[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06 07 08 09 10 RFC 5838

Please refresh this draft.
Thanks,
Acee


Network Working Group                                 A. Lindem (Editor)
Internet-Draft                                              S. Mirtorabi
Expires: September 7, 2006                                        A. Roy
                                                                M. Barnes
                                                            Cisco Systems
                                                                 Q. Vohra
                                                         Juniper Networks
                                                            March 6, 2006


                  Support of address families in OSPFv3
                      draft-ietf-ospf-af-alt-03.txt

Status of this Memo

    By submitting this Internet-Draft, each author represents that any
    applicable patent or other IPR claims of which he or she is aware
    have been or will be disclosed, and any of which he or she becomes
    aware will be disclosed, in accordance with Section 6 of 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 September 7, 2006.

Copyright Notice

    Copyright (C) The Internet Society (2006).

Abstract

    This document describes a mechanism for supporting multiple address
    families in OSPFv3 using multiple instances.  It maps an address
    family (AF) to an OSPFv3 instance using the Instance ID field in the
    OSPFv3 packet header.  This approach is fairly simple and minimizes



Lindem (Editor), et al.    Expires September 7, 2006            [Page 1]

Internet-Draft                  OSPFv3 AF                     March 2006


    extensions to OSPFv3 for supporting multiple AF's.

Table of Contents

    1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
      1.1   Design Considerations  . . . . . . . . . . . . . . . . . .  3
      1.2   Requirements notation  . . . . . . . . . . . . . . . . . .  3
    2.  Proposed Solution  . . . . . . . . . . . . . . . . . . . . . .  4
      2.1   Instance ID values for new AF's  . . . . . . . . . . . . .  4
      2.2   OSPFv3 Options and Prefix Options Chnages  . . . . . . . .  4
        2.2.1   OSPFv3 Options . . . . . . . . . . . . . . . . . . . .  4
        2.2.2   Prefix Options . . . . . . . . . . . . . . . . . . . .  5
      2.3   Advertising Prefixes in new AF's . . . . . . . . . . . . .  5
      2.4   Changes to the Hello processing  . . . . . . . . . . . . .  5
      2.5   Next hop for IPv4 unicast and multicast AF's . . . . . . .  6
      2.6   Operation over Virtual Links . . . . . . . . . . . . . . .  6
    3.  Backward Compatibility . . . . . . . . . . . . . . . . . . . .  8
    4.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
    5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
    6.  Normative References . . . . . . . . . . . . . . . . . . . . . 10
        Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 10
    A.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 12
        Intellectual Property and Copyright Statements . . . . . . . . 13




























Lindem (Editor), et al.    Expires September 7, 2006            [Page 2]

Internet-Draft                  OSPFv3 AF                     March 2006


1.  Introduction

    OSPFv3 has been defined to support IPv6 unicast AF.  There is a need
    to carry other AFs in OSPFv3 such as multicast IPv6, unicast or
    multicast IPv4.  This document introduces these other AFs in OSPFv3
    by reserving Instance IDs and using one OSPFv3 instance for one AF.

1.1  Design Considerations

    This section describes the rationale for adopting the multiple
    instance ID approach for supporting multiple address families in
    OSPFv3.  As described earlier, OSPFv3 is designed to support multiple
    instances.  Hence mapping an instance to an address family doesn't
    introduce new mechanisms in the protocol.  It minimizes the protocol
    extensions required and it simplifies the implementation.  The
    presence of a separate link state database per address family is also
    easier to debug and operate.  Additionally, it doesn't change the
    existing instance, area and interface based configuration model in
    most OSPF implementations.

1.2  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 RFC2119 [RFC2119].


























Lindem (Editor), et al.    Expires September 7, 2006            [Page 3]

Internet-Draft                  OSPFv3 AF                     March 2006


2.  Proposed Solution

    Currently the entire Instance ID number space is used for IPv6
    unicast.  We propose to assign different ranges to different AF's in
    order to support other AF's in OSPFv3.  Each AF will establish
    different adjacency, have different link state database and compute
    different shortest path tree.  Additionally, the current LSAs that
    are defined to carry IPv6 unicast prefix can be used without any
    modification in different instances to carry different AF's prefixes.

    It should be noted that OSPFv3 is running on the top of IPv6 and uses
    IPv6 link local address for OSPFv3 control packet and next hop
    calculation.  Therefore, it is required that IPv6 be enabled on a
    link, although the link may not be participating in IPv6 unicast AF.

2.1  Instance ID values for new AF's

    Instance ID zero is already used by default for IPv6 unicast AF.  We
    define the following ranges for different AF's.  The first value of
    each range is considered as the default value for the corresponding
    AF.

       Instance ID # 0    -  # 31     IPv6 unicast AF
       Instance ID # 32   -  # 63     IPv6 multicast AF
       Instance ID # 64   -  # 95     IPv4 unicast AF
       Instance ID # 96   -  # 127    IPv4 multicast AF
       Instance ID # 128  -  # 255    Reserved


2.2  OSPFv3 Options and Prefix Options Chnages

    A new bit is added to the OSPFv3 options field and a couple of the
    bits are only applicable to the IPv6 unicast AF.

2.2.1  OSPFv3 Options



                                1                     2
            0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8  9  0  1  2  3
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+--+-+-+--+--+--+
           | | | | | | | | | | | | | | | |AF|*|*|DC|R|N|MC| E|V6|
           +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+--+-+-+--+--+--+

                            The Options field






Lindem (Editor), et al.    Expires September 7, 2006            [Page 4]

Internet-Draft                  OSPFv3 AF                     March 2006


    V6-bit
       The V6 bit is used in OSPFv3 to exclude a node from IPv6 unicast
       route calculation but allow it in the SPF calculation for other
       address families.  Since Instance ID now denotes the AF
       explicitly, this bit is ignored in AF's other than IPv6 unicast.

    MC-bit
       This bit is not used in other AF's introduced in this document.

    AF-bit
       When a router supports AF, it MUST set this new bit in the Options
       field of Hello Packets, DD packets and LSAs.


2.2.2  Prefix Options


                 0  1  2  3  4  5  6  7
                +--+--+--+--+--+--+--+--+
                |  |  |  |  | P|* |LA|NU|
                +--+--+--+--+--+--+--+--+



    MC-bit
       This bit is not used in other AF's introduced in this document.

    NU-bit
       The NU bit must be clear in all unicast AF's and it must be set in
       all multicast AF's.

    Note that all bits unused in a given AF could be redefined later.

2.3  Advertising Prefixes in new AF's

    Each Prefix defined in OSPFv3 has a prefix length field.  This
    facilitate advertising prefixes of different lengths in different
    AF's.  The existing LSAs defined in OSPFv3 are used for this purpose
    and there is no need to define new LSAs.

2.4  Changes to the Hello processing

    When a router does not support an AF but it is configured with an
    Instance ID in the same range, packets could be blackholed.  This
    could happen due to misconfiguration or router downgrade to a
    previous code level.  Blackholing is possible because the router
    which doesn't support the AF can still be included in the SPF
    calculated path as long as it establishes adjacencies using the



Lindem (Editor), et al.    Expires September 7, 2006            [Page 5]

Internet-Draft                  OSPFv3 AF                     March 2006


    Instance ID corresponding to the AF.  Note that router and network
    LSAs are AF independent.

    In order to avoid the above situation, hello processing is changed in
    order to only establish adjacency with the routers that have the AF-
    bit set in their Options field.

    Receiving Hello Packets is specified in section 3.2.2.1 of [OSPFV3].
    The following check is added to Hello reception:


    o  When a router participate in an AF (sets the AF-bit in Options
       field) it MUST discard Hello packets having the AF-bit clear in
       the Options field.  The only exception is IPv6 unicast AF, where
       this check MUST NOT be done (to help backward compatibility).


2.5  Next hop for IPv4 unicast and multicast AF's

    OSPFv3 runs on the top of IPv6 and uses IPv6 link local addresses for
    OSPFv3 control packets and next hop calculations.  Although IPV6 link
    local addresses could be used as next hops for IPv4 address families,
    it is desirable to have IPv4 next hop addresses.  For example, in
    IPv4 multicast having the nexthop address the same as the PIM
    neighbor address (IPv4 address) makes it easier to know to which
    upstream neighbor to send a PIM join when doing a RPF lookup for a
    source.  It is also easier for troubleshooting purposes to have a
    next hop with the same semantics as the AF.

    In order to achieve this, the link's IPv4 address will be advertised
    in the "link local address" field of the IPv4 instance's Link-LSA.
    This address is placed in the first 32 bit of "link local address"
    field and used for IPv4 next hop calculations.

    We call direct interface address (DIA) the address that is reachable
    directly via the link provided that a layer 3 to layer 2 mapping is
    available.  Note that there is no explicit need for the IPv4 link
    addresses to be on the same subnet.  An implementation should resolve
    layer 3 to layer 2 mappings via ARP or ND for a DIA even if the IPv4
    address is not on the same subnet as the router's interface IP
    address.

2.6  Operation over Virtual Links

    OSPFv3 control packets sent over a virtual link are IPv6 packets and
    may traverse multiples hops.  Therefore, there must be a global IPv6
    address associated with the virtual link so that the control packet
    is forwarded correctly by the intermediate hops between VL end



Lindem (Editor), et al.    Expires September 7, 2006            [Page 6]

Internet-Draft                  OSPFv3 AF                     March 2006


    points.  Although this requirement can be satisfied in IPv6 unicast
    AF, this will not function in other AFs as there cannot be a multihop
    forwarding based on global IPv6 address or such a path may not exist.
    Therefore virtual link are not currently supported in other AF's.















































Lindem (Editor), et al.    Expires September 7, 2006            [Page 7]

Internet-Draft                  OSPFv3 AF                     March 2006


3.  Backward Compatibility

    Each new AF will have their corresponding Instance ID and can operate
    with the existing non-capable routers in IPv6 unicast topology.
    Further, when a non-capable router uses an Instance ID which is
    reserved for a given AF, since the non-capable router will not have
    the AF-bit set in the Hello an adjacency will not be established with
    an AF capable router.  Therefore, there are no backward compatibility
    issues.  AF's can be gradually deployed without disturbing networks
    with current non-capable routers.









































Lindem (Editor), et al.    Expires September 7, 2006            [Page 8]

Internet-Draft                  OSPFv3 AF                     March 2006


4.  Security Considerations

    The function described in this document does not create any new
    security issues for the OSPF protocol.  Security considerations for
    the OSPFv are covered in [OSPFV3].














































Lindem (Editor), et al.    Expires September 7, 2006            [Page 9]

Internet-Draft                  OSPFv3 AF                     March 2006


5.  IANA Considerations

    The following IANA assignments are to be made from existing
    registries:

    o  An OSPFv3 options bit will be allocated for support of address
       families using separate instances.


6.  Normative References

    [OSPFV3]   Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
               RFC 2740, December 1999.

    [RFC2119]  Bradner, S., "Key words for use in RFC's to Indicate
               Requirement Levels", RFC 2119, March 1997.


Authors' Addresses

    Acee Lindem
    Cisco Systems
    7025 Kit Creek Road
    Research Triangle Park, NC  27709
    USA

    Email: acee@cisco.com


    Sina Mirtorabi
    Cisco Systems
    225 West Tasman Drive
    San Jose, CA  95134
    USA

    Email: sina@cisco.com


    Abhay Roy
    Cisco Systems
    225 West Tasman Drive
    San Jose, CA  95134
    USA

    Email: akr@cisco.com






Lindem (Editor), et al.    Expires September 7, 2006           [Page 10]

Internet-Draft                  OSPFv3 AF                     March 2006


    Michael Barnes
    Cisco Systems
    225 West Tasman Drive
    San Jose, CA  95134
    USA

    Email: mjbarnes@cisco.com


    Quaizar Vohra
    Juniper Networks
    1194 N. Mathilda Ave.
    Sunnyvale, CA  94089
    USA

    Email: qv@juniper.net



































Lindem (Editor), et al.    Expires September 7, 2006           [Page 11]

Internet-Draft                  OSPFv3 AF                     March 2006


Appendix A.  Acknowledgments

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
















































Lindem (Editor), et al.    Expires September 7, 2006           [Page 12]

Internet-Draft                  OSPFv3 AF                     March 2006


Intellectual Property Statement

    The IETF takes no position regarding the validity or scope of any
    Intellectual Property Rights or other rights that might be claimed to
    pertain to the implementation or use of the technology described in
    this document or the extent to which any license under such rights
    might or might not be available; nor does it represent that it has
    made any independent effort to identify any such rights.  Information
    on the procedures with respect to rights in RFC documents can be
    found in BCP 78 and BCP 79.

    Copies of IPR disclosures made to the IETF Secretariat and any
    assurances of licenses to be made available, or the result of an
    attempt made to obtain a general license or permission for the use of
    such proprietary rights by implementers or users of this
    specification can be obtained from the IETF on-line IPR repository at
    http://www.ietf.org/ipr.

    The IETF invites any interested party to bring to its attention any
    copyrights, patents or patent applications, or other proprietary
    rights that may cover technology that may be required to implement
    this standard.  Please address the information to the IETF at
    ietf-ipr@ietf.org.


Disclaimer of Validity

    This document and the information contained herein are provided on an
    "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
    OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
    ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
    INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
    INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
    WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.


Copyright Statement

    Copyright (C) The Internet Society (2006).  This document is subject
    to the rights, licenses and restrictions contained in BCP 78, and
    except as set forth therein, the authors retain all their rights.


Acknowledgment

    Funding for the RFC Editor function is currently provided by the
    Internet Society.




Lindem (Editor), et al.    Expires September 7, 2006           [Page 13]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/