HIP Working Group T. Sun
Internet-Draft H. Deng
Intended status: Informational D. Liu
Expires: January 11, 2011 China Mobile
July 10, 2010
Route Configuration by DHCPv6 Option for Hosts with Multiple Interfaces
draft-sun-mif-route-config-dhcp6-02
Abstract
Currently, more and more hosts have multiple interfaces such as GPRS,
WiFi etc. One key issue is how to make the applications on the host
access the network accordingly through the proper interfaces. The
approach presented in this document is to extend DHCPv6 option to
configure route tables of the hosts. In this way, the hosts can
select a appropriate route.
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 January 11, 2011.
Copyright Notice
Copyright (c) 2010 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
Sun, et al. Expires January 11, 2011 [Page 1]
Internet-Draft Route Configuration by DHCPv6 July 2010
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Solution of Multiple Interface Usage . . . . . . . . . . . . . 4
3. DHCPv6 Option Extensions . . . . . . . . . . . . . . . . . . . 6
3.1. Host and Server Behavior . . . . . . . . . . . . . . . . . 6
3.2. Route Information Option . . . . . . . . . . . . . . . . . 6
3.3. Some Considerations of the DHCPv6 Option . . . . . . . . . 7
3.3.1. Conflict of Route Rules . . . . . . . . . . . . . . . 7
3.3.2. Application Situations . . . . . . . . . . . . . . . . 7
3.3.3. Not Limited to DHCP Servers . . . . . . . . . . . . . 7
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.1. Normative References . . . . . . . . . . . . . . . . . . . 11
6.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
Sun, et al. Expires January 11, 2011 [Page 2]
Internet-Draft Route Configuration by DHCPv6 July 2010
1. Introduction
A host such as a laptop or a smart-phone may have multiple interfaces
for connections, e.g., a wired Ethernet LAN, a 802.11 LAN, a 3G
cellular network, one or multiple VPNs or tunnels. In view of more
and more versatile applications, users may expect a host to utilize
several interfaces simultaneously.
An application uses certain interface through select the
corresponding source IP address. if the applicaiton does not specifiy
it, the transport layer must ask the IP layer. According to
[RFC1122] all the packets whose destination IP addresses are not
specified in the route table will be sent to the default gateway for
forwarding. Accordingly, the IP address corresponding to the default
gateway will be chosen as the source IP address.
To avoid all packets passing through the same interface corresponding
to the default gateway, the approach proposed in this document
configures certain routes in route tables of the host. The
configuration information is obtained through DHCP messages which
extend the DHCPv6 option.
An optional extension to Router Advertisement messages is described
in [RFC4191] for communicating default router preferences and more-
specific routes from routers to hosts. To address multi-homed
problems in a flexible way, [I-D.hui-mif-dhcpv4-routing-02] extends
DHCPv4 through introducing TOS and specific routes into DHCP options.
This document considers the situations for IPv6 cases. Similar
approach was presented in [I-D.dec-dhcpv6-route-option-03] , however,
TOS and metrics information have not been involved.
Sun, et al. Expires January 11, 2011 [Page 3]
Internet-Draft Route Configuration by DHCPv6 July 2010
2. Solution of Multiple Interface Usage
The procedures for a host to configure the routing information and
select the interface are depicted in Figure 1. The routing
configuration procedures are shown as steps a1) to a3).
a1) An interface sends Information-requirement when the connection
is established or when an existing connection receives
reconfiguration message from the server.
a2) The server sends routing information through DHCPv6 option as to
be defined in Section 3.2.
a3) The routing information received from the interface is used to
update the routing table of the host.
The procedures that an application employs an interface for network
access are depicted in Figure 1 as steps b1) to b4).
b1) An application calls sockets to build IP packets.
b2) The socket selects source address based on the routing table.
b3) The socket sends packets to the corresponding interface.
b4) The interface will forward the packets to the next hop (the
corresponding gateway).
+----+ a1 +---------+ b4 +-------+
|DHCP|<--------- |Interface|--------->|Network|
+----+ --------> +---------+ +-------+
a2 | |
| |
b3 | |
^ | a3
| ----->----+
| |
+-----------+ b1 +------+ +-----------+
|Application|---->|Socket|<------|Route Table|
+-----------+ +------+ b2 +-----------+
Figure 1: The procedures of updating a routing table and select an
interface for an application
Notice that the approach proposed in this document is feasible under
Sun, et al. Expires January 11, 2011 [Page 4]
Internet-Draft Route Configuration by DHCPv6 July 2010
the strong ES model as defined in [RFC1122].
Sun, et al. Expires January 11, 2011 [Page 5]
Internet-Draft Route Configuration by DHCPv6 July 2010
3. DHCPv6 Option Extensions
3.1. Host and Server Behavior
The host must include "Option Request" option to let the server know
the option the host interested. The request option code is set as
the "Route Information" defined in Section 3.2.
The server constructs a Reply message to provide route information to
the host. Also, a server may send a Reconfigure Message to a host.
The host may initiate a request when receiving the Reconfigure
message for the host.
3.2. Route Information Option
The DHCPv6 option is extended to contain multiple pieces of route
information. Each piece of route information contains TOS, metric,
destination IP address and the next hop IP address. The ROUTE_INFO
option is depicted in Figure 2.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ROUTE_INFO | option-len | Preference 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ TOS 1 | Metric 1 | Dest. Add. Pref. Len| Dest. Add. Pref. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ Next Hop IPv6 Address .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ Preference N | TOS N | Metric N | Dest. Add. Pref. Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ Dest. Add. Pref. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ Next Hop IPv6 Address .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The Route Information Option
option-code:OPTION_ROUTE_INFO (should be defined by IANA).
Sun, et al. Expires January 11, 2011 [Page 6]
Internet-Draft Route Configuration by DHCPv6 July 2010
option-len: length of the route rule field in octets.
Preference N: An integer to indicate the priority of applying the Nth
route rule. The Preference identified the priority of a rule. if
there are conflications, e.g., two rules have the same "Dest. Add.
Pref." but different "Next Hop IPv6 Address", the rule with high
preference SHOULD be applied by the host.
TOS N: The Nth TOS (Type-of-Service, 8 bits).
Metric N:The Nth route metric ranging from 1 to 9999.
Dest. Add. Prefix Len: Length of the IPv6 destination address
prefix, an 8-bit unsigned integer ranging from 0 to 128.
Dest. Add. Prefix: The IPv6 destination address prefix
Next Hop IPv6 Address: A 128-bit IPv6 address that will be used as
the next hop when forwarding packets.
In the above, the "Preference" of one route rule comes before the
"metric." Namely, if there are conflict routes for one destination,
the one with highest preference value should be used. For example,
the network administrator may prefer one route in a connection for
security or reliability considerations, even though the metric of the
route is large.
3.3. Some Considerations of the DHCPv6 Option
3.3.1. Conflict of Route Rules
The host can use such information obatined from the DHCP message to
build a "connection manager" on the host or to update the "Policy
Table" defined in [RFC3484]. For the situations where a route option
conflicts with one previous route rules, the latter one will override
the previous rule.
3.3.2. Application Situations
There are two situations when DHCPv6 is applied, i.e., with or
without stateless autoconfiguration. For the stateless case, since
the address has been configured based on the link-local/site-local
address, the DHCPv6 is used to obtain options.
3.3.3. Not Limited to DHCP Servers
The solution presented in this document is with the context of DHCP
message. It should be pointed out that similar message may not be
Sun, et al. Expires January 11, 2011 [Page 7]
Internet-Draft Route Configuration by DHCPv6 July 2010
conveyed by certain node in the network instead of a DHCP server.
Such a node, for example in mobile network, may be the "ANDSF (Access
Network Discovery and Selection function)" defined in TS 23.402.
Sun, et al. Expires January 11, 2011 [Page 8]
Internet-Draft Route Configuration by DHCPv6 July 2010
4. IANA Considerations
The option code of OPTION_ROUTE_INFO will be defined by IANA.
Sun, et al. Expires January 11, 2011 [Page 9]
Internet-Draft Route Configuration by DHCPv6 July 2010
5. Security Considerations
The security issues in this document are similar with those that have
been met when using DHCPv6 options.
The interface selection is affected by the routing and address
selection rules sent from servers. Therefore, incorrect information
received by hosts will cause improper interface selection leading to
bad user experiences. Attacks such as deny of services (DoS) or man-
in-the-middle may redirect host's solicitation, change the
information or flood the host with invalidate messages. Approaches
to guarantee the communication securities between hosts and servers
should be applied based on the network access types of the
interfaces.
Sun, et al. Expires January 11, 2011 [Page 10]
Internet-Draft Route Configuration by DHCPv6 July 2010
6. References
6.1. Normative References
[RFC1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, October 1989.
[RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6)", RFC 2461,
December 1998.
[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.
[RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and
More-Specific Routes", RFC 4191, November 2005.
6.2. Informative References
[I-D.blanchet-mif-problem-statement]
Blanchet, M. and P. Seite, "Multiple Interfaces Problem
Statement", May 2010, <draft-ietf-mif-problem-statement
(work in progress)>.
[I-D.dec-dhcpv6-route-option-03]
Dec, W. and R. Johnson, "DHCPv6 Route Option", March 2010,
<draft-dec-dhcpv6-route-option-03(work in progress)>.
[I-D.hui-mif-dhcpv4-routing-02]
Hui, M. and H. Deng, "Extension of DHCPv4 for policy
routing of multiple interfaces terminal", March 2010,
<draft-hui-mif-dhcpv4-routing-02(work in progress)>.
Sun, et al. Expires January 11, 2011 [Page 11]
Internet-Draft Route Configuration by DHCPv6 July 2010
Authors' Addresses
Tao Sun
China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District
Beijing 100053
China
Email: suntao@chinamobile.com
Hui Deng
China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District
Beijing 100053
China
Email: denghui@chinamobile.com
Dapeng Liu
China Mobile
Unit2, 28 Xuanwumenxi Ave,Xuanwu District
Beijing 100053
China
Email: liudapeng@chinamobile.com
Sun, et al. Expires January 11, 2011 [Page 12]