draft-ietf-dhc-relay-port-04.txt   draft-ietf-dhc-relay-port-05.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 20, 2017 April 18, 2017 Expires: October 27, 2017 April 25, 2017
Generalized UDP Source Port for DHCP Relay Generalized UDP Source Port for DHCP Relay
draft-ietf-dhc-relay-port-04 draft-ietf-dhc-relay-port-05
Abstract Abstract
This document proposes an extension to the DHCP and DHCPv6 protocols This document proposes an extension to the DHCP protocols that allows
that allows any valid number to be used as the relay agent's UDP a relay agent to receive packets from a server or an upstream relay
source port for DHCP packets. agent on any UDP port, not just the default port 67 for IPv4 or
default port 547 for IPv6.
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 October 20, 2017. This Internet-Draft will expire on October 27, 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 10 skipping to change at page 2, line 10
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
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 Specifications . . . . . . . . . . . . . . . 3
3.1. Changes to DHCP in RFC 2131 . . . . . . . . . . . . . . . 4 3.1. Changes to DHCPv4 in RFC 2131 . . . . . . . . . . . . . . 3
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 DHCP . . . . . . . . . . . . . 5 4.1. Source Port Sub-option for DHCPv4 . . . . . . . . . . . . 4
4.2. Relay Source Port Option for DHCPv6 . . . . . . . . . . . 5 4.2. Relay Source Port Option for DHCPv6 . . . . . . . . . . . 5
5. Relay Agent and Server Behavior . . . . . . . . . . . . . . . 6 5. Relay Agent and Server Behavior . . . . . . . . . . . . . . . 6
5.1. DHCP . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. DHCPv4 . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. DHCPv6 . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.2. DHCPv6 . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.3. Compatibility . . . . . . . . . . . . . . . . . . . . . . 7 5.3. Compatibility . . . . . . . . . . . . . . . . . . . . . . 7
6. A DHCPv6 Cascaded Relay Example . . . . . . . . . . . . . . . 7 6. An IPv6 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 . . . . . . . . . . . . . . . . . . . . . 9 10. Normative References . . . . . . . . . . . . . . . . . . . . 9
10.1. Changes to draft-ietf-dhc-relay-port-04 . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 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 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. They also define both the server
the server side and client side port numbers. The DHCP server port side and client side port numbers. The IPv4 server port is UDP
is UDP number (67) and the client port is UDP number (68); for DHCPv6 number (67) and the client port is UDP number (68); for IPv6 the
the server port is (546) and the client port is (547). 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
certain DHCP relay operations. For instance, in a large scale DHCP certain DHCP relay operations. For instance, in a large scale DHCP
relay implementation on a single switch node, the DHCP relay relay implementation on a single switch node, the DHCP relay
functionality may be partitioned among multiple relay processes. All functionality may be partitioned among multiple relay processes. All
these DHCP relay processes may share the same IP address of the 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 switch node. If the UDP source port has to be a fixed number as
currently specified, the transport socket operation of DHCP packets currently specified, the transport socket operation of DHCP packets
would need to go through a central entity or process which would would need to go through a central entity or process which would
defeat the purpose of distributing DHCP relay functionality. defeat the purpose of distributing DHCP relay functionality.
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based on DHCP relay computational load. But rather DHCP relay could based on DHCP relay computational load. But rather DHCP relay could
just be one of the functions in a multi-process implementation. just be one of the functions in a multi-process implementation.
Although assigning a different IP/IPv6 source address for each DHCP Although assigning a different IP/IPv6 source address for each DHCP
relay process can be a solution, it would introduce operational and relay process can be a solution, it would introduce operational and
network management complexities, especially given the scarceness of network management complexities, especially given the scarceness of
the IPv4 addresses. the IPv4 addresses.
This document proposes an extension to relax the fixed UDP source This document proposes an extension to relax the fixed UDP source
port requirement for the DHCP relay agents. This extension requires port requirement for the DHCP relay agents. This extension requires
a DHCP server or relay agent, in the case of cascaded relay agents a DHCP server to remember the inbound packet's UDP port number along
[RFC3315], to remember the inbound packet's UDP port number along
with the IP/IPv6 address. The DHCP server when sending back replies with the IP/IPv6 address. The DHCP server when sending back replies
MUST use the UDP port number that the incoming relay agent uses MUST use the UDP port number that the incoming relay agent uses
instead of the fixed DHCP port number. instead of the fixed DHCP port number. In the case of IPv6 cascaded
relay agents [RFC3315], the upstream relay agent needs to use the
"Relay Source Port Option" to record the downstream source port and
it MUST use this recorded port number instead of the fixed DHCP port
number when replaying the reply messages.
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. Terminology 2. Terminology
Downstream Device: In the DHCP relay context, it refers to the next Downstream Device: In the DHCP relay context, it refers to the next
skipping to change at page 3, line 44 skipping to change at page 3, line 42
Relay Source Port: This is the UDP port that a relay agent uses to Relay Source Port: This is the UDP port that a relay agent uses to
receive Relay-forward Messages from an upstream device. receive Relay-forward Messages from an upstream device.
Downstream Source Port: This is the UDP port that the downstream Downstream Source Port: This is the UDP port that the downstream
device uses when forwarding Relay-forward Messages to this device uses when forwarding Relay-forward Messages to this
relay agent device. This UDP port is to be used by this relay agent device. This UDP port is to be used by this
relay agent device when forwarding the Relay-reply Messages relay agent device when forwarding the Relay-reply Messages
to that downstream device. to that downstream device.
Non-DHCP UDP Port: Any valid UDP port other than port 67 for DHCP Non-DHCP UDP Port: Any valid UDP port other than port 67 for DHCPv4
and port 547 for DHCPv6. and port 547 for DHCPv6.
3. Changes to DHCP and DHCPv6 Specifications 3. Changes to DHCP Specifications
3.1. Changes to DHCP in RFC 2131
3.1. Changes to DHCPv4 in RFC 2131
Section 4.1 of RFC 2131 [RFC2131] specifies that: Section 4.1 of RFC 2131 [RFC2131] specifies that:
DHCP uses UDP as its transport protocol. DHCP messages from a DHCP uses UDP as its transport protocol. DHCP messages from a
client to a server are sent to the 'DHCP server' port (67), and client to a server are sent to the 'DHCP server' port (67), and
DHCP messages from a server to a client are sent to the 'DHCP DHCP messages from a server to a client are sent to the 'DHCP
client' port (68). client' port (68).
This specification adds the following extension to the above This specification adds the following extension to the above
paragraph. paragraph.
skipping to change at page 4, line 41 skipping to change at page 4, line 38
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 or DHCPv6 server can implicitly determine the UDP Although a DHCP server can implicitly determine the UDP source port
source port when it receives a message from a relay agent, this sub- when it receives a message from a relay agent, this sub-option makes
option makes the request explicit for the server to use a non-DHCP the request explicit for the server to use a non-DHCP UDP port in the
UDP port in the reply message. When DHCPv6 cascaded relay agents are reply message. When IPv6 cascaded relay agents are involved, the
involved, the downstream non-DHCP UDP port needs to be recorded using downstream non-DHCP UDP port needs to be recorded using the option.
the option.
4.1. Source Port Sub-option for DHCP 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 DHCP [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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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.
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 MUST 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 (not 547) communicating with the IPv6 server and the upstream relay
by a DHCPv6 relay agent that detects the use of a non-DHCP UDP port agent, or by a IPv6 relay agent that detects the use of a non-DHCP
by a downstream relay agent. UDP port (not 547) 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RELAY_RELAY_PORT | Option-Len | | OPTION_RELAY_RELAY_PORT | Option-Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream Source Port | | Downstream Source Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where: Where:
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 IPv6
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 (not 547).
5. Relay Agent and Server Behavior 5. Relay Agent and Server Behavior
5.1. DHCP 5.1. DHCPv4
When a relay agent uses a non-DHCP UDP port communicating with the When a relay agent uses a non-DHCP UDP port (not 67) communicating
DHCP server, it MUST include the "Source Port Sub-option" in Relay- with the DHCP server, it MUST include the "Source Port Sub-option" in
forward messages to indicate that. Relay-forward messages to indicate that.
When a DHCP server receives a message from a relay agent with the When an IPv4 server receives a message from a relay agent with the
"Source Port Sub-option", it MUST remember the UDP source port of 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 message and use that port number as the UDP destination port when
sending the reply message to the same relay agent. sending the reply message to the same relay agent.
5.2. DHCPv6 5.2. DHCPv6
The DHCPv6 relay agent MUST include the "Relay Source Port Option" The IPv6 relay agent MUST include the "Relay Source Port Option" when
when it uses a non-DHCP UDP port to communicate to a DHCPv6 server or it uses a non-DHCP UDP port (not 547) to communicate to a DHCPv6
an upstream DHCPv6 relay agent. Also when a DHCPv6 relay agent server or an upstream IPv6 relay agent. Also when an IPv6 relay
detects that a downstream relay agent uses a non-DHCP UDP port in the agent detects that a downstream relay agent uses a non-DHCP UDP port
packet, it MUST record the port number in the "Downstream Source in the packet, it MUST record the port number in the "Downstream
Port" field of this option. If this option is included to indicate Source Port" field of this option. If this option is included to
only the local non-DHCP UDP port usage and there is no downstream indicate only the local non-DHCP UDP port usage and there is no
relay agent's non-DHCP UDP port usage, the field Downstream Source downstream relay agent's non-DHCP UDP port usage, the field
Port field MUST be set to zero. Downstream Source Port field MUST be set to zero.
The DHCPv6 relay agent MUST include this option in the following The IPv6 relay agent MUST include this option in the following three
three cases: cases:
1) The local relay agent uses a non-DHCP UDP port. 1) The local relay agent uses a non-DHCP UDP port (not 547).
2) the downstream relay agent uses a non-DHCP UDP port. 2) the downstream relay agent uses a non-DHCP UDP port (not 547).
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 (not 547).
In the first case, the value of the "Downstream Source Port" field is In the first case, the value of the "Downstream Source Port" field is
set to zero. In the other two cases, the value of the field is set set to zero. In the other two cases, the value of the field 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 an IPv6 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 IPv6 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.
5.3. Compatibility 5.3. Compatibility
skipping to change at page 7, line 26 skipping to change at page 7, line 23
Sites that need for relay agents to specify a source port will need Sites that need for relay agents to specify a source port will need
to install new DHCP server and DHCP relay agent software with this to install new DHCP server and DHCP relay agent software with this
feature. If a site installs only DHCP relay agent software with this feature. If a site installs only DHCP relay agent software with this
feature, there is no possibility that the DHCP server will be able to feature, there is no possibility that the DHCP server will be able to
communicate to the relay agent. communicate to the relay agent.
The implementation is advised to allow configuration for 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 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. relay agent either using a normal DHCP UDP port or non-DHCP UDP port.
6. A DHCPv6 Cascaded Relay Example 6. An IPv6 Cascaded Relay Example
An example of DHCPv6 cascaded relay agents with the "Relay Source An example of IPv6 cascaded relay agents with the "Relay Source Port
Port Option" is shown below. 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 IPv6 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 (not 547). Relay2 is the
device of Relay1. upstream 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
that the UDP source port used by Relay1 is 1000. Relay2 will include that the UDP source port used by Relay1 is 1000. Relay2 will include
the "Relay Source Port Option" and it sets the "Downstream Source the "Relay Source Port Option" and it sets the "Downstream Source
Port" field in the option to 1000. The DHCPv6 server copies the Port" field in the option to 1000. The IPv6 server copies the "Relay
"Relay Source Port Option" when replying with the Relay-reply Source Port Option" when replying with the Relay-reply message.
message.
When Relay2 receives the Relay-reply message with the "Relay Source When Relay2 receives the Relay-reply message with the "Relay Source
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 IPv6 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 an IPv6 client.
7. IANA Considerations 7. IANA Considerations
A new sub-option, DHCP Relay Source Port, is defined in this document A new sub-option, DHCPv4 Relay Source Port, is defined in this
within the DHCP Relay Agent Information Option. It needs to be document within the IPv4 Relay Agent Information Option. It needs to
assigned by IANA from the DHCP Relay Agent sub-options space be assigned by IANA in the "DHCP Relay Agent Sub-Option Codes"
[RFC3046]. registry, http://www.iana.org/assignments/bootp-dhcp-parameters as
specified in [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, in the "Option Codes" registry for DHCPv6,
http://www.iana.org/assignments/dhcpv6-parameters as specified in
[RFC3315].
8. Security Considerations 8. Security Considerations
If the network uses firewall to block or allow DHCP packets with both [RFC3118] and [RFC3315] described many of the threats in using DHCP.
static UDP source and destination port numbers, this may no longer This extension does not raise addition security issues.
match the packets from new DHCP relay agent and server software. The
firewall rules need to be modified only to match the DHCP server side Although if the network uses firewall to block or allow DHCP packets
of the UDP port number, and if necessary, IP addresses and other with both static UDP source and destination port numbers, this may no
attributes. longer match the packets from new DHCP relay agent and server
software. The 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 attributes.
9. Acknowledgments 9. Acknowledgments
The authors would like to thank Peter Arberg, Bhanu Gopalasetty, The authors would like to thank Peter Arberg, Luyuan Fang, Bhanu
Andre Kostur, Ted Lemon, and Kishore Seshadri for their review and Gopalasetty, Andre Kostur, Ted Lemon, Kishore Seshadri and Jackelyn
comments of this document. Shen for their review and comments of this document.
The authors would like to thank Bernie Volz for discussions that led 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. Normative References
10.1. Changes to draft-ietf-dhc-relay-port-04
o Posted the draft in April 2017.
o Rephrased the relay agent and server requirement with this relay
port feature.
10.2. Changes to draft-ietf-dhc-relay-port-03
o Posted the draft in April 2017.
o Added the "Relay Agent and Server Behavior" section.
10.3. Changes to draft-ietf-dhc-relay-port-02
o Posted the draft in February 2017.
o Added the Terminology section.
o Defined the Sub-option and Option names for DHCP and DHCPv6.
o Added the DHCPv6 cascaded relay agents example.
10.4. Changes to draft-ietf-dhc-relay-port-01
o Posted the draft in January 2017.
o Change the DHCPv6 Relay Source Port Option, UDP Source Port field
to Downstream Source Port. Add the option handling mechanism for
DHCPv6 server and relay agents.
10.5. Changes to draft-ietf-dhc-relay-port-00
o Posted first version of working group draft in October 2016.
o This draft was renamed from draft-shen-dhc-client-port-03.txt.
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,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, DOI 10.17487/RFC2131, March 1997, RFC 2131, DOI 10.17487/RFC2131, March 1997,
<http://www.rfc-editor.org/info/rfc2131>. <http://www.rfc-editor.org/info/rfc2131>.
[RFC3046] Patrick, M., "DHCP Relay Agent Information Option", [RFC3046] Patrick, M., "DHCP Relay Agent Information Option",
RFC 3046, DOI 10.17487/RFC3046, January 2001, RFC 3046, DOI 10.17487/RFC3046, January 2001,
<http://www.rfc-editor.org/info/rfc3046>. <http://www.rfc-editor.org/info/rfc3046>.
[RFC3118] Droms, R., Ed. and W. Arbaugh, Ed., "Authentication for
DHCP Messages", RFC 3118, DOI 10.17487/RFC3118, June 2001,
<http://www.rfc-editor.org/info/rfc3118>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <http://www.rfc-editor.org/info/rfc3315>. 2003, <http://www.rfc-editor.org/info/rfc3315>.
Authors' Addresses Authors' Addresses
Naiming Shen Naiming Shen
Cisco Systems Cisco Systems
560 McCarthy Blvd. 560 McCarthy Blvd.
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