draft-ietf-dhc-dhcpv4-over-dhcpv6-09.txt   rfc7341.txt 
DHC Working Group Q. Sun Internet Engineering Task Force (IETF) Q. Sun
Internet-Draft Y. Cui Request for Comments: 7341 Y. Cui
Intended status: Standards Track Tsinghua University Category: Standards Track Tsinghua University
Expires: December 13, 2014 M. Siodelski ISSN: 2070-1721 M. Siodelski
ISC ISC
S. Krishnan S. Krishnan
Ericsson Ericsson
I. Farrer I. Farrer
Deutsche Telekom AG Deutsche Telekom AG
June 11, 2014 August 2014
DHCPv4 over DHCPv6 Transport DHCPv4-over-DHCPv6 (DHCP 4o6) Transport
draft-ietf-dhc-dhcpv4-over-dhcpv6-09
Abstract Abstract
IPv4 connectivity is still needed as networks migrate towards IPv6. IPv4 connectivity is still needed as networks migrate towards IPv6.
Users require IPv4 configuration even if the uplink to their service Users require IPv4 configuration even if the uplink to their service
provider supports IPv6 only. This document describes a mechanism for provider supports IPv6 only. This document describes a mechanism for
obtaining IPv4 configuration information dynamically in IPv6 networks obtaining IPv4 configuration information dynamically in IPv6 networks
by carrying DHCPv4 messages over DHCPv6 transport. Two new DHCPv6 by carrying DHCPv4 messages over DHCPv6 transport. Two new DHCPv6
messages and two new DHCPv6 options are defined for this purpose. messages and two new DHCPv6 options are defined for this purpose.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
This Internet-Draft will expire on December 13, 2014. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7341.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 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
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction ....................................................3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language ...........................................3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology .....................................................3
4. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Applicability ...................................................4
5. Architecture Overview . . . . . . . . . . . . . . . . . . . . 4 5. Architecture Overview ...........................................4
6. New DHCPv6 Messages . . . . . . . . . . . . . . . . . . . . . 5 6. New DHCPv6 Messages .............................................6
6.1. Message Types . . . . . . . . . . . . . . . . . . . . . . 6 6.1. Message Types ..............................................6
6.2. Message Formats . . . . . . . . . . . . . . . . . . . . . 6 6.2. Message Formats ............................................6
6.3. DHCPv4-query Message Flags . . . . . . . . . . . . . . . 7 6.3. DHCPv4-query Message Flags .................................7
6.4. DHCPv4-response Message Flags . . . . . . . . . . . . . . 7 6.4. DHCPv4-response Message Flags ..............................7
7. New DHCPv6 Options . . . . . . . . . . . . . . . . . . . . . 7 7. New DHCPv6 Options ..............................................7
7.1. DHCPv4 Message Option Format . . . . . . . . . . . . . . 7 7.1. DHCPv4 Message Option Format ...............................7
7.2. 4o6 Server Address Option Format . . . . . . . . . . . . 8 7.2. DHCP 4o6 Server Address Option Format ......................8
8. Use of the DHCPv4-query Unicast Flag . . . . . . . . . . . . 9 8. Use of the DHCPv4-query Unicast Flag ............................9
9. DHCP 4o6 Client Behavior . . . . . . . . . . . . . . . . . . 10 9. DHCP 4o6 Client Behavior .......................................10
10. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . 12 10. Relay Agent Behavior ..........................................12
11. DHCP 4o6 Server Behavior . . . . . . . . . . . . . . . . . . 12 11. DHCP 4o6 Server Behavior ......................................12
12. Security Considerations . . . . . . . . . . . . . . . . . . . 13 12. Security Considerations .......................................13
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 13. IANA Considerations ...........................................14
14. Contributors List . . . . . . . . . . . . . . . . . . . . . . 14 14. Contributors List .............................................14
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 15. References ....................................................14
15.1. Normative References . . . . . . . . . . . . . . . . . . 14 15.1. Normative References .....................................14
15.2. Informative References . . . . . . . . . . . . . . . . . 15 15.2. Informative References ...................................15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
As the migration towards IPv6 continues, IPv6-only networks will As the migration towards IPv6 continues, IPv6-only networks will
become more prevalent. In such networks, IPv4 connectivity will become more prevalent. In such networks, IPv4 connectivity will
continue to be provided as a service over IPv6-only networks. In continue to be provided as a service over IPv6-only networks. In
addition to provisioning IPv4 addresses for clients of this service, addition to provisioning IPv4 addresses for clients of this service,
other IPv4 configuration parameters may also be needed (e.g. other IPv4 configuration parameters may also be needed (e.g.,
addresses of IPv4-only services). addresses of IPv4-only services).
This document describes a transport mechanism to carry DHCPv4 This document describes a transport mechanism to carry DHCPv4
messages using the DHCPv6 protocol for the dynamic provisioning of messages using the DHCPv6 protocol for the dynamic provisioning of
IPv4 addresses and other DHCPv4 specific configuration parameters IPv4 addresses and other DHCPv4 specific configuration parameters
across IPv6-only networks. It leverages the existing DHCPv4 across IPv6-only networks. It leverages the existing DHCPv4
infrastructure, e.g. failover, DNS updates, DHCP Leasequery, etc. infrastructure, e.g., failover, DNS updates, DHCP Leasequery, etc.
When IPv6 multicast is used to transport 4o6 messages, another When IPv6 multicast is used to transport DHCP 4o6 messages, another
benefit is that the operator can gain information about the benefit is that the operator can gain information about the
underlying IPv6 network the 4o6 client is connected to from the the underlying IPv6 network to which the DHCP 4o6 client is connected
DHCPv6 relay agents the request has passed through. from the DHCPv6 relay agents through which the request has passed.
2. Requirements Language 2. 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 [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Terminology 3. Terminology
This document makes use of the following terms: This document makes use of the following terms:
CPE: Customer Premises Equipment (also CPE:
known as Customer Provided Customer Premises Equipment (also known as Customer Provided
Equipment), which provides access for Equipment), which provides access for devices connected to a Local
devices connected to a Local Area Area Network (LAN), typically at the customer's site/home, to the
Network (typically at the customer's Internet Service Provider's (ISP's) network.
site/home) to the Internet Service
Provider's network.
DHCP 4o6 client (or client): A DHCP client supporting both the DHCP 4o6 client (or client):
DHCPv6 protocol [RFC3315] as well as A DHCP client supporting both the DHCPv6 protocol [RFC3315] as
the DHCPv4 over DHCPv6 protocol well as the DHCPv4 over DHCPv6 protocol described in this
described in this document. Such a document. Such a client is capable of requesting IPv6
client is capable of requesting IPv6 configuration using DHCPv6 and IPv4 configuration using DHCPv4
configuration using DHCPv6 and IPv4 over DHCPv6.
configuration using DHCPv4 over
DHCPv6.
DHCP 4o6 server (or server): A DHCP server that is capable of DHCP 4o6 server (or server):
processing DHCPv4 packets A DHCP server that is capable of processing DHCPv4 packets
encapsulated in the DHCPv4 Message encapsulated in the DHCPv4 Message option (defined below).
option (defined below).
DHCPv4 over DHCPv6: A protocol described in this DHCPv4 over DHCPv6:
document, used to carry DHCPv4 A protocol (described in this document) used to carry DHCPv4
messages in the payload of DHCPv6 messages in the payload of DHCPv6 messages.
messages.
4. Applicability 4. Applicability
The mechanism described in this document is not universally The mechanism described in this document is not universally
applicable. This is intended as a special-purpose mechanism that applicable. This is intended as a special-purpose mechanism that
will be implemented on nodes that must obtain IPv4 configuration will be implemented on nodes that must obtain IPv4 configuration
information using DHCPv4 in specific environments where native DHCPv4 information using DHCPv4 in specific environments where native DHCPv4
is not available. Such nodes are expected to follow the advice in is not available. Such nodes are expected to follow the advice in
the "client behavior" section; nodes that do not require this Section 9; nodes that do not require this functionality are expected
functionality are expected not to implement it, or not to enable it not to implement it, or not to enable it by default. This mechanism
by default. This mechanism may be enabled using an administrative may be enabled using an administrative control, or it may be enabled
control, or may be enabled automatically in accordance with the needs automatically in accordance with the needs of some dual-stack
of some dual-stack transition mechanism such as transition mechanism such as [LW4OVER6]. Such mechanisms are beyond
[I-D.ietf-softwire-lw4over6]. Such mechanisms are beyond the scope the scope of this document.
of this document.
5. Architecture Overview 5. Architecture Overview
The architecture described here addresses a typical use case, where a The architecture described here addresses a typical use case, where a
DHCP client's uplink supports IPv6 only and the Service Provider's DHCP client's uplink supports IPv6 only and the Service Provider's
network supports IPv6 and limited IPv4 services. In this scenario, network supports IPv6 and limited IPv4 services. In this scenario,
the client can only use the IPv6 network to access IPv4 services, so the client can only use the IPv6 network to access IPv4 services, so
IPv4 services must be configured using IPv6 as the underlying network IPv4 services must be configured using IPv6 as the underlying network
protocol. protocol.
Although the purpose of this document is to address the problem of Although the purpose of this document is to address the problem of
communication between the DHCPv4 client and the DHCPv4 server, the communication between the DHCPv4 client and the DHCPv4 server, the
mechanism that it describes does not restrict the transported mechanism that it describes does not restrict the transported
messages types to DHCPv4 only. As the DHCPv4 message is a special messages types to DHCPv4 only. As the DHCPv4 message is a special
type of BOOTP message, BOOTP messages [RFC0951] MAY also be type of BOOTP message, BOOTP messages [RFC951] MAY also be
transported using the same mechanism. transported using the same mechanism.
DHCP clients may be running on CPE devices, end hosts or any other DHCP clients may be running on CPE devices, end hosts, or any other
device that supports the DHCP client function. This document uses device that supports the DHCP-client function. This document uses
the CPE as an example for describing the mechanism. This does not the CPE as an example for describing the mechanism. This does not
preclude any end-host, or other device requiring IPv4 configuration, preclude any end host, or other device requiring IPv4 configuration,
from implementing DHCPv4 over DHCPv6 in the future. from implementing DHCPv4 over DHCPv6 in the future.
This mechanism works by carrying DHCPv4 messages encapsulated within This mechanism works by carrying DHCPv4 messages encapsulated within
the newly defined DHCPv6 messages. The DHCPv6 relay encapsulation is the newly defined DHCPv6 messages. The DHCPv6-relay encapsulation is
used solely to deliver DHCPv4 packets to a DHCPv4-capable server, and used solely to deliver DHCPv4 packets to a DHCPv4-capable server, and
do not allocate any IPv6 addresses nor provide IPv6 configuration does not allocate any IPv6 addresses nor does it provide
information to the client. Figure 1, below, illustrates one possible IPv6-configuration information to the client. Figure 1, below,
deployment architecture of this mechanism. illustrates one possible deployment architecture of this mechanism.
The DHCP 4o6 client implements a new DHCPv6 message called The DHCP 4o6 client implements a new DHCPv6 message called
DHCPv4-query, which contains a new option called the DHCPv4 Message DHCPv4-query, which carries a DHCPv4 message encapsulated in the new
option encapsulating a DHCPv4 message sent by the client. The format DHCPv4 Message option. The DHCPv6 message can be transmitted either
of this option is described in Section 7.1. via DHCPv6 Relay Agents or directly to the DHCP 4o6 server.
The DHCPv6 message can be transmitted either via DHCPv6 Relay Agents The server replies with a new DHCPv6 message called DHCPv4-response,
or directly to the DHCP 4o6 server. The server replies with a which carries the DHCPv4 message from the server, encapsulated in the
DHCPv4-response message, which is a new DHCPv6 message carrying the DHCPv4 Message option.
DHCPv4 response encapsulated in the DHCPv4 Message option.
_____________ _____________ _____________ _____________
/ \ / \ / \ / \
| | | | | | | |
+--------+-+ IPv6 +-+-----------+-+ IPv6 +-+--------+ +--------+-+ IPv6 +-+-----------+-+ IPv6 +-+--------+
| DHCP 4o6 | network | DHCPv6 | network | DHCP 4o6 | | DHCP 4o6 | Network | DHCPv6 | Network | DHCP 4o6 |
| client +---------+ Relay Agent +---------+ Server | | Client +---------+ Relay Agent +---------+ Server |
| (on CPE) | | | | | | (on CPE) | | | | |
+--------+-+ +-+-----------+-+ +-+--------+ +--------+-+ +-+-----------+-+ +-+--------+
| | | | | | | |
\_____________/ \_____________/ \_____________/ \_____________/
Figure 1: Architecture Overview Figure 1: Architecture Overview
Before the client can use DHCPv4 over DHCPv6, it MUST obtain the Before the client can use DHCPv4 over DHCPv6, it MUST obtain the
necessary IPv6 configuration. The client requests the 4o6 Server necessary IPv6 configuration. The client requests the DHCP 4o6
Address option from the server by sending the option code in Option Server Address option from the server by sending the option code in
Request option as described in [RFC3315]. If the server responds an Option Request option as described in [RFC3315]. If the server
with the 4o6 Server Address option, it is an indication to the client responds with the DHCP 4o6 Server Address option, it is an indication
to attempt using DHCPv4 over DHCPv6 to obtain IPv4 configuration. to the client to attempt using DHCPv4 over DHCPv6 to obtain IPv4
Otherwise, the client MUST NOT use DHCPv4 over DHCPv6 to request IPv4 configuration. Otherwise, the client MUST NOT use DHCPv4 over DHCPv6
configuration. to request IPv4 configuration.
The client obtains the address(es) of the DHCP 4o6 server(s) from the The client obtains the address(es) of the DHCP 4o6 server(s) from the
4o6 Server Address option and uses them to communicate with the DHCP DHCP 4o6 Server Address option and uses it (them) to communicate with
4o6 servers as described in Section 9. If the 4o6 Server Address the DHCP 4o6 servers as described in Section 9. If the DHCP 4o6
option contains no addresses (is empty), the client uses the well- Server Address option contains no addresses (is empty), the client
known All_DHCP_Relay_Agents_and_Servers multicast address to uses the well-known All_DHCP_Relay_Agents_and_Servers multicast
communicate with the DHCP 4o6 server(s). address to communicate with the DHCP 4o6 server(s).
Before applying for an IPv4 address via a DHCPv4-query message, the Before applying for an IPv4 address via a DHCPv4-query message, the
client must identify a suitable network interface for the address. client must identify a suitable network interface for the address.
Once the request is acknowledged by the server, the client can Once the request is acknowledged by the server, the client can
configure the address and other relevant parameters on this configure the address and other relevant parameters on this
interface. The mechanism for determining a suitable interface is out interface. The mechanism for determining a suitable interface is out
of the scope of the document. of the scope of the document.
6. New DHCPv6 Messages 6. New DHCPv6 Messages
Two new DHCPv6 messages carry DHCPv4 messages between the client and Two new DHCPv6 messages carry DHCPv4 messages between the client and
the server using the DHCPv6 protocol: DHCPv4-query and the server using the DHCPv6 protocol: DHCPv4-query and
DHCPv4-response. This section describes the structures of these DHCPv4-response. This section describes the structures of these
messages. messages.
6.1. Message Types 6.1. Message Types
DHCPV4-QUERY (TBD): The DHCP 4o6 client sends a DHCPv4-query DHCPV4-QUERY (20): The DHCP 4o6 client sends a DHCPv4-query message
message to a DHCP 4o6 server. The DHCPv4 to a DHCP 4o6 server. The DHCPv4 Message option carried by this
Message option carried by this message message contains a DHCPv4 message that the DHCP 4o6 client uses to
contains a DHCPv4 message that the DHCP 4o6 request IPv4 configuration parameters from the server.
client uses to request IPv4 configuration
parameters from the server.
DHCPv4-RESPONSE (TBD): A DHCP 4o6 server sends a DHCPv4-response DHCPV4-RESPONSE (21): A DHCP 4o6 server sends a DHCPv4-response
message to a DHCP 4o6 client. It contains a message to a DHCP 4o6 client. It contains a DHCPv4 Message option
DHCPv4 Message option carrying a DHCPv4 carrying a DHCPv4 message in response to a DHCPv4 message received
message in response to a DHCPv4 message by the server in the DHCPv4 Message option of the DHCPv4-query
received by the server in the DHCPv4 Message message.
option of the DHCPv4-query message.
6.2. Message Formats 6.2. Message Formats
Both DHCPv6 messages defined in this document share the following Both DHCPv6 messages defined in this document share the following
format: format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg-type | flags | | msg-type | flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. options . . options .
. (variable) . . (variable) .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The format of DHCPv4-query and DHCPv4-response messages Figure 2: The Format of DHCPv4-query and DHCPv4-response Messages
msg-type Identifies the message type. It can be either msg-type: Identifies the message type. It can be either
DHCPV4-QUERY (TBD) or DHCPV4-RESPONSE (TBD) DHCPV4-QUERY (20) or DHCPV4-RESPONSE (21) corresponding to the
corresponding to the contained DHCPv4-query or contained DHCPv4-query or DHCPv4-response, respectively.
DHCPv4-response, respectively.
flags Specifies flags providing additional information flags: Specifies flags providing additional information required by
required by the server to process the DHCPv4 message the server to process the DHCPv4 message encapsulated in the
encapsulated in the DHCPv4-query message, or required DHCPv4-query message, or required by the client to process a
by the client to process a DHCPv4 message DHCPv4 message encapsulated in the DHCPv4-response message.
encapsulated in the DHCPv4-response message.
options Options carried by the message. The DHCPv4 Message options: Options carried by the message. The DHCPv4 Message Option
Option (described in Section 7.1) MUST be carried by (described in Section 7.1) MUST be carried by the message. Only
the message. Only DHCPv6 options for IPv4 DHCPv6 options for IPv4 configuration may be included in this
configuration may be included in this field. It MUST field. It MUST NOT contain DHCPv6 options related solely to IPv6,
NOT contain DHCPv6 options related solely to IPv6, or or IPv6-only service configuration.
IPv6-only service configuration.
6.3. DHCPv4-query Message Flags 6.3. DHCPv4-query Message Flags
The "flags" field of the DHCPv4-query is used to carry additional The "flags" field of the DHCPv4-query is used to carry additional
information that may be used by the server to process the information that may be used by the server to process the
encapsulated DHCPv4 message. Currently only one bit of this field is encapsulated DHCPv4 message. Currently, only one bit of this field
used. Remaining bits are reserved for the future use. The "flags" is used. Remaining bits are reserved for the future use. The
field has the following format: "flags" field has the following format:
0 1 2 0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|U| MBZ | |U| MBZ |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: DHCPv4-query flags format Figure 3: DHCPv4-query Flags Format
U Unicast Flag. If set to 1, it indicates that the U: Unicast flag. If set to 1, it indicates that the DHCPv4 message
DHCPv4 message encapsulated within the DHCPv4-query encapsulated within the DHCPv4-query message would be sent to a
message would be sent to a unicast address if it was unicast address if it were sent using IPv4. If this flag is set
sent using IPv4. If this flag is set to 0, it to 0, it indicates that the DHCPv4 message would be sent to the
indicates that the DHCPv4 message would be sent to broadcast address if it were sent using IPv4. The usage of the
the broadcast address if it was sent using IPv4. The flag is described in detail in Section 8.
usage of the flag is described in detail in
Section 8.
MBZ Bits MUST be set to zero when sending and MUST be MBZ: Bits MUST be set to zero when sending and MUST be ignored when
ignored when receiving. receiving.
6.4. DHCPv4-response Message Flags 6.4. DHCPv4-response Message Flags
This document introduces no flags to be carried in the "flags" field This document introduces no flags to be carried in the "flags" field
of the DHCPv4-response message. They are all reserved for the future of the DHCPv4-response message. They are all reserved for future
use. The DHCP 4o6 server MUST set all bits of this field to 0 and use. The DHCP 4o6 server MUST set all bits of this field to 0 and
the DHCP 4o6 client MUST ignore the content in this field. the DHCP 4o6 client MUST ignore the content in this field.
7. New DHCPv6 Options 7. New DHCPv6 Options
7.1. DHCPv4 Message Option Format 7.1. DHCPv4 Message Option Format
The DHCPv4 Message option carries a DHCPv4 message that is sent by The DHCPv4 Message option carries a DHCPv4 message that is sent by
the client or the server. Such messages exclude any IP or UDP the client or the server. Such messages exclude any IP or UDP
headers. headers.
skipping to change at page 8, line 16 skipping to change at page 8, line 18
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. DHCPv4-message . . DHCPv4-message .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: DHCPv4 Message option Format Figure 4: DHCPv4 Message Option Format
option-code OPTION_DHCPV4_MSG (TBD). option-code: OPTION_DHCPV4_MSG (87).
option-len Length of the DHCPv4 message. option-len: Length of the DHCPv4 message.
DHCPv4-message The DHCPv4 message sent by the client or the server. DHCPv4-message: The DHCPv4 message sent by the client or the server.
In a DHCPv4-query message it contains a DHCPv4 In a DHCPv4-query message, it contains a DHCPv4 message sent by a
message sent by a client. In a DHCPv4-response client. In a DHCPv4-response message, it contains a DHCPv4
message it contains a DHCPv4 message sent by a server message sent by a server in response to a client.
in response to a client.
7.2. 4o6 Server Address Option Format 7.2. DHCP 4o6 Server Address Option Format
The 4o6 Server Address option is sent by a server to a client The DHCP 4o6 Server Address option is sent by a server to a client
requesting IPv6 configuration using DHCPv6 [RFC3315]. It carries a requesting IPv6 configuration using DHCPv6 [RFC3315]. It carries a
list of DHCP 4o6 servers' IPv6 addresses that the client should list of DHCP 4o6 servers' IPv6 addresses that the client should
contact to obtain IPv4 configuration. This list may include contact to obtain IPv4 configuration. This list may include
multicast and unicast addresses. The client sends its requests to multicast and unicast addresses. The client sends its requests to
all unique addresses carried in this option. all unique addresses carried in this option.
This option may also carry no IPv6 addresses, which instructs the This option may also carry no IPv6 addresses, which instructs the
client to use the All_DHCP_Relay_Agents_and_Servers multicast address client to use the All_DHCP_Relay_Agents_and_Servers multicast address
as the destination address. as the destination address.
The presence of this option in the server's response indicates to the The presence of this option in the server's response indicates to the
client that it should use DHCPv4 over DHCPv6 to obtain IPv4 client that it should use DHCPv4 over DHCPv6 to obtain IPv4
configuration. If the option is absent, the client MUST NOT enable configuration. If the option is absent, the client MUST NOT enable
DHCPv4-over-DHCPv6 function. DHCPv4-over-DHCPv6 functionality.
The format of the 4o6 Server Address option is: The format of the DHCP 4o6 Server Address option is:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. IPv6 Address(es) . . IPv6 Address(es) .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: 4o6 Servers Address Option Format Figure 5: DHCP 4o6 Servers Address Option Format
option-code OPTION_DHCP4_O_DHCP6_SERVER (TBD). option-code: OPTION_DHCP4_O_DHCP6_SERVER (88).
option-len Length of the IPv6 address(es) carried by the option, option-len: Length of the IPv6 address(es) carried by the option,
i.e. multiple of 16 octets. Minimal length of this i.e., multiple of 16 octets. Minimal length of this option is 0.
option is 0.
IPv6 Address Zero or more IPv6 addresses of the DHCP 4o6 IPv6 Address: Zero or more IPv6 addresses of the DHCP 4o6 server(s).
Server(s).
8. Use of the DHCPv4-query Unicast Flag 8. Use of the DHCPv4-query Unicast Flag
A DHCPv4 client conforming to [RFC2131] may send its DHCPREQUEST A DHCPv4 client conforming to [RFC2131] may send its DHCPREQUEST
message to either a broadcast or unicast address depending on its message to either a broadcast or unicast address depending on its
state. For example, a client in the RENEWING state uses a unicast state. For example, a client in the RENEWING state uses a unicast
address to contact the DHCPv4 server to renew its lease. A client in address to contact the DHCPv4 server to renew its lease. A client in
the REBINDING state uses a broadcast address. the REBINDING state uses a broadcast address.
In DHCPv4 over DHCPv6, IPv6 is used to deliver DHCPv4 messages to the In DHCPv4 over DHCPv6, IPv6 is used to deliver DHCPv4 messages to the
DHCP 4o6 server. There is no relation between the outer IPv6 address DHCP 4o6 server. There is no relation between the outer IPv6 address
and the inner DHCPv4 message. As a result, the server is unable to and the inner DHCPv4 message. As a result, the server is unable to
determine whether the received DHCPv4 messages should have been sent determine whether the received DHCPv4 messages should have been sent
using broadcast or unicast in IPv4 by checking the IPv6 address. using broadcast or unicast in IPv4 by checking the IPv6 address.
In order to allow the server to determine the client's state, the In order to allow the server to determine the client's state, the
"Unicast" flag is carried in the DHCPv4-query message. The client Unicast flag is carried in the DHCPv4-query message. The client MUST
MUST set this flag to 1 when the DHCPv4 message would have been sent set this flag to 1 when the DHCPv4 message would have been sent to
to the unicast address if using DHCPv4 over IPv4. This flag MUST be the unicast address if using DHCPv4 over IPv4. This flag MUST be set
set to 0 if the DHCPv4 client would have sent the message to the to 0 if the DHCPv4 client would have sent the message to the
broadcast address in IPv4. The choice whether a given message should broadcast address in IPv4. The choice whether a given message should
be sent to a broadcast or unicast address is made based on the be sent to a broadcast or unicast address is made based on the
[RFC2131] and its extensions. [RFC2131] and its extensions.
Note: The "Unicast" flag reflects how the DHCPv4 packet would have Note: The Unicast flag reflects how the DHCPv4 packet would have been
been sent; not how the DHCPv6 packet itself is sent. sent; not how the DHCPv6 packet itself is sent.
9. DHCP 4o6 Client Behavior 9. DHCP 4o6 Client Behavior
The client MUST obtain necessary IPv6 configuration from a DHCPv6 The client MUST obtain necessary IPv6 configuration from a DHCPv6
server before using DHCPv4 over DHCPv6. The client requests the 4o6 server before using DHCPv4 over DHCPv6. The client requests the DHCP
Server Address option using Option Request option (ORO) in every 4o6 Server Address option using the Option Request option (ORO) in
Solicit, Request, Renew, Rebind and Information-request message. If every Solicit, Request, Renew, Rebind, and Information-request
the DHCPv6 server includes the 4o6 Server Address option in its message. If the DHCPv6 server includes the DHCP 4o6 Server Address
response, it is an indication that the client can use DHCPv4 over option in its response, it is an indication that the client can use
DHCPv6 to obtain the IPv4 configuration (by sending DHCPv4 messages DHCPv4 over DHCPv6 to obtain the IPv4 configuration (by sending
encapsulated in DHCPv4-query messages). DHCPv4 messages encapsulated in DHCPv4-query messages).
The client MUST NOT use DHCPv4 over DHCPv6 to request IPv4 The client MUST NOT use DHCPv4 over DHCPv6 to request IPv4
configuration if the DHCPv6 server does not include the 4o6 Server configuration if the DHCPv6 server does not include the DHCP 4o6
Address option. If the IPv6 configuration that contained the 4o6 Server Address option. If the IPv6 configuration that contained the
Server Address option subsequently expires, or if the renewed IPv6 DHCP 4o6 Server Address option subsequently expires, or if the
configuration does not contain the 4o6 Server Address option, the renewed IPv6 configuration does not contain the DHCP 4o6 Server
client MUST stop using DHCPv4 over DHCPv6 to request or renew IPv4 Address option, the client MUST stop using DHCPv4 over DHCPv6 to
configuration. However, the client continues to request 4o6 Server request or renew IPv4 configuration. However, the client continues
Address option in the messages sent to the DHCPv6 server as long as to request DHCP 4o6 Server Address option in the messages sent to the
it desires to use DHCPv4 over DHCPv6. DHCPv6 server as long as it desires to use DHCPv4 over DHCPv6.
It is possible in a multi-homed configuration for there to be more It is possible in a multihomed configuration for there to be more
than one DHCPv6 configuration active at the same time that contains a than one DHCPv6 configuration containing a DHCP 4o6 Server Address
4o6 Server Address option. In this case, the configurations are Option active at the same time. In this case, the configurations are
treated as being independent, so that when any such configuration is treated as being independent, so that when any such configuration is
active, a DHCPv4-over-DHCPv6 function may be enabled for that active, a DHCPv4-over-DHCPv6 function may be enabled for that
configuration. configuration.
An implementation may also treat such configurations as being An implementation may also treat such configurations as being
exclusive, such that only one is kept active at a time. In this exclusive, such that only one is kept active at a time. In this
case, the client keeps the same configuration active continuously as case, the client keeps the same configuration active continuously as
long as it is valid. If that configuration becomes invalid but one long as it is valid. If that configuration becomes invalid but one
or more other configurations remain valid, the client activates one or more other configurations remain valid, the client activates one
of the remaining valid configurations. of the remaining valid configurations.
Which strategy to follow is dependent on the implementation: keeping Which strategy to follow is dependent on the implementation: keeping
multiple configurations active at the same time may provide useful multiple configurations active at the same time may provide useful
redundancy in some applications, but may be needlessly complex in redundancy in some applications but may be needlessly complex in
other cases. other cases.
If the client receives the 4o6 Server Address option and DHCPv4 If the client receives the DHCP 4o6 Server Address option and DHCPv4
[RFC2131] is used on the interface over which the DHCPv6 option was [RFC2131] is used on the interface over which the DHCPv6 option was
received, the client MUST stop using the IPv4 configuration received received, the client MUST stop using the IPv4 configuration received
using DHCPv4 on this interface. The client MAY send a DHCPRELEASE to using DHCPv4 on this interface. The client MAY send a DHCPRELEASE to
the DHCPv4 server to relinquish an existing lease as described in the DHCPv4 server to relinquish an existing lease as described in
[RFC2131] in section 4.4.6. The client MUST NOT use DHCPv4 on this Section 4.4.6 of [RFC2131]. The client MUST NOT use DHCPv4 on this
interface as long as it receives 4o6 Server Address option in the interface as long as it receives DHCP 4o6 Server Address option in
messages received from the DHCPv6 server. the messages received from the DHCPv6 server.
If the client receives a 4o6 Server Address option that contains no If the client receives a DHCP 4o6 Server Address option that contains
IP addresses, i.e. the option is empty, the client MUST send its no IP addresses, i.e., the option is empty, the client MUST send its
requests to the All_DHCP_Relay_Agents_and_Servers multicast address. requests to the All_DHCP_Relay_Agents_and_Servers multicast address.
If there is a list of IP addresses in the option, the client SHOULD If there is a list of IP addresses in the option, the client SHOULD
send requests to each unique address carried by the option. send requests to each unique address carried by the option.
If the client obtained stateless IPv6 configuration by sending If the client obtained stateless IPv6 configuration by sending an
Information-request message to the server, the client MUST follow the Information-request message to the server, the client MUST follow the
rules in [RFC4242] to periodically refresh the DHCPv4-over-DHCPv6 rules in [RFC4242] to periodically refresh the DHCPv4-over-DHCPv6
configuration (i.e. list of DHCP 4o6 servers) as well as other configuration (i.e., list of DHCP 4o6 servers) as well as other
configuration data. The client which obtained stateful IPv6 configuration data. The client that obtained stateful IPv6
configuration will refresh the status of DHCPv4-over-DHCPv6 function configuration will refresh the status of DHCPv4-over-DHCPv6 function
when extending a lifetime of acquired IPv6 address (Renew and Rebind when extending a lifetime of acquired IPv6 address (Renew and Rebind
messages). messages).
The client MUST employ an IPv6 address of an appropriate scope to The client MUST employ an IPv6 address of an appropriate scope from
source the DHCPv4-query message from. When the client sends a which to source the DHCPv4-query message. When the client sends a
DHCPv4-query message to the multicast address, it MUST use a link- DHCPv4-query message to the multicast address, it MUST use a link-
local address as the source address as described in [RFC3315]. When local address as the source address as described in [RFC3315]. When
the client sends a DHCPv4-query message using unicast, the source the client sends a DHCPv4-query message using unicast, the source
address MUST be an address of appropriate scope, acquired in advance. address MUST be an address of appropriate scope, acquired in advance.
The client generates a DHCPv4 message and stores it verbatim in the The client generates a DHCPv4 message and stores it verbatim in the
DHCPv4 Message option carried by the DHCPv4-query message. The DHCPv4 Message option carried by the DHCPv4-query message. The
client MUST put exactly one DHCPv4 Message option into a single client MUST put exactly one DHCPv4 Message option into a single
DHCPv4-query message. The client MUST NOT request the 4o6 Server DHCPv4-query message. The client MUST NOT request the DHCP 4o6
Address option in the DHCPv4-query message. Server Address option in the DHCPv4-query message.
The client MUST follow rules defined in Section 8 when setting the The client MUST follow the rules defined in Section 8 when setting
Unicast flag based on the DHCPv4 destination. the Unicast flag based on the DHCPv4 destination.
On receiving a DHCPv4-response message, the client MUST look for the On receiving a DHCPv4-response message, the client MUST look for the
DHCPv4 Message option within this message. If this option is not DHCPv4 Message option within this message. If this option is not
found, the DHCPv4-response message is discarded. If the DHCPv4 found, the DHCPv4-response message is discarded. If the DHCPv4
Message option is present, the client extracts the DHCPv4 message it Message option is present, the client extracts the DHCPv4 message it
contains and processes it as described in section 4.4 of [RFC2131]. contains and processes it as described in Section 4.4 of [RFC2131].
When dealing with IPv4 configuration, the client MUST follow the When dealing with IPv4 configuration, the client MUST follow the
normal DHCPv4 retransmission requirements and strategy as specified normal DHCPv4 retransmission requirements and strategy as specified
in section 4.1 of [RFC2131]. There are no explicit transmission in Section 4.1 of [RFC2131]. There are no explicit transmission
parameters associated with a DHCPv4-query message, as this is parameters associated with a DHCPv4-query message, as this is
governed by the DHCPv4 [RFC2131] "state machine". governed by the DHCPv4 "state machine" [RFC2131].
The client MUST implement [RFC4361] to ensure that the device The client MUST implement [RFC4361] to ensure that the device
correctly identifies itself. It MUST send a 'client identifier' correctly identifies itself. It MUST send a 'client identifier'
option when using DHCPv4 over DHCPv6. option when using DHCPv4 over DHCPv6.
10. Relay Agent Behavior 10. Relay Agent Behavior
When a DHCPv6 relay agent receives a DHCPv4-query message, it may not When a DHCPv6 relay agent receives a DHCPv4-query message, it may not
recognize this message. The unknown message MUST be forwarded as recognize this message. The unknown message MUST be forwarded as
described in [I-D.ietf-dhc-dhcpv6-unknown-msg]. described in [RFC7283].
If it recognises the message, the DHCPv6 relay agent MAY allow the A DHCPv6 relay agent that can recognize DHCP 4o6 messages MAY allow
configuration of a dedicated DHCPv4 over DHCPv6 specific destination the configuration of a separate set of destination addresses for such
address(es), differing from the address(es) of the DHCPv6-only messages in addition to the destination addresses used for relaying
server(s). To implement this function, the relay checks the received the other DHCPv6 messages. To implement this function, the relay
DHCPv6 message type and forwards according to the following logic: checks the received DHCPv6 message type and forwards according to the
following logic:
1. If the message type is DHCPV4-QUERY, the packet is relayed to the 1. If the message type is DHCPV4-QUERY, the packet is relayed to the
configured DHCP 4o6 Server's address(es) in the form of normal configured DHCP 4o6 Server's address(es) in the form of a normal
DHCPv6 packet (i.e. DHCPv6/UDP/IPv6). DHCPv6 packet (i.e., DHCPv6/UDP/IPv6).
2. For any other DHCPv6 message type, forward according to section 2. For any other DHCPv6 message type, forward according to section
20 of [RFC3315]. 20 of [RFC3315].
The above logic only allows for separate relay destinations The above logic only allows for separate relay destinations
configured on the relay agent closest to the client (single relay configured on the relay agent closest to the client (single relay
hop). Multiple relaying hops are not considered in the case of hop). Multiple relaying hops are not considered in the case of
separate relay destinations. separate relay destinations.
11. DHCP 4o6 Server Behavior 11. DHCP 4o6 Server Behavior
When the server receives a DHCPv4-query message from a client, it When the server receives a DHCPv4-query message from a client, it
searches for the DHCPv4 Message option. The server discards a packet searches for the DHCPv4 Message option. The server discards a packet
without this option. In addition, the server MAY notify an without this option. In addition, the server MAY notify an
administrator about the receipt of this malformed packet. The administrator about the receipt of this malformed packet. The
mechanism for this notification is out of scope for this document. mechanism for this notification is out of scope for this document.
If the server finds a valid DHCPv4 Message option, it extracts the If the server finds a valid DHCPv4 Message option, it extracts the
original DHCPv4 message. Since the DHCPv4 message is encapsulated in original DHCPv4 message. Since the DHCPv4 message is encapsulated in
the DHCPv6 message, it lacks the information which is typically used the DHCPv6 message, it lacks the information that is typically used
by the DHCPv4 server, implementing [RFC2131], to make address by the DHCPv4 server, implementing [RFC2131], to make address-
allocation decisions, e.g. giaddr for relayed messages and IPv4 allocation decisions, e.g., giaddr for relayed messages and IPv4
address of the interface which the server is using to communicate address of the interface that the server is using to communicate with
with directly connected client. Therefore, the DHCP 4o6 server a directly connected client. Therefore, the DHCP 4o6 server
allocates addresses according to the local address assignment allocates addresses according to the policies on local address
policies determined by the server administrator. For example, if the assignment determined by the server administrator. For example, if
DHCPv4-query message has been sent via a relay, the server MAY use the DHCPv4-query message has been sent via a relay, the server MAY
the link-address field of the Relay-forward message as a lookup for use the link-address field of the Relay-forward message as a lookup
the IPv4 subnet to assign DHCPv4 address from. If the DHCPv4-query for the IPv4 subnet from which to assign a DHCPv4 address. If the
message has been sent from a directly connected client, the server DHCPv4-query message has been sent from a directly connected client,
MAY use IPv6 source address of the message to determine the the server MAY use the IPv6 source address of the message to
appropriate IPv4 subnet to use for DHCPv4 address assignment. determine the appropriate IPv4 subnet to use for DHCPv4 address
assignment.
Alternatively, the server may act as a DHCPv4 relay agent and forward Alternatively, the server may act as a DHCPv4 relay agent and forward
the DHCPv4 packet to a "normal" DHCPv4 server. The details of such a the DHCPv4 packet to a "normal" DHCPv4 server. The details of such a
solution have not been considered by the working group; describing solution have not been considered by the working group; describing
that solution is out of scope of this document and is left as future that solution is out of scope of this document and is left as future
work should the need for it arise. work should the need for it arise.
The server SHOULD use the "flags" field of the DHCPv4-query message The server SHOULD use the "flags" field of the DHCPv4-query message
to create a response (server to client DHCPv4 message). The use of to create a response (server to client DHCPv4 message). The use of
this field is described in detail in Section 8. this field is described in detail in Section 8.
skipping to change at page 13, line 26 skipping to change at page 13, line 29
in the payload of a DHCPv4 Message option, which it puts into the in the payload of a DHCPv4 Message option, which it puts into the
DHCPv4-response message. DHCPv4-response message.
If the DHCPv4-query message was received directly by the server, the If the DHCPv4-query message was received directly by the server, the
DHCPv4-response message MUST be unicast from the interface on which DHCPv4-response message MUST be unicast from the interface on which
the original message was received. the original message was received.
If the DHCPv4-query message was received in a Relay-forward message, If the DHCPv4-query message was received in a Relay-forward message,
the server creates a Relay-reply message with the DHCPv4-response the server creates a Relay-reply message with the DHCPv4-response
message in the payload of a Relay Message option, and responds as message in the payload of a Relay Message option, and responds as
described in section 20.3 of [RFC3315]. described in Section 20.3 of [RFC3315].
12. Security Considerations 12. Security Considerations
In this specification, DHCPv4 messages are encapsulated in the newly In this specification, DHCPv4 messages are encapsulated in the newly
defined option and messages. This is similar to the handling of the defined option and messages. This is similar to the handling of the
current relay agent messages. In order to bypass firewalls or current relay agent messages. In order to bypass firewalls or
network authentication gateways, a malicious attacker may leverage network authentication gateways, a malicious attacker may leverage
this feature to convey other messages using DHCPv6, i.e. use DHCPv6 this feature to convey other messages using DHCPv6, i.e., use DHCPv6
as a form of encapsulation. However, the potential risk from this is as a form of encapsulation. However, the potential risk from this is
no more severe than that with the current DHCPv4 and DHCPv6 practice. no more severe than that with the current DHCPv4 and DHCPv6 practice.
It is possible for a rogue server to reply with a 4o6 Server Address It is possible for a rogue server to reply with a DHCP 4o6 Server
Option containing duplicated IPv6 addresses, which could cause an Address option containing duplicated IPv6 addresses, which could
amplification attack. To avoid this, the client MUST check if there cause an amplification attack. To avoid this, the client MUST check
are duplicate IPv6 addresses in a 4o6 Server Address Option when if there are duplicate IPv6 addresses in a DHCP 4o6 Server Address
receiving one. The client MUST ignore any but the first instance of option when receiving one. The client MUST ignore any but the first
each address. instance of each address.
When considering whether to enable DHCPv4-over-DHCPv6, one important When considering whether to enable DHCPv4-over-DHCPv6, one important
consideration is that when it is enabled, this gives the DHCPv6 consideration is that when it is enabled, this gives the DHCPv6
server the ability to shut off DHCPv4 traffic, and, consequently, server the ability to shut off DHCPv4 traffic, and, consequently,
IPv4 traffic, on the interface that is configured to do DHCPv4-over- IPv4 traffic, on the interface that is configured to do DHCPv4-over-
DHCPv6. For this reason, DHCPv4-over-DHCPv6 should only be enabled DHCPv6. For this reason, DHCPv4-over-DHCPv6 should only be enabled
in situations where there is a clear trust relationship that in situations where there is a clear trust relationship that
eliminates this concern. For instance, a CPE device can safely eliminates this concern. For instance, a CPE device can safely
enable this on its WAN interface, because it is reasonable to assume enable this on its WAN interface, because it is reasonable to assume
that an ISP will not accidentally configure DHCPv4 over DHCPv6 that an ISP will not accidentally configure DHCPv4 over DHCPv6
service on that link, and that it will be impractical for an attacker service on that link, and that it will be impractical for an attacker
to set up a rogue DHCPv6 server in the ISP's network. to set up a rogue DHCPv6 server in the ISP's network.
13. IANA Considerations 13. IANA Considerations
IANA is requested to allocate two DHCPv6 option codes for use by IANA has allocated two DHCPv6 option codes for use by
OPTION_DHCPV4_MSG and OPTION_DHCP4_O_DHCP6_SERVER from the "Option OPTION_DHCPV4_MSG (87) and OPTION_DHCP4_O_DHCP6_SERVER (88) from the
Codes" table, and two DHCPv6 message type codes for the DHCPV4-QUERY "Option Codes" table. Also, IANA has allocated two DHCPv6 message
and DHCPV4-RESPONSE from the "Message Types" table of the Dynamic type codes for the DHCPV4-QUERY (20) and DHCPV4-RESPONSE (21) from
Host Configuration Protocol for IPv6 (DHCPv6) Registry. Both tables the "Message Types" table of the "Dynamic Host Configuration Protocol
can be found at http://www.iana.org/assignments/dhcpv6-parameters/. for IPv6 (DHCPv6)" registry. Both tables can be found at
<http://www.iana.org/assignments/dhcpv6-parameters/>.
14. Contributors List 14. Contributors List
Many thanks to Ted Lemon, Bernie Volz, Tomek Mrugalski, Cong Liu and Many thanks to Ted Lemon, Bernie Volz, Tomek Mrugalski, Cong Liu, and
Yuchi Chen, for their great contributions to the specification. Yuchi Chen for their great contributions to the specification.
15. References 15. References
15.1. Normative References 15.1. Normative References
[I-D.ietf-dhc-dhcpv6-unknown-msg]
Cui, Y., Sun, Q., and T. Lemon, "Handling Unknown DHCPv6
Messages", draft-ietf-dhc-dhcpv6-unknown-msg-08 (work in
progress), March 2014.
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, March 1997. 2131, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC4242] Venaas, S., Chown, T., and B. Volz, "Information Refresh [RFC4242] Venaas, S., Chown, T., and B. Volz, "Information Refresh
Time Option for Dynamic Host Configuration Protocol for Time Option for Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 4242, November 2005. IPv6 (DHCPv6)", RFC 4242, November 2005.
[RFC4361] Lemon, T. and B. Sommerfeld, "Node-specific Client [RFC4361] Lemon, T. and B. Sommerfeld, "Node-specific Client
Identifiers for Dynamic Host Configuration Protocol Identifiers for Dynamic Host Configuration Protocol
Version Four (DHCPv4)", RFC 4361, February 2006. Version Four (DHCPv4)", RFC 4361, February 2006.
[RFC7283] Cui, Y., Sun, Q., and T. Lemon, "Handling Unknown DHCPv6
Messages", RFC 7283, July 2014.
15.2. Informative References 15.2. Informative References
[I-D.ietf-softwire-lw4over6] [LW4OVER6]
Cui, Y., Qiong, Q., Boucadair, M., Tsou, T., Lee, Y., and Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
I. Farrer, "Lightweight 4over6: An Extension to the DS- Farrer, "Lightweight 4over6: An Extension to the DS-Lite
Lite Architecture", draft-ietf-softwire-lw4over6-10 (work Architecture", Work in Progress, June 2014.
in progress), June 2014.
[RFC0951] Croft, B. and J. Gilmore, "Bootstrap Protocol", RFC 951, [RFC951] Croft, B. and J. Gilmore, "Bootstrap Protocol", RFC 951,
September 1985. September 1985.
Authors' Addresses Authors' Addresses
Qi Sun Qi Sun
Tsinghua University Tsinghua University
Beijing 100084 Beijing 100084
P.R.China P.R. China
Phone: +86-10-6278-5822 Phone: +86-10-6278-5822
Email: sunqi@csnet1.cs.tsinghua.edu.cn EMail: sunqi@csnet1.cs.tsinghua.edu.cn
Yong Cui Yong Cui
Tsinghua University Tsinghua University
Beijing 100084 Beijing 100084
P.R.China P.R. China
Phone: +86-10-6260-3059 Phone: +86-10-6260-3059
Email: yong@csnet1.cs.tsinghua.edu.cn EMail: yong@csnet1.cs.tsinghua.edu.cn
Marcin Siodelski Marcin Siodelski
Internet Systems Consortium
950 Charter Street 950 Charter Street
Redwood City, CA 94063 Redwood City, CA 94063
USA USA
Phone: +1 650 423 1431 EMail: msiodelski@gmail.com
Email: msiodelski@gmail.com
Suresh Krishnan Suresh Krishnan
Ericsson Ericsson
8400 Blvd. Decarie
Town of Mount Royal, Quebec
Canada
EMail: suresh.krishnan@ericsson.com
Email: suresh.krishnan@ericsson.com
Ian Farrer Ian Farrer
Deutsche Telekom AG Deutsche Telekom AG
GTN-FM4,Landgrabenweg 151 CTO-ATI, Landgrabenweg 151
Bonn, NRW 53227 Bonn, NRW 53227
Germany Germany
Email: ian.farrer@telekom.de EMail: ian.farrer@telekom.de
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