IS-IS Extensions for BIER-TEFutureweiBoston, MAUSAHuaimo.chen@futurewei.comFutureweimichael.mcbride@futurewei.comChina TelecomBeiqijia Town, Changping DistrictBeijing102209Chinawangaj3@chinatelecom.cnVerizon Inc.13101 Columbia PikeSilver SpringMD 20904USA 301 502-1347gyan.s.mishra@verizon.comCasa SystemsUSAyfan@casa-systems.comFujitsuUSAliulei.kddi@gmail.comVolta NetworksMcLeanVAUSAxufeng.liu.ietf@gmail.comThis document describes IS-IS extensions for distributing BitPositions
configured on the links
in "Bit Index Explicit Replication Traffic Engineering"
(BIER-TE) domain.
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
when, and only when, they appear in all capitals, as shown here. 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
of X.This document proposes IS-IS extensions for distributing BitPositions
configured on the links
in "Bit Index Explicit Replication Traffic Engineering" (BIER-TE)
domain.Bit Index Explicit Replication.BIER Traffic Engineering.Bit-Forwarding Router.Bit-Forwarding Ingress Router.Bit-Forwarding Egress Router.BFR Identifier.
It is a number in the range [1,65535].BFR Neighbor.Intermediate System to Intermediate System.This section describes protocol extensions to IS-IS
for distributing BIER-TE information
such as the BitPositions configured on the links in
a BIER-TE domain.An Extended IS Reachability TLV (Type 22)
defined in
may contain Sub-TLVs (such as those for TE)
that apply to a link/interface to a neighbor.
To encode multiple links or interfaces to neighbors,
the structure inside TLV is repeated.
MT Intermediate Systems TLV (Type 222) defined in
may contain Sub-TLVs (such as those for TE)
that apply to a link/interface.
It is aligned with Extended IS
Reachability TLV (Type 22) beside an additional two bytes in front at
the beginning of the TLV for MT-ID.BIER-TE Info Sub-TLV of the following format is defined and
used in Extended IS Reachability TLV (Type 22) and/or
MT Intermediate Systems TLV (Type 222) to
advertise the BIER-TE information about a link or interface.
TBD1 is to be assigned by IANA.Variable, dependent on Sub-Sub-TLVs.Unique value identifying a 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
.SHOULD be set to zero on transmission
and MUST be ignored on receipt.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 to an Intermediate System
neighbor.A 2-octet field encoding the BitPosition
of the connection on the designated Intermediate Systems (Dis) end.
This field is valid when the neighbor is a pseudonode.
If the neighbor is not a pseudonode, this field MUST be ignored.
The DisEndBitPosition may be configured on
the link/interface to a transit network
(i.e., broadcast link or say LAN).
No Sub-Sub-TLV is defined so far.
Note that if each of BitPosition and DrEndBitPosition uses more than
2 octets, we use 4 or more octets for each of them.
TBD.Under "Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223"
for IS-IS TLV Codepoints, IANA is
requested to assign a new codepoint for
BIER-TE Info Sub-TLV as follows:
The authors would like to thank Tony Przygienda and Acee Lindem
for their comments on this work.