draft-ietf-idr-bgpls-segment-routing-epe-11.txt   draft-ietf-idr-bgpls-segment-routing-epe-12.txt 
Network Working Group S. Previdi, Ed. Network Working Group S. Previdi, Ed.
Internet-Draft C. Filsfils Internet-Draft C. Filsfils
Intended status: Standards Track Cisco Systems, Inc. Intended status: Standards Track Cisco Systems, Inc.
Expires: September 14, 2017 K. Patel Expires: October 30, 2017 K. Patel
Arrcus, Inc. Arrcus, Inc.
S. Ray S. Ray
Individual Contributor Individual Contributor
J. Dong J. Dong
M. Chen
Huawei Technologies Huawei Technologies
March 13, 2017 April 28, 2017
Segment Routing BGP Egress Peer Engineering BGP-LS Extensions BGP-LS extensions for Segment Routing BGP Egress Peer Engineering
draft-ietf-idr-bgpls-segment-routing-epe-11 draft-ietf-idr-bgpls-segment-routing-epe-12
Abstract Abstract
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. A segment can represent any prepending the packet with an SR header. A segment can represent any
instruction, topological or service-based. SR allows to enforce a instruction, topological or service-based. SR allows to enforce a
flow through any topological path and service chain while maintaining flow through any topological path and service chain while maintaining
per-flow state only at the ingress node of the SR domain. per-flow state only at the ingress node of the SR domain.
skipping to change at page 2, line 12 skipping to change at page 2, line 10
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 14, 2017. This Internet-Draft will expire on October 30, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 36 skipping to change at page 2, line 34
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Segment Routing Documents . . . . . . . . . . . . . . . . . . 3 2. Segment Routing Documents . . . . . . . . . . . . . . . . . . 3
3. BGP Peering Segments . . . . . . . . . . . . . . . . . . . . 4 3. BGP Peering Segments . . . . . . . . . . . . . . . . . . . . 4
4. Link NLRI for BGP-EPE Connectivity Description . . . . . . . 5 4. Link NLRI for BGP-EPE Connectivity Description . . . . . . . 5
4.1. BGP Router ID and Member ASN . . . . . . . . . . . . . . 5 4.1. BGP Router ID and Member ASN . . . . . . . . . . . . . . 5
4.2. BGP-EPE Node Descriptors . . . . . . . . . . . . . . . . 6 4.2. Mandatory BGP-EPE Node Descriptors . . . . . . . . . . . 6
4.3. Link Attributes . . . . . . . . . . . . . . . . . . . . . 7 4.3. Optional BGP-EPE Node Descriptors . . . . . . . . . . . . 7
5. Peer Node and Peer Adjacency Segments . . . . . . . . . . . . 9 4.4. Link Attributes . . . . . . . . . . . . . . . . . . . . . 7
5.1. Peer Node Segment (Peer-Node-SID) . . . . . . . . . . . . 9 5. Peer-Node and Peer-Adj SIDs . . . . . . . . . . . . . . . . . 9
5.2. Peer Adjacency Segment (Peer-Adj-SID) . . . . . . . . . . 10 5.1. Peer-Node-SID . . . . . . . . . . . . . . . . . . . . . . 10
5.3. Peer Set Segment . . . . . . . . . . . . . . . . . . . . 11 5.2. Peer-Adj-SID . . . . . . . . . . . . . . . . . . . . . . 11
5.3. Peer-Set-SID . . . . . . . . . . . . . . . . . . . . . . 12
6. Illustration . . . . . . . . . . . . . . . . . . . . . . . . 12 6. Illustration . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Reference Diagram . . . . . . . . . . . . . . . . . . . . 12 6.1. Reference Diagram . . . . . . . . . . . . . . . . . . . . 12
6.2. Peer Node Segment for Node D . . . . . . . . . . . . . . 14 6.2. Peer-Node-SID for Node D . . . . . . . . . . . . . . . . 14
6.3. Peer Node Segment for Node F . . . . . . . . . . . . . . 14 6.3. Peer-Node-SID for Node F . . . . . . . . . . . . . . . . 15
6.4. Peer Node Segment for Node E . . . . . . . . . . . . . . 14 6.4. Peer-Node-SID for Node E . . . . . . . . . . . . . . . . 15
6.5. Peer Adjacency Segment for Node E, Link 1 . . . . . . . . 15 6.5. Peer-Adj-SID for Node E, Link 1 . . . . . . . . . . . . . 15
6.6. Peer Adjacency Segment for Node E, Link 2 . . . . . . . . 15 6.6. Peer-Adj-SID for Node E, Link 2 . . . . . . . . . . . . . 16
7. Implementation Status . . . . . . . . . . . . . . . . . . . . 16 7. Implementation Status . . . . . . . . . . . . . . . . . . . . 16
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
8.1. New BGP-LS Protocol-ID . . . . . . . . . . . . . . . . . 17 8.1. New BGP-LS Protocol-ID . . . . . . . . . . . . . . . . . 17
8.2. Node Descriptors and Link Attribute TLVs . . . . . . . . 17 8.2. Node Descriptors and Link Attribute TLVs . . . . . . . . 18
9. Manageability Considerations . . . . . . . . . . . . . . . . 18 9. Manageability Considerations . . . . . . . . . . . . . . . . 18
10. Security Considerations . . . . . . . . . . . . . . . . . . . 18 10. Security Considerations . . . . . . . . . . . . . . . . . . . 19
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
13.1. Normative References . . . . . . . . . . . . . . . . . . 19 13.1. Normative References . . . . . . . . . . . . . . . . . . 19
13.2. Informative References . . . . . . . . . . . . . . . . . 19 13.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
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. A segment can represent any prepending the packet with an SR header with segment identifiers
instruction, topological or service-based. SR allows to enforce a (SID). A SID can represent any instruction, topological or service-
flow through any topological path and service chain while maintaining based. SR allows to enforce a flow through any topological path and
per-flow state only at the ingress node of the SR domain. service chain while maintaining per-flow state only at the ingress
node of the SR domain.
The Segment Routing architecture can be directly applied to the MPLS The Segment Routing architecture can be directly applied to the MPLS
dataplane with no change on the forwarding plane. It requires minor dataplane with no change on the forwarding plane. It requires minor
extension to the existing link-state routing protocols. extension to the existing link-state routing protocols.
This document outline a BGP-LS extension for exporting BGP peering This document outline a BGP-LS extension for exporting BGP peering
node topology information (including its peers, interfaces and node topology information (including its peers, interfaces and
peering ASs) in a way that is exploitable in order to compute peering ASs) in a way that is exploitable in order to compute
efficient BGP Egress Peer Engineering (BGP-EPE) policies and efficient BGP Egress Peer Engineering (BGP-EPE) policies and
strategies. strategies.
This document defines new types of segments: a Peer Node segment This document defines the BGP-LS extensions required to support the
describing the BGP session between two nodes; a Peer Adjacency Peer Node SID describing the BGP session between two nodes, the Peer
Segment describing the link (one or more) that is used by the BGP Adjacency SID describing the link (one or more) that is used by the
session; the Peer Set Segment describing an arbitrary set of sessions BGP session and the Peer Set SID describing an arbitrary set of
or links between the local BGP node and its peers. sessions or links between the local BGP node and its peers. These
SIDs represent the segments defined in
[I-D.ietf-spring-segment-routing-central-epe].
While an egress point topology usually refers to eBGP sessions While an egress point 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. context of iBGP sessions.
2. Segment Routing Documents 2. Segment Routing Documents
The main reference for this document is the SR architecture defined The main reference for this document is the SR architecture defined
in [I-D.ietf-spring-segment-routing]. in [I-D.ietf-spring-segment-routing].
The Segment Routing BGP Egress Peer Engineering (BGP-EPE) The Segment Routing BGP Egress Peer Engineering (BGP-EPE)
architecture is described in architecture is described in
[I-D.ietf-spring-segment-routing-central-epe]. [I-D.ietf-spring-segment-routing-central-epe].
3. BGP Peering Segments 3. BGP Peering Segments
As defined in [I-D.ietf-spring-segment-routing-central-epe], an BGP- As defined in [I-D.ietf-spring-segment-routing-central-epe], a BGP-
EPE enabled Egress PE node MAY advertise segments corresponding to EPE enabled Egress PE node MAY advertise SIDs corresponding to its
its attached peers. These segments are called BGP peering segments attached peers. These SIDs are called BGP peering segments or BGP
or BGP Peering SIDs. In case of eBGP, they enable the expression of Peering SIDs. In case of eBGP, they enable the expression of source-
source-routed inter-domain paths. routed inter-domain paths.
An ingress border router of an AS may compose a list of segments to An ingress border router of an AS may compose a list of SIDs to steer
steer a flow along a selected path within the AS, towards a selected a flow along a selected path within the AS, towards a selected egress
egress border router C of the AS and through a specific peer. At border router C of the AS and through a specific peer. At minimum, a
minimum, a BGP-EPE policy applied at an ingress PE involves two BGP-EPE policy applied at an ingress PE involves two SIDs: the Node
segments: the Node SID of the chosen egress PE and then the BGP SID of the chosen egress PE and then the BGP Peering SID for the
Peering Segment for the chosen egress PE peer or peering interface. chosen egress PE peer or peering interface.
This document defines the BGP-EPE Peering Segments: This document defines the BGP-LS extensions for the BGP-EPE Peering
SIDs:
o Peer Node Segment (Peer-Node-SID) o Peer Node Segment (Peer-Node-SID)
o Peer Adjacency Segment (Peer-Adj-SID) o Peer Adjacency Segment (Peer-Adj-SID)
o Peer Set Segment (Peer-Set-SID) o Peer Set Segment (Peer-Set-SID)
Each BGP session MUST be described by a Peer Node Segment. The that have been defined in
[I-D.ietf-spring-segment-routing-central-epe].
Each BGP session MUST be described by a Peer Node SID. The
description of the BGP session MAY be augmented by additional description of the BGP session MAY be augmented by additional
Adjacency Segments. Finally, each Peer Node Segment and Peer Adjacency SIDs. Finally, each Peer Node SID and Peer Adjacency SID
Adjacency Segment MAY be part of the same group/set so to be able to MAY be part of the same group/set so to be able to group EPE
group EPE resources under a common Peer-Set Segment Identifier (SID). resources under a common Peer-Set SID.
Therefore, when the extensions defined in this document are applied Therefore, when the extensions defined in this document are applied
to the use case defined in to the use case defined in
[I-D.ietf-spring-segment-routing-central-epe]: [I-D.ietf-spring-segment-routing-central-epe]:
o One Peer Node Segment MUST be present. o One Peer-Node-SID MUST be present.
o One or more Peer Adjacency Segments MAY be present. o One or more Peer-Adj-SID MAY be present.
o Each of the Peer Node and Peer Adjacency Segment MAY use the same o Each of the Peer-Node-SID Peer-Adj-SID MAY use the same Peer-Set-
Peer-Set. SID.
While an egress point topology usually refers to eBGP sessions While an egress point 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. context of iBGP sessions.
4. Link NLRI for BGP-EPE Connectivity Description 4. Link NLRI for BGP-EPE Connectivity Description
This section describes the NLRI used for describing the connectivity This section describes the NLRI used for describing the connectivity
of the BGP Egress router. The connectivity is based on links and of the BGP Egress router. The connectivity is based on links and
remote peers/ASs and therefore the existing Link-Type NLRI (defined remote peers/ASs and therefore the existing Link NLRI Type (defined
in [RFC7752]) is used. A new Protocol-ID is used: BGP (codepoint 7 in [RFC7752]) is used. A new Protocol-ID is used: BGP (codepoint 7
assigned by IANA (Section 8) from the registry "BGP-LS Protocol- assigned by IANA (Section 8) from the registry "BGP-LS Protocol-
IDs"). IDs").
The use of a new Protocol-ID allows separation and differentiation The use of a new Protocol-ID allows separation and differentiation
between the NLRIs carrying BGP-EPE descriptors from the NLRIs between the NLRIs carrying BGP-EPE descriptors from the NLRIs
carrying IGP link-state information as defined in [RFC7752]. The carrying IGP link-state information as defined in [RFC7752]. The
Link NLRI Type uses descriptors and attributes already defined in Link NLRI Type uses descriptors and attributes already defined in
[RFC7752] in addition to new TLVs defined in the following sections [RFC7752] in addition to new TLVs defined in the following sections
of this document. of this document.
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Type: 517 (assigned by IANA (Section 8) from the registry "BGP- Type: 517 (assigned by IANA (Section 8) from the registry "BGP-
LS Node Descriptor, Link Descriptor, Prefix Descriptor, and LS Node Descriptor, Link Descriptor, Prefix Descriptor, and
Attribute TLVs"). Attribute TLVs").
Length: 4 octets Length: 4 octets
Value: 4 octet unsigned integer representing the Member ASN Value: 4 octet unsigned integer representing the Member ASN
inside the Confederation.[RFC5065]. inside the Confederation.[RFC5065].
4.2. BGP-EPE Node Descriptors 4.2. Mandatory BGP-EPE Node Descriptors
The following Node Descriptors Sub-TLVs MUST appear in the Link NLRI The following Node Descriptors Sub-TLVs MUST appear in the Link NLRI
as Local Node Descriptors: as Local Node Descriptors:
o BGP Router-ID, which contains the BGP Identifier of the local BGP- o BGP Router-ID, which contains the BGP Identifier of the local BGP-
EPE capable node. EPE capable node.
o Autonomous System Number, which contains the local ASN or local o Autonomous System Number, which contains the local ASN or local
confederation identifier (ASN) if confederations are used. confederation identifier (ASN) if confederations are used.
o BGP-LS Identifier. o BGP-LS Identifier.
It has to be noted that [RFC6286] (section 2.1) requires the BGP It has to be noted that [RFC6286] (section 2.1) requires the BGP
identifier (router-id) to be unique within an Autonomous System. identifier (router-id) to be unique within an Autonomous System.
Therefore, the <ASN, BGP identifier> tuple is globally unique. Therefore, the <ASN, BGP identifier> tuple is globally unique.
The following Node Descriptors Sub-TLVs MAY appear in the Link NLRI
as Local Node Descriptors:
o Member-ASN, which contains the ASN of the confederation member
(when BGP confederations are used).
o Node Descriptors as defined in [RFC7752].
The following Node Descriptors Sub-TLVs MUST appear in the Link NLRI The following Node Descriptors Sub-TLVs MUST appear in the Link NLRI
as Remote Node Descriptors: as Remote Node Descriptors:
o BGP Router-ID, which contains the BGP Identifier of the peer node. o BGP Router-ID, which contains the BGP Identifier of the peer node.
o Autonomous System Number, which contains the peer ASN or the peer o Autonomous System Number, which contains the peer ASN or the peer
confederation identifier (ASN), if confederations are used. confederation identifier (ASN), if confederations are used.
4.3. Optional BGP-EPE Node Descriptors
The following Node Descriptors Sub-TLVs MAY appear in the Link NLRI
as Local Node Descriptors:
o Member-ASN, which contains the ASN of the confederation member
(when BGP confederations are used).
o Node Descriptors as defined in [RFC7752].
The following Node Descriptors Sub-TLVs MAY appear in the Link NLRI The following Node Descriptors Sub-TLVs MAY appear in the Link NLRI
as Remote Node Descriptors: as Remote Node Descriptors:
o Member-ASN, which contains the ASN of the confederation member o Member-ASN, which contains the ASN of the confederation member
(when BGP confederations are used). (when BGP confederations are used).
o Node Descriptors as defined in defined in [RFC7752]. o Node Descriptors as defined in defined in [RFC7752].
4.3. Link Attributes 4.4. Link Attributes
The following BGP-LS Link attributes TLVs are used with the Link The following BGP-LS Link attributes TLVs are used with the Link
NLRI: NLRI:
+----------+---------------------------+----------+ +----------+---------------------------+----------+
| TLV Code | Description | Length | | TLV Code | Description | Length |
| Point | | | | Point | | |
+----------+---------------------------+----------+ +----------+---------------------------+----------+
| 1101 | Peer Node Segment | variable | | 1101 | Peer Node Segment | variable |
| | Identifier (Peer-Node-SID)| | | | Identifier (Peer-Node-SID)| |
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where: where:
Figure 2 Figure 2
o Type: 1101 or 1102 or 1103 (assigned by IANA (Section 8) from the o Type: 1101 or 1102 or 1103 (assigned by IANA (Section 8) from the
registry "BGP-LS Node Descriptor, Link Descriptor, Prefix registry "BGP-LS Node Descriptor, Link Descriptor, Prefix
Descriptor, and Attribute TLVs"). Descriptor, and Attribute TLVs").
o Length: variable. o Length: variable.
o Flags: following flags have been defined: o Flags: one octet of flags used when advertising a Peer-Adj-SID
(Peer-Node and Peer-Set SIDs don't have flags defined). The
following Peer-Adj-SID flags have been defined:
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|V|L| | |V|L| |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
where: where:
* V-Flag: Value flag. If set, then the Adj-SID carries a value. * V-Flag: Value flag. If set, then the Adj-SID carries a value.
By default the flag is SET. By default the flag is SET.
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o SID/Index/Label. According to the TLV length and to the V and L o SID/Index/Label. According to the TLV length and to the V and L
flags settings, it contains either: flags 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 MUST
be set. be set.
* A 4 octet index defining the offset in the SRGB (Segment * A 4 octet index defining the offset in the SRGB (Segment
Routing Global Block as defined in Routing Global Block as defined in
[I-D.ietf-spring-segment-routing] advertised by this router. [I-D.ietf-spring-segment-routing] advertised by this router.
In this case the SRGB MUST be advertised using the extensions In this case, the SRGB MUST be advertised using the extensions
defined in [I-D.ietf-idr-bgp-ls-segment-routing-ext]. defined in [I-D.ietf-idr-bgp-ls-segment-routing-ext].
* A 16 octet IPv6 address. In this case the V flag MUST be set. * A 16 octet IPv6 address. In this case the V flag MUST be set.
The L flag MUST be unset if the IPv6 address is globally The L flag MUST be unset if the IPv6 address is globally
unique. unique.
The values of the Peer-Node-SID, Peer-Adj-SID and Peer-Set-SID Sub- The values of the Peer-Node-SID, Peer-Adj-SID and Peer-Set-SID Sub-
TLVs SHOULD be persistent across router restart. TLVs SHOULD be persistent across router restart.
The Peer-Node-SID MUST be present when BGP-LS is used for the use The Peer-Node-SID MUST be present when BGP-LS is used for the use
skipping to change at page 9, line 14 skipping to change at page 9, line 35
The Peer-Adj-SID and Peer-Set-SID SubTLVs MAY be present when BGP-LS The Peer-Adj-SID and Peer-Set-SID SubTLVs MAY be present when BGP-LS
is used for the use case described in is used for the use case described in
[I-D.ietf-spring-segment-routing-central-epe] and MAY be omitted for [I-D.ietf-spring-segment-routing-central-epe] and MAY be omitted for
other use cases. other use cases.
In addition, BGP-LS Nodes and Link Attributes, as defined in In addition, BGP-LS Nodes and Link Attributes, as defined in
[RFC7752] MAY be inserted in order to advertise the characteristics [RFC7752] MAY be inserted in order to advertise the characteristics
of the link. of the link.
5. Peer Node and Peer Adjacency Segments 5. Peer-Node and Peer-Adj SIDs
In this section the following Peer Segments are defined: In this section the following SIDs are defined:
Peer Node Segment (Peer-Node-SID) Peer Node Segment Identifier (Peer-Node-SID)
Peer Adjacency Segment (Peer-Adj-SID) Peer Adjacency Segment Identifier (Peer-Adj-SID)
Peer Set Segment (Peer-Set-SID) Peer Set Segment Identifier (Peer-Set-SID)
The Peer Node, Peer Adjacency and Peer Set segments can be either a The Peer-Node, Peer-Adj and Peer-Set SIDs can be either a local or a
local or a global segment (depending on the setting of the V and L global (depending on the setting of the V and L flags defined in
flags defined in Figure 2. For example, when BGP-EPE is used in the Figure 2. For example, when BGP-EPE is used in the context of a SR
context of a SR network over the IPv6 dataplane, it is likely the network over the IPv6 dataplane, it is likely the case that the IPv6
case that the IPv6 addresses used as SIDs will be global. addresses used as SIDs will be global.
5.1. Peer Node Segment (Peer-Node-SID) 5.1. Peer-Node-SID
The Peer Node Segment describes the BGP session peer (neighbor). It The Peer-Node-SID describes the BGP session peer (neighbor). It MUST
MUST be present when describing a BGP-EPE topology as defined in be present when describing a BGP-EPE topology as defined in
[I-D.ietf-spring-segment-routing-central-epe]. The Peer Node Segment [I-D.ietf-spring-segment-routing-central-epe]. The Peer-Node-SID is
is encoded within the BGP-LS Link NLRI specified in Section 4. encoded within the BGP-LS Link NLRI specified in Section 4.
The Peer Node Segment, at the BGP node advertising it, has the The Peer-Node-SID, at the BGP node advertising it, has the following
following semantic: semantic:
o SR header operation: NEXT (as defined in o SR header operation: NEXT (as defined in
[I-D.ietf-spring-segment-routing]). [I-D.ietf-spring-segment-routing]).
o Next-Hop: the connected peering node to which the segment is o Next-Hop: the connected peering node to which the segment is
related. related.
The Peer Node Segment is advertised with a Link NLRI, where: The Peer-Node-SID is advertised with a Link NLRI, where:
o Local Node Descriptors contains o Local Node Descriptors contains
Local BGP Router-ID of the BGP-EPE enabled egress PE. Local BGP Router-ID of the BGP-EPE enabled egress PE.
Local ASN. Local ASN.
BGP-LS Identifier. BGP-LS Identifier.
o Remote Node Descriptors contains o Remote Node Descriptors contains
Peer BGP Router-ID (i.e.: the peer BGP ID used in the BGP session). Peer BGP Router-ID (i.e.: the peer BGP ID used in the BGP session).
skipping to change at page 10, line 26 skipping to change at page 10, line 50
* IPv4 Neighbor Address (Sub-TLV 260) contains the BGP session * IPv4 Neighbor Address (Sub-TLV 260) contains the BGP session
IPv4 peer address. IPv4 peer address.
* IPv6 Interface Address (Sub-TLV 261) contains the BGP session * IPv6 Interface Address (Sub-TLV 261) contains the BGP session
IPv6 local address. IPv6 local address.
* IPv6 Neighbor Address (Sub-TLV 262) contains the BGP session * IPv6 Neighbor Address (Sub-TLV 262) contains the BGP session
IPv6 peer address. IPv6 peer address.
o Link Attribute contains the Peer-Node-SID TLV as defined in o Link Attribute contains the Peer-Node-SID TLV as defined in
Section 4.3. Section 4.4.
o In addition, BGP-LS Link Attributes, as defined in [RFC7752], MAY o In addition, BGP-LS Link Attributes, as defined in [RFC7752], MAY
be inserted in order to advertise the characteristics of the link. be inserted in order to advertise the characteristics of the link.
5.2. Peer Adjacency Segment (Peer-Adj-SID) 5.2. Peer-Adj-SID
The Peer Adjacency Segment, at the BGP node advertising it, has the The Peer-Adj-SID, at the BGP node advertising it, has the following
following semantic: semantic:
o SR header operation: NEXT (as defined in o SR header operation: NEXT (as defined in
[I-D.ietf-spring-segment-routing]). [I-D.ietf-spring-segment-routing]).
o Next-Hop: the interface peer address. o Next-Hop: the interface peer address.
The Peer Adjacency Segment is advertised with a Link NLRI, where: The Peer-Adj-SID is advertised with a Link NLRI, where:
o Local Node Descriptors contains o Local Node Descriptors contains
Local BGP Router-ID of the BGP-EPE enabled egress PE. Local BGP Router-ID of the BGP-EPE enabled egress PE.
Local ASN. Local ASN.
BGP-LS Identifier. BGP-LS Identifier.
o Remote Node Descriptors contains o Remote Node Descriptors contains
Peer BGP Router-ID (i.e.: the peer BGP ID used in the BGP session). Peer BGP Router-ID (i.e.: the peer BGP ID used in the BGP session).
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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 used with the Peer-Adj-SID contains the TLV as o Link attribute used with the Peer-Adj-SID contains the TLV as
defined in Section 4.3. defined in Section 4.4.
In addition, BGP-LS Link Attributes, as defined in [RFC7752], MAY be In addition, BGP-LS Link Attributes, as defined in [RFC7752], MAY be
inserted in order to advertise the characteristics of the link. inserted in order to advertise the characteristics of the link.
5.3. Peer Set Segment 5.3. Peer-Set-SID
The Peer Adjacency Segment, at the BGP node advertising it, has the The Peer-Set-SID, at the BGP node advertising it, has the following
following semantic: semantic:
o SR header operation: NEXT (as defined in o SR header operation: NEXT (as defined in
[I-D.ietf-spring-segment-routing]). [I-D.ietf-spring-segment-routing]).
o Next-Hop: load balance across any connected interface to any peer o Next-Hop: load balance across any connected interface to any peer
in the related set. in the related set.
The Peer Set Segment is advertised within a Link NLRI (describing a The Peer-Set-SID is advertised within a Link NLRI (describing a Peer
Peer Node Segment or a Peer Adjacency segment) as a BGP-LS attribute. Node Segment or a Peer Adjacency segment) as a BGP-LS attribute.
The Peer Set Attribute contains the Peer-Set-SID TLV, defined in The Peer Set Attribute contains the Peer-Set-SID TLV, defined in
Section 4.3 identifying the set of which the Peer Node Segment or Section 4.4 identifying the set of which the Peer-Node-SID or Peer-
Peer Adjacency Segment is a member. Adj-SID is a member.
6. Illustration 6. Illustration
6.1. Reference Diagram 6.1. Reference Diagram
The following reference diagram is used throughout this document. The following reference diagram is used throughout this document.
The solution is illustrated for IPv6 with MPLS-based segments and the The solution is illustrated for IPv6 with MPLS-based SIDs and the
BGP-EPE topology is based on eBGP sessions between external peers. BGP-EPE topology is based on eBGP sessions between external peers.
As stated in Section 3, the solution illustrated hereafter is equally As stated in Section 3, the solution illustrated hereafter is equally
applicable to an iBGP session topology. In other words, the solution applicable to an iBGP session topology. In other words, the solution
also applies to the case where C, D, F, and E are in the same AS and also applies to the case where C, D, F, and E are in the same AS and
run iBGP sessions between each other. run iBGP sessions between each other.
+------+ +------+
| | | |
+---D H +---D H
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o Multi-hop eBGP peering with E on ip address 2001:db8:e::e (E) o Multi-hop eBGP peering with E on ip address 2001:db8:e::e (E)
C's resolution of the multi-hop eBGP session to E: C's resolution of the multi-hop eBGP session to E:
o Static route 2001:db8:e::e/128 via 2001:db8:ce1::e o Static route 2001:db8:e::e/128 via 2001:db8:ce1::e
o Static route 2001:db8:e::e/128 via 2001:db8:ce2::e o Static route 2001:db8:e::e/128 via 2001:db8:ce2::e
Node C configuration is such that: Node C configuration is such that:
o A Peer Node segment (Peer-Node-SID) is allocated to each peer (D, o A Peer-Node-SID is allocated to each peer (D, F and E).
F and E).
o An Peer Adjacency segment (Peer-Adj-SID) is defined for each o An Peer-Adj-SID is defined for each recursing interface to a
recursing interface to a multi-hop peer (CE upper and lower multi-hop peer (CE upper and lower interfaces).
interfaces).
o A Peer Set segment (Peer-Set-SID) is defined to include all peers o A Peer-Set-SID is defined to include all peers in AS3 (peers F and
in AS3 (peers F and E). E).
Local BGP-LS Identifier in router C is set to 10000. Local BGP-LS Identifier in router C is set to 10000.
The Link NLRI Type is used in order to encode C's connectivity. The The Link NLRI Type is used in order to encode C's connectivity. The
Link NLRI uses the Protocol-ID value (to be assigned by IANA) Link NLRI uses the Protocol-ID value (to be assigned by IANA)
Once the BGP-LS update is originated by C, it may be advertised to Once the BGP-LS update is originated by C, it may be advertised to
internal (iBGP) as well as external (eBGP) neighbors supporting the internal (iBGP) as well as external (eBGP) neighbors supporting the
BGP-LS EPE extensions defined in this document. BGP-LS EPE extensions defined in this document.
6.2. Peer Node Segment for Node D 6.2. Peer-Node-SID for Node D
Descriptors: Descriptors:
o Local Node Descriptors (BGP Router-ID, local ASN, BGP-LS o Local Node Descriptors (BGP Router-ID, local ASN, BGP-LS
Identifier): 192.0.2.3, AS1, 10000 Identifier): 192.0.2.3, AS1, 10000
o Remote Node Descriptors (BGP Router-ID, peer ASN): 192.0.2.4, AS2 o Remote Node Descriptors (BGP Router-ID, peer ASN): 192.0.2.4, AS2
o Link Descriptors (BGP session IPv6 local address, BGP session IPv6 o Link Descriptors (BGP session IPv6 local address, BGP session IPv6
neighbor address): 2001:db8:cd::c, 2001:db8:cd::d neighbor address): 2001:db8:cd::c, 2001:db8:cd::d
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Identifier): 192.0.2.3, AS1, 10000 Identifier): 192.0.2.3, AS1, 10000
o Remote Node Descriptors (BGP Router-ID, peer ASN): 192.0.2.4, AS2 o Remote Node Descriptors (BGP Router-ID, peer ASN): 192.0.2.4, AS2
o Link Descriptors (BGP session IPv6 local address, BGP session IPv6 o Link Descriptors (BGP session IPv6 local address, BGP session IPv6
neighbor address): 2001:db8:cd::c, 2001:db8:cd::d neighbor address): 2001:db8:cd::c, 2001:db8:cd::d
Attributes: Attributes:
o Peer-Node-SID: 1012 o Peer-Node-SID: 1012
o Link Attributes: see section 3.3.2 of [RFC7752] o Link Attributes: see section 3.3.2 of [RFC7752]
6.3. Peer Node Segment for Node F 6.3. Peer-Node-SID for Node F
Descriptors: Descriptors:
o Local Node Descriptors (BGP Router-ID, ASN, BGPLS Identifier): o Local Node Descriptors (BGP Router-ID, ASN, BGPLS Identifier):
192.0.2.3, AS1, 10000 192.0.2.3, AS1, 10000
o Remote Node Descriptors (BGP Router-ID ASN): 192.0.2.6, AS3 o Remote Node Descriptors (BGP Router-ID ASN): 192.0.2.6, AS3
o Link Descriptors (BGP session IPv6 local address, BGP session IPv6 o Link Descriptors (BGP session IPv6 local address, BGP session IPv6
peer address): 2001:db8:cf::c, 2001:db8:cf::f peer address): 2001:db8:cf::c, 2001:db8:cf::f
Attributes: Attributes:
o Peer-Node-SID: 1022 o Peer-Node-SID: 1022
o Peer-Set-SID: 1060 o Peer-Set-SID: 1060
o Link Attributes: see section 3.3.2 of [RFC7752] o Link Attributes: see section 3.3.2 of [RFC7752]
6.4. Peer Node Segment for Node E 6.4. Peer-Node-SID for Node E
Descriptors: Descriptors:
o Local Node Descriptors (BGP Router-ID, ASN, BGP-LS Identifier): o Local Node Descriptors (BGP Router-ID, ASN, BGP-LS Identifier):
192.0.2.3, AS1, 10000 192.0.2.3, AS1, 10000
o Remote Node Descriptors (BGP Router-ID, ASN): 192.0.2.5, AS3 o Remote Node Descriptors (BGP Router-ID, ASN): 192.0.2.5, AS3
o Link Descriptors (BGP session IPv6 local address, BGP session IPv6 o Link Descriptors (BGP session IPv6 local address, BGP session IPv6
peer address): 2001:db8:c::c, 2001:db8:e::e peer address): 2001:db8:c::c, 2001:db8:e::e
Attributes: Attributes:
o Peer-Node-SID: 1052 o Peer-Node-SID: 1052
o Peer-Set-SID: 1060 o Peer-Set-SID: 1060
6.5. Peer Adjacency Segment for Node E, Link 1 6.5. Peer-Adj-SID for Node E, Link 1
Descriptors: Descriptors:
o Local Node Descriptors (BGP Router-ID, ASN, BGP-LS Identifier): o Local Node Descriptors (BGP Router-ID, ASN, BGP-LS Identifier):
192.0.2.3, AS1, 10000 192.0.2.3, AS1, 10000
o Remote Node Descriptors (BGP Router-ID, ASN): 192.0.2.5, AS3 o Remote Node Descriptors (BGP Router-ID, ASN): 192.0.2.5, AS3
o Link Descriptors (local interface identifier, IPv6 peer interface o Link Descriptors (local interface identifier, IPv6 peer interface
address): 0.0.0.1.0.0.0.0 , 2001:db8:ce1::e address): 0.0.0.1.0.0.0.0 , 2001:db8:ce1::e
Attributes: Attributes:
o Peer-Adj-SID: 1032 o Peer-Adj-SID: 1032
o LinkAttributes: see section 3.3.2 of [RFC7752] o LinkAttributes: see section 3.3.2 of [RFC7752]
6.6. Peer Adjacency Segment for Node E, Link 2 6.6. Peer-Adj-SID for Node E, Link 2
Descriptors: Descriptors:
o Local Node Descriptors (BGP Router-ID, ASN, BGP-LS Identifier): o Local Node Descriptors (BGP Router-ID, ASN, BGP-LS Identifier):
192.0.2.3, AS1, 10000 192.0.2.3, AS1, 10000
o Remote Node Descriptors (BGP Router-ID, ASN): 192.0.2.5, AS3 o Remote Node Descriptors (BGP Router-ID, ASN): 192.0.2.5, AS3
o Link Descriptors (local interface identifier, IPv6 peer interface o Link Descriptors (local interface identifier, IPv6 peer interface
address): 0.0.0.2.0.0.0.0 , 2001:db8:ce2::e address): 0.0.0.2.0.0.0.0 , 2001:db8:ce2::e
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+-----------------------------------------------------------+ +-----------------------------------------------------------+
| Codepoint | Description | Status | | Codepoint | Description | Status |
+-----------------------------------------------------------+ +-----------------------------------------------------------+
| 1101 | Peer-Node-SID | Assigned by IANA | | 1101 | Peer-Node-SID | Assigned by IANA |
| 1102 | Peer-Adj-SID | Assigned by IANA | | 1102 | Peer-Adj-SID | Assigned by IANA |
| 1103 | Peer-Set-SID | Assigned by IANA | | 1103 | Peer-Set-SID | Assigned by IANA |
+------------+----------------------------------------------+ +------------+----------------------------------------------+
9. Manageability Considerations 9. Manageability Considerations
This BGP-LS ([RFC7752]) extensions that are described in this The BGP-LS ([RFC7752]) extensions that are described in this document
document consists of additional BGP-LS descriptors and TLVs that will consist of additional BGP-LS descriptors and TLVs that will follow
follow the same manageability functions of BGP-LS, described in the same manageability functions of BGP-LS, described in [RFC7752].
[RFC7752].
The operator MUST be capable of configuring, enabling, disabling the The operator MUST be capable of configuring, enabling, disabling the
advertisement of each of the Peer-Node-SID, Peer-Adj-SID and Peer- advertisement of each of the Peer-Node-SID, Peer-Adj-SID and Peer-
Set-SID as well as to control which information is advertised to Set-SID as well as to control which information is advertised to
which internal or external peer. This is not different from what is which internal or external peer. This is not different from what is
required by a BGP speaker in terms of information origination and required by a BGP speaker in terms of information origination and
advertisement. In addition, the advertisement of EPE information advertisement. In addition, the advertisement of EPE information
MUST conform to standard BGP advertisement and propagation rules MUST conform to standard BGP advertisement and propagation rules
(iBGP, eBGP, Route-Reflectors, Confederations). (iBGP, eBGP, Route-Reflectors, Confederations).
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this document apply. this document apply.
The Security Section of [RFC7752] also applies to: The Security Section of [RFC7752] also applies to:
o New Node Descriptors Sub-TLVs: BGP-Router-ID and BGP- o New Node Descriptors Sub-TLVs: BGP-Router-ID and BGP-
Confederation-Member; Confederation-Member;
o New BGP-LS Attributes TLVs: Peer-Node-SID, Peer-Adj-SID and Peer- o New BGP-LS Attributes TLVs: Peer-Node-SID, Peer-Adj-SID and Peer-
Set-SID. Set-SID.
The extensions defined in this document do not introduce any
additional security aspects of BGP-LS.
11. Contributors 11. Contributors
Acee Lindem gave a substantial contribution to this document. Mach (Guoyi) Chen
Huawei Technologies
China
Email: mach.chen@huawei.com
Acee Lindem
Cisco Systems Inc.
US
Email: acee@cisco.com
12. Acknowledgements 12. Acknowledgements
The authors would like to thank Jakob Heitz, Howard Yang, Hannes The authors would like to thank Jakob Heitz, Howard Yang, Hannes
Gredler, Peter Psenak, Ketan Jivan Talaulikar, Arjun Sreekantiah and Gredler, Peter Psenak, Ketan Jivan Talaulikar, Arjun Sreekantiah and
Bruno Decraene for their feedback and comments. Bruno Decraene for their feedback and comments.
13. References 13. References
13.1. Normative References 13.1. Normative References
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Keyur Patel Keyur Patel
Arrcus, Inc. Arrcus, Inc.
Email: Keyur@arrcus.com Email: Keyur@arrcus.com
Saikat Ray Saikat Ray
Individual Contributor Individual Contributor
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
Mach (Guoyi) Chen
Huawei Technologies
Huawei Campus, No. 156 Beiqing Rd.
Beijing 100095
China
Email: mach.chen@huawei.com
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