rfc9086.original   rfc9086.txt 
Inter-Domain Routing S. Previdi Internet Engineering Task Force (IETF) S. Previdi
Internet-Draft Individual Request for Comments: 9086 Huawei Technologies
Intended status: Standards Track K. Talaulikar, Ed. Category: Standards Track K. Talaulikar, Ed.
Expires: November 17, 2019 C. Filsfils ISSN: 2070-1721 C. Filsfils
Cisco Systems, Inc. Cisco Systems, Inc.
K. Patel K. Patel
Arrcus, Inc. Arrcus, Inc.
S. Ray S. Ray
Individual Contributor Individual
J. Dong J. Dong
Huawei Technologies Huawei Technologies
May 16, 2019 August 2021
BGP-LS extensions for Segment Routing BGP Egress Peer Engineering Border Gateway Protocol - Link State (BGP-LS) Extensions for Segment
draft-ietf-idr-bgpls-segment-routing-epe-19 Routing BGP Egress Peer Engineering
Abstract Abstract
Segment Routing (SR) leverages source routing. A node steers a A node steers a packet through a controlled set of instructions,
packet through a controlled set of instructions, called segments, by called segments, by prepending the packet with a list of segment
prepending the packet with an SR header. A segment can represent any identifiers (SIDs). A segment can represent any instruction,
instruction, topological or service-based. SR segments allow topological or service based. SR segments allow steering a flow
steering a flow through any topological path and service chain while through any topological path and service chain while maintaining per-
maintaining per-flow state only at the ingress node of the SR domain. flow state only at the ingress node of the SR domain.
This document describes an extension to BGP Link-State (BGP-LS) for
advertisement of BGP Peering Segments along with their BGP peering
node information so that efficient BGP Egress Peer Engineering (EPE)
policies and strategies can be computed based on Segment Routing.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", This document describes an extension to Border Gateway Protocol -
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and Link State (BGP-LS) for advertisement of BGP Peering Segments along
"OPTIONAL" in this document are to be interpreted as described in BCP with their BGP peering node information so that efficient BGP Egress
14 [RFC2119] [RFC8174] when, and only when, they appear in all Peer Engineering (EPE) policies and strategies can be computed based
capitals, as shown here. on Segment Routing.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on November 17, 2019. Information about the current status of this document, any errata,
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https://www.rfc-editor.org/info/rfc9086.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction
2. BGP Peering Segments . . . . . . . . . . . . . . . . . . . . 4 2. Requirements Language
3. BGP-LS NLRI Advertisement for BGP Protocol . . . . . . . . . 5 3. BGP Peering Segments
3.1. BGP Router-ID and Member AS Number . . . . . . . . . . . 6 4. BGP-LS NLRI Advertisement for BGP Protocol
3.2. Mandatory BGP Node Descriptors . . . . . . . . . . . . . 6 4.1. BGP Router-ID and Member AS Number
3.3. Optional BGP Node Descriptors . . . . . . . . . . . . . . 7 4.2. Mandatory BGP Node Descriptors
4. BGP-LS Attributes for BGP Peering Segments . . . . . . . . . 7 4.3. Optional BGP Node Descriptors
4.1. Advertisement of the PeerNode SID . . . . . . . . . . . . 10 5. BGP-LS Attributes for BGP Peering Segments
4.2. Advertisement of the PeerAdj SID . . . . . . . . . . . . 11 5.1. Advertisement of the PeerNode SID
4.3. Advertisement of the PeerSet SID . . . . . . . . . . . . 12 5.2. Advertisement of the PeerAdj SID
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 5.3. Advertisement of the PeerSet SID
5.1. New BGP-LS Protocol-ID . . . . . . . . . . . . . . . . . 13 6. IANA Considerations
5.2. Node Descriptors and Link Attribute TLVs . . . . . . . . 13 6.1. New BGP-LS Protocol-ID
6. Manageability Considerations . . . . . . . . . . . . . . . . 14 6.2. Node Descriptors and Link Attribute TLVs
7. Security Considerations . . . . . . . . . . . . . . . . . . . 15 7. Manageability Considerations
8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 15 8. Security Considerations
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 16 9. References
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 9.1. Normative References
10.1. Normative References . . . . . . . . . . . . . . . . . . 16 9.2. Informative References
10.2. Informative References . . . . . . . . . . . . . . . . . 17 Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17 Contributors
Authors' Addresses
1. Introduction 1. Introduction
Segment Routing (SR) leverages source routing. A node steers a Segment Routing (SR) leverages source routing. A node steers a
packet through a controlled set of instructions, called segments, by packet through a controlled set of instructions, called segments, by
prepending the packet with an SR header with segment identifiers prepending the packet with a list of segment identifiers (SIDs). A
(SID). A SID can represent any instruction, topological or service- SID can represent any instruction, topological or service based. SR
based. SR segments allows to enforce a flow through any topological segments allows to enforce a flow through any topological path or
path or service function while maintaining per-flow state only at the service function while maintaining per-flow state only at the ingress
ingress node of the SR domain. node of the SR domain.
The SR architecture [RFC8402] defines three types of BGP Peering The SR architecture [RFC8402] defines three types of BGP Peering
Segments that may be instantiated at a BGP node: Segments that may be instantiated at a BGP node:
o Peer Node Segment (PeerNode SID) : instruction to steer to a * Peer Node Segment (PeerNode SID) : instruction to steer to a
specific peer node specific peer node
o Peer Adjacency Segment (PeerAdj SID) : instruction to steer over a * Peer Adjacency Segment (PeerAdj SID) : instruction to steer over a
specific local interface towards a specific peer node specific local interface towards a specific peer node
o Peer Set Segment (PeerSet SID) : instruction to load-balance to a * Peer Set Segment (PeerSet SID) : instruction to load-balance to a
set of specific peer nodes set of specific peer nodes
SR can be directly applied to either to an MPLS dataplane (SR/MPLS) SR can be directly applied to either an MPLS data plane (SR-MPLS)
with no change on the forwarding plane or to a modified IPv6 with no change on the forwarding plane or to a modified IPv6
forwarding plane (SRv6). forwarding plane (SRv6).
This document describes extensions to the BGP Link-State NLRI (BGP-LS This document describes extensions to the BGP - Link State Network
NLRI) and the BGP-LS Attribute defined for BGP-LS [RFC7752] for Layer Reachability Information (BGP-LS NLRI) and the BGP-LS Attribute
advertising BGP peering segments from a BGP node along with its defined for BGP-LS [RFC7752] for advertising BGP peering segments
peering topology information (i.e., its peers, interfaces, and from a BGP node along with its peering topology information (i.e.,
peering ASs) to enable computation of efficient BGP Egress Peer its peers, interfaces, and peering Autonomous Systems (ASes)) to
Engineering (BGP-EPE) policies and strategies using the SR/MPLS enable computation of efficient BGP Egress Peer Engineering (BGP-EPE)
dataplane. The corresponding extensions for SRv6 are specified in policies and strategies using the SR-MPLS data plane. The
[I-D.dawra-idr-bgpls-srv6-ext]. corresponding extensions for SRv6 are specified in [BGPLS-SRV6].
[I-D.ietf-spring-segment-routing-central-epe] illustrates a [RFC9087] illustrates a centralized controller-based BGP Egress Peer
centralized controller-based BGP Egress Peer Engineering solution Engineering solution involving SR path computation using the BGP
involving SR path computation using the BGP Peering Segments. This Peering Segments. This use case comprises a centralized controller
use case comprises a centralized controller that learns the BGP that learns the BGP Peering SIDs via BGP-LS and then uses this
Peering SIDs via BGP-LS and then uses this information to program a information to program a BGP-EPE policy at any node in the domain to
BGP-EPE policy at any node in the domain to perform traffic steering perform traffic steering via a specific BGP egress node to specific
via a specific BGP egress node to a specific EBGP peer(s) optionally External BGP (EBGP) peer(s) optionally also over a specific
also over a specific interface. The BGP-EPE policy can be realized interface. The BGP-EPE policy can be realized using the SR Policy
using the SR Policy framework framework [SR-POLICY].
[I-D.ietf-spring-segment-routing-policy].
This document introduces a new BGP-LS Protocol-ID for BGP and defines This document introduces a new BGP-LS Protocol-ID for BGP and defines
new BGP-LS Node and Link Descriptor TLVs to facilitate advertising new BGP-LS Node and Link Descriptor TLVs to facilitate advertising
BGP-LS Link NLRI to represent the BGP peering topology. Further, it BGP-LS Link NLRI to represent the BGP peering topology. Further, it
specifies the BGP-LS Attribute TLVs for advertisement of the BGP specifies the BGP-LS Attribute TLVs for advertisement of the BGP
Peering Segments (i.e., PeerNode SID, PeerAdj SID, and PeerSet SID) Peering Segments (i.e., PeerNode SID, PeerAdj SID, and PeerSet SID)
to be advertised in the same BGP-LS Link NLRI. to be advertised in the same BGP-LS Link NLRI.
2. BGP Peering Segments 2. Requirements Language
As described in [RFC8402], a BGP-EPE enabled Egress PE node The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
instantiates SR Segments corresponding to its attached peers. These "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
segments are called BGP Peering Segments or BGP Peering SIDs. In "OPTIONAL" in this document are to be interpreted as described in
case of EBGP, they enable the expression of source-routed inter- BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
domain paths. capitals, as shown here.
3. BGP Peering Segments
As described in [RFC8402], a BGP-EPE-enabled Egress Provider Edge
(PE) node instantiates SR Segments corresponding to its attached
peers. These segments are called BGP Peering Segments or BGP Peering
SIDs. In the case of EBGP, they enable the expression of source-
routed interdomain paths.
An ingress border router of an AS may compose a list of SIDs to steer An ingress border router of an AS may compose a list of SIDs to steer
a flow along a selected path within the AS, towards a selected egress a flow along a selected path within the AS, towards a selected egress
border router C of the AS, and to a specific EBGP peer. At minimum, border router C of the AS, and to a specific EBGP peer. At minimum,
a BGP-EPE policy applied at an ingress PE involves two SIDs: the Node a BGP-EPE policy applied at an ingress PE involves two SIDs: the Node
SID of the chosen egress PE and then the BGP Peering SID for the SID of the chosen egress PE and then the BGP Peering SID for the
chosen egress PE peer or peering interface. chosen egress PE peer or peering interface.
Each BGP session MUST be described by a PeerNode SID. The Each BGP session MUST be described by a PeerNode SID. The
description of the BGP session MAY be augmented by additional PeerAdj description of the BGP session MAY be augmented by additional PeerAdj
SIDs. Finally, multiple PeerNode SIDs or PeerAdj SIDs MAY be part of SIDs. Finally, multiple PeerNode SIDs or PeerAdj SIDs MAY be part of
the same group/set in order to group EPE resources under a common the same group/set in order to group EPE resources under a common
PeerSet SID. These BGP Peering SIDs and their encoding are described PeerSet SID. These BGP Peering SIDs and their encoding are described
in detail in Section 4. in detail in Section 5.
The following BGP Peering SIDs need to be instantiated on a BGP The following BGP Peering SIDs need to be instantiated on a BGP
router for each of its BGP peer sessions that are enabled for Egress router for each of its BGP peer sessions that are enabled for Egress
Peer Engineering: Peer Engineering:
o One PeerNode SID MUST be instantiated to describe the BGP peer * One PeerNode SID MUST be instantiated to describe the BGP peer
session. session.
o One or more PeerAdj SID MAY be instantiated corresponding to the * One or more PeerAdj SID MAY be instantiated corresponding to the
underlying link(s) to the directly connected BGP peer session. underlying link(s) to the directly connected BGP peer session.
o A PeerSet SID MAY be instantiated and additionally associated and * A PeerSet SID MAY be instantiated and additionally associated and
shared between one or more PeerNode SIDs or PeerAdj SIDs. shared between one or more PeerNode SIDs or PeerAdj SIDs.
While an egress point in a topology usually refers to EBGP sessions While an egress point in a topology usually refers to EBGP sessions
between external peers, there's nothing in the extensions defined in between external peers, there's nothing in the extensions defined in
this document that would prevent the use of these extensions in the this document that would prevent the use of these extensions in the
context of IBGP sessions. However, unlike EBGP sessions which are context of Internal BGP (IBGP) sessions. However, unlike EBGP
generally between directly connected BGP routers which are also along sessions, which are generally between directly connected BGP routers
the traffic forwarding path, IBGP peer sessions may be setup to BGP also along the traffic forwarding path, IBGP peer sessions may be set
routers which are not in the forwarding path. As such, when the IBGP up to BGP routers that are not in the forwarding path. As such, when
design includes sessions with route-reflectors, a BGP router SHOULD the IBGP design includes sessions with route reflectors, a BGP router
NOT instantiate a BGP Peering SID for those sessions to peer nodes SHOULD NOT instantiate a BGP Peering SID for those sessions to peer
which are not in the forwarding path since the purpose of BGP Peering nodes that are not in the forwarding path since the purpose of BGP
SID is to steer traffic to that specific peers. Thus, the Peering SID is to steer traffic to those specific peers. Thus, the
applicability for IBGP peering may be limited to only those applicability for IBGP peering may be limited to only those
deployments where the IBGP peer is also along the forwarding data deployments where the IBGP peer is also along the forwarding data
path. path.
Any BGP Peering SIDs instantiated on the node are advertised via BGP- Any BGP Peering SIDs instantiated on the node are advertised via BGP-
LS Link NLRI type as described in the sections below. An LS Link NLRI type as described in the sections below. An
illustration of the BGP Peering SIDs' allocations in a reference BGP illustration of the BGP Peering SIDs' allocations in a reference BGP
peering topology along with the information carried in the BGP-LS peering topology along with the information carried in the BGP-LS
Link NLRI and its corresponding BGP-LS Attribute are described in Link NLRI and its corresponding BGP-LS Attribute are described in
[I-D.ietf-spring-segment-routing-central-epe]. [RFC9087].
3. BGP-LS NLRI Advertisement for BGP Protocol 4. BGP-LS NLRI Advertisement for BGP Protocol
This section describes the BGP-LS NLRI encodings that describe the This section describes the BGP-LS NLRI encodings that describe the
BGP peering and link connectivity between BGP routers. BGP peering and link connectivity between BGP routers.
This document specifies the advertisement of BGP peering topology This document specifies the advertisement of BGP peering topology
information via BGP-LS Link NLRI type which requires use of a new information via BGP-LS Link NLRI type, which requires use of a new
BGP-LS Protocol-ID. BGP-LS Protocol-ID.
+-------------+----------------------------------+ +=============+==================================+
| Protocol-ID | NLRI information source protocol | | Protocol-ID | NLRI Information Source Protocol |
+-------------+----------------------------------+ +=============+==================================+
| 7 | BGP | | 7 | BGP |
+-------------+----------------------------------+ +-------------+----------------------------------+
Table 1: BGP-LS Protocol Identifier for BGP Table 1: BGP-LS Protocol Identifier for BGP
The use of a new Protocol-ID allows separation and differentiation The use of a new Protocol-ID allows separation and differentiation
between the BGP-LS NLRIs carrying BGP information from the BGP-LS between the BGP-LS NLRIs carrying BGP information from the BGP-LS
NLRIs carrying IGP link-state information defined in [RFC7752]. NLRIs carrying IGP link-state information defined in [RFC7752].
The BGP Peering information along with their Peering Segments are The BGP Peering information along with their Peering Segments are
advertised using BGP-LS Link NLRI type with the Protocol-ID set to advertised using BGP-LS Link NLRI type with the Protocol-ID set to
BGP. The BGP-LS Link NLRI type uses the Descriptor TLVs and BGP-LS BGP. BGP-LS Link NLRI type uses the Descriptor TLVs and BGP-LS
Attribute TLVs as defined in [RFC7752]. In order to correctly Attribute TLVs as defined in [RFC7752]. In order to correctly
describe BGP nodes, new TLVs are defined in this section. describe BGP nodes, new TLVs are defined in this section.
[RFC7752] defines Link NLRI Type is as follows: [RFC7752] defines BGP-LS Link NLRI type as follows:
0 1 2 3 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 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 | | Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | | Identifier |
| (64 bits) | | (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Local Node Descriptors // // Local Node Descriptors //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Remote Node Descriptors // // Remote Node Descriptors //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Link Descriptors // // Link Descriptors //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: BGP-LS Link NLRI Figure 1: BGP-LS Link NLRI
Node Descriptors and Link Descriptors are defined in [RFC7752]. Node Descriptors and Link Descriptors are defined in [RFC7752].
3.1. BGP Router-ID and Member AS Number 4.1. BGP Router-ID and Member AS Number
Two new Node Descriptors TLVs are defined in this document: Two new Node Descriptor TLVs are defined in this document:
o BGP Router Identifier (BGP Router-ID): * BGP Router Identifier (BGP Router-ID):
Type: 516 Type: 516
Length: 4 octets Length: 4 octets
Value: 4 octet unsigned non-zero integer representing the BGP Value: 4-octet unsigned non-zero integer representing the BGP
Identifier as defined in [RFC6286]. Identifier as defined in [RFC6286]
o Member-AS Number (Member-ASN) * Member-AS Number (Member-ASN)
Type: 517 Type: 517
Length: 4 octets Length: 4 octets
Value: 4 octet unsigned non-zero integer representing the Value: 4-octet unsigned non-zero integer representing the
Member-AS Number [RFC5065]. Member-AS Number [RFC5065]
3.2. Mandatory BGP Node Descriptors 4.2. Mandatory BGP Node Descriptors
The following Node Descriptors TLVs MUST be included in BGP-LS NLRI The following Node Descriptor TLVs MUST be included in BGP-LS NLRI as
as Local Node Descriptors when distributing BGP information: Local Node Descriptors when distributing BGP information:
o BGP Router-ID (TLV 516), which contains a valid BGP Identifier of * BGP Router-ID (TLV 516), which contains a valid BGP Identifier of
the local BGP node. the local BGP node.
o Autonomous System Number (TLV 512) [RFC7752], which contains the * Autonomous System Number (TLV 512) [RFC7752], which contains the
ASN or AS Confederation Identifier (ASN) [RFC5065], if Autonomous System Number (ASN) or AS Confederation Identifier (an
confederations are used, of the local BGP node. ASN) [RFC5065], if confederations are used, of the local BGP node.
Note that [RFC6286] (section 2.1) requires the BGP identifier Note that Section 2.1 of [RFC6286] requires the BGP identifier
(Router-ID) to be unique within an Autonomous System and non-zero. (Router-ID) to be unique within an Autonomous System and non-zero.
Therefore, the <ASN, BGP Router-ID> tuple is globally unique. Their Therefore, the <ASN, BGP Router-ID> tuple is globally unique. Their
use in the Node Descriptor helps map Link-State NLRIs with BGP use in the Node Descriptor helps map Link-State NLRIs with BGP
protocol-ID to a unique BGP router in the administrative domain where protocol-ID to a unique BGP router in the administrative domain where
BGP-LS is enabled. BGP-LS is enabled.
The following Node Descriptors TLVs MUST be included in BGP-LS Link The following Node Descriptor TLVs MUST be included in BGP-LS Link
NLRI as Remote Node Descriptors when distributing BGP information: NLRI as Remote Node Descriptors when distributing BGP information:
o BGP Router-ID (TLV 516), which contains the valid BGP Identifier * BGP Router-ID (TLV 516), which contains the valid BGP Identifier
of the peer BGP node. of the peer BGP node.
o Autonomous System Number (TLV 512) [RFC7752], which contains the * Autonomous System Number (TLV 512) [RFC7752], which contains the
ASN or the AS Confederation Identifier (ASN) [RFC5065], if ASN or the AS Confederation Identifier (an ASN) [RFC5065], if
confederations are used, of the peer BGP node. confederations are used, of the peer BGP node.
3.3. Optional BGP Node Descriptors 4.3. Optional BGP Node Descriptors
The following Node Descriptors TLVs MAY be included in BGP-LS NLRI as The following Node Descriptor TLVs MAY be included in BGP-LS NLRI as
Local Node Descriptors when distributing BGP information: Local Node Descriptors when distributing BGP information:
o Member-ASN (TLV 517), which contains the ASN of the confederation * Member-ASN (TLV 517), which contains the ASN of the confederation
member (i.e., Member-AS Number), if BGP confederations are used, member (i.e., Member-AS Number), if BGP confederations are used,
of the local BGP node. of the local BGP node.
o Node Descriptors as defined in [RFC7752]. * Node Descriptors as defined in [RFC7752].
The following Node Descriptors TLVs MAY be included in BGP-LS Link The following Node Descriptor TLVs MAY be included in BGP-LS Link
NLRI as Remote Node Descriptors when distributing BGP information: NLRI as Remote Node Descriptors when distributing BGP information:
o Member-ASN (TLV 517), which contains the ASN of the confederation * Member-ASN (TLV 517), which contains the ASN of the confederation
member (i.e., Member-AS Number), if BGP confederations are used, member (i.e., Member-AS Number), if BGP confederations are used,
of the peer BGP node. of the peer BGP node.
o Node Descriptors as defined in [RFC7752]. * Node Descriptors as defined in [RFC7752].
4. BGP-LS Attributes for BGP Peering Segments 5. BGP-LS Attributes for BGP Peering Segments
This section defines the BGP-LS Attributes corresponding to the This section defines the BGP-LS Attributes corresponding to the
following BGP Peer Segment SIDs: following BGP Peer Segment SIDs:
Peer Node Segment Identifier (PeerNode SID) * Peer Node Segment Identifier (PeerNode SID)
Peer Adjacency Segment Identifier (PeerAdj SID)
Peer Set Segment Identifier (PeerSet SID) * Peer Adjacency Segment Identifier (PeerAdj SID)
The following new BGP-LS Link attributes TLVs are defined for use * Peer Set Segment Identifier (PeerSet SID)
with BGP-LS Link NLRI for advertising BGP Peering SIDs:
+----------+---------------------------+ The following new BGP-LS Link Attribute TLVs are defined for use with
| TLV Code | Description | BGP-LS Link NLRI for advertising BGP Peering SIDs:
| Point | |
+----------+---------------------------+
| 1101 | PeerNode SID |
| 1102 | PeerAdj SID |
| 1103 | PeerSet SID |
+----------+---------------------------+
Figure 2: BGP-LS TLV code points for BGP-EPE +================+==============+
| TLV Code Point | Description |
+================+==============+
| 1101 | PeerNode SID |
+----------------+--------------+
| 1102 | PeerAdj SID |
+----------------+--------------+
| 1103 | PeerSet SID |
+----------------+--------------+
PeerNode SID, PeerAdj SID, and PeerSet SID have all the same format Table 2: BGP-LS TLV Code
defined here below: Points for BGP-EPE
PeerNode SID, PeerAdj SID, and PeerSet SID all have the same format
as defined below:
0 1 2 3 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 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 | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Weight | Reserved | | Flags | Weight | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) | | SID/Label/Index (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: BGP Peering SIDs TLV Format Figure 2: BGP Peering SIDs TLV Format
o Type: 1101, 1102 or 1103 as listed in Figure 2. * Type: 1101, 1102, or 1103 as listed in Table 2
o Length: variable. Valid values are either 7 or 8 based on the * Length: variable. Valid values are either 7 or 8 based on whether
whether the encoding is done as a SID Index or a label. the encoding is done as a SID Index or a label.
o Flags: one octet of flags with the following definition: * Flags: one octet of flags with the following definition:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|V|L|B|P| Rsvd | |V|L|B|P| Rsvd |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 4: Peering SID TLV Flags Format Figure 3: Peering SID TLV Flags Format
* V-Flag: Value flag. If set, then the SID carries a label - V-Flag: Value Flag. If set, then the SID carries a label
value. By default the flag is SET. value. By default, the flag is SET.
* L-Flag: Local Flag. If set, then the value/index carried by - L-Flag: Local Flag. If set, then the value/index carried by
the SID has local significance. By default the flag is SET. the SID has local significance. By default, the flag is SET.
* B-Flag: Backup Flag. If set, the SID refers to a path that is - B-Flag: Backup Flag. If set, the SID refers to a path that is
eligible for protection using fast re-route (FRR). The eligible for protection using fast reroute (FRR). The
computation of the backup forwarding path and its association computation of the backup forwarding path and its association
with the BGP Peering SID forwarding entry is implementation with the BGP Peering SID forwarding entry is implementation
specific. [I-D.ietf-spring-segment-routing-central-epe] specific. Section 3.6 of [RFC9087] discusses some of the
section 3.6 discusses some of the possible ways of identifying possible ways of identifying backup paths for BGP Peering SIDs.
backup paths for BGP Peering SIDs.
* P-Flag: Persistent Flag: If set, the SID is persistently - P-Flag: Persistent Flag: If set, the SID is persistently
allocated, i.e., the SID value remains consistent across router allocated, i.e., the SID value remains consistent across router
restart and session/interface flap. restart and session/interface flap.
* Rsvd bits: Reserved for future use and MUST be zero when - Rsvd bits: Reserved for future use and MUST be zero when
originated and ignored when received. originated and ignored when received.
o Weight: 1 octet. The value represents the weight of the SID for * Weight: 1 octet. The value represents the weight of the SID for
the purpose of load balancing. An example use of the weight is the purpose of load balancing. An example use of the weight is
described in [RFC8402]. described in [RFC8402].
o SID/Index/Label. According to the TLV length and to the V and L * SID/Index/Label. According to the TLV length and the V- and
flags settings, it contains either: L-Flag settings, it contains either:
* A 3 octet local label where the 20 rightmost bits are used for - A 3-octet local label where the 20 rightmost bits are used for
encoding the label value. In this case, the V and L flags MUST encoding the label value. In this case, the V- and L-Flags
be SET. MUST be SET.
* A 4 octet index defining the offset in the Segment Routing - A 4-octet index defining the offset in the Segment Routing
Global Block (SRGB) [RFC8402] advertised by this router. In Global Block (SRGB) [RFC8402] advertised by this router. In
this case, the SRGB MUST be advertised using the extensions this case, the SRGB MUST be advertised using the extensions
defined in [I-D.ietf-idr-bgp-ls-segment-routing-ext]. defined in [RFC9085].
The values of the PeerNode SID, PeerAdj SID, and PeerSet SID Sub-TLVs The values of the PeerNode SID, PeerAdj SID, and PeerSet SID Sub-TLVs
SHOULD be persistent across router restart. SHOULD be persistent across router restart.
When enabled for Egress Peer Engineering, the BGP router MUST include When enabled for Egress Peer Engineering, the BGP router MUST include
the PeerNode SID TLV in the BGP-LS Attribute for the BGP-LS Link NLRI the PeerNode SID TLV in the BGP-LS Attribute for the BGP-LS Link NLRI
corresponding to its BGP peering sessions. The PeerAdj SID and corresponding to its BGP peering sessions. The PeerAdj SID and
PeerSet SID TLVs MAY be included in the BGP-LS Attribute for the BGP- PeerSet SID TLVs MAY be included in the BGP-LS Attribute for the BGP-
LS Link NLRI. LS Link NLRI.
Additional BGP-LS Link Attribute TLVs, as defined in [RFC7752] MAY be Additional BGP-LS Link Attribute TLVs as defined in [RFC7752] MAY be
included with the BGP-LS Link NLRI in order to advertise the included with the BGP-LS Link NLRI in order to advertise the
characteristics of the peering link. E.g., one or more interface characteristics of the peering link, e.g., one or more interface
addresses (TLV 259 or TLV 261) of the underlying link(s) over which a addresses (TLV 259 or TLV 261) of the underlying link(s) over which a
multi-hop BGP peering session is setup may be included in the BGP-LS multi-hop BGP peering session is set up may be included in the BGP-LS
Attribute along with the PeerNode SID TLV. Attribute along with the PeerNode SID TLV.
4.1. Advertisement of the PeerNode SID 5.1. Advertisement of the PeerNode SID
The PeerNode SID TLV includes a SID associated with the BGP peer node The PeerNode SID TLV includes a SID associated with the BGP peer node
that is described by a BGP-LS Link NLRI as specified in Section 3. that is described by a BGP-LS Link NLRI as specified in Section 4.
The PeerNode SID, at the BGP node advertising it, has the following The PeerNode SID, at the BGP node advertising it, has the following
semantics (as defined in [RFC8402]): semantics (as defined in [RFC8402]):
o SR operation: NEXT. * SR operation: NEXT
o Next-Hop: the connected peering node to which the segment is * Next-Hop: the connected peering node to which the segment is
associated. associated
The PeerNode SID is advertised with a BGP-LS Link NLRI, where: The PeerNode SID is advertised with a BGP-LS Link NLRI, where:
o Local Node Descriptors include: * Local Node Descriptors include:
* Local BGP Router-ID (TLV 516) of the BGP-EPE enabled egress PE. - Local BGP Router-ID (TLV 516) of the BGP-EPE-enabled Egress PE
* Local ASN (TLV 512). - Local ASN (TLV 512)
o Remote Node Descriptors include: * Remote Node Descriptors include:
* Peer BGP Router-ID (TLV 516) (i.e., the peer BGP ID used in the - Peer BGP Router-ID (TLV 516) (i.e., the peer BGP ID used in the
BGP session) BGP session)
* Peer ASN (TLV 512). - Peer ASN (TLV 512)
o Link Descriptors include the addresses used by the BGP session * Link Descriptors include the addresses used by the BGP session
encoded using TLVs as defined in [RFC7752]: encoded using TLVs as defined in [RFC7752]:
* IPv4 Interface Address (TLV 259) contains the BGP session IPv4 - IPv4 Interface Address (TLV 259) contains the BGP session IPv4
local address. local address.
* IPv4 Neighbor Address (TLV 260) contains the BGP session IPv4 - IPv4 Neighbor Address (TLV 260) contains the BGP session IPv4
peer address. peer address.
* IPv6 Interface Address (TLV 261) contains the BGP session IPv6 - IPv6 Interface Address (TLV 261) contains the BGP session IPv6
local address. local address.
* IPv6 Neighbor Address (TLV 262) contains the BGP session IPv6 - IPv6 Neighbor Address (TLV 262) contains the BGP session IPv6
peer address. peer address.
o Link Attribute TLVs include the PeerNode SID TLV as defined in * Link Attribute TLVs include the PeerNode SID TLV as defined in
Figure 3. Figure 2.
4.2. Advertisement of the PeerAdj SID 5.2. Advertisement of the PeerAdj SID
The PeerAdj SID TLV includes a SID associated with the underlying The PeerAdj SID TLV includes a SID associated with the underlying
link to the BGP peer node that is described by a BGP-LS Link NLRI as link to the BGP peer node that is described by a BGP-LS Link NLRI as
specified in Section 3. specified in Section 4.
The PeerAdj SID, at the BGP node advertising it, has the following The PeerAdj SID, at the BGP node advertising it, has the following
semantics (as defined in [RFC8402]): semantics (as defined in [RFC8402]):
o SR operation: NEXT. * SR operation: NEXT
o Next-Hop: the interface peer address. * Next-Hop: the interface peer address
The PeerAdj SID is advertised with a BGP-LS Link NLRI, where: The PeerAdj SID is advertised with a BGP-LS Link NLRI, where:
o Local Node Descriptors include: * Local Node Descriptors include:
* Local BGP Router-ID (TLV 516) of the BGP-EPE enabled egress PE. - Local BGP Router-ID (TLV 516) of the BGP-EPE-enabled Egress PE
* Local ASN (TLV 512). - Local ASN (TLV 512)
o Remote Node Descriptors include: * Remote Node Descriptors include:
* Peer BGP Router-ID (TLV 516) (i.e., the peer BGP ID used in the - Peer BGP Router-ID (TLV 516) (i.e., the peer BGP ID used in the
BGP session). BGP session)
* Peer ASN (TLV 512). - Peer ASN (TLV 512)
o Link Descriptors MUST include the following TLV, as defined in * Link Descriptors MUST include the following TLV, as defined in
[RFC7752]: [RFC7752]:
* Link Local/Remote Identifiers (TLV 258) contains the 4-octet - Link Local/Remote Identifiers (TLV 258) contains the 4-octet
Link Local Identifier followed by the 4-octet Link Remote Link Local Identifier followed by the 4-octet Link Remote
Identifier. The value 0 is used by default when the link Identifier. The value 0 is used by default when the link
remote identifier is unknown. remote identifier is unknown.
o Additional Link Descriptors TLVs, as defined in [RFC7752], MAY * Additional Link Descriptors TLVs, as defined in [RFC7752], MAY
also be included to describe the addresses corresponding to the also be included to describe the addresses corresponding to the
link between the BGP routers: link between the BGP routers:
* IPv4 Interface Address (Sub-TLV 259) contains the address of - IPv4 Interface Address (Sub-TLV 259) contains the address of
the local interface through which the BGP session is the local interface through which the BGP session is
established. established.
* IPv6 Interface Address (Sub-TLV 261) contains the address of - IPv6 Interface Address (Sub-TLV 261) contains the address of
the local interface through which the BGP session is the local interface through which the BGP session is
established. established.
* IPv4 Neighbor Address (Sub-TLV 260) contains the IPv4 address - IPv4 Neighbor Address (Sub-TLV 260) contains the IPv4 address
of the peer interface used by the BGP session. of the peer interface used by the BGP session.
* IPv6 Neighbor Address (Sub-TLV 262) contains the IPv6 address - IPv6 Neighbor Address (Sub-TLV 262) contains the IPv6 address
of the peer interface used by the BGP session. of the peer interface used by the BGP session.
o Link Attribute TLVs include the PeerAdj SID TLV as defined in * Link Attribute TLVs include the PeerAdj SID TLV as defined in
Figure 3. Figure 2.
4.3. Advertisement of the PeerSet SID 5.3. Advertisement of the PeerSet SID
The PeerSet SID TLV includes a SID that is shared amongst BGP peer The PeerSet SID TLV includes a SID that is shared amongst BGP peer
nodes or the underlying links that are described by BGP-LS Link NLRI nodes or the underlying links that are described by BGP-LS Link NLRI
as specified in Section 3. as specified in Section 4.
The PeerSet SID, at the BGP node advertising it, has the following The PeerSet SID, at the BGP node advertising it, has the following
semantics (as defined in [RFC8402]): semantics (as defined in [RFC8402]):
o SR operation: NEXT. * SR operation: NEXT
o Next-Hop: load balance across any connected interface to any peer * Next-Hop: load-balance across any connected interface to any peer
in the associated peer set. in the associated peer set
The PeerSet SID TLV containing the same SID value (encoded as defined The PeerSet SID TLV containing the same SID value (encoded as defined
in Figure 3) is included in the BGP-LS Attribute for all of the BGP- in Figure 2) is included in the BGP-LS Attribute for all of the BGP-
LS Link NLRI corresponding to the PeerNode or PeerAdj segments LS Link NLRI corresponding to the PeerNode or PeerAdj segments
associated with the peer set. associated with the peer set.
5. IANA Considerations 6. IANA Considerations
This document defines: This document defines:
A new Protocol-ID: BGP. The codepoint is from the "BGP-LS * A new Protocol-ID: BGP. The code point is from the "BGP-LS
Protocol-IDs" registry. Protocol-IDs" registry.
Two new TLVs: BGP-Router-ID and BGP Confederation Member. The * Two new TLVs: BGP-Router-ID and BGP Confederation Member. The
codepoints are in the "BGP-LS Node Descriptor, Link Descriptor, code points are in the "BGP-LS Node Descriptor, Link Descriptor,
Prefix Descriptor, and Attribute TLVs" registry. Prefix Descriptor, and Attribute TLVs" registry.
Three new BGP-LS Attribute TLVs: PeerNode SID, PeerAdj SID and * Three new BGP-LS Attribute TLVs: PeerNode SID, PeerAdj SID, and
PeerSet SID. The codepoints are in the "BGP-LS Node Descriptor, PeerSet SID. The code points are in the "BGP-LS Node Descriptor,
Link Descriptor, Prefix Descriptor, and Attribute TLVs" registry. Link Descriptor, Prefix Descriptor, and Attribute TLVs" registry.
5.1. New BGP-LS Protocol-ID 6.1. New BGP-LS Protocol-ID
This document defines a new value in the registry "BGP-LS Protocol- This document defines a new value in the registry "BGP-LS Protocol-
IDs": IDs":
+------------------------------------------------------+ +=============+==================================+===========+
| Codepoint | Description | Status | | Protocol-ID | NLRI information source protocol | Reference |
+------------------------------------------------------+ +=============+==================================+===========+
| 7 | BGP | Early Allocation by IANA | | 7 | BGP | RFC 9086 |
+------------------------------------------------------+ +-------------+----------------------------------+-----------+
Figure 5: BGP Protocol Codepoint Table 3: BGP-LS Protocol-ID
5.2. Node Descriptors and Link Attribute TLVs 6.2. Node Descriptors and Link Attribute TLVs
This document defines 5 new TLVs in the registry "BGP-LS Node This document defines five new TLVs in the registry "BGP-LS Node
Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs": Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs":
o Two new node descriptor TLVs * Two new Node Descriptor TLVs
o Three new link attribute TLVs * Three new Link Attribute TLVs
All the new 5 codepoints are in the same registry: "BGP-LS Node All five of the new code points are in the same registry: "BGP-LS
Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs". Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
TLVs".
The following new Node Descriptors TLVs are defined: The following new Node Descriptor TLVs are defined:
+-------------------------------------------------------------------+ +================+==========================+===========+
| Codepoint | Description | Status | | TLV Code Point | Description | Reference |
+-------------------------------------------------------------------+ +================+==========================+===========+
| 516 | BGP Router-ID | Early Allocation by IANA | | 516 | BGP Router-ID | RFC 9086 |
| 517 | BGP Confederation Member | Early Allocation by IANA | +----------------+--------------------------+-----------+
+------------+------------------------------------------------------+ | 517 | BGP Confederation Member | RFC 9086 |
+----------------+--------------------------+-----------+
Figure 6: BGP-LS Descriptor TLVs Codepoints Table 4: BGP-LS Descriptor TLV Code Points
The following new Link Attribute TLVs are defined: The following new Link Attribute TLVs are defined:
+-------------------------------------------------------------------+ +================+==============+===========+
| Codepoint | Description | Status | | TLV Code Point | Description | Reference |
+-------------------------------------------------------------------+ +================+==============+===========+
| 1101 | PeerNode SID | Early Allocation by IANA | | 1101 | PeerNode SID | RFC 9086 |
| 1102 | PeerAdj SID | Early Allocation by IANA | +----------------+--------------+-----------+
| 1103 | PeerSet SID | Early Allocation by IANA | | 1102 | PeerAdj SID | RFC 9086 |
+------------+------------------------------------------------------+ +----------------+--------------+-----------+
| 1103 | PeerSet SID | RFC 9086 |
+----------------+--------------+-----------+
Figure 7: BGP-LS Attribute TLVs Codepoints Table 5: BGP-LS Attribute TLV Code Points
6. Manageability Considerations 7. Manageability Considerations
The new protocol extensions introduced in this document augment the The new protocol extensions introduced in this document augment the
existing IGP topology information BGP-LS distribution [RFC7752] by existing IGP topology information BGP-LS distribution [RFC7752] by
adding support for distribution of BGP peering topology information. adding support for distribution of BGP peering topology information.
As such, the Manageability Considerations section of [RFC7752] As such, Section 6 of [RFC7752] (Manageability Considerations)
applies to these new extensions as well. applies to these new extensions as well.
Specifically, the malformed Link-State NLRI and BGP-LS Attribute Specifically, the malformed Link-State NLRI and BGP-LS Attribute
tests for syntactic checks in the Fault Management section of tests for syntactic checks in Section 6.2.2 of [RFC7752] (Fault
[RFC7752] now apply to the TLVs defined in this document. The Management) now apply to the TLVs defined in this document. The
semantic or content checking for the TLVs specified in this document semantic or content checking for the TLVs specified in this document
and their association with the BGP-LS NLRI types or their associated and their association with the BGP-LS NLRI types or their associated
BGP-LS Attributes is left to the consumer of the BGP-LS information BGP-LS Attributes is left to the consumer of the BGP-LS information
(e.g., an application or a controller) and not the BGP protocol. (e.g., an application or a controller) and not the BGP protocol.
A consumer of the BGP-LS information retrieves this information from A consumer of the BGP-LS information retrieves this information from
a BGP Speaker, over a BGP-LS session (refer Section 1 and 2 of a BGP Speaker, over a BGP-LS session (refer to Sections 1 and 2 of
[RFC7752]). The handling of semantic or content errors by the [RFC7752]). The handling of semantic or content errors by the
consumer would be dictated by the nature of its application usage and consumer would be dictated by the nature of its application usage and
hence is beyond the scope of this document. It may be expected that is hence beyond the scope of this document. It may be expected that
an error detected in the NLRI descriptor TLVs would result in that an error detected in the NLRI Descriptor TLVs would result in that
specific NLRI update being unusable and hence its update to be specific NLRI update being unusable and hence its update to be
discarded along with an error log. While an error in Attribute TLVs discarded along with an error log, whereas an error in Attribute TLVs
would result in only that specific attribute being discarded with an would result in only that specific attribute being discarded with an
error log. error log.
The operator MUST be provided with the options of configuring, The operator MUST be provided with the options of configuring,
enabling, and disabling the advertisement of each of the PeerNode enabling, and disabling the advertisement of each of the PeerNode
SID, PeerAdj SID, and PeerSet SID as well as control of which SID, PeerAdj SID, and PeerSet SID as well as control of which
information is advertised to which internal or external peer. This information is advertised to which internal or external peer. This
is not different from what is required by a BGP speaker in terms of is not different from what is required by a BGP speaker in terms of
information origination and advertisement. information origination and advertisement.
BGP Peering Segments are associated with the normal BGP routing BGP Peering Segments are associated with the normal BGP routing
peering sessions. However, the BGP peering information along with peering sessions. However, the BGP peering information along with
these Peering Segments themselves are advertised via a distinct BGP- these Peering Segments themselves are advertised via a distinct BGP-
LS peering session. It is expected that this isolation as described LS peering session. It is expected that this isolation as described
in [RFC7752] is followed when advertising BGP peering topology in [RFC7752] is followed when advertising BGP peering topology
information via BGP-LS. information via BGP-LS.
BGP-EPE functionality enables the capability for instantiation of an BGP-EPE functionality enables the capability for instantiation of an
SR path for traffic engineering a flow via an egress BGP router to a SR path for traffic engineering a flow via an egress BGP router to a
specific peer, bypassing the normal BGP best path routing for that specific peer, bypassing the normal BGP best-path routing for that
flow and any routing policies implemented in BGP on that egress BGP flow and any routing policies implemented in BGP on that egress BGP
router. As with any traffic engineering solution, the controller or router. As with any traffic-engineering solution, the controller or
application implementing the policy needs to ensure that there is no application implementing the policy needs to ensure that there is no
looping or mis-routing of traffic. Traffic counters corresponding to looping or misrouting of traffic. Traffic counters corresponding to
the MPLS label of the BGP Peering SID on the router would indicate the MPLS label of the BGP Peering SID on the router would indicate
the traffic being forwarded based on the specific EPE path. the traffic being forwarded based on the specific EPE path.
Monitoring these counters and the flows hitting the corresponding Monitoring these counters and the flows hitting the corresponding
MPLS forwarding entry would help identify issues, if any, with MPLS forwarding entry would help identify issues, if any, with
traffic engineering over the EPE paths. Errors in the encoding or traffic engineering over the EPE paths. Errors in the encoding or
decoding of the SR information in the TLVs defined in this document decoding of the SR information in the TLVs defined in this document
may result in the unavailability of such information to a Centralized may result in the unavailability of such information to a Centralized
EPE Controller or incorrect information being made available to it. EPE Controller or incorrect information being made available to it.
This may result in the controller not being able to perform the This may result in the controller not being able to perform the
desired SR based optimization functionality or to perform it in an desired SR-based optimization functionality or performing it in an
unexpected or inconsistent manner. The handling of such errors by unexpected or inconsistent manner. The handling of such errors by
applications like such a controller may be implementation specific applications like such a controller may be implementation specific
and out of scope of this document. and out of scope of this document.
7. Security Considerations 8. Security Considerations
[RFC7752] defines BGP-LS NLRI to which the extensions defined in this [RFC7752] defines BGP-LS NLRI to which the extensions defined in this
document apply. The Security Considerations section of [RFC7752] document apply. Section 8 of [RFC7752] also applies to these
also applies to these extensions. The procedures and new TLVs extensions. The procedures and new TLVs defined in this document, by
defined in this document, by themselves, do not affect the BGP-LS themselves, do not affect the BGP-LS security model discussed in
security model discussed in [RFC7752]. [RFC7752].
BGP-EPE enables engineering of traffic when leaving the BGP-EPE enables engineering of traffic when leaving the
administrative domain via an egress BGP router. Therefore precaution administrative domain via an egress BGP router. Therefore,
is necessary to ensure that the BGP peering information collected via precaution is necessary to ensure that the BGP peering information
BGP-LS is limited to specific consumers in a secure manner. Segment collected via BGP-LS is limited to specific consumers in a secure
Routing operates within a trusted domain [RFC8402] and its security manner. Segment Routing operates within a trusted domain [RFC8402],
considerations also apply to BGP Peering Segments. The BGP-EPE and its security considerations also apply to BGP Peering Segments.
policies are expected to be used entirely within this trusted SR The BGP-EPE policies are expected to be used entirely within this
domain (e.g., between multiple AS/domains within a single provider trusted SR domain (e.g., between multiple AS/domains within a single
network). provider network).
The isolation of BGP-LS peering sessions is also required to ensure The isolation of BGP-LS peering sessions is also required to ensure
that BGP-LS topology information (including the newly added BGP that BGP-LS topology information (including the newly added BGP
peering topology) is not advertised to an external BGP peering peering topology) is not advertised to an external BGP peering
session outside an administrative domain. session outside an administrative domain.
8. Contributors 9. References
Mach (Guoyi) Chen
Huawei Technologies
China
Email: mach.chen@huawei.com
Acee Lindem
Cisco Systems Inc.
US
Email: acee@cisco.com
9. Acknowledgements
The authors would like to thank Jakob Heitz, Howard Yang, Hannes
Gredler, Peter Psenak, Arjun Sreekantiah and Bruno Decraene for their
feedback and comments. Susan Hares helped in improving the clarity
of the document with her substantial contributions during her
shepherd's review. The authors would also like to thank Alvaro
Retana for his extensive review and comments which helped correct
issues and improve the document.
10. References
10.1. Normative References
[I-D.ietf-idr-bgp-ls-segment-routing-ext] 9.1. Normative References
Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H.,
and M. Chen, "BGP Link-State extensions for Segment
Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-14
(work in progress), May 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous [RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
System Confederations for BGP", RFC 5065, System Confederations for BGP", RFC 5065,
DOI 10.17487/RFC5065, August 2007, DOI 10.17487/RFC5065, August 2007,
<https://www.rfc-editor.org/info/rfc5065>. <https://www.rfc-editor.org/info/rfc5065>.
skipping to change at page 17, line 14 skipping to change at line 738
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>. July 2018, <https://www.rfc-editor.org/info/rfc8402>.
10.2. Informative References [RFC9085] Previdi, S., Talaulikar, K., Ed., Filsfils, C., Gredler,
H., and M. Chen, "Border Gateway Protocol - Link State
(BGP-LS) Extensions for Segment Routing", RFC 9085,
DOI 10.17487/RFC9085, August 2021,
<https://www.rfc-editor.org/info/rfc9085>.
[I-D.dawra-idr-bgpls-srv6-ext] 9.2. Informative References
[BGPLS-SRV6]
Dawra, G., Filsfils, C., Talaulikar, K., Chen, M., Dawra, G., Filsfils, C., Talaulikar, K., Chen, M.,
daniel.bernier@bell.ca, d., Uttaro, J., Decraene, B., and Bernier, D., and B. Decraene, "BGP Link State Extensions
H. Elmalky, "BGP Link State Extensions for SRv6", draft- for SRv6", Work in Progress, Internet-Draft, draft-ietf-
dawra-idr-bgpls-srv6-ext-06 (work in progress), March idr-bgpls-srv6-ext-08, 8 June 2021,
2019. <https://datatracker.ietf.org/doc/html/draft-ietf-idr-
bgpls-srv6-ext-08>.
[I-D.ietf-spring-segment-routing-central-epe] [RFC9087] Filsfils, C., Ed., Previdi, S., Dawra, G., Ed., Aries, E.,
Filsfils, C., Previdi, S., Dawra, G., Aries, E., and D. and D. Afanasiev, "Segment Routing Centralized BGP Egress
Afanasiev, "Segment Routing Centralized BGP Egress Peer Peer Engineering", RFC 9087, DOI 10.17487/RFC9087, August
Engineering", draft-ietf-spring-segment-routing-central- 2021, <https://www.rfc-editor.org/info/rfc9087>.
epe-10 (work in progress), December 2017.
[I-D.ietf-spring-segment-routing-policy] [SR-POLICY]
Filsfils, C., Sivabalan, S., daniel.voyer@bell.ca, d., Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and
bogdanov@google.com, b., and P. Mattes, "Segment Routing P. Mattes, "Segment Routing Policy Architecture", Work in
Policy Architecture", draft-ietf-spring-segment-routing- Progress, Internet-Draft, draft-ietf-spring-segment-
policy-03 (work in progress), May 2019. routing-policy-13, 28 May 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-spring-
segment-routing-policy-13>.
Acknowledgements
The authors would like to thank Jakob Heitz, Howard Yang, Hannes
Gredler, Peter Psenak, Arjun Sreekantiah, and Bruno Decraene for
their feedback and comments. Susan Hares helped in improving the
clarity of the document with her substantial contributions during her
shepherd's review. The authors would also like to thank Alvaro
Retana for his extensive review and comments, which helped correct
issues and improve the document.
Contributors
Mach(Guoyi) Chen
Huawei Technologies
China
Email: mach.chen@huawei.com
Acee Lindem
Cisco Systems Inc.
United States of America
Email: acee@cisco.com
Authors' Addresses Authors' Addresses
Stefano Previdi Stefano Previdi
Individual Huawei Technologies
Email: stefano@previdi.net Email: stefano@previdi.net
Ketan Talaulikar (editor) Ketan Talaulikar (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
India India
Email: ketant@cisco.com Email: ketant@cisco.com
Clarence Filsfils Clarence Filsfils
Cisco Systems, Inc. Cisco Systems, Inc.
Brussels Brussels
Belgium Belgium
Email: cfilsfil@cisco.com Email: cfilsfil@cisco.com
Keyur Patel Keyur Patel
Arrcus, Inc. Arrcus, Inc.
skipping to change at page 18, line 17 skipping to change at line 817
Belgium Belgium
Email: cfilsfil@cisco.com Email: cfilsfil@cisco.com
Keyur Patel Keyur Patel
Arrcus, Inc. Arrcus, Inc.
Email: Keyur@arrcus.com Email: Keyur@arrcus.com
Saikat Ray Saikat Ray
Individual Contributor Individual
Email: raysaikat@gmail.com Email: raysaikat@gmail.com
Jie Dong Jie Dong
Huawei Technologies Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd. Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095 Beijing
100095
China China
Email: jie.dong@huawei.com Email: jie.dong@huawei.com
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