| 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
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.
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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.
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].
This memo makes use of the terms defined in [RFC4970] and [I-D.wijnands-bier-architecture].
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.
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 ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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.
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.
TBD
TBD.
This document does not introduce any new security risk.
| [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. |
| [I-D.ietf-ospf-routable-ip-address] | Xu, X., Chunduri, U. and M. Bhatia, "Carrying Routable IP Addresses in OSPF RI LSA", Internet-Draft draft-ietf-ospf-routable-ip-address-00, September 2014. |
| [I-D.wijnands-bier-architecture] | Wijnands, I., Rosen, E., Dolganow, A. and T. Przygienda, "Multicast using Bit Index Explicit Replication", Internet-Draft draft-wijnands-bier-architecture-00, September 2014. |
| [I-D.xu-bier-encapsulation] | Xu, X. and S. Somasundaram, "BIER Encapsulation", Internet-Draft draft-xu-bier-encapsulation-00, September 2014. |