Internet DRAFT - draft-xu-ospf-bier-cap

draft-xu-ospf-bier-cap







Network Working Group                                              X. Xu
Internet-Draft                                                    Huawei
Intended status: Standards Track                        October 16, 2014
Expires: April 19, 2015


Advertising Bit Index Explicit Replication (BIER) Capability Using OSPF
                       draft-xu-ospf-bier-cap-00

Abstract

   Bit Index Explicit Replication (BIER) is a new multicast forwarding
   paradigm which doesn't require an explicit tree-building protocol and
   doesn't require intermediate routers to maintain any multicast state.
   A BFR cannot send a BIER packet to a given nexthop router unless that
   nexthop router has indicated that it can support the BIER forwarding
   procedure.  This document defines a mechanism to signal that
   capability using OSPF.  This mechanism is useful when the unicast
   route distribution is also done via OSPF.

Status of This Memo

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   This Internet-Draft will expire on April 19, 2015.

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   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Advertising BIER Capability . . . . . . . . . . . . . . . . .   3
     3.1.  BIER Capability TLV . . . . . . . . . . . . . . . . . . .   3
     3.2.  BFR-ID Sub-TLV  . . . . . . . . . . . . . . . . . . . . .   4
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Bit Index Explicit Replication (BIER)
   [I-D.wijnands-bier-architecture] is a new multicast forwarding
   paradigm which doesn't require an explicit tree-building protocol and
   doesn't require intermediate routers to maintain any multicast state.
   As described in [I-D.wijnands-bier-architecture], BIER requires that
   a multicast data packet (e.g., an IP packet or an MPLS packet) to be
   encapsulated with a BIER header that carries the information needed
   for supporting the BIER forwarding procedures.
   [I-D.xu-bier-encapsulation] proposes a transport-indepedent BIER
   encapsulation header which is applicable in any kind of transport
   networks.  A BFR cannot send a BIER packet to a given nexthop router
   unless that nexthop router has indicated that it can support the BIER
   forwarding procedure.  This document defines a mechanism to signal
   that capability using OSPF.  This mechanism is useful when the
   unicast route distribution is also done via OSPF.

1.1.  Requirements Language

   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].








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2.  Terminology

   This memo makes use of the terms defined in [RFC4970] and
   [I-D.wijnands-bier-architecture].

3.  Advertising BIER Capability

   BIER-capable routers need to advertise their capabilities of
   performing BIER forwarding procedures by using a TLV within the body
   of the OSPF Router Information (RI) Opaque LSA [RFC4970], referred to
   as BIER Capability TLV.  The format of the BIER Capability TLV is
   shown in Section 3.1.

3.1.  BIER Capability TLV

      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=TBD1           |            Length             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |   BS Length   |                   Reserved                    |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     ~                          Sub-TLVs                             ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type: TBD1.

      Length: variable.

      BS Length: This 8-bit field indicates the length of the BitString
      in 4-byte unit.  In other words, if the BitString length is 4*n
      byte, this field should be filled with n (e.g., if the length of
      the BitString is 32 bits, the length field is set to 1, if the
      length of the BitString is 64 bits, the length field is set to
      2...).  For more details about the BS Length, see section 3 of
      [I-D.xu-bier-encapsulation].

      Sub-TLVs: contains zero or more sub-TLVs corresponding to the
      particular BIER-capability related attributes.  The BFR-ID sub-TLV
      as defined in Section 3.2 is one such sub-TLV which is used to
      indicate the corrresponding BFR-ID of the originating router.
      Other sub-TLVs are to be defined in the future.

   The BIER Capability TLV could not appear more than once wihin a given
   OSPF RI LSA.  The scope of the advertisement depends on the
   application but it is recommended that it SHOULD be domain-wide.





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3.2.  BFR-ID Sub-TLV

   The type of BFR-ID sub-TLV is TBD2 and the length is 2, the value
   field is filled with the BFR-ID of the originating router.

   By carrying the BIER Capability TLV (with the BFR-ID sub-TLV
   contained) and the Routable IP address TLV
   [I-D.ietf-ospf-routable-ip-address] concurrently within the body of
   the OSPF RI LSA, the mapping between BFR-ID (contained in the BFR-ID
   sub-TLV) and BFR-prefix (contained in the Routable IP Address TLV)
   can be extracted accordingly.

4.  Acknowledgements

   TBD

5.  IANA Considerations

   TBD.

6.  Security Considerations

   This document does not introduce any new security risk.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4970]  Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S.
              Shaffer, "Extensions to OSPF for Advertising Optional
              Router Capabilities", RFC 4970, July 2007.

7.2.  Informative References

   [I-D.ietf-ospf-routable-ip-address]
              Xu, X., Chunduri, U., and M. Bhatia, "Carrying Routable IP
              Addresses in OSPF RI LSA", draft-ietf-ospf-routable-ip-
              address-00 (work in progress), September 2014.

   [I-D.wijnands-bier-architecture]
              Wijnands, I., Rosen, E., Dolganow, A., and T. Przygienda,
              "Multicast using Bit Index Explicit Replication", draft-
              wijnands-bier-architecture-00 (work in progress),
              September 2014.




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   [I-D.xu-bier-encapsulation]
              Xu, X. and S. Somasundaram, "BIER Encapsulation", draft-
              xu-bier-encapsulation-00 (work in progress), September
              2014.

Author's Address

   Xiaohu Xu
   Huawei

   Email: xuxiaohu@huawei.com








































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