softwires WG X. Xu
Internet-Draft D. Guo
Intended status: Informational Huawei Technologies
Expires: September 15, 2011 O. Troan
W. Townsley
Cisco
March 14, 2011
IPv6 Host Configuration in 6rd
draft-guo-softwire-6rd-ipv6-config-02.txt
Abstract
The 6rd [RFC5969] linktype does not support IPv6 link-local
addressing, multicast and 6rd nodes are off-link from each other.
The host configuration protocol DHCPv6 [RFC3315] relies on link-local
addressing and multicast to function. This document specifies how
DHCPv6 can be used across a 6rd link.
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 September 15, 2011.
Copyright Notice
Copyright (c) 2011 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
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
1. Introduction
IPv6 rapid deployment on IPv4 infrastructures (6rd) [RFC5969] enables
a service provider to rapidly deploy IPv6 service to residential
sites via stateless tunneling across its existing IPv4 network.
With 6rd, a 6rd CE can provide address assignments to hosts on the
LAN side, but there is no provision for providing other configuration
information to hosts on the LAN.
If only DNS configuration is required on IPv6-only hosts, DNS Proxy
[RFC5625] mechanism implemented on the 6rd CE would be enough.
Otherwise, stateless DHCPv6 [RFC3736] SHOULD be supported in 6rd for
IPv6 hosts to obtain other configuration information besides DNS.
As specified in the DHCPv6 specification [RFC3315], "...The client
MUST use a link-local address assigned to the interface for which it
is requesting configuration information as the source address in the
header of the IP datagram." A DHCPv6 client uses the
All_DHCP_Servers_or_Relays IPv6 multicast address as the destination
address of requests it sends. Link-local addresses are not supported
on 6rd links. 6rd as described in [RFC5969] does not support
multicast.
This document describes how DHCPv6 service can be provided across a
6rd link.
2. Conventions
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 RFC 2119 [RFC2119].
3. DHCPv6 over 6rd links
There are two problems to be solved with regards to providing DHCPv6
service over a 6rd link:
o A DHCPv6 client uses an IPv6 link-local address as the source
address when requesting configuration information [RFC3315].
Link-local addressing is not supported on an 6rd link.
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o A DHCPv6 client sends a request to the
All_DHCP_Relay_Agent_and_Servers multicast address. 6rd as
specified in [RFC5969] does not support IPv6 multicast.
The first problem can be solved by changing the DHCPv6 protocol to
allow for a global address to be used as the source address in
requests. Another solution that does not require protocol changes,
is to send DHCPv6 requests via a local DHCPv6 relay on the 6rd CE.
The 6rd CE MUST support a local DHCPv6 client and relay. The DHCPv6
client running on the 6rd CE's virtual tunnel interface MUST send
DHCPv6 messages through a local DHCPv6 relay that encapsulates the
client message and forwards it to a DHCPv6 server or relay using one
of the 6rd CE's global unicast addresses as the source address.
The 6rd CE DHCPv6 relay agent SHOULD use the 6rd BR IPv6 anycast
address as the destination address, section 20 of [RFC3315]. If the
6rd link supports multicast [I-D.ietf-mboned-auto-multicast] the 6rd
CE DHCPv6 relay MAY use the All_DHCP_Servers [RFC3315] as the
destination address of Relay-forward messages.
The 6rd BRs in the 6rd domain must be configured as DHCPv6 relays or
servers on their 6rd virtual interfaces.
The 6rd CE SHOULD behave according to
[I-D.ietf-v6ops-ipv6-cpe-router]. In particular it operates a DHCPv6
client on the WAN side (6rd virtual) interface and as a DHCPv6 server
on the LAN-side interface(s).
4. IANA Considerations
This specification does not require any IANA actions.
5. Security Considerations
There are no new security considerations pertaining to this document.
6. Acknowledgements
7. References
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7.1. 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.
[RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol
(DHCP) Service for IPv6", RFC 3736, April 2004.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification",
RFC 5969, August 2010.
7.2. Informative References
[I-D.ietf-mboned-auto-multicast]
Thaler, D., Talwar, M., Aggarwal, A., Vicisano, L., and T.
Pusateri, "Automatic IP Multicast Without Explicit Tunnels
(AMT)", draft-ietf-mboned-auto-multicast-10 (work in
progress), March 2010.
[I-D.ietf-v6ops-ipv6-cpe-router]
Singh, H., Beebee, W., Donley, C., Stark, B., and O.
Troan, "Basic Requirements for IPv6 Customer Edge
Routers", draft-ietf-v6ops-ipv6-cpe-router-09 (work in
progress), December 2010.
[RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines",
BCP 152, RFC 5625, August 2009.
Authors' Addresses
Xiaohu Xu
Huawei Technologies
No.3 Xinxi Rd., Shang-Di Information Industry Base
Beijing, Hai-Dian District 100085
P.R. China
Phone: +86 10 82882573
Email: xuxh@huawei.com
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Dayong Guo
Huawei Technologies
No.3 Xinxi Rd., Shang-Di Information Industry Base
Beijing, Hai-Dian District 100085
P.R. China
Phone: +86-10-82882578
Email: guoseu@huawei.com
Ole Troan
Cisco
Oslo,
Norway
Email: ot@cisco.com
Mark Townsley
Cisco
Paris,
France
Email: mark@townsley.net
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