Network Working Group B. Sarikaya
Internet-Draft F. Xia
Expires: March 12, 2010 Huawei USA
P. Seite
France Telecom
September 8, 2009
DHCPv6 Extension for Configuring Hosts with Multiple Interfaces
draft-sarikaya-mif-dhcpv6solution-02.txt
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Abstract
This document defines a DHCPv6 option to help configure a multi-homed
host's routing table with new entries when the host attaches to a new
network on a new interface.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Configuring Routing Tables of Multi-homed Hosts . . . . . . . . 3
4. DHCPv6 Option . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . . 7
8.2. Informative references . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
Traditional routing considered only the destination address in
IPv4/v6 header. Policy routing on the hand considers all of the
fields in the header sometimes even the payload. In IPv6, the hosts
receive router advertisements containing information useful for
policy routing. However in some networks, e.g. cellular networks,
DHCP servers can be used to help multi-homed mobile nodes configure
their routing tables.
Using a single default route would lead to routing of all flows
through a single interface. Such a configuration makes it impossible
to use multiple interfaces simultaneously if the host is multi-homed.
Requirements of supporting multiple interfaces in hosts without
involving mobility protocols are discussed in
[I-D.williams-mif-problem-scenarios]. DHCP is identified as a
protocol to communicate interface management policies between MIF
nodes and the network.
The IPv6 hosts receive router advertisements and then populate their
Default Router List and Prefix List based on information in the
router advertisements (RA) [RFC2461]. [RFC4191] extended RAs with
Route Information Option and added Default Router Preference. Such
RAs if available would help multi-homed mobile nodes configure better
to enable the simultanenous use of all interfaces.
In this document we define a new DHCPv6 option. This option is to
inform multi-homed hosts about the routes and other useful
information available on the new network that the host has just
connected. It is appropriate to use DHCP for this purpose because
DHCP is already needed for initial configuration of the host's
interface, e.g. for address assignment.
2. Terminology
This document uses the terminology defined in [RFC3315], [RFC3633].
3. Configuring Routing Tables of Multi-homed Hosts
IPv6 routing table contains these entries: prefix, prefix length,
preference value, lifetime, and the address of the next-hop router.
Multi-homed hosts receive configuration information on each
interface. Routers send router advertisements. DHCP servers provide
host configuration information. SDOs are defining servers such as
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Access Network Discovery and Selection Function (ANDSF). ANDSF can
also provide node configuration information on SDO interfaces.
Configuration information helps host set up and update important
databases that the host uses such as the routing table.
Since IPv6 allows multiple unicast addresses to be assigned to
interfaces, IPv6 hosts face the problem of default source and
destination address selection when initiating communication.
[RFC3484] defined algorithms for this purpose.
In this document we extend DHCPv6 with an option called multi-homed
routing policy entry option. Using this option DHCPv6 server can
inform DHCPv6 client on the default routes available on the interface
which the host is about to connect. The option also allows DHCP
server to provide more information on the flows such as the traffic
classes, more sophisticated flow description and Quality of Service
description associated with each interface. The host receives the
route information ordered with priority which allows the host to
select the right interface to start communication.
4. DHCPv6 Option
A new option is defined to carry the host routing information. It is
shown in Figure 1.
DHCP server MAY send a Reply message containing multi-homed routing
policy entry option. DHCP client MUST add an entry to its routing
table based on this option. DHCP client MAY modify other tables such
as Default Router List or Pref List [RFC4191].
DHCP Client MAY include multi-homed routing policy entry option in
Option Request Option [RFC3315] in DHCP Request message. DHCP Server
MUST include multi-homed routing policy entry option in the
corresponding Reply message. The option contains a list of routing
policies, each of them containing the flow description, quality of
service description followed by the route to apply when packet to
forward is matching.
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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_MHRPE | option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FD-length | PID | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Flow Description ... |
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoSD-length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| QoS Description ... |
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prefix-length | |
+-+-+-+-+-+-+-+-+ IPv6 prefix |
| (16 octets) |
| |
| |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | TOS | Reserved +
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Router Address (16 octets) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prefix-length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: DHCP Option
o option-code: OPTION_MHRPE multi-homed routing policy entry option
(TBD)
o Option-length: Total length of prefix-length, IPv6 prefix, TOS and
Reserved fields in octets; It should be a multiple of 36.
o FD-len: length of the flow description.
o PID: The Policy Identifier field is an 8-bit unsigned integer that
includes the identifier for the policy.
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o Flow Description: This field contains flow information such as
flow identifier, priority, etc. This field is of length FD-length
- 8.
o QoSD-length: length of the Quality of Service description.
o QoS Description: This field contains quality of service
information associated with each interface, e.g. on 3G 150kbps for
video on WiFi 400kbps for video. This field is of length QoSD-
length - 16.
o prefix-len: Prefix length of the destination prefix over which the
flow will be routed
o IPv6 prefix: Destination prefix overwhich the flow will be routed
o TOS: Traffic class for the flow, 8 bits
o Reserved: 16 bits set to zero by the sender ignored by the
receiver
o IPv6 Router Address: Deafault router address for this route. This
field is 16 octets.
o Prefix-length: Length of the prefix of IPv6 router address field.
It is 8 bits.
o Reserved: 24 bits set to zero by the sender ignored by the
receiver
5. Security Considerations
This document does not by itself introduce any security issues.
6. IANA Considerations
IANA is requested to assign an option code to the following options
from the option-code space defined in "DHCPv6 Options" section of the
DHCPv6 specification [RFC3315].
Option Name Value Described in
OPTION_MHPTE TBD Section 4
7. Acknowledgements
TBD.
8. References
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8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2629] Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
June 1999.
[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.
[I-D.williams-mif-problem-scenarios]
Williams, C. and J. Qin, "MIF Problem Requirements and
Scenarios", draft-williams-mif-problem-scenarios-00 (work
in progress), July 2009.
[I-D.ietf-mext-flow-binding]
Soliman, H., Montavont, N., and K. Kuladinithi, "Flow
Bindings in Mobile IPv6 and NEMO Basic Support",
draft-ietf-mext-flow-binding-03 (work in progress),
July 2009.
8.2. Informative references
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
[RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and
More-Specific Routes", RFC 4191, November 2005.
[RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461,
December 1998.
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Authors' Addresses
Behcet Sarikaya
Huawei USA
1700 Alma Dr. Suite 500
Plano, TX 75075
Phone: +1 972-509-5599
Email: sarikaya@ieee.org
Frank Xia
Huawei USA
1700 Alma Dr. Suite 500
Plano, TX 75075
Phone: +1 972-509-5599
Email: xiayangsong@huawei.com
Pierrick Seite
France Telecom
4, rue du Clos Courtel
BP 91226
Cesson-Sevigne, 35512
France
Email: pierrick.seite@orange-ftgroup.com
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