Network Working Group S. Daniel Park
Internet-Draft Samsung Electronics
Expires : 26 September 2004 A.K. Vijayabhaskar
Hewlett-Packard
27 March 2004
Configured Tunnel End Point Option for DHCPv6
draft-ietf-dhc-dhcpv6-ctep-opt-01.txt
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Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
For the newly deployed IPv6 networks to interoperate with vastly
deployed IPv4 networks, various transition mechanisms had been
proposed. One such mechanism is configured tunnels. This document
provides a mechanism by which the DHCPv6 servers can provide
information about the various configured tunnel end points to reach
the IPv6 nodes which are separated by IPv4 networks.
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1. Introduction
In the initial deployment of IPv6, the IPv6 nodes may need to
communicate with the other IPv6 nodes via IPv4 networks. Configured
tunnels [3] provide a way to encapsulate the IPv6 packets in IPv4
packets and tunnel them in the IPv4 network.
This document defines a new option called Configured Tunnel End
Point by which the DHCPv6 [1] server can notify the client with the
list of end point of the configured tunnels to the various IPv6
networks separated by the IPv4 networks.
2. Background
Configured Tunnel described in this document is a simple and
temporary mechanism which allows isolated IPv6 networks or hosts,
attached to a legacy IPv4 network which has no native IPv6
connectivity, to communicate with other such IPv6 networks or hosts
with manual configuration. The configured tunnel end-point received
from the DHCPv6 server is not used for IPv6 connectivity as long as
IPv6 networks or hosts are communicating with other IPv6 networks or
hosts via IPv6 network which has native IPv6 connectivity and only
available when communicating with other IPv6 networks or hosts via
IPv4 networks.
In this scenario, 6to4 [4] can be a possible alternative instead of
configured tunnel and does not require IPv4-compatible IPv6
addresses or configured tunnels.
As indicated in [4], the mechanisms are intended as a start-up
transition tool used during the period of co-existence of IPv4 and
IPv6. It is not intended as a permanent solution.
3. Requirements
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in RFC 2119 [2]
4. Terminology
This document uses terminology specific to IPv6 and DHCPv6 as
defined in "Terminology" section of the DHCPv6 specification [1].
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5. Configured Tunnel End Point Option
The Configured Tunnel End Point Option gives the information to the
clients about the Configured Tunnel End Point [3] to be contacted
for reaching the nodes in the various IPv6 networks which are
separated by IPv4 networks. The clients are expected to install
these routes in their machines.
The format of the Configured Tunnel End Point Option is as shown
below:
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_CTEP | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prefix-len | |
+-+-+-+-+-+-+-+-+ |
| |
| Destination Prefix (16 bytes) |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+ |
| Configured TEP Address (16 bytes) |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | prefix-len | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
| Destination Prefix (16 bytes) |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |
| Configured TEP Address (16 bytes) |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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option-code: OPTION_CTEP (TBD)
option-len: Total length of the prefix-len, Destination Prefix and
Configured Tunnel Address lists in octets; It should be
a multiple of 33.
prefix-len: prefix length of the Destination Prefix
Destination Prefix: An IPv6 Prefix;
Configured TEP Address: IPv6 Address of the Configured TEP. This
address is a IPv4-compatible IPv6 address.
The clients are expected to install the routes identified by the
tuples <Destination Prefix/prefix-len, Configured TEP Address> once
they receive this option from the server.
6. Appearance of this option
The Configured Tunnel End Point Option MUST NOT appear in other
than the following messages: Solicit, Advertise, Request, Renew,
Rebind, Information-Request and Reply.
The option numbers of Configured Tunnel End Point option MAY appear
in the Option Request Option [1] in the following messages: Solicit,
Request, Renew, Rebind, Information-Request and Reconfigure.
7. Security Considerations
The Configured Tunnel End Point Option may be used by an intruder
DHCPv6 server to provide invalid or incorrect configured tunnel end
point. This makes the client unable to reach its destination IPv6
node or to reach incorrect destination. The latter one has very
severe security issues as IPv6 destination is spoofed here.
To avoid attacks through this option, the DHCPv6 client SHOULD use
authenticated DHCP (see section "Authentication of DHCP messages" in
the DHCPv6 specification [1]).
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8. 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 [1].
Option Name Value Described in
OPTION_CTEP TBD Section 4
9. References
9.1 Normative References
[1] Bound, J., Carney, M., Perkins, C., Lemon, T., Volz, B. and
R.Droms (ed.), "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, July 2003.
[2] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
9.2 Informative References
[3] Gilligan, R, Nordmark, E., "Transition Mechanisms for IPv6
Hosts and Routers", RFC 2893, August 2000.
[4] Carpenter, B., Moore K., "Connection of IPv6 Domains via IPv4
Clouds", RFC 3056, February 2001.
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Authors' Addresses
Soohong Daniel Park
Mobile Platform Laboratory
Samsung Electronics.
Suwon
Korea
Phone: +81-31-200-4508
E-Mail: soohong.park@samsung.com
Vijayabhaskar A K
Hewlett-Packard STSD-I
29, Cunningham Road
Bangalore - 560052
India
Phone: +91-80-2053085
E-Mail: vijayak@india.hp.com
Acknowledgements
Thanks to the DHC Working Group for their time and input into the
specification. In particular, thanks to Pekka Savola, Bernie Volz,
Ralph Droms, Margaret Wasserman for their valuable comments on this
work.
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