4 Relay Agent Information Option. It needs document within the DHCPv4 Relay Agent Information Option. It needs
to be assigned by IANA from the DHCP Relay Agent sub-options space to be assigned by IANA from the DHCP Relay Agent sub-options space
[RFC3046]. [RFC3046].
skipping to change at page 6, line 28 skipping to change at page 7, line 7
comments of this document. comments of this document.
The authors would like to thank Bernie Volz for discussions that lead The authors would like to thank Bernie Volz for discussions that lead
to the definition of The Relay Agent Source Port sub-option and to the definition of The Relay Agent Source Port sub-option and
DHCPv6 Relay Agent Source Port Option. DHCPv6 Relay Agent Source Port Option.
The RFC text was produced using Marshall Rose's xml2rfc tool. The RFC text was produced using Marshall Rose's xml2rfc tool.
8. Document Change Log 8. Document Change Log
8.1. Changes to draft-ietf-dhc-relay-port-00 8.1. Changes to draft-ietf-dhc-relay-port-01
o Posted the draft in January 2017.
o Change the DHCPv6 Relay Agent Source Port Option, UDP Source Port
field to Downstream UDP Source Port. Add the option handling
mechanism for DHCPv6 server and relay agents.
8.2. Changes to draft-ietf-dhc-relay-port-00
o Posted first version of working group draft in October 2016. o Posted first version of working group draft in October 2016.
o This draft was renamed from draft-shen-dhc-client-port-03.txt. o This draft was renamed from draft-shen-dhc-client-port-03.txt.
9. Normative References 9. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
 End of changes. 15 change blocks. 
37 lines changed or deleted 70 lines changed or added

This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/