draft-ietf-dhc-relay-port-02.txt   draft-ietf-dhc-relay-port-03.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: September 1, 2017 February 28, 2017 Expires: October 13, 2017 April 11, 2017
Generalized UDP Source Port for DHCP Relay Generalized UDP Source Port for DHCP Relay
draft-ietf-dhc-relay-port-02 draft-ietf-dhc-relay-port-03
Abstract Abstract
This document proposes an extension to the DHCP and DHCPv6 protocols This document proposes an extension to the DHCP and DHCPv6 protocols
that allows any valid number to be used as the relay agent UDP source that allows any valid number to be used as the relay agent's UDP
port for DHCP packets. source port for DHCP packets.
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
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 September 1, 2017. This Internet-Draft will expire on October 13, 2017.
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
skipping to change at page 2, line 11 skipping to change at page 2, line 11
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
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Changes to DHCP and DHCPv6 Specifications . . . . . . . . . . 3 3. Changes to DHCP and DHCPv6 Specifications . . . . . . . . . . 3
3.1. Changes to DHCP in RFC 2131 . . . . . . . . . . . . . . . 3 3.1. Changes to DHCP in RFC 2131 . . . . . . . . . . . . . . . 4
3.2. Changes to DHCPv6 in RFC 3315 . . . . . . . . . . . . . . 4 3.2. Changes to DHCPv6 in RFC 3315 . . . . . . . . . . . . . . 4
4. Relay Source Port Sub-option and Option . . . . . . . . . . . 4 4. Relay Source Port Sub-option and Option . . . . . . . . . . . 4
4.1. Source Port Sub-option for DHCPv4 . . . . . . . . . . . . 4 4.1. Source Port Sub-option for DHCP . . . . . . . . . . . . . 5
4.2. Relay Source Port Option for DHCPv6 . . . . . . . . . . . 5 4.2. Relay Source Port Option for DHCPv6 . . . . . . . . . . . 5
5. A DHCPv6 Cascaded Relay Example . . . . . . . . . . . . . . . 6 5. Relay Agent and Server Behavior . . . . . . . . . . . . . . . 6
6. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1. DHCP . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. DHCPv6 . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.3. Compatibility . . . . . . . . . . . . . . . . . . . . . . 7
6. A DHCPv6 Cascaded Relay Example . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
10. Document Change Log . . . . . . . . . . . . . . . . . . . . . 8 10. Document Change Log . . . . . . . . . . . . . . . . . . . . . 9
10.1. Changes to draft-ietf-dhc-relay-port-02 . . . . . . . . 8 10.1. Changes to draft-ietf-dhc-relay-port-03 . . . . . . . . 9
10.2. Changes to draft-ietf-dhc-relay-port-01 . . . . . . . . 9 10.2. Changes to draft-ietf-dhc-relay-port-02 . . . . . . . . 9
10.3. Changes to draft-ietf-dhc-relay-port-00 . . . . . . . . 9 10.3. Changes to draft-ietf-dhc-relay-port-01 . . . . . . . . 9
10.4. Changes to draft-ietf-dhc-relay-port-00 . . . . . . . . 9
11. Normative References . . . . . . . . . . . . . . . . . . . . 9 11. Normative References . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
RFC 2131 [RFC2131] and RFC 3315 [RFC3315] specify the use of UDP as 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 transport protocol for DHCP and DHCPv6. They also define both
the server side and client side port numbers. The DHCP server port 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 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). the server port is (546) and the client port is (547).
This fixed UDP port of DHCP protocol scheme creates challenges in This fixed UDP port of DHCP protocol scheme creates challenges in
skipping to change at page 4, line 28 skipping to change at page 4, line 36
Clients listen for DHCP messages on UDP port 546. Servers and Clients listen for DHCP messages on UDP port 546. Servers and
relay agents listen for DHCP messages on UDP port 547. relay agents listen for DHCP messages on UDP port 547.
This specification adds the following extension to the above This specification adds the following extension to the above
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 is port 547 if there is no explicit configuration for The default UDP port is 547 if there is no explicit configuration
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 or DHCPv6 server can implicitly determine a UDP Although a DHCP or DHCPv6 server can implicitly determine the UDP
source port when it receives an inbound message from a relay agent, source port when it receives a message from a relay agent, this sub-
this sub-option makes the request explicit for the server to use a option makes the request explicit for the server to use a non-DHCP
non-DHCP UDP port in the reply message. When DHCPv6 cascaded relay UDP port in the reply message. When DHCPv6 cascaded relay agents are
agents are involved, the downstream non-DHCP UDP port needs to be involved, the downstream non-DHCP UDP port needs to be recorded using
recorded using the option. the option.
4.1. Source Port Sub-option for DHCPv4 4.1. Source Port Sub-option for DHCP
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]. It part of the relay-agent-information option for DHCP [RFC3046].
SHOULD be used by a relay agent that uses a non-DHCP UDP port
communicating with the DHCP server.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where: Where:
SubOpt Code: SUBOPT_RELAY_PORT. 8 bits value, to be assigned by SubOpt Code: SUBOPT_RELAY_PORT. 8 bits value, to be assigned by
IANA. IANA.
Len: 8 bits value to be set to 0. Len: 8 bits value to be set to 0.
When a DHCP server receives a message from a relay agent with the
"Source Port Sub-option", it MUST remember the UDP source port of the
message and use that port number as the UDP destination port when
sending the reply message to the same relay agent.
4.2. Relay Source Port Option for DHCPv6 4.2. Relay Source Port Option for DHCPv6
The "Relay Source Port Option" is a new DHCPv6 option. It SHOULD be The "Relay Source Port Option" is a new DHCPv6 option. It MUST be
used either by a DHCPv6 relay agent that uses a non-DHCP UDP port used either by a DHCPv6 relay agent that uses a non-DHCP UDP port
communicating with the DHCP server and the upstream relay agent, or 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 DHCPv6 relay agent that detects the use of a non-DHCP UDP port
by a downstream relay agent. by a downstream relay agent.
The format of the "Relay Source Port Option" is shown below: The format of the "Relay Source Port Option" is shown 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 5, line 47 skipping to change at page 6, line 10
Option-Code: OPTION_RELAY_RELAY_PORT. 16 bits value, to be Option-Code: OPTION_RELAY_RELAY_PORT. 16 bits value, to be
assigned by IANA. assigned by IANA.
Option-Len: 16 bits value to be set to 2. Option-Len: 16 bits value to be set to 2.
Downstream Source Port: 16 bits value. To be set by the DHCPv6 Downstream Source Port: 16 bits value. To be set by the DHCPv6
relay either to the downstream relay agent's UDP source relay either to the downstream relay agent's UDP source
port used for the UDP packet, or to zero if only the port used for the UDP packet, or to zero if only the
local relay agent uses the non-DHCP UDP port. local relay agent uses the non-DHCP UDP port.
The DHCPv6 relay agent SHOULD include the "Relay Source Port Option" 5. Relay Agent and Server Behavior
5.1. DHCP
When a relay agent uses a non-DHCP UDP port communicating with the
DHCP server, it MUST include the "Source Port Sub-option" in Relay-
forward messages to indicate that.
When a DHCP server receives a message from a relay agent with the
"Source Port Sub-option", it MUST remember the UDP source port of the
message and use that port number as the UDP destination port when
sending the reply message to the same relay agent.
5.2. DHCPv6
The DHCPv6 relay agent MUST include the "Relay Source Port Option"
when it uses a non-DHCP UDP port to communicate to a DHCPv6 server or when it uses a non-DHCP UDP port to communicate to a DHCPv6 server or
an upstream DHCPv6 relay agent. Also when a DHCPv6 relay agent an upstream DHCPv6 relay agent. Also when a DHCPv6 relay agent
detects that a downstream relay agent uses a non-DHCP UDP port in the detects that a downstream relay agent uses a non-DHCP UDP port in the
packet, it MUST record the port number in the "Downstream Source packet, it MUST record the port number in the "Downstream Source
Port" field of this option. If this option is included to indicate 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 only the local non-DHCP UDP port usage and there is no downstream
relay agent's non-DHCP UDP port usage, the field Downstream Source relay agent's non-DHCP UDP port usage, the field Downstream Source
Port field MUST be set to zero. Port field MUST be set to zero.
The DHCPv6 relay agent SHOULD include this option in the following The DHCPv6 relay agent MUST include this option in the following
three cases: three cases:
1) The local relay agent uses a non-DHCP UDP port. 1) The local relay agent uses a non-DHCP UDP port.
2) the downstream relay agent uses a non-DHCP UDP port. 2) the downstream relay agent uses a non-DHCP UDP port.
3) the local relay agent and the downstream relay agent both use 3) the local relay agent and the downstream relay agent both use
non-DHCP UDP ports. non-DHCP UDP ports.
In the first case, the value of the field in "Downstream Source Port" In the first case, the value of the "Downstream Source Port" field is
field is set to zero. In the other two cases, the value of the field set to zero. In the other two cases, the value of the field is set
is set to the UDP port number that the downstream relay agent uses. to the UDP port number that the downstream relay agent uses.
When a DHCPv6 server receives a Relay-forward message with the "Relay When a DHCPv6 server receives a Relay-forward message with the "Relay
Source Port Option", it MUST copy the option when constructing the Source Port Option", it MUST copy the option when constructing the
Relay-reply chain in response to the Relay-forward message. This Relay-reply chain in response to the Relay-forward message. This
option MUST NOT appear in any message other than a Relay-forward or option MUST NOT appear in any message other than a Relay-forward or
Relay-reply message. Additionally, the DHCPv6 server MUST check and Relay-reply message. Additionally, the DHCPv6 server MUST check and
use the UDP source port from the UDP packet of the Relay-forward use the UDP source port from the UDP packet of the Relay-forward
message in replying to the relay agent. message in replying to the relay agent.
When a relay agent receives a Relay-reply message with the "Relay When a relay agent receives a Relay-reply message with the "Relay
Source Port Option" from a server or from an upstream relay agent, if Source Port Option" from a server or from an upstream relay agent, if
the "Downstream Source Port" field in the option is non-zero, it MUST the "Downstream Source Port" field in the option is non-zero, it MUST
use this UDP port number to forward the Relay-reply message to the use this UDP port number to forward the Relay-reply message to the
downstream relay agent. downstream relay agent.
5. A DHCPv6 Cascaded Relay Example 5.3. Compatibility
With this source port generalization, the DHCP and DHCPv6 server MUST
be upgraded to support the extension specified in this document
before the extension is used by a relay agent.
The implementation is advised to allow configuration for relay agent
specifying a DHCP relay port number. It can be used to allow the
relay agent either using a normal DHCP UDP port or non-DHCP UDP port.
6. A DHCPv6 Cascaded Relay Example
An example of DHCPv6 cascaded relay agents with the "Relay Source An example of DHCPv6 cascaded relay agents with the "Relay Source
Port Option" is shown below. Port Option" is shown below.
(forward) (forward) (forward) (forward) (forward) (forward)
Relay1 ----------> Relay2 ----------> Relay3 ----------> Server Relay1 ----------> Relay2 ----------> Relay3 ----------> Server
(1000) (547) (547) (1000) (547) (547)
(reply) (reply) (reply) (reply) (reply) (reply)
<---------- <---------- <---------- <---------- <---------- <----------
In the above diagram, all the DHCPv6 devices support this generalized In the above diagram, all the DHCPv6 devices support this generalized
UDP source port extension except for Relay3. Relay1 is the only UDP source port extension except for Relay3. Relay1 is the only
relay agent device uses a non-DHCP UDP port. Relay2 is the upstream relay agent device uses a non-DHCP UDP port. Relay2 is the upstream
device of Relay1. device of Relay1.
Both Relay1 and Relay2 include the "Relay Source Port Option" in Both Relay1 and Relay2 include the "Relay Source Port Option" in
Relay-forward message. Relay1 sets the "Downstream Source Port" Relay-forward message. Relay1 sets the "Downstream Source Port"
field in the option to zero. Relay2 notices the "Relay Source Port field in the option to zero. Relay2 notices the "Relay Source Port
Option" is included in the message from Relay1, and it determines Option" is included in the message from Relay1, and it determines
skipping to change at page 7, line 37 skipping to change at page 8, line 18
Port Option", it finds the "Downstream Source Port" field has the Port Option", it finds the "Downstream Source Port" field has the
value of 1000. Relay2 then uses this port number in the UDP packet value of 1000. Relay2 then uses this port number in the UDP packet
when sending the Relay-reply message to Relay1. when sending the Relay-reply message to Relay1.
When Relay1 receives the Relay-reply message with the "Relay Source When Relay1 receives the Relay-reply message with the "Relay Source
Port Option", it finds that the "Downstream Source Port" field has Port Option", it finds that the "Downstream Source Port" field has
the value of zero. Relay1 then uses the normal DHCP port 547 in the the value of zero. Relay1 then uses the normal DHCP port 547 in the
packet sending the Relay-reply message to its downstream relay agent packet sending the Relay-reply message to its downstream relay agent
or uses UDP port 546 to a DHCPv6 client. or uses UDP port 546 to a DHCPv6 client.
6. Compatibility
With this source port generalization for DHCP and DHCPv6, the server
behavior is compatible with the relay agent that uses the normal DHCP
UDP port. The DHCP server will use the well-known UDP port (67 or
547) when sending Relay-reply message back to the relay agent. It is
recommended to upgrade the server side first before using a non-DHCP
UDP port for a relay agent.
The implementation is advised to allow configuration for relay agent
specifying a DHCP relay port number. It can be used to allow the
relay agent either using a normal DHCP UDP port or non-DHCP UDP port.
7. IANA Considerations 7. IANA Considerations
A new sub-option, DHCP Relay Source Port, is defined in this document A new sub-option, DHCP Relay Source Port, is defined in this document
within the DHCPv4 Relay Agent Information Option. It needs to be within the DHCP Relay Agent Information Option. It needs to be
assigned by IANA from the DHCP Relay Agent sub-options space assigned by IANA from the DHCP Relay Agent sub-options space
[RFC3046]. [RFC3046].
A new option, DHCPv6 Relay Source Port, is defined in this document A new option, DHCPv6 Relay Source Port, is defined in this document
for DHCPv6 and it needs to be assigned by IANA for the DHCPv6 option for DHCPv6 and it needs to be assigned by IANA for the DHCPv6 option
code. code.
8. Security Considerations 8. Security Considerations
If the network uses firewall to block or allow DHCP packets with both If the network uses firewall to block or allow DHCP packets with both
skipping to change at page 8, line 31 skipping to change at page 8, line 44
firewall rules need to be modified only to match the DHCP server side firewall rules need to be modified only to match the DHCP server side
of the UDP port number, and if necessary, IP addresses and other of the UDP port number, and if necessary, IP addresses and other
attributes. attributes.
9. Acknowledgments 9. Acknowledgments
The authors would like to thank Peter Arberg, Bhanu Gopalasetty, The authors would like to thank Peter Arberg, Bhanu Gopalasetty,
Andre Kostur, Ted Lemon, and Kishore Seshadri for their review and Andre Kostur, Ted Lemon, and Kishore Seshadri for their review and
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 led
to the definition of The Relay Source Port sub-option and DHCPv6 to the definition of The Relay Source Port sub-option and DHCPv6
Relay Source Port Option. Relay 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.
10. Document Change Log 10. Document Change Log
10.1. Changes to draft-ietf-dhc-relay-port-02 10.1. Changes to draft-ietf-dhc-relay-port-03
o Posted the draft in April 2017.
o Added the "Relay Agent and Server Behavior" section.
10.2. Changes to draft-ietf-dhc-relay-port-02
o Posted the draft in February 2017. o Posted the draft in February 2017.
o Added the Terminology section. o Added the Terminology section.
o Defined the Sub-option and Option names for DHCPv4 and DHCPv6. o Defined the Sub-option and Option names for DHCP and DHCPv6.
o Added the DHCPv6 cascaded relay agents example. o Added the DHCPv6 cascaded relay agents example.
10.2. Changes to draft-ietf-dhc-relay-port-01 10.3. Changes to draft-ietf-dhc-relay-port-01
o Posted the draft in January 2017. o Posted the draft in January 2017.
o Change the DHCPv6 Relay Source Port Option, UDP Source Port field o Change the DHCPv6 Relay Source Port Option, UDP Source Port field
to Downstream Source Port. Add the option handling mechanism for to Downstream Source Port. Add the option handling mechanism for
DHCPv6 server and relay agents. DHCPv6 server and relay agents.
10.3. Changes to draft-ietf-dhc-relay-port-00 10.4. 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.
11. Normative References 11. 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. 27 change blocks. 
58 lines changed or deleted 73 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/