OSPFv3 over IPv4 for IPv6 Transition
draft-chen-ospf-transition-to-ospfv3-00
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Ing-Wher Chen , Acee Lindem | ||
| Last updated | 2014-01-27 | ||
| Replaced by | draft-ietf-ospf-transition-to-ospfv3, RFC 7949 | ||
| Stream | (None) | ||
| Formats | plain text htmlized pdfized bibtex | ||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-chen-ospf-transition-to-ospfv3-00
Internet Draft I. Chen
<draft-chen-ospf-transition-to-ospfv3-00.txt> A. Lindem
Category: Informational Ericsson
Expires in 6 months January 26, 2014
OSPFv3 over IPv4 for IPv6 Transition
<draft-chen-ospf-transition-to-ospfv3-00.txt>
Status of this Memo
Distribution of this memo is unlimited.
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), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on date.
Copyright Notice
Copyright (c) 2014 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.
Abstract
This draft defines a mechanism to use IPv4 to transport OSPFv3
I. Chen & A. Lindem Expires in 6 months [Page 1]
Internet Draft transition-to-ospfv3 January 26, 2014
packets, in order to facilitate transition from IPv4-only to IPv6 and
dual-stack within a routing domain. Using OSPFv3 over IPv4 with the
existing OSPFv3 Address Family extension simplifies transition from
an OSFPv2 IPv4-only routing domain to an OSPFv3 dual-stack routing
domain, and later possibly to an IPv6-only routing domain.
I. Chen & A. Lindem Expires in 6 months [Page 2]
Internet Draft transition-to-ospfv3 January 26, 2014
Table of Contents
1. Introduction ....................................................3
2. Encapsulation in IPv4 ...........................................4
2.1. Source Address .............................................6
2.2. Destination ................................................6
2.3. Operation over Virtual Link ................................6
3. Security Considerations .........................................7
4. IANA Considerations .............................................7
5. References ......................................................7
1. Introduction
To facilitate transition from IPv4 [RFC791] to IPv6 [RFC2460], dual-
stack or IPv6 routing protocols should be gradually deployed. Dual-
stack routing protocols, such as Border Gateway Protocol [RFC4271],
have an advantage during the transition, because both IPv4 and IPv6
topologies can be transported using either IPv4 or IPv6. Some
IPv4-specific and IPv6-specific routing protocols share enough
similarities in their protocol packet formats and protocol signaling
that it is trivial to build an initial IPv6 routing domain over IPv4,
allowing IPv6 routing domains be deployed and tested before de-
commissioning IPv4 and moving to an IPv6-only network.
In the case of Open Shortest Path First (OSPF) interior gateway
routing protocol (IGP), OSPFv2 [RFC2328] is the IGP deployed over
IPv4, while OSPFv3 [RFC5340] is the IGP deployed over IPv6. OSPFv3
further supports multiple address families [RFC5838], including both
the IPv6 unicast address family and the IPv4 unicast address family.
Consequently, it is possible to deploy OSPFv3 over IPv4 without any
changes to to either OSPFv3 or IPv4.
This draft specifies how to use IPv4 packets to transport OSPFv3
packets. The mechanism takes advantage of the fact that OSPFv2 and
OSPFv3 share the same IP protocol number, 89. Additionally, OSPFv2
and OSPFv3 also share the same OSPF packet header format, while the
OSPF packet header has its own OSPF version number that distinguishes
an OSPFv2 packet from an OSPFv3 packet.
In normal operation, it is expected that the IPv4 topology within the
OSPF domain will be congruent with the IPv6 topology of that OSPF
domain. In such cases, it is expected that either all OSPFv3 packets
will be carried over IPv4 or that all OSPFv3 packets will be carried
over IPv6.
If the IPv4 topology and IPv6 topology are not identical, the most
likely cause (as of the date this draft was written) is that some
parts of the network deployment are not yet upgraded to support both
I. Chen & A. Lindem Expires in 6 months [Page 3]
Internet Draft transition-to-ospfv3 January 26, 2014
IPv4 and IPv6. In situations where the IPv4 deployment is a proper
superset of the IPv6 deployment, it is expected that OSPFv3 packets
would be carried over IPv4, until the rest of the network deployment
is upgraded to support IPv6 in addition to IPv4. In situations where
the IPv6 deployment is a proper superset of the IPv4 deployment, for
example as IPv4 is phased out, it is expected that OSPFv3 would be
carried over IPv6.
Throughout this document, OSPF is used when the text applies to both
OSPFv2 and OSPFv3. OSPFv2 or OSPFv3 is used when the text is
specific to one version of the OSPF protocol. Similarly, IP is used
when the text describes either version of the Internet protocol.
IPv4 or IPv6 is used when the text is specific to a single version of
the protocol.
2. Encapsulation in IPv4
Unlike 6to4 encapsulation [RFC3056] that tunnels IPv6 traffic through
an IPv4 network, this draft proposes that an OSPFv3 packet be
directly encapsulated within an IPv4 packet as the payload, without
the IPv6 packet header, as illustrated in Figure 1. In this case,
the IPv4 packet has an IPv4 protocol type of 89, denoting that the
payload is an OSPF packet. The payload of the IPv4 packet consists
of an OSPFv3 packet, beginning with the OSPF packet header, in which
the OSPF version number is 3.
An OSPFv3 packet followed by a OSPF link-local signaling (LLS)
extension data block [RFC5613] encapsulated in an IPv4 packet is
illustrated in Figure 2.
I. Chen & A. Lindem Expires in 6 months [Page 4]
Internet Draft transition-to-ospfv3 January 26, 2014
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ^
| 4 | IHL |Type of Service| Total Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Identification |Flags| Fragment Offset | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Time to Live | Protocol 89 | Header Checksum | IPv4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Header
| Source Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Destination Address | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Options | Padding | v
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ^
| 3 | Type | Packet length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router ID | OSPFv3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Header
| Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Checksum | Instance ID | 0 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ v
| OSPFv3 Body ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: An IPv4 packet encapsulating an OSPFv3 packet.
+---------------+
| IPv4 Header |
+---------------+
| OSPFv3 Header |
|...............|
| |
| OSPFv3 Body |
| |
+---------------+
| |
| LLS Data |
| |
+---------------+
Figure 2: The IPv4 packet encapsulating an OSPFv3 packet with
a trailing OSPF link-local signaling data block.
I. Chen & A. Lindem Expires in 6 months [Page 5]
Internet Draft transition-to-ospfv3 January 26, 2014
2.1. Source Address
Consistent with OSPFv2, the IPv4 source address of an OSPF protocol
packet is one end of a router adjacency. For OSPFv3 over IPv4, the
source address is the IPv4 unicast address of the interface
transmitting the packet.
2.2. Destination Address
As defined in OSPFv2, the IPv4 destination address of an OSPF
protocol packet is either an IPv4 multicast address or the IPv4
unicast address of the other end of the adjacency. Two well-known
link-local multicast addresses are assigned to OSPFv2, the
AllSPFRouters address 224.0.0.5 and the AllDRouters address
224.0.0.6. The multicast address used depends on the OSPF packet
type, the OSPF interface type, and the OSPF router's role on the
multi-access networks.
Thus, for an OSPFv3 over IPv4 packet to be sent to AllSPFRouters,
the destination address field in the IPv4 packet should be
224.0.0.5. For an OSPFv3 over IPv4 packet to be sent to
AllDRouters, the destination address field in the IPv4 packet
should be 224.0.0.6.
When an OSPF router sends a unicast OSPF packet over a connected
interface, the destination of such an IP packet is the address
assigned to the receiving interface. Thus, a unicast OSPFv3 packet
carried in an IPv4 packet would specify the IPv4 unicast address of
the receiving interface as the destination address.
2.3. Operation over Virtual Link
When an OSPF router sends an OSPF packet over a virtual link, the
receiving router is a router which is not directly connected to the
sending router. Thus, the destination IP address of the IP packet
must be a reachable unicast IP address of the receiving router.
Because IPv6 is the presumed Internet protocol and an IPv4
destination is not routable, OSPFv3 address family extension
[RFC5838] specifies that only IPv6 address family virtual links are
supported.
As illustrated in Figure 1, this draft proposes that an OSPFv3
packet be carried within an IPv4 packet. As a result, an IPv4
packet in which the destination field is a unicast IPv4 address
assigned to the virtual router is routable, and OSPFv3 virtual
links in IPv4 unicast address families can be supported and the
restriction in Section 2.8 of RFC 5838 [RFC5838] can be removed.
If IPv4 transport, as specified herein, is used for IPv6 address
I. Chen & A. Lindem Expires in 6 months [Page 6]
Internet Draft transition-to-ospfv3 January 26, 2014
families, virtual links cannot be supported. Hence, it is
RECOMMENDED to use the IP transport matching the address family in
OSPF routing domains requiring virtual links.
3. Security Considerations
As described in [RFC4552], OSPFv3 uses IPsec [RFC4301] for
authentication and confidentiality. Consequently, an OSPFv3 packet
carried within an IPv4 packet requires IPsec to provide
authentication and confidentiality. Because IPsec is more commonly
implemented and more widely available on IPv4 systems than on IPv6
systems, this use is not more problematic than use of IPsec with
OSPFv3 over IPv6. Further work such as [ipsecospf] might be required
for IPv4 IPsec.
An optional OSPFv3 Authentication Trailer [RFC6505] also has been
defined as an alternative to using IPsec. The calculation of the
authentication data in the Authentication Trailer includes the source
IPv6 address to protect an OSPFv3 router from Man-in-the-Middle
attacks. For IPv4 encapsulation described in this draft, the IPv4
source address should be placed in the first 4 bytes of Apad followed
by the hexadecimal value 0x878FE1F3 repeated (L-4)/4 times, where L
is the length of hash measured in octet.
The processing of the optional Authentication Trailer is confined
entirely within the OSPFv3 protocol, in which each OSPFv3 router is
responsible for the authentication without involvement from IPsec or
any other IP layer. Consequently, except for calculation of the
value Apad, transporting OSPFv3 packets using IPv4 does not change
the operation of the optional OSPFv3 Authentication Trailer. At
present, that Authentication Trailer has limited implementation and
also limited deployment.
4. IANA Considerations
No actions are required from IANA as result of the publication of
this document.
5. References
5.1 Normative References
[RFC791] Postel, J., "Internet Protocol", STD 5, RFC 791, September
1981.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
I. Chen & A. Lindem Expires in 6 months [Page 7]
Internet Draft transition-to-ospfv3 January 26, 2014
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, July 2008.
[RFC2328] Moy, J., "OSPF Version 2", STD54, RFC 2328, April 1998.
[RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and
R. Aggarwal, "Support of Address Families in OSPFv3", RFC
5838, April 2010.
5.2. Informative References
[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, January
2006.
[RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains
via IPv4 Clouds", RFC 3056, February 2001.
[RFC5613] Zinin, A., Roy, A., Nguyen, L., Friedman, B., and D.
Yeung, "OSPF Link-Local Signaling", RFC 5613, August 2009.
[RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality
for OSPFv3", RFC 4552, June 2006.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
[RFC6505] Bhatia, M., Manral, V., and A. Lindem, "Supporting
Authentication Trailer for OSPFv3", RFC 6506, February
2012.
[ipsecospf] Gupta, M. and Melam, M, Work in progress, "draft-gupta-
ospf-ospfv2-sec-01.txt", August 2009.
Authors' Addresses
I. Chen
Ericsson
Email: ing-wher.chen@ericsson.com
A. Lindem
Ericsson
Email: acee.lindem@ericsson.com
I. Chen & A. Lindem Expires in 6 months [Page 8]