One document matched: draft-hu-dhc-dhcpv6-for-dual-stack-hosts-00.txt
DHC Working Group Y. Hu
Internet-Draft ZTE Corporation
Intended status: Standards Track Feb 22, 2011
Expires: August 26, 2011
DHCPV6 for dual-stack hosts
draft-hu-dhc-dhcpv6-for-dual-stack-hosts-00
Abstract
A dual-stack host may wish to obtain IPv4 and/or IPv6 configuration
settings via the Dynamic Host Configuration Protocol (DHCP).Network
operators deploy seperate DHCPv4 servers and DHCPv6 servers,hosts get
IPv4 parameters via DHCPv4 servers and IPv6 parameters via DHCPv6
servers. This document describes a solution,there is only a single
intergrated DHCPv6 server deployed in the ISP network,hosts obtain
both IPv4 and IPv6 configuration settings from this server.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
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
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 26, 2011.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
Hu Expires August 26, 2011 [Page 1]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Definitions and Terminology . . . . . . . . . . . . . . . 4
3. Scenario and Network architecture . . . . . . . . . . . . . . 4
3.1. Get all ip settings using dhcpv6 protocol . . . . . . . . 4
3.2. Get ipv4 settings via protocol translation . . . . . . . . 5
4. Host's implementation and behavior . . . . . . . . . . . . . . 6
4.1. Tyep 1 dual stack host . . . . . . . . . . . . . . . . . . 6
4.2. Tyep 2 dual stack host . . . . . . . . . . . . . . . . . . 7
4.3. Tyep 3 dual stack host . . . . . . . . . . . . . . . . . . 7
5. Server's implementation and behavior . . . . . . . . . . . . . 8
6. Network's behavior . . . . . . . . . . . . . . . . . . . . . . 9
7. General Considerations and protocol translation . . . . . . . 9
7.1. New DHCPv6 Options for IPv4 Parameters . . . . . . . . . . 9
7.2. Protocol translation . . . . . . . . . . . . . . . . . . . 9
8. Other Considerations . . . . . . . . . . . . . . . . . . . . . 10
8.1. Options for location identifing . . . . . . . . . . . . . 10
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. Security Considerations . . . . . . . . . . . . . . . . . . . 11
11. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11
12. Normative references . . . . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12
Hu Expires August 26, 2011 [Page 2]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
1. Introduction
RFC4477 describes issues identified with dual IP version DHCP
interactions and also promotes potential solutions to solve these
issues.There are mainly two solutions:1/ seperate DHCP servers for
IPv6 and IPv4; 2/ a single DHCPv6 server for both IPv6 and IPv4. The
second solution may be to modify DHCPv6 to be able to return IPv4
information.This solution is hinted in the DHCPv6
specification[RFC3315]:"If there is sufficient interest and
demand,integration can be specified in a document that extends DHCPv6
to carry IPv4 addresses and configuration information." This
solution may allow DHCP for IPv4 to be completely replaced by DHCPv6
with additional IPv4 information options, for dual-stack nodes.
This solution would avoid redundancy and simplify management for
servers. But as RFC4477 described,there are also a number of
potential problems with this approach,the most important problem is:
the IPv4 only nodes would not have any DHCP service available to
them,DHCPv4 servers need to be configured anyway to support IPv4-only
hosts.This problem also exists for the dual-stack hosts which can't
obtain IPv4 information using DHCPv6,because the DHCPv6 client
software on these hosts has not been modified and updated.
This document will develop the solution in details,deploying single
DHCPv6 sever which can serve for both IPv6/IPv4 hosts or dual-stack
hosts. The considered aspect of the solution include: host's
implementation and behave/sever's implementation and behave/network's
behave.
In this document, we focus on the specific solution for operating
DHCP in a mixed (typically dual-stack) IPv4 and IPv6 environment
within a single administrative domain.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC2119.
2.1. Abbreviations
DHCP: Dynamic Host Configuration Protocol
DHCPv4: Dynamic Host Configuration Protocol for IPv4
DHCPv6: Dynamic Host Configuration Protocol for IPv6
Hu Expires August 26, 2011 [Page 3]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
CPE: Customer Premises Equipment
BRAS: Broadband Remote Access Server
2.2. Definitions and Terminology
3. Scenario and Network architecture
This section will describe two typical scenarioes.
3.1. Get all ip settings using dhcpv6 protocol
+------+------+
| DHCPv6 | A single DHCPv6 Server which maintains both
| Server | IPv4 and IPv6 setting for endusers(hosts).
+------+--/\--+
_________|__||_______
/ || \
| ISP Core Network |
\____________||_______/
| ||
| ||
+------+--\/--+
| BRAS(PE) | A BRAS or Provider Edge Router.
| | User management/DHCPv6 relay agent
+------+--/\--+
| ||
_________|__\/_____
/ \
| Access Network |
\____________/\_____/
| ||
| ||
+------+--\/--+
| CPE |
+------+--/\--+ /Dual-stack host obtain IPv4/IPv6 settings
| || ------| by sending a DHCPv6 request msg,and
_____|__\/__ | would receive a DHCPv6 reply msg
| dual-stack | | containing the parameters
| host | \which are requested.
|____________|
Figure 1: GET IP SETTINGS USING DHCPV6 PROTOCOL
Hu Expires August 26, 2011 [Page 4]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
In the isp network, a DHCPv6 server would be deployed to config both
IPv4 and IPv6 parameters for hosts. Dual-stack host can certainly
obtain IPv6 settings using DHCPv6 protocol.If it wish to obtain IPv4
settings,it send a DHCPv6 request message containning the new options
designed for IPv4,and the server also return a DHCPv6 reply message
containing the parameters which are requested.
In this scenario,the dhcpv6 client software must be modified and
updated to support that.
3.2. Get ipv4 settings via protocol translation
+------+------+
| DHCPv6 | A single DHCPv6 Server which maintains both
| Server | IPv4 and IPv6 setting for endusers(hosts).
+------+--/\--+ Can only process DHCPv6 messages.
_________|__||_______
/ || \
| ISP Core Network |
\____________||_______/
| ||
| || /
+------+--\/--+ ________ |The DHCPv4 msg send by host should be
| BRAS(PE) | | |translated to DHCPv6 msg and send to
| | | |Server.
+------+--/\--+ | |Also,the DHCPv6 msg replied by Server
| || |----|should be translated to DHCPv4 msg and
_________|__\/_____ | |returned to host.
/ \ | |
| Access Network | | |The point to do translation may be
\____________/\_____/ | |CPE,Access Node or BRAS.In this figure,
| || | \the msg be translated in CPE.
| || |
+------+--\/--+ ________|
| CPE |
+------+--/ \-+ / Dual-stack host can not send a DHCPv6
| ||| -------| request msg to obtain IPv4 settings.
_____|__\ /_ | It is the old type,can only send and
| dual-stack | \ receive DHCPv4 msgs to config IPv4 parameters
| host |
|____________|
Figure 2: COMPATIBILITY AND PROTOCOL TRANSLATION
In this scenario,the DHCPv6 client software on the host has not been
Hu Expires August 26, 2011 [Page 5]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
modified and updated,the hosts can only send and receive DHCPv4
messages to config IPv4 parameters. But the server is DHCPv6
only,can only process DHCPv6 messages,so the DHCPv4 message send by
host should be translated to DHCPv6 message in somewhere and then
send to server.Also, the DHCPv6 message replied by Server should be
translated to DHCPv4 message and then returned to host. The
translation point may be CPE,Access Node or BRAS.
4. Host's implementation and behavior
There would be 3 types of dual stack hosts:
Type 1:old type dual stack, having DHCPv4 client and DHCPv6
client,the DHCPv6 client was not modified.
Type 2:new type dual stack, having DHCPv4 client and DHCPv6
client,the DHCPv6 client has been modified and updated.
Type 3:DHCPv6 only client.
4.1. Tyep 1 dual stack host
+------+------+ +------+------+
| DHCPv6 | | DHCPv4 |
| Client | | Client |
+------+------+ +------+------+
| |
+------+------+ +------+------+
| IPv6 | | IPv4 |
| Stack | | Stack |
+------+------+ +------+------+
| |
+------+----------------+------+
| Link Layer |
+------+----------------+------+
Figure 3: PROTOCOL STACK OF TYPE1 HOST
Hosts of this type have not modified the DHCPv6 client software,so
they can not obtain IPv4 settings using DHCPv6 protocolGBP[not]they
can only use DHCPv4 protocol to get IPv4 parameters.
Hu Expires August 26, 2011 [Page 6]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
4.2. Tyep 2 dual stack host
+---------+-----------+ +----+---+
| DHCPv6 | | DHCPv4 |
| Client | | Client |
+-----+------------+--+ +----+---+
+ + +
+-----+-------+ +-+----------+---+
| IPv6 | | IPv4 |
| Stack | | Stack |
+------+------+ +-------+--------+
| |
+------+-----------------+--------+
| Link Layer |
+------+-----------------+--------+
Figure 4: PROTOCOL STACK OF TYPE2 HOST
Hosts of type 2 can certainly get IPv4/IPv6 settings using DHCPv4/
DHCPv6 client,they can also use DHCPv6 client to get IPv4 settings.
4.3. Tyep 3 dual stack host
+------+----------------+------+
| DHCPv6 |
| Client |
+------+----------------+------+
| |
+------+------+ +------+------+
| IPv6 | | IPv4 |
| Stack | | Stack |
+------+------+ +------+------+
| |
+------+----------------+------+
| Link Layer |
+------+----------------+------+
Figure 5: PROTOCOL STACK OF TYPE3 HOST
Hosts of type 3 have only DHCPv6 client, they obtain both IPv6
settings and IPv4 settings using the DHCPv6 only client.But this type
is the future type, we will mainly disscuss the type 1 and type 2.
Hu Expires August 26, 2011 [Page 7]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
5. Server's implementation and behavior
+---------------+ +----------------+
| IPv6 settings | | IPv4 settings |
| ----------- | | ------------ |
| |IPv6 prefix| | | |IPv4 Address| |
| ----------- | | ------------ |
| ----------- | | ----------- |
| | DNS | | | | DNS | |
| ----------- | | ----------- |
| ... | | ... |
| | | |
+------+--------+ +--------+-------+
| |
| |
+-----------------------------------+
| -------------- -------------- |
| |IPv6 Related | | IPv4 Related | |
| | Strategy | | Strategy | |
| -------------- -------------- |
| Strategy Management |
+-----------------------------------+
| |
+------+--------------------+-------+
| GENERAL DHCPv6 MESSAGE PROCESS |
| |
+------+--------------------+-------+
Figure 6: CONCEPTIONAL IMPLEMENTAION MODEL OF SERVER
The servers are DHCPv6 only,they can only process DHCPv6 messages,so
a general DHCPv6 message process modual must be implemented.
The servers must maintain both ipv6 and ipv4 settings for hosts,these
settings may be:IPv6 prefixs which would be designated or
allocated,IPv4 address pool,information about DNS, and so on.
A Strategy Management Modual should be implemented to decide how to
designate or allocate IP settings for hosts.There would be seperate
strategy for IPv6 or IPv4,and also common strategy for both IPv6 and
IPv4.
Hu Expires August 26, 2011 [Page 8]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
6. Network's behavior
If an ISP has deployed a DHCPv6 server in it's network,which would
serve for dual stack hosts,and the hosts can be divided into Type 1
and Type 2.
Hosts of Type 1 would send DHCPv6 messages to request IPv6 parameters
and send DHCPv4 messages to request IPv4 parameters,if the CPE in
home network can't translate the DHCPv4 messages to DHCPv6 ones,the
messages must be translated in the ISP network, may be in Access Node
or BRAS.
Consider a host of Type 2,how dose it know to request IPv4 settings
using DHCPv4 or DHCPv6? There are two possible solutions:1/the
strategy been manually configured in host; 2/a mechanism for the ISP
network to notify the host,like the mechanism using the M bit and O
bit in RA message(RFC2461 section4.2).
7. General Considerations and protocol translation
7.1. New DHCPv6 Options for IPv4 Parameters
In RFC3315 and other RFCs related to DHCPv6,many options have been
defined to carry IPv6 information and parameters, but there are no
DHCPv6 options been defined to carry IPv4 settings,so new DHCPv6
options need be defined to carry IPv4 information such as IPv4
address.
The new options will be defined in other document.
7.2. Protocol translation
In Figure 2, the protocol translation was executed in CPE, in this
section,we will disccuss the scenario where BRAS do the protocol
translation.
Hu Expires August 26, 2011 [Page 9]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
+------+------+
| DHCPv6 |
| Server |
+------+--/\--+
_________|__||_______
/ || \
| ISP Core Network |
\____________||_______/
| ||
| ||------DHCPv6 message
+------+--\/--+
| BRAS(PE) |
| | ------Protocol translation
+------+--/ \-+
| |||------DHCPv4 message
_________|__\ /____
/ \
| Access Network |
\____________/ \____/
| |||------DHCPv4 message
| |||
+------+--\ /-+
| CPE |
+------+--/ \-+
| |||------DHCPv4 message
_____|__\ /_
| dual-stack |
| host |
|____________|
Figure 7: PROTOCOL TRANSLATION IN BRAS
The DHCPv4 messages send by hosts arrive at the BRAS device,then BRAS
translates the DHCPv4 messages to DHCPv6 correspondent ones and send
to the DHCPv6 server.
The translation can also be executed in Access Node.
8. Other Considerations
8.1. Options for location identifing
There are DHCP options defined to identify the remote connection of
the circuit or used as a host identifier;these options are defined
seperately for DHCPv6 and DHCPv4.For example:RFC3046 defined DHCPv4
option 82(Relay Agent Imformation Option) and 2 suboptions(Agent
Hu Expires August 26, 2011 [Page 10]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
Circuit ID Sub-option/Agent Remote ID Sub-option),RFC3993 defined a
sub-option of option82(Subscriber-ID Suboption),while RFC4649 defined
DHCPv6 option 37(Relay Agent Remote-ID Option) and RFC4580 defined
DHCPv6 option 38(Relay Agent Subscriber-ID Option).
These options are added by the DHCP relay agent and may be processed
by DHCP server.When the DHCP protocol translation be executed, these
options should be processed carefully.
9. IANA Considerations
TBD.
10. Security Considerations
TBD.
11. Acknowledgement
Thanks for the authors of RFC4477.
12. Normative references
[RFC3046] Patrick, M., "DHCP Relay Agent Information Option",
RFC 3046, January 2001.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3993] Johnson, R., Palaniappan, T., and M. Stapp, "Subscriber-ID
Suboption for the Dynamic Host Configuration Protocol
(DHCP) Relay Agent Option", RFC 3993, March 2005.
[RFC4477] Chown, T., Venaas, S., and C. Strauf, "Dynamic Host
Configuration Protocol (DHCP): IPv4 and IPv6 Dual-Stack
Issues", RFC 4477, May 2006.
[RFC4580] Volz, B., "Dynamic Host Configuration Protocol for IPv6
(DHCPv6) Relay Agent Subscriber-ID Option", RFC 4580,
June 2006.
[RFC4649] Volz, B., "Dynamic Host Configuration Protocol for IPv6
(DHCPv6) Relay Agent Remote-ID Option", RFC 4649,
Hu Expires August 26, 2011 [Page 11]
Internet-Draft DHCPV6 for dual-stack hosts Feb 2011
August 2006.
Author's Address
Yuxing Hu
ZTE Corporation
4F,RD Building 2,Zijinghua Road
Yuhuatai District,Nanjing 210012
P.R.China
Email: hu.yuxing@zte.com.cn
Hu Expires August 26, 2011 [Page 12]
| PAFTECH AB 2003-2026 | 2026-04-22 23:17:54 |