IS-IS Extensions for BIER-TEFutureweiBoston, MAUSAhchen.ietf@gmail.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.comAlef EdgeUSAxufeng.liu.ietf@gmail.comThis document describes IS-IS extensions for distributing
the BitPositions configured on a Bit-Forwarding Router (BFR)
in a "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.
There are three types of BitPositions (BPs) in a BIER-TE domain:
link BitPosition (BP), routed BP and localdecap BP.
A link BP is a BP configured on a link from
Bit-Forwarding Router (BFR) X to BFR Y
for a forward connected adjacency from X to Y.
A routed BP is a BP configured on BFR X
for a forward routed adjacency from X to a remote BFR Z
not directly connected to X.
A localdecap BP is a BP configured on a BFR.
describes IS-IS Extensions for distributing
the BFR identifier (BFR-id) configured on a BFR.
This document specifies IS-IS extensions for distributing
the BitPositions configured a BFR
in a BIER-TE domain.
The BitPositions distributed may be used
by a BFR as a Point of Local Repair (PLR) for
Fast-ReRoute (FRR).This section describes protocol extensions to IS-IS
for distributing the BitPositions configured on a BFR 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.Link-BP 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 a link BP.
TBD1 is to be assigned by IANA.Variable, dependent on Sub-Sub-TLVs.They are defined in
Section 6.1 of .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 exists when the neighbor is a pseudonode.
If the neighbor is not a pseudonode, this field MUST NOT exist.
The DisEndBitPosition may be configured on
the link/interface to a transit network
(i.e., broadcast link or say LAN) as described in
.
No Sub-Sub-TLVs are currently defined.
A Sub-TLV, called Node BPs Sub-TLV, is defined and
carried within the TLVs
235, 237 , 135 , or
236 .
It contains Sub-Sub-TLVs. Two types of Sub-Sub-TLVs are defined.
One is for a Routed BitPosition and
the other for a Localdecap BitPosition.
The Node BPs Sub-TLV has the following format:
TBD2 is to be assigned by IANA.Variable.They are defined in
Section 6.1 of .They are Routed-BP Sub-Sub-TLVs for Routed BPs
and/or Localdecap-BP Sub-Sub-TLV for Localdecap BP.The Routed-BP Sub-Sub-TLV has the following format:
1 is the type for routed BP.It is 4.A 2-octet field encoding the BitPosition
configured on a BFR for a forward routed adjacency to a remote BFR.
A 2-octet field encoding the BFR-id of
the remote BFR.The Localdecap-BP Sub-Sub-TLV has the following format:
2 is the type for localdecap BP.It is 2.A 2-octet field encoding the
localdecap BitPosition configured on a BFR.Protocol extensions defined in this document do not
affect the IS-IS security.Under "IS-IS Sub-TLVs for TLVs Advertising Neighbor Information"
registry, IANA is
requested to assign a new Sub-TLV Type for
Link BP as follows:
+=======+=============+==+==+==+===+===+===+=============+
| Type |Description |22|23|25|141|222|223|reference |
+=======+=============+==+==+==+===+===+===+=============+
| TBD1 | Link BP |y |y |n | n | y | y |This document|
+-------+-------------+--+--+--+---+---+---+-------------+
Under "IS-IS Sub-TLVs for TLVs Advertising Prefix Reachability"
registry,
IANA is requested to assign a new Sub-TLV Type for Node BPs
as follows:
+=======+=============+==+===+===+===+===+=============+
| Type |Description |27|135|235|236|237|reference |
+=======+=============+==+===+===+===+===+=============+
| TBD2 | Node BPs |n | y | y | y | y |This document|
+-------+-------------+--+---+---+---+---+-------------+
IANA is requested to create a new sub-registry
"Sub-Sub-TLVs for Node BPs Sub-TLV" as follows:
+==============+===================+=====================+
| Type | Name | reference |
+==============+===================+=====================+
| 0 | Reserved |
+--------------+-------------------+---------------------+
| 1 | Routed BP | This document |
+--------------+-------------------+---------------------+
| 2 | Localdecap BP | This document |
+--------------+-------------------+---------------------+
| 3 - 255 | Unassigned |
+--------------+-------------------+---------------------+
AcknowledgmentsThe authors would like to thank Acee Lindem, Les Ginsberg,
Tony Przygienda, Jeffrey Zhang and
Toerless Eckert for their comments on this work.