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[RFC9262] introduces Bit Index
Explicit Replication (BIER) Traffic/Tree Engineering (BIER-TE).
It is an architecture for per-packet stateless explicit
point to multipoint (P2MP) multicast path/tree.
A link in a BIER-TE domain has its BitPositions.
For a link between two nodes X and Y, there are two BitPositions for
two forward connected adjacencies. These two
adjacency BitPositions could be configured on nodes X and Y respectively.
The BitPosition configured on X is the forward connected adjacency of
Y. The BitPosition configured on Y is the forward connected adjacency
This document proposes OSPF extensions for distributing BitPositions
configured on the links
in "Bit Index Explicit Replication Traffic Engineering" (BIER-TE)
This section describes protocol extensions to OSPFv2
for distributing BIER-TE information
such as the BitPositions configured on the links in
a BIER-TE domain.¶
[RFC7684] defines the OSPFv2 Extended Link TLV
to advertise the information about a link.
Multiple Link TLVs for the links of a router are included
in the OSPFv2 Extended Link Opaque LSA of the router.
The OSPFv2 Extended Link TLV has the following format:¶
MUST be set to 0 on transmission and MUST
be ignored on reception.¶
Under the OSPFv2 Extended Link TLV for a link,
a Sub-TLV, called BIER-TE Sub-TLV, is
defined for distributing BIER-TE information about the link.
A BIER-TE Sub-TLV is included in the Link TLV for a link of
Link Type Point-to-Point or Broadcast
(or say LAN or Transit Network).
The BIER-TE Sub-TLV has the following format:¶
Multi-Topology ID identifying the topology
that is associated with the BIER-TE sub-domain.¶
Single-octet BIER Algorithm used to calculate
underlay paths to reach other BFRs. Values are allocated
from the "BIER Algorithm" registry defined in
Single-octet IGP Algorithm used to either modify,
enhance, or replace the calculation of underlay paths to reach
other BFRs as defined by the BAR value. Values are defined
in the "IGP Algorithm Types" registry.¶
A 2-octet field encoding the BitPosition
locally configured on the link/interface when the Link Type of
the link in the OSPFv2 Extended Link TLV containing this Sub-TLV
is 1 (i.e., Point-to-Point connection to another router) or
2 (i.e., connection to Transit Network or say LAN).¶
A 2-octet field encoding the BitPosition
of the connection on the designated router (DR) end. This field is
valid when the Link Type in the OSPFv2 Extended Link TLV
containing this Sub-TLV is 2 (i.e., Transit Network or LAN).
For the other value of the Link Type, this field MUST be ignored. The
DrEndBitPosition may be configured on
the link/interface to a transit network
(i.e., broadcast link or say LAN) as described in
Psenak, P., Gredler, H., Shakir, R., Henderickx, W., Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Advertisement", RFC 7684, DOI 10.17487/RFC7684, , <https://www.rfc-editor.org/info/rfc7684>.
Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., Przygienda, T., and S. Aldrin, "Multicast Using Bit Index Explicit Replication (BIER)", RFC 8279, DOI 10.17487/RFC8279, , <https://www.rfc-editor.org/info/rfc8279>.
Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation for Bit Index Explicit Replication (BIER) in MPLS and Non-MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, , <https://www.rfc-editor.org/info/rfc8296>.
Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. Zhang, "Bit Index Explicit Replication (BIER) Support via IS-IS", RFC 8401, DOI 10.17487/RFC8401, , <https://www.rfc-editor.org/info/rfc8401>.