Network Working Group B. Sarikaya
Internet-Draft F. Xia
Intended status: Standards Track Huawei USA
Expires: January 2, 2011 P. Seite
France Telecom
July 1, 2010
DHCPv6 Extension for Configuring Hosts with Multiple Interfaces
draft-sarikaya-mif-dhcpv6solution-04.txt
Abstract
This document defines DHCPv6 Options to configure a multi-homed
host's routing table with new entries when the host attaches to a new
network on a new interface.
Status of this Memo
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This Internet-Draft will expire on January 2, 2011.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Configuring Routing Tables of Multi-homed Hosts . . . . . . . 3
4. DHCPv6 Option . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Option Format . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Flow Description Sub-option . . . . . . . . . . . . . . . 6
4.3. QoS Info Sub-option . . . . . . . . . . . . . . . . . . . 6
4.4. Flow Route Prefix Sub-option . . . . . . . . . . . . . . . 7
4.5. IPv6 Router Address Sub-option . . . . . . . . . . . . . . 8
4.6. Interface Info Sub-option . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . . 10
8.2. Informative references . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
Traditional routing considered only the destination address in
IPv4/v6 header. Policy-based routing on the hand considers other
fields in the header sometimes even the payload. In IPv6, the hosts
receive router advertisements (RA) containing information useful for
enforcing policy-based 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.ietf-mif-problem-statement], [I-D.yang-mif-req]. 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 [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 simultaneous use of all interfaces.
In this document we define a new DHCPv6 [RFC3315] 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] and
[RFC3633].
3. Configuring Routing Tables of Multi-homed Hosts
An IPv6 routing table contains these entries (non exhaustive list):
prefix, prefix length, preference value, lifetime, and the address of
the next-hop router.
Multi-homed hosts receive configuration information on each
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interface. Routers send router advertisements. DHCP servers provide
host configuration information. SDOs are defining servers such as
Access Network Discovery and Selection Function (ANDSF) [3GPP23402].
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] defines algorithms for this purpose.
In this document we define a new DHCPv6 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 more
sophisticated flow description. The host receives the route
information ordered with priority which allows the host to select the
right interface to start communication.
DHCP server gets information about host's interface using Interface
Info Sub-option included in the multi-homed routing policy entry
option. A MIF host MAY include one Interface Info Sub-option for
each of its interfaces. A MIF host requesting routing information
MAY set preferred-lifetime to a value in multi-homed routing policy
entry option. DHCP server considers preferred-lifetime value it
received and it sets valid-lifetime value in the reply. Valid-
lifetime value defines the expiration value of the routing policy
entry.
Policy entries are identified using Policy Identifiers (PID). Each
option MUST have a unique PID.
4. DHCPv6 Option
4.1. Option Format
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
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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 followed by
the route to apply when datagram to forward is matching.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-option-code | sub-option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-option-content |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PID | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| preferred-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: DHCPv6 Multi-Homed Routing Policy Option
o Option-code: OPTION_MHRPE multi-homed routing policy entry option
(To be assigned by IANA)
o Option-length: Total length of the sub-options + 4.
o sub-option-code: the code of the included sub option. In this
document SUB_OPTION_FLOW_DESC, SUB_OPTION_QOS_INFO,
SUB_OPTION_PREFIX and SUB_OPTION_ROUTER_ADDRESS are defined.
o sub-option-len: length of the sub-option.
o sub-option-content: content of the sub-option.
o PID: The Policy Identifier field is an 8-bit unsigned integer that
includes the identifier for the policy.
o Reserved: 24 bits set to zero by the sender ignored by the
receiver
o preferred-lifetime: The preferred lifetime in units of seconds for
the multi-homed routing policy entry option.
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o valid lifetime: The valid lifetime in units of seconds for the
multi-homed routing policy entry option.
4.2. Flow Description Sub-option
Flow Description Sub-option is used to describe the flow for this
route. More than one flow description MAY be included. Flow
descriptions are usually in binary format but textual formats are
also allowed. The preferred interface for this flow is included in
Interface Info Sub-option.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUB_OPTION_FLOW_DESC | sub-option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FD-Type | FD-len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Flow Description ... |
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Flow Description Sub-option
o option-code: SUB_OPTION_FLOW_DESC (to be assigned by IANA)
o option-length: Variable.
o FD-Type: type of the flow description:
o
o (0) Reserved
o (1) Binary
o (2) Text
o FD-len: length of the flow description that follows in bytes.
o Flow Description: This field contains flow description in binary
such as in [I-D.ietf-mext-binary-ts] or in textual format. This
field is of length FD-length.
4.3. QoS Info Sub-option
This Sub-option contains quality of service information associated
with each interface as specified in Interface Info Sub-option, e.g.
on 3G 150kbps for video on WiFi 400kbps for video.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUB_OPTION_QOS_INFO | sub-option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|QoS Information Code |QoS Information Sub-Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|QoS Information value |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: QoS Sub-option
o option-code: SUB_OPTION_QOS_INFO (to be assigned by IANA)
o option-length: Variable.
o QoS information Code: this field identifies the type of the QoS
information:
o
o (0) Reserved
o (1) Packet rate
o (2) One-way delay metric
o (3) Inter-packet delay variation
o QoS information Sub-code: this field carries the sub-type of the
QoS information. The following sub-types have been identified:
o
o (0) None
o (1) Reserved rate
o (2) Available rate
o (3) Loss rate
o (4) Minimum one-way delay
o (5) Maximum one-way delay
o (6) Average one-way delay
o QoS information value: this field indicates the value of the QoS
information. The corresponding units depend on the instantiation
of the QoS information code.
4.4. Flow Route Prefix Sub-option
This Sub-option defines IPv6 prefix over which the flow as defined in
flow description sub-option will be routed. One flow route prefix
sub-option MAY be included for each flow description sub-option.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUB_OPTION_FR_PREFIX | sub-option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prefix-len | |
+-+-+-+-+-+-+-+-+ IPv6 prefix |
| (variable) |
| |
~ ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Flow Route Prefix Sub-option
o option-code: SUB_OPTION_FR_PREFIX (to be assigned by IANA)
o option-length: Variable.
o prefix-len: Prefix length of the destination prefix over which the
flow will be routed
o IPv6 prefix: Destination prefix over which the flow will be
routed. The first prefix-len bits make up the prefix. The rest
is ignored.
4.5. IPv6 Router Address Sub-option
This sub-option defines the default router address for this route.
Flow Route Prefix Sub-option and IPv6 Router Address Sub-option
define a route.
For each flow there MUST be at least one route. If more than one
route is defined the first route is the primary route.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUB_OPTION_ROUTER_ADDRESS | sub-option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 Router Address (16 octets) |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prefix-length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: IPv6 Router Address Sub-option
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o option-code: SUB_OPTION_ROUTER_ADDRESS (to be assigned by IANA)
o option-length: 24.
o IPv6 Router Address: Default 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
4.6. Interface Info Sub-option
Interface Info Sub-option is used to provide information about each
interface of the host. One such sub-option SHOULD be included for
each interface of a MIF host.
Link layer address is a MAC address for IEEE interfaces such as
Ethernet or Wi-Fi. Link layer address could be International Mobile
Subscriber Identity (IMSI) for some 3G or 4G interfaces.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUB_OPTION_INTERFACE_INFO | sub-option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ATT | Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Link Layer Address |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: Interface Info Sub-option
o option-code: SUB_OPTION_INTERFACE_INFO (to be assigned by IANA)
o option-length: 16.
o ATT: This is an 8-bit field that specifies the access technology
of the interface. The values for this field are assigned from
Access Technology Type Option type values of IANA related to
[RFC5213].
o Length: The length in bytes of Link Layer address
o The variable length link-layer address. MAC address (if exists)
is placed as value in this field.
5. Security Considerations
This document does not by itself introduce any security issues.
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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 4.1 |
| SUB_OPTION_FLOW_DESC | TBD | Section 4.2 |
| SUB_OPTION_QOS_INFO | TBD | Section 4.3 |
| SUB_OPTION_FR_PREFIX | TBD | Section 4.4 |
| SUB_OPTION_ROUTER_ADDRESS | TBD | Section 4.5 |
| SUB_OPTION_INTERFACE_INFO | TBD | Section 4.6 |
+---------------------------+-------+--------------+
Table 1: DHCPv6 Options
7. Acknowledgements
The authors acknowledge Mohamed Boucadair who provided useful
comments for this document.
8. References
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.ietf-mif-problem-statement]
Blanchet, M. and P. Seite, "Multiple Interfaces Problem
Statement", draft-ietf-mif-problem-statement-04 (work in
progress), May 2010.
[I-D.yang-mif-req]
Yang, P., Seite, P., Williams, C., and J. Qin,
"Requirements on multiple Interface (MIF) of simple IP",
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draft-yang-mif-req-00 (work in progress), March 2009.
[I-D.ietf-mext-flow-binding]
Soliman, H., Tsirtsis, G., Montavont, N., Giaretta, G.,
and K. Kuladinithi, "Flow Bindings in Mobile IPv6 and NEMO
Basic Support", draft-ietf-mext-flow-binding-06 (work in
progress), March 2010.
[I-D.ietf-mext-binary-ts]
Tsirtsis, G., Giaretta, G., Soliman, H., and N. Montavont,
"Traffic Selectors for Flow Bindings",
draft-ietf-mext-binary-ts-04 (work in progress),
February 2010.
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.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[3GPP23402]
"3GPP TS 23.402. Architecture enhancements for non-3GPP
accesses.", June 2009.
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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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