Inter-Domain Routing Yisong Liu
Internet Draft China Mobile
Intended status: Standard Track C. Lin
Expires: March 23, 2025 New H3C Technologies
H. Bidgoli
Nokia
Z. Zhang
ZTE Corporation
September 23, 2024
Distribution of SR P2MP Policies and State using BGP-LS
draft-liu-idr-bgpls-sr-p2mp-policy-distribution-04
Abstract
This document specifies the extensions to BGP Link State (BGP-LS) to
distribute SR P2MP Policies and state. This allows operators to
establish a consistent view of the underlying multicast network
state, providing an efficient mechanism for the advertisement and
synchronization of SR P2MP policies.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on March 23, 2025.
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Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Introduction ................................................ 3
1.1. Requirements Language .................................. 3
2. P2MP Policy NLRI Type ....................................... 3
3. P2MP Policy Descriptor ...................................... 6
3.1. P2MP Policy Candidate Path Descriptor .................. 6
3.2. P2MP Policy Instance Descriptor ........................ 7
3.3. P2MP Policy downstream node Descriptor ................. 8
4. P2MP Policy States TLV ..................................... 10
4.1. SR P2MP Policy Name TLV ............................... 10
4.2. SR P2MP Policy Candidate Path Name TLV ................ 10
4.3. SR P2MP Policy Candidate Path State TLV ............... 11
4.4. Leaf List TLV ......................................... 12
4.4.1. Leaf Sub-TLV ..................................... 13
4.5. Path Instance TLV ..................................... 14
4.5.1. Instance id Sub-TLV .............................. 15
4.6. Replication Segment TLV ............................... 16
4.7. Downstream List TLV ................................... 17
4.7.1. Downstream node Sub-TLV .......................... 19
4.8. Downstream-node Segment list TLV ...................... 20
4.8.1. Segment Sub-TLV .................................. 22
5. IANA Considerations ........................................ 22
6. Security Considerations .................................... 23
7. References ................................................. 23
7.1. Normative References .................................. 23
Contributors .................................................. 24
Authors' Addresses ............................................ 25
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1. Introduction
As described in [RFC7752], BGP Link State (BGP-LS) provides a
mechanism by which link-state and TE information can be collected
from networks and shared with external components using the BGP
routing protocol.
[draft-ietf-pim-sr-p2mp-policy] describes architecture to construct
a Point-to-Multipoint (P2MP) tree to deliver Multi-point services in
a Segment Routing domain.
[draft-ietf-idr-sr-p2mp-policy] defines the extension of BGP, which
is used for the controller to advertise P2MP Policy to a group of
nodes.
SR P2MP policies are set of policies that enable architecture for
P2MP service delivery. A P2MP policy consists of candidate paths
that connect the Root of the Tree to a set of Leaves. The P2MP
policy is composed of replication segments.
This document defines the extension of BGP-LS, which is used to
collect the state information of SR P2MP Policy on nodes. This
information can be used by external components for path computation,
re-optimization, service placement, network visualization, etc.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. P2MP Policy NLRI Type
The "Link-State NLRI" defined in [RFC7752] is extended to carry the
P2MP Policy information. BGP speakers that wish to exchange P2MP
Policy information MUST use the BGP Multiprotocol Extensions
Capability Code(1) to advertise the corresponding (AFI, SAFI) pair,
as specified in [RFC4760]. New TLVs carried in the Link_State
Attribute defined in [RFC7752] are also defined to carry the
attributes of a P2MP Policy in the subsequent sections.
The format of "Link-State NLRI" is defined in [RFC7752] as follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NLRI Type | Total NLRI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Link-State NLRI (variable) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A new NLRI Type needs to be defined to identify P2MP Policy
information.
o SR P2MP Policy Candidate Path NLRI (value TBD1)
The general format of the SR P2MP Policy NLRI defined in this
document is as follows:
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
+-+-+-+-+-+-+-+-+
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Node Descriptor TLV //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// P2MP Policy Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where
o Protocol-ID: Protocol-ID field specifies the component that owns
the P2MP Policy state in the advertising node
+-------------+--------------------------------------------+
| Protocol-ID | NLRI information source protocol |
+-------------+--------------------------------------------+
| TBD2 | P2MP Policy |
+-------------+--------------------------------------------+
o "Identifier" is an 8 octet value as defined in [RFC7752].
o "Local Node Descriptor" (TLV 256) as defined in [RFC7752] that
describes the advertising node.
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o "P2MP Policy Descriptors" consists of one or more of the TLVs
listed as below for use with the P2MP Policy NLRI type
advertisement.
+-----------+----------------------------------------+
| Codepoint | Descriptor TLVs |
+-----------+----------------------------------------+
| TBD3 | P2MP Policy Candidate Path
| TBD4 | P2MP Policy Instance |
| TBD5 | P2MP Policy downstream node |
+-----------+----------------------------------------+
The Local Node Descriptor TLV MUST include the following Node
Descriptor TLVs:
o BGP Router-ID (TLV 516) [RFC9086], which contains a valid BGP
Identifier of the local node.
o Autonomous System Number (TLV 512) [RFC7752], which contains the
ASN or AS Confederation Identifier (ASN) [RFC5065], if
confederations are used, of the local node.
The Local Node Descriptor TLV SHOULD include at least one of the
following Node Descriptor TLVs:
o IPv4 Router-ID of Local Node (TLV 1028) [RFC7752], which contains
the IPv4 TE Router-ID of the local node when one is provisioned.
o IPv6 Router-ID of Local Node (TLV 1029) [RFC7752], which contains
the IPv6 TE Router-ID of the local node when one is provisioned.
The Local Node Descriptor TLV MAY include the following Node
Descriptor TLVs:
o BGP Confederation Member (TLV 517) [RFC9086], which contains the
ASN of the confederation member (i.e. Member-AS Number), if BGP
confederations are used, of the local node.
o Node Descriptors as defined in [RFC7752].
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3. P2MP Policy Descriptor
This section defines the P2MP Policy Descriptors TLVs which are used
to describe the P2MP Policy being advertised by using the NLRI types
defined in Section 2.
3.1. P2MP Policy Candidate Path Descriptor
The P2MP Policy Candidate Path Descriptor TLV identifies a Segment
Routing P2MP Policy Candidate Path (CP) as defined in [draft-ietf-
idr-sr-p2mp-policy]. This descriptor is used to report the state
information of the P2MP Policy candidate path.
The TLV has the following format:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Root-ID (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tree-ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Distinguisher (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD6
o Length: variable (valid values are 16, or 28)
o Flags: 2-octet field with following bit positions defined. Other
bits MUST be cleared by the originator and MUST be ignored by a
receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- R-Flag: Indicates the Root-ID length and if it is 16 octets
value when set and is 4 octets value when clear.
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o Reserved: 2 octets which MUST be set to 0 by the originator and
MUST be ignored by a receiver.
o Root-ID: IPv4/IPv6 address of the head-end (Root) of the p2mp
tree, based on AFI.
o Tree-ID: a unique 4 octets identifier of the p2mp tree on the
head-end (root)router.
o Distinguisher: 4-octets value uniquely identifying the policy in
the context of <Tree-ID, Originating Router's IP> tuple.
3.2. P2MP Policy Instance Descriptor
The P2MP Policy Instance Descriptor TLV identifies a P2MP Policy
instance as defined in [draft-ietf-idr-sr-p2mp-policy]. This
descriptor is used to report the state information of the P2MP
Policy instance.
The TLV has the following format:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Root-ID (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tree-ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Distinguisher (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Node-ID (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance-ID | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD7
o Length: variable
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o Flags: 2-octet field with following bit positions defined. Other
bits MUST be cleared by the originator and MUST be ignored by a
receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|N| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- R-Flag: Indicates the Root-ID length and if it is 16 octets
value when set and is 4 octets value when clear.
- N-Flag: Indicates the Node-ID length and if it is 16 octets
value when set and is 4 octets value when clear.
o Reserved1: 2 octets which MUST be set to 0 by the originator and
MUST be ignored by a receiver.
o Root-ID: Same definition as in Section 3.1.
o Tree-ID: Same definition as in Section 3.1.
o Distinguisher: Same definition as in Section 3.1.
o Node-ID: Advertising Node's IPv4/IPv6 address.
o Instance-ID: 2-octets value uniquely identifying the path-
instance with in the p2mp-policy.
o Reserved2: 2-octets field which MUST be set to 0 by the
originator and MUST be ignored by a receiver.
3.3. P2MP Policy downstream node Descriptor
The P2MP Policy downstream node Descriptor TLV identifies a
downstream node in a P2MP Policy instance as defined in [draft-ietf-
idr-sr-p2mp-policy].
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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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Root-ID (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tree-ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Distinguisher (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Node-ID (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Instance-ID | Reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Downstream-Node (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Outgoing-TreeSID (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD8
o Length: variable
o Flags: 2-octet field with following bit positions defined. Other
bits MUST be cleared by the originator and MUST be ignored by a
receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R|N|D|O| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- R-Flag: Indicates the Root-ID length and if it is 16 octets
value when set and is 4 octets value when clear.
- N-Flag: Indicates the Node-ID length and if it is 16 octets
value when set and is 4 octets value when clear.
- D-Flag: Indicates the Downstream-Node length and if it is
16 octets value when set and is 4 octets value when clear.
- O-Flag: Indicates the Outgoing-TreeSID length and if it is
16 octets value when set and is 4 octets value when clear.
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o Reserved1: 2 octets which MUST be set to 0 by the originator and
MUST be ignored by a receiver.
o Root-ID: Same definition as in Section 3.1.
o Tree-ID: Same definition as in Section 3.1.
o Distinguisher: Same definition as in Section 3.1.
o Node-ID: Advertising Node's IPv4/IPv6 address.
o Instance-ID: 2-octets value uniquely identifying the path-
instance with in the p2mp-policy.
o Reserved2: 2-octets field which MUST be set to 0 by the
originator and MUST be ignored by a receiver.
o Downstream-Node: Downstream Node Identifier
o Outgoing-TreeSID: The outgoing SID for this branch (MPLS or SRv6)
4. P2MP Policy States TLV
This section defines the various TLVs which enable the node to
report the state of SR P2MP Policy. These TLVs (and their sub-TLVs)
are carried in the optional non-transitive BGP Attribute "LINK_STATE
Attribute" defined in [RFC7752] associated with the SR P2MP Policy
NLRI type.
4.1. SR Policy Name TLV
This TLV is used when the root node distributing the NLRI whose P2MP
Policy Descriptor is "P2MP Policy Candidate Path Descriptor".
For the format definition of Segment Sub-TLV, refer to Section 5.4
of [draft-ietf-idr-bgp-ls-sr-policy-00].
4.2. SR Candidate Path Name TLV
This TLV is used when the root node distributing the NLRI whose P2MP
Policy Descriptor is "P2MP Policy Candidate Path Descriptor".
For the format definition of Segment Sub-TLV, refer to Section 5.5
of [draft-ietf-idr-bgp-ls-sr-policy-00].
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4.3. SR P2MP Policy Candidate Path State TLV
The SR P2MP Policy Candidate Path (CP) State TLV provides the
operational status and attributes of the SR P2MP Policy at the CP
level. Only a single instance of this TLV is advertised for a given
CP. If multiple instances are present, then the first one is
considered valid and the rest are ignored.
This TLV is used when the root node distributing the NLRI whose P2MP
Policy Descriptor is "P2MP Policy Candidate Path Descriptor".
The TLV has the following format:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD9
o Length: 8 octets
o Flags: 2-octet field that indicates attribute and status of the
CP. The following is the bit positions definition. Other bits
MUST be cleared by the originator and MUST be ignored by a
receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|A|B|E|V|O|D|C|I|T|U| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
- S-Flag: Indicates the CP is in an administrative shut state
when set
- A-Flag: Indicates the CP is the active path (i.e. one
provisioned in the forwarding plane) for the P2MP Policy when set
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- B-Flag: Indicates the CP is the backup path (i.e. one
identified for path protection of the active path) for the SR Policy
when set
- E-Flag: Indicates that the CP has been evaluated for
validity (e.g. headend may evaluate CPs based on their preferences)
when set
- V-Flag: Indicates the CP has at least one valid instance
when set. When the E-Flag is clear (i.e. the CP has not been
evaluated), then this flag MUST be set to 0 by the originator and
ignored by the receiver.
- D-Flag: Indicates the CP was delegated for computation to a
PCE/controller when set.
- C-Flag: Indicates the CP was provisioned by a
PCE/controller when set.
- I-Flag: Indicates the CP will perform the "drop upon
invalid" behavior when no other active path is available for this
P2MP Policy and this path is the one with the best preference
amongst the available CPs.
- T-Flag: Indicates the CP has been marked as eligible for
use as Transit Policy on the headend when set.
- U-Flag: Indicates the P2MP Policy that the CP belongs to is
dropping traffic as a result of the "drop upon invalid" behavior
being activated.
o RESERVED: 2 octet2. MUST be set to 0 by the originator and MUST
be ignored by a receiver.
o Preference: 4-octet value which indicates the preference of the
CP.
4.4. SR P2MP Policy Leaf List TLV
The SR P2MP Policy leaf List TLV is used to report leaf list of a
CP. If multiple instances are present, then the first one is
considered valid and the rest are ignored.
This TLV is used when the root node distributing the NLRI whose P2MP
Policy Descriptor is "P2MP Policy Candidate Path Descriptor".
The TLV has the following format:
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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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD10
o Length: variable
o Flags: 2-octet field that indicates attribute and status of the
leaf list. The following is the bit positions definition. Other
bits MUST be cleared by the originator and MUST be ignored by a
receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|V| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- D-Flag: Indicates the leaf list is comprised of SRv6 SIDs
when set and indicates it is comprised of SR/MPLS labels when clear.
- V-Flag: Indicates the leaf list has passed verification or
its verification was not required when set and failed verification
when clear.
o RESERVED: 2 octets. MUST be set to 0 by the originator and MUST
be ignored by a receiver.
o Sub-TLVs: variable and contains the ordered set of leaf and any
other optional attributes associated with the specific leaf list.
4.4.1. SR P2MP Policy Leaf Sub-TLV
SR P2MP Policy Leaf Sub-TLV describes a single leaf in a leaf list.
One or more instances of this sub-TLV in an ordered manner
constitute a leaf list for a P2MP Policy candidate path.
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The TLV has the following format:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address (4 or 16 octets) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
o Type: TBD11
o Length: variable (valid values are 4, or 16)
o Address: leaf's IPv4/IPv6 address
4.5. P2MP Policy Path Instance TLV
The P2MP Policy path instance TLV is used to report path instance of
a P2MP Policy candidate path. If multiple instances are present,
then the first one is considered valid and the rest are ignored.
The TLV has the following format:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD12
o Length: variable
o RESERVED: 2 octets. MUST be set to 0 by the originator and MUST
be ignored by a receiver.
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o Flags: 2-octet field that indicates attribute and status of the
leaf list. The following is the bit positions definition. Other
bits MUST be cleared by the originator and MUST be ignored by a
receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- A-Flag: Indicates the instance-id is an active instance when
set and the instance-id is not active instance when clear.
o Sub-TLVs: variable and contains the ordered set of instance-id.
4.5.1. P2MP Policy Instance id Sub-TLV
The P2MP Policy instance id sub-TLV describes a single instance in a
path instance. One or more instances of this sub-TLV in an ordered
manner constitute a leaf list for a P2MP Policy candidate path.
The TLV has the following format:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| instance-id //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD13
o Length: variable
o Flags: 2-octet field that indicates attribute and status of the
leaf list. The following is the bit positions definition. Other
bits MUST be cleared by the originator and MUST be ignored by a
receiver.
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0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|A| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- A-Flag: Indicates the instance-id is an active instance when
set and the instance-id is not active instance when clear.
o RESERVED: 2 octets. MUST be set to 0 by the originator and MUST
be ignored by a receiver.
o Instance-id: 4-octect field identifier.
4.6. P2MP Policy Replication Segment TLV
The P2MP Policy replication segment TLV describes the incoming
replication segment of a P2MP Policy Instance. Only a single
instance of this TLV is advertised for a given instance. If multiple
instances are present, then the first one is considered valid and
the rest are ignored.
This TLV is used when the root node distributing the NLRI whose P2MP
Policy Descriptor is "P2MP Policy Instance Descriptor".
The TLV has the following format:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Replication SID (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD
o Length: variable(valid value is 8 or 20)
o RESERVED: 2 octets. MUST be set to 0 by the originator and MUST
be ignored by a receiver.
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o Flags: 2-octet field that indicates attribute and status of the
leaf list. The following is the bit positions definition. Other
bits MUST be cleared by the originator and MUST be ignored by a
receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|B|U|F| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- D-Flag: Indicates the dataplane for the "Replication SID"
and if they are 16 octet SRv6 SID when set and are 4 octet SR/MPLS
label value when clear.
- B-Flag: Indicates the allocation of the value in the
"Replication SID" field when set and indicates that BSID is not
allocated when clear.
- U-Flag: Indicates the specified "Replication SID" value is
unavailable when set.
- F-Flag: Indicates the BSID value is one allocated
dynamically due to fallback (e.g. when specified "Replication SID"
is unavailable) when set.
o Replication SID: It indicates the incoming replication SID of
instance.
4.7. P2MP Policy Downstream List TLV
The P2MP Policy downstream list TLV describes the downstream node
list of a P2MP Policy Instance. Only a single instance of this TLV
is advertised for a given instance. If multiple instances are
present, then the first one is considered valid and the rest are
ignored.
This TLV is used when the root node distributing the NLRI whose P2MP
Policy Descriptor is "P2MP Policy Instance Descriptor".
The TLV has the following format:
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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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD
o Length: variable
o RESERVED: 2 octets. MUST be set to 0 by the originator and MUST
be ignored by a receiver.
o Flags: 2-octet field that indicates attribute and status of the
leaf list. The following is the bit positions definition. Other
bits MUST be cleared by the originator and MUST be ignored by a
receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|B|U|F| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- D-Flag: Indicates the dataplane for the "Replication SID"
and if they are 16 octet SRv6 SID when set and are 4 octet SR/MPLS
label value when clear.
- B-Flag: Indicates the allocation of the value in the
"Replication SID" field when set and indicates that BSID is not
allocated when clear.
- U-Flag: Indicates the specified "Replication SID" value is
unavailable when set.
- F-Flag: Indicates the BSID value is one allocated
dynamically due to fallback (e.g. when specified "Replication SID"
is unavailable) when set.
o Sub-TLVs: variable and contains the ordered set of downstream
node and any other optional attributes associated with the
specific downstream list.
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4.7.1. P2MP Policy Downstream node Sub-TLV
The P2MP Policy downstream node Sub-TLV describes a single
downstream node in a downstream list. One or more instances of this
sub-TLV in an ordered manner constitute a downstream list for a P2MP
Policy instance.
This TLV is used when the root node distributing the NLRI whose P2MP
Policy Descriptor is "P2MP Policy Instance Descriptor".
The TLV has the following format:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Downstream-Node |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Outgoing-TreeSID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD
o Length: variable
o RESERVED: 2 octets. MUST be set to 0 by the originator and MUST
be ignored by a receiver.
o Flags: 2-octet field that indicates attribute and status of the
downstream node. The following is the bit positions definition.
Other bits MUST be cleared by the originator and MUST be ignored
by a receiver.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|O| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- D-Flag: Indicates the downstream-Node length and if it is 16
octets value when set and is 4 octets value when clear.
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- O-Flag: Indicates the Outgoing-TreeSID length and if it is
16 octets value when set and is 4 octets value when clear.
o Downstream-Node: Downstream Node Identifier
o Outgoing-TreeSID: The outgoing SID for this branch (MPLS or SRv6)
o Sub-TLVs: variable and contains the ordered set of optional
attributes associated with the specific downstream node.
4.8. P2MP Policy Downstream-node Segment list TLV
The P2MP Policy Downstream Segment list TLV describes a segment list
for a downstream node. One or more instances of this TLV in an
ordered manner constitute a set of segment list for a downstream
node.
This TLV is used when the advertising node distributing the NLRI
whose P2MP Policy Descriptor is "P2MP Policy downstream node
Descriptor ".
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | RESERVED |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| segment List id | protection segment list id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-TLVs (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
o Type: TBD
o Length: variable
o Flags: 2-octet field that indicates attribute and status of the
leaf list. The following is the bit positions definition. Other
bits MUST be cleared by the originator and MUST be ignored by a
receiver.
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0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D|E|C|V|R|F|A|T|M| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- D-Flag: Indicates the SID-List is comprised of SRv6 SIDs
when set and indicates it is comprised of SR/MPLS labels when clear.
- E-Flag: Indicates that SID-List is an explicit path when
set and indicates a dynamic path when clear.
- C-Flag: Indicates that SID-List has been computed for a
dynamic path when set. It is always reported as set for explicit
paths.
- V-Flag: Indicates the SID-List has passed verification or
its verification was not required when set and failed verification
when clear.
- R-Flag: Indicates that the first Segment has been resolved
when set and failed resolution when clear.
- F-Flag: Indicates that the computation for the dynamic path
failed when set and succeeded (or not required in case of explicit
path) when clear
- A-Flag: Indicates that all the SIDs in the SID-List belong
to the specified algorithm when set.
- T-Flag: Indicates that all the SIDs in the SID-List belong
to the specified topology (identified by the multi-topology ID) when
set.
- M-Flag: Indicates that the SID-list has been removed from
the forwarding plane due to fault detection by a monitoring
mechanism (e.g. BFD) when set and indicates no fault detected or
monitoring is not being done when clear.
o RESERVED: 2 octets. MUST be set to 0 by the originator and MUST
be ignored by a receiver.
o Segment List id: 2 octets value indicating the segment list id
o Protection Segment List id: 2 octets value indicating the segment
list id that is being used as protection. If there is no segment
for protection, this field should be set 0.
o Weight: 4 octets value indicating the weight associated with
segment list.
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o Sub-TLVs: variable and contains the ordered set of segment any
other optional attributes associated with the specific segment
list.
4.8.1. Segment Sub-TLV
The segment Sub-TLV describes a single segment in a segment list.
One or more instances of this sub-TLV in an ordered manner
constitute a segment list for a P2MP Policy downstream-node.
For the format definition of Segment Sub-TLV, refer to Section 5.8
of [draft-ietf-idr-bgp-ls-sr-policy-00].
5. IANA Considerations
5.1. BGP-LS NLRI-Type
IANA maintains a registry called "BGP-LS NLRI-Types" in the "Border
Gateway Protocol - Link State (BGP-LS) Parameters" registry group.
This document is to apply for a P2MP Policy NLRI-Type.
+------+-------------------------------+---------------+
| Type | NLRI Type | Reference |
+------+-------------------------------+---------------+
| TBD | P2MP Policy NLRI | this document |
+------------------------------------------------------+
5.2. BGP-LS Protocol-ID
IANA maintains a registry called "BGP-LS Protocol-IDs" in the
"Border Gateway Protocol - Link State (BGP-LS) Parameters"
registry group.
This document is to apply for a P2MP Policy ptotocol-ID.
+-------------+----------------------------------+---------------+
| Protocol-ID | NLRI information source protocol | Reference |
+-------------+----------------------------------+---------------+
| TBD | P2MP Policy | this document |
+-------------+----------------------------------+---------------+
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5.3. BGP-LS TLV
IANA maintains a registry called "Node Anchor, Link Descriptor and
Link Attribute TLVs" in the "Border Gateway Protocol - Link State
(BGP-LS) Parameters" registry group.
This document is to apply for a set of TLVs
+-------+----------------------------------------+--------------+
| Code | Description |Value defined |
| Point | | in |
+-------+----------------------------------------+--------------+
| TBD |P2MP Policy Candidate Path Descriptor | this document|
| TBD | P2MP Policy Instance Descriptor | this document|
| TBD | P2MP Policy downstream node Descriptor | this document|
| TBD | P2MP Policy Candidate Path State | this document|
| TBD | P2MP Policy leaf List | this document|
| TBD | P2MP Policy leaf | this document|
| TBD | P2MP Policy Path Instance | this document|
| TBD | P2MP Policy Instance id | this document|
| TBD | P2MP Policy Replication Segment | this document|
| TBD | P2MP Policy Downstream List | this document|
| TBD | P2MP Policy Downstream Node | this document|
| TBD |P2MP Policy Downstream Node segment list | this document|
+---------------------------------------------------------------+
6. Security Considerations
TBD
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI
10.17487/RFC2119, March 1997, <https://www.rfc-
editor.org/info/rfc2119>.
[RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, DOI
10.17487/RFC4760, January 2007, <https://www.rfc-
editor.org/info/rfc4760>.
[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
System Confederations for BGP", RFC 5065, DOI
10.17487/RFC5065, August 2007, <https://www.rfc-
editor.org/info/rfc5065>.
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[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A.,
and S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016, <https://www.rfc-
editor.org/info/rfc7752>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9086] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Patel,
K.,Ray, S., and J. Dong, "Border Gateway Protocol - Link
State (BGP-LS) Extensions for Segment Routing BGP Egress
Peer Engineering", RFC 9086, DOI 10.17487/RFC9086, August
2021, <https://www.rfc-editor.org/info/rfc9086>.
[draft-ietf-pim-sr-p2mp-policy-06] D. Voyer,C. Filsfils,H. Bidgoli,
Z. Zhang, "Segment Routing Point-to-Multipoint Policy",
draft-ietf-pim-sr-p2mp-policy-06,
DOI 10.17487/draft-ietf-pim-sr-p2mp-policy-06, April
2023.
[draft-ietf-idr-sr-p2mp-policy-00] Hooman Bidgoli , Daniel Voyer,
Andrew Stone, Rishabh Parekh, Serge Krier, Swadesh Agrawal,
"Advertising p2mp policies in BGP", draft-ietf-
idr-sr-p2mp-policy-00, DOI 10.17487/draft-ietf-idr-sr-
p2mp-policy-00, May 2022.
[draft-ietf-idr-bgp-ls-sr-policy-00] S. Previdi,K. Talaulikar,J. Dong,
H. Gredler,J. Tantsura, "Advertisement of Segment Routing
Policies using BGP Link-State", draft-ietf-idr-bgp-ls-sr-
policy-00, DOI 10.17487/draft-ietf-idr-bgp-ls-sr-policy-00,
March 2023.
Contributors
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Authors' Addresses
Yisong Liu
China Mobile
China
Email: liuyisong@chinamobile.com
Changwang Lin
New H3C Technologies
Beijing
China
Email: linchangwang.04414@h3c.com
Hooman Bidgoli
Nokia
Ottawa
Canada
Email: hooman.bidgoli@nokia.com
Zheng(Sandy) Zhang
ZTE Corporation
Email: zhang.zheng@zte.com.cn
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