Internet DRAFT - draft-ietf-dhc-dhcpv6-ctep-opt
draft-ietf-dhc-dhcpv6-ctep-opt
Network Working Group S. Daniel Park
Internet-Draft SAMSUNG Electronics
Expires: April 22, 2006 A. Vijayabhaskar
HP
October 22, 2005
Configured Tunnel End Point Option for DHCPv6
draft-ietf-dhc-dhcpv6-ctep-opt-02.txt
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Copyright (C) The Internet Society (2005). 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 tunnel discovery mechanism by which the DHCPv6 servers can
provide information about the available 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 [RFC4213] 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 [RFC3315] 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 [RFC3056] can be a possible alternative
instead of configured tunnel.
As indicated in [RFC3056], 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 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].
4. Terminology
This document uses terminology specific to IPv6 and DHCPv6 as defined
in "Terminology" section of the DHCPv6 specification [RFC3315].
5. Configured Tunnel End Point Option
The Configured Tunnel End Point Option gives the information to the
clients about the Configured Tunnel End Point [RFC4213] to be
contacted for reaching the nodes in the various IPv6 networks which
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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 | |
+-+-+-+-+-+-+-+-+ |
| |
| Configured TEP Address (16 bytes) |
| |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |... (if multiple tunnels are in use)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_CTEP (TBD)
option-len: Total length of the prefix-len, Configured Tunnel Address
lists in octets; It should be a multiple of 17.
prefix-len: prefix length of this Configured TEP Address in bits.
Configured TEP Address: IPv6 Address of the Configured TEP.
The clients are expected to install the routes identified by the
tuples (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 [RFC3315] in the following messages:
Solicit, Request, Renew, Rebind, Information-Request and Reconfigure.
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7. multiple Tunnel End Point Considerations
For the simple tunnel discovery, one tunnel endpoint is generally
used and it assumes that all the networks will be reached through the
same endpoint. In this case, one Configured TEP field in the TEP
option is used for configured tunnel service.
The list of endpoints can be installed if the IPv6 host load-sharing
is honored, but there may not be a need for installing multiple
configured tunnel endpoints unless administrator wants two for
redundancy purposes. It is beyond scope of this document.
8. 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 [RFC3315]).
9. 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_CTEP TBD Section 4
10. References
10.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
10.2 Informative References
[RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains
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via IPv4 Clouds", RFC 3056, February 2001.
[RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
for IPv6 Hosts and Routers", RFC 4213, October 2005.
Authors' Addresses
Soohong Daniel Park
SAMSUNG Electronics
416 Maetan-3dong, Yeongtong-gu
Suwon-si, Gyeonggi-do 442-742
KOREA
Phone: +82 31 200 4635
EMail: soohong.park@samsung.com
Vijayabhaskar A K
Hewlett-Packard
29, Cunningham Road
Bangalore 560052
INDIA
Phone: +91 80 205308582
EMail: vijayak@india.hp.com
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