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Versions: 00 01 02 03 draft-ietf-ospf-ospfv3-autoconfig

Network Working Group                                          A. Lindem
Internet-Draft                                                  J. Arkko
Intended status: Standards Track                                Ericsson
Expires: September 11, 2012                               March 10, 2012


                       OSPFv3 Auto-Configuration
                draft-acee-ospf-ospfv3-autoconfig-01.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.

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   This Internet-Draft will expire on September 11, 2012.

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   Copyright (c) 2012 IETF Trust and the persons identified as the
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   described in the Simplified BSD License.



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   This document may contain material from IETF Documents or IETF
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   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
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   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
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   8.  Normative References . . . . . . . . . . . . . . . . . . . . . 12
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13



















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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.

   The RFC text was produced using Marshall Rose's xml2rfc tool.
















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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 OSPv3.  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 auto-configure the Interface
       Instance ID to be the IANA reserved value TBD to prevent
       inadvertent adjacencies with OSPFv3 implementation that don't
       support this specification.  Implementations SHOULD add a simple
       configuration option to disable this and use the default OSPFv3
       Interface Instance ID, if interoperability with legacy OSPFv3
       routers is desired.














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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.







































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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.








































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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.

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
   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.



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        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
   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-



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   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
   neighbor adjacencies MUST be reestablished.










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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.































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7.  IANA Considerations

   This specification allocates a new OSPFv3 Interface Instance ID, TBD,
   for OSPFv3 auto-configured interfaces as described in Section 2.  The
   "OSPFv3 Instance ID Address Family Values" registry should be
   extended to include Instance ID allocations other than those
   corresponding to address families.

   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.



























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8.  Normative References

   [OSPFV3]   Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, July 2008.

   [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.
































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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


































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