Internet DRAFT - draft-acee-ospf-ospfv3-autoconfig
draft-acee-ospf-ospfv3-autoconfig
Network Working Group A. Lindem
Internet-Draft J. Arkko
Intended status: Standards Track Ericsson
Expires: January 10, 2013 July 9, 2012
OSPFv3 Auto-Configuration
draft-acee-ospf-ospfv3-autoconfig-03.txt
Abstract
OSPFv3 is a candidate for deployments in environments where auto-
configuration is a requirement. One such environment is the IPv6
home network where users expect to simply plug in a router and have
it automatically use OSPFv3 for intra-domain routing. This document
describes the necessary mechanisms for OSPFv3 to be self-configuring.
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 10, 2013.
Copyright Notice
Copyright (c) 2012 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
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Lindem & Arkko Expires January 10, 2013 [Page 1]
Internet-Draft OSPFv3 Auto-Configuration July 2012
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3
1.2. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 3
2. OSPFv3 Default Configuration . . . . . . . . . . . . . . . . . 4
3. OSPFv3 Router ID Selection . . . . . . . . . . . . . . . . . . 5
4. OSPFv3 Adjacency Formation . . . . . . . . . . . . . . . . . . 6
5. OSPFv3 Duplicate Router-ID Detection and Resolution . . . . . 7
5.1. Duplicate Router-ID Detection for Neighbors . . . . . . . 7
5.2. Duplicate Router-ID Detection for OSPFv3 Routers that
are not Neighbors . . . . . . . . . . . . . . . . . . . . 7
5.2.1. OSPFv3 Router Auto-Configuration LSA . . . . . . . . . 7
5.2.2. Router-Hardware-Fingerprint TLV . . . . . . . . . . . 9
5.3. Duplicate Router-ID Resolution . . . . . . . . . . . . . . 9
5.4. Change to Received Self-Originated LSA Processing . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. Management Considerations . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9. Normative References . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
Lindem & Arkko Expires January 10, 2013 [Page 2]
Internet-Draft OSPFv3 Auto-Configuration July 2012
1. Introduction
OSPFv3 [OSPFV3] is a candidate for deployments in environments where
auto-configuration is a requirement. Its operation is largely
unchanged from the base OSPFv3 protocol specification [OSPFV3].
The following aspects of OSPFv3 auto-configuration are described:
1. Default OSPFv3 Configuration
2. Unique OSPFv3 Router-ID generation
3. OSPFv3 Adjacency Formation
4. Duplicate OSPFv3 Router-ID Resolution
1.1. Requirements notation
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-KEYWORDS].
1.2. Acknowledgments
This specification was inspired by the work presented in the Homenet
working group meeting in October 2011 in Philadelphia, Pennsylvania.
In particular, we would like to thank Fred Baker, Lorenzo Colitti,
Ole Troan, Mark Townsley, and Michael Richardson.
Arthur Dimitrelis and Aidan Williams did prior work in OSPFv3 auto-
configuration in the expired "Autoconfiguration of routers using a
link state routing protocol" IETF Draft. There are many similarities
between the concepts and techniques in this document.
Thanks for Abhay Roy and Manav Bhatia for comments regarding
duplicate router-id processing.
Thanks for Alvaro Retana and Michael Barnes for comments regarding
OSPFv3 Instance ID auto-configuration.
The RFC text was produced using Marshall Rose's xml2rfc tool.
Lindem & Arkko Expires January 10, 2013 [Page 3]
Internet-Draft OSPFv3 Auto-Configuration July 2012
2. OSPFv3 Default Configuration
For complete auto-configuration, OSPFv3 will need to choose suitable
configuration defaults. These include:
1. Area 0 Only - All auto-configured OSPFv3 interfaces MUST be in
area 0.
2. OSPFv3 SHOULD be auto-configured on for IPv6 on all interfaces
intended as general IPv6-capable routers. Optionally, an
interface MAY be excluded if it is clear that running OSPFv3 on
the interface is not required. For example, if manual
configuration or an other condition indicates that an interface
is connected to an Internet Service Provider (ISP), there is
typically no need to employ OSPFv3. However, note that in many
environments it can be useful to test whether an OSPFv3 adjacency
can be established. In home networking environments, an
interface where no OSPFv3 neighbors are found but a DHCP prefix
can be acquired may be considered as an ISP interface.
3. OSPFv3 interfaces will be auto-configured to an interface type
corresponding to their layer-2 capability. For example, Ethernet
interfaces will be auto-configured as broadcast networks and
Point-to-Point Protocol (PPP) interfaces will be auto-configured
as Point-to-Point interfaces. Most extant OSPFv3 implementations
do this already.
4. OSPFv3 interfaces MUST auto-configure the default HelloInterval
and RouterDeadInterval as specified in [OSPFV3].
5. All OSPFv3 interfaces SHOULD be auto-configured to use an
Interface Instance ID of 0 that corresponds to the base IPv6
unicast address family instance ID as defined in [OSPFV3-AF].
Similarly, if IPv4 unicast addresses are advertised in a separate
auto-configured OSPFv3 instance, the base IPv4 unicast address
family instance ID value, i.e., 64, SHOULD be auto-configured as
the Interface Instance ID for all interfaces corresponding to the
OSPFv3 instance [OSPFV3-AF].
Lindem & Arkko Expires January 10, 2013 [Page 4]
Internet-Draft OSPFv3 Auto-Configuration July 2012
3. OSPFv3 Router ID Selection
As OSPFv3 Router implementing this specification must select a unique
Router-ID. A pseudo-random number SHOULD be used for the OSPFv3
Router-ID. The generation should be seeded with a variable that is
likely to be unique in that environment. A good choice of seed would
be some portion or hash of the Route-Hardware-Fingerprint as
described in Section 5.2.2.
Since there is a possibility of a Router ID collision, duplicate
Router ID detection and resolution are required as described in
Section 5 and Section 5.3.
Lindem & Arkko Expires January 10, 2013 [Page 5]
Internet-Draft OSPFv3 Auto-Configuration July 2012
4. OSPFv3 Adjacency Formation
Since OSPFv3 uses IPv6 link-local addresses for all protocol messages
other than message sent on virtual links (which are not applicable to
auto-configuration), OSPFv3 adjacency formation can proceed as soon
as a Router-ID has been selected and the IPv6 link-local address has
completed Duplicate Address Detection (DAD) as specified in IPv6
Stateless Address Autoconfiguration [SLAAC]. Otherwise, there is no
change to the OSPFv3 base specification except with respect to
duplicate Router-ID detection and resolution as described in
Section 5 and Section 5.3.
Lindem & Arkko Expires January 10, 2013 [Page 6]
Internet-Draft OSPFv3 Auto-Configuration July 2012
5. OSPFv3 Duplicate Router-ID Detection and Resolution
There are two cases of duplicate OSPFv3 Router-ID detection. One
where the OSPFv3 router with the duplicate Router-ID is directly
connected and one where it is not. In both cases, the resolution is
for one of the routers with the duplicate OSPFv3 Router-ID to select
a new one.
5.1. Duplicate Router-ID Detection for Neighbors
In this case, a duplicate Router-ID is detected if any valid OSPFv3
packet is received with the same OSPFv3 Router-ID but a different
IPv6 link-local source address. Once that occurs, the OSPFv3 router
with the numerically smaller IPv6 link-local address will need to
select a new Router-ID as described in Section 5.3. Note that the
fact that the OSPFv3 router is a neighbor on a non-virtual interface
implies that the router is directly connected. An OSPFv3 router
implementing this specification should assure that the inadvertent
connection of multiple router interfaces to the same physical link in
not misconstrued as detection of a different OSPFv3 router with a
duplicate Router-ID.
5.2. Duplicate Router-ID Detection for OSPFv3 Routers that are not
Neighbors
OSPFv3 Routers implementing auto-configuration, as specified herein,
MUST originate an Auto-Config (AC) Link State Advertisement (LSA)
including the Router-Hardware-Fingerprint Type-Length-Value (TLV).
The Router-Hardware-Fingerprint TLV contains a variable length value
that has a very high probability of uniquely identifying the
advertising OSPFv3 router. An OSPFv3 router implementing this
specification MUST compare a received self-originated Auto-Config
LSA's Router-Hardware-Fingerprint TLV against its own router hardware
fingerprint. If the fingerprints are not equal, there is a Router-ID
conflict and the OSPFv3 Router with the numerically smaller router
hardware fingerprint MUST select a new Router-ID as described in
Section 5.3.
This new LSA is designated for information related to OSPFv3 Auto-
configuration and, in the future, could be used other auto-
configuration information, e.g., global IPv6 prefixes. However, this
is beyond the scope of this document.
5.2.1. OSPFv3 Router Auto-Configuration LSA
The OSPFv3 Auto-Configuration (AC) LSA has a function code of TBD and
the S1/S2 bits set to B'01' indicating Area Flooding Scope. The U
bit will be set indicating that the OSPFv3 AC LSA should be flooded
Lindem & Arkko Expires January 10, 2013 [Page 7]
Internet-Draft OSPFv3 Auto-Configuration July 2012
even if it is not understood. The Link State ID (LSID) value will be
a integer index used to discriminate between multiple AC LSAs
originated by the same OSPF Router. This specification only
describes the contents of an AC LSA with a Link State ID (LSID) of 0.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS age |1|0|1| TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link State ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS checksum | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- TLVs -+
| ... |
OSPFv3 Auto-Configuration (AC) LSA
The format of the TLVs within the body of an AC LSA is the same as
the format used by the Traffic Engineering Extensions to OSPF [TE].
The LSA payload consists of one or more nested Type/Length/Value
(TLV) triplets. The format of each TLV is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Value... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Format
The Length field defines the length of the value portion in octets
(thus a TLV with no value portion would have a length of 0). The TLV
is padded to 4-octet alignment; padding is not included in the length
Lindem & Arkko Expires January 10, 2013 [Page 8]
Internet-Draft OSPFv3 Auto-Configuration July 2012
field (so a 3-octet value would have a length of 3, but the total
size of the TLV would be 8 octets). Nested TLVs are also 32-bit
aligned. For example, a 1-byte value would have the length field set
to 1, and 3 octets of padding would be added to the end of the value
portion of the TLV. Unrecognized types are ignored.
The new LSA is designated for information related to OSPFv3 Auto-
configuration and, in the future, can be used other auto-
configuration information, e.g., global IPv6 prefixes.
5.2.2. Router-Hardware-Fingerprint TLV
The Router-Hardware-Fingerprint TLV is the first TLV defined for the
OSPFv3 Auto-Configuration (AC) LSA. It will have type 1 and MUST be
advertised in the LSID OSPFv3 AC LSA with an LSID of 0. It SHOULD
occur, at most, once and the first instance of the TLV will take
precedence over preceding TLV instances. The length of the Router-
Hardware-Fingerprint is variable but must be 32 bytes or greater.
The contents of the hardware fingerprint should be some combination
of MAC addresses, CPU ID, or serial number(s) that provides an
extremely high probability of uniqueness. It MUST be based on
hardware attributes that will not change across hard and soft
restarts.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1 | >32 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router Hardware Fingerprint |
o
o
o
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Router-Hardware-Fingerprint TLV Format
5.3. Duplicate Router-ID Resolution
The OSPFv3 Router selected to resolve the duplicate OSPFv3 Router-ID
condition must select a new OSPFv3 Router-ID. After selecting a new
Router-ID, the Router-LSA with the prior duplicate Router-ID MUST be
purged. all self-originated LSAs MUST be reoriginated, and any OSPFv3
Lindem & Arkko Expires January 10, 2013 [Page 9]
Internet-Draft OSPFv3 Auto-Configuration July 2012
neighbor adjacencies MUST be reestablished.
5.4. Change to Received Self-Originated LSA Processing
RFC 2328 [OSPFV2], Section 13.4, describes the processing of received
self-originated LSAs. If the received LSA doesn't exist, the
receiving router will purge it from the OSPF routing domain. If the
LSA is newer than the version in the Link State Database (LSDB), the
receiving router will originate a newer version by advancing the LSA
sequence number and reflooding. Since it is possible for an auto-
configured OSPFv3 router to choose a duplicate OSPFv3 Router-ID,
OSPFv3 routers implementing this specification should detect when
multiple instances of the same self-originated LSA are purged or
reoriginated since this is indicative of an OSPFv3 router with a
duplicate Router-ID in the OSPFv3 routing domain. When this
condition is detected, the OSPFv3 Router SHOULD delay self-originated
LSA processing for LSAs that have recently been purged or reflooded.
This specification recommends 10 seconds as the interval defining
recent self-originated LSA processing and an exponential back off of
1 to 8 seconds for the processing delay.
Lindem & Arkko Expires January 10, 2013 [Page 10]
Internet-Draft OSPFv3 Auto-Configuration July 2012
6. Security Considerations
A unique OSPFv3 Interface Instance ID is used for auto-configuration
to prevent inadvertent OSPFv3 adjacency formation, see Section 2
The goals of security and complete OSPFv3 auto-configuration are
somewhat contradictory. When no explicit security configuration
takes place, auto-configuration implies that additional devices
placed in the network are automatically adopted as a part of the
network. However, auto-configuration can also be combined with
password configuration (see below) or future extensions for automatic
pairing between devices. These mechanisms can help provide an
automatically configured, securely routed network.
It is RECOMMENDED that OSPFv3 routers supporting this specification
also offer an option to explicitly configure a password for HMAC- SHA
authentication as described in [OSPFV3-AUTH-TRAILER]. When
configured, the password will be used on all auto-configured
interfaces with the Security Association Identifier (SA ID) set to 1
and HMAC-SHA-256 will be used as the authentication algorithm.
Lindem & Arkko Expires January 10, 2013 [Page 11]
Internet-Draft OSPFv3 Auto-Configuration July 2012
7. Management Considerations
It is RECOMMENDED that OSPFv3 routers supporting this specification
also allow explicit configuration of OSPFv3 parameters as specified
in Appendix C of [OSPFV3]. This is in addition to the authentication
key configuration recommended in Section 6. However, it is
acknowledged that there may be some deployment scenarios where manual
configuration is not required.
Lindem & Arkko Expires January 10, 2013 [Page 12]
Internet-Draft OSPFv3 Auto-Configuration July 2012
8. IANA Considerations
This specification allocates a new OSPFv3 LSA, OSPFv3 Auto-
Configuration (AC) LSA, TBD, as described in Section 5.2.1.
This specification also creates a registry for OSPFv3 Auto-
Configuration (AC) LSA TLVs. This registry should be placed in the
existing OSPFv3 IANA registry, and new values can be allocated via
IETF Consensus or IESG Approval.
Three initial values are allocated:
o 0 is marked as reserved.
o 1 is Router-Hardware-Fingerprint TLV (Section 5.2.2).
o 65535 is an Auto-configuration-Experiment-TLV, a common value that
can be used for experimental purposes.
Lindem & Arkko Expires January 10, 2013 [Page 13]
Internet-Draft OSPFv3 Auto-Configuration July 2012
9. Normative References
[OSPFV2] Moy, J., "OSPF Version 2", RFC 2328, April 1998.
[OSPFV3] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, July 2008.
[OSPFV3-AF]
Lindem, A., Mirtorabi, S., Roy, A., Barnes, M., and R.
Aggarwal, "Support of Address Families in OSPFv3",
RFC 5838, April 2010.
[OSPFV3-AUTH-TRAILER]
Bhatia, M., Manral, V., and A. Lindem, "Supporting
Authentication Trailer for OSPFv3", RFC 6506,
February 2012.
[RFC-KEYWORDS]
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[SLAAC] Thomson, S., Narten, T., and J. Tatuya, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007.
[TE] Katz, D., Yeung, D., and K. Kompella, "Traffic Engineering
Extensions to OSPF", RFC 3630, September 2003.
Lindem & Arkko Expires January 10, 2013 [Page 14]
Internet-Draft OSPFv3 Auto-Configuration July 2012
Authors' Addresses
Acee Lindem
Ericsson
102 Carric Bend Court
Cary, NC 27519
USA
Email: acee.lindem@ericsson.com
Jari Arkko
Ericsson
Jorvas, 02420
Finland
Email: jari.arkko@piuha.net
Lindem & Arkko Expires January 10, 2013 [Page 15]
