draft-ietf-idr-bgpls-segment-routing-epe-02.txt   draft-ietf-idr-bgpls-segment-routing-epe-03.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: June 23, 2016 S. Ray Expires: September 22, 2016 S. Ray
Individual Contributor Individual Contributor
K. Patel K. Patel
Cisco Systems, Inc. Cisco Systems, Inc.
J. Dong J. Dong
M. Chen M. Chen
Huawei Technologies Huawei Technologies
December 21, 2015 March 21, 2016
Segment Routing Egress Peer Engineering BGP-LS Extensions Segment Routing BGP Peer Engineering BGP-LS Extensions
draft-ietf-idr-bgpls-segment-routing-epe-02 draft-ietf-idr-bgpls-segment-routing-epe-03
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.
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 egress This document outline a BGP-LS extension for exporting BGP peering
point 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 Egress Point Engineering policies and strategies. efficient BGP Peering Engineering policies and strategies.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 2, line 12 skipping to change at page 2, line 12
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 June 23, 2016. This Internet-Draft will expire on September 22, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 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
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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 EPE Connectivity Description . . . . . . . . . 5 4. Link NLRI for BGP-PE Connectivity Description . . . . . . . . 5
4.1. BGP Router ID and Member ASN . . . . . . . . . . . . . . 5 4.1. BGP Router ID and Member ASN . . . . . . . . . . . . . . 5
4.2. EPE Node Descriptors . . . . . . . . . . . . . . . . . . 6 4.2. BGP-PE Node Descriptors . . . . . . . . . . . . . . . . . 6
4.3. Link Attributes . . . . . . . . . . . . . . . . . . . . . 7 4.3. Link Attributes . . . . . . . . . . . . . . . . . . . . . 7
5. Peer Node and Peer Adjacency Segments . . . . . . . . . . . . 9 5. Peer Node and Peer Adjacency Segments . . . . . . . . . . . . 9
5.1. Peer Node Segment (Peer-Node-SID) . . . . . . . . . . . . 9 5.1. Peer Node Segment (Peer-Node-SID) . . . . . . . . . . . . 9
5.2. Peer Adjacency Segment (Peer-Adj-SID) . . . . . . . . . . 10 5.2. Peer Adjacency Segment (Peer-Adj-SID) . . . . . . . . . . 10
5.3. Peer Set Segment . . . . . . . . . . . . . . . . . . . . 11 5.3. Peer Set Segment . . . . . . . . . . . . . . . . . . . . 11
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 Segment for Node D . . . . . . . . . . . . . . 14
6.3. Peer Node Segment for Node H . . . . . . . . . . . . . . 14 6.3. Peer Node Segment for Node H . . . . . . . . . . . . . . 14
6.4. Peer Node Segment for Node E . . . . . . . . . . . . . . 14 6.4. Peer Node Segment for Node E . . . . . . . . . . . . . . 14
skipping to change at page 3, line 24 skipping to change at page 3, line 24
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.
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 egress This document outline a BGP-LS extension for exporting BGP peering
point 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 Egress Point Engineering policies and strategies. efficient BGP Peer Engineering (BGP-PE) policies and strategies.
This document defines new types of segments: a Peer Node segment This document defines new types of segments: a Peer Node segment
describing the BGP session between two nodes; a Peer Adjacency describing the BGP session between two nodes; a Peer Adjacency
Segment describing the link (one or more) that is used by the BGP Segment describing the link (one or more) that is used by the BGP
session; the Peer Set Segment describing an arbitrary set of sessions session; the Peer Set Segment describing an arbitrary set of sessions
or links between the local BGP node and its peers. or links between the local BGP node and its peers.
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 Egress Peer Engineering architecture is described The Segment Routing BGP Peer Engineering (BGP-PE) architecture is
in [I-D.ietf-spring-segment-routing-central-epe]. described in [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 EPE As defined in [I-D.ietf-spring-segment-routing-central-epe], an BGP-
enabled Egress PE node MAY advertise segments corresponding to its PE enabled Egress PE node MAY advertise segments corresponding to its
attached peers. These segments are called BGP peering segments or attached peers. These segments are called BGP peering segments or
BGP Peering SIDs. They enable the expression of source-routed inter- BGP Peering SIDs. In case of eBGP, they enable the expression of
domain paths. source-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 segments to
steer a flow along a selected path within the AS, towards a selected steer a flow along a selected path within the AS, towards a selected
egress border router C of the AS and through a specific peer. At egress border router C of the AS and through a specific peer. At
minimum, a BGP Peering Engineering policy applied at an ingress PE minimum, a BGP-PE policy applied at an ingress PE involves two
involves two segments: the Node SID of the chosen egress PE and then segments: the Node SID of the chosen egress PE and then the BGP
the BGP Peering Segment for the chosen egress PE peer or peering Peering Segment for the chosen egress PE peer or peering interface.
interface.
This document defines the BGP EPE Peering Segments: This document defines the BGP-PE Peering Segments:
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 Each BGP session MUST be described by a Peer Node Segment. 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 Segments. Finally, each Peer Node Segment and Peer
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o One or more Peer Adjacency Segments MAY be present. o One or more Peer Adjacency Segments MAY be present.
o Each of the Peer Node and Peer Adjacency Segment MAY use the same o Each of the Peer Node and Peer Adjacency Segment MAY use the same
Peer-Set. Peer-Set.
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 EPE Connectivity Description 4. Link NLRI for BGP-PE 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-Type NLRI (defined
in [I-D.ietf-idr-ls-distribution]) is used. A new Protocol ID is in [RFC7752]) is used. A new Protocol ID is used (codepoint to be
used (codepoint to be assigned by IANA, suggested value 7). assigned by IANA, suggested value 7).
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 carrying IGP link-state information as defined in [RFC7752]. The
[I-D.ietf-idr-ls-distribution]. The Link NLRI Type uses descriptors Link NLRI Type uses descriptors and attributes already defined in
and attributes already defined in [I-D.ietf-idr-ls-distribution] in [RFC7752] in addition to new TLVs defined in the following sections
addition to new TLVs defined in the following sections of this of this document.
document.
The extensions defined in this document apply to both internal and The extensions defined in this document apply to both internal and
external BGP-LS EPE advertisements. external BGP-LS EPE advertisements.
[I-D.ietf-idr-ls-distribution] defines Link NLRI Type is as follows: [RFC7752] defines Link NLRI Type is 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 //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Node Descriptors and Link Descriptors are defined in Node Descriptors and Link Descriptors are defined in [RFC7752].
[I-D.ietf-idr-ls-distribution].
4.1. BGP Router ID and Member ASN 4.1. BGP Router ID and Member ASN
Two new Node Descriptors Sub-TLVs are defined in this document: Two new Node Descriptors Sub-TLVs are defined in this document:
o BGP Router Identifier (BGP Router-ID): o BGP Router Identifier (BGP Router-ID):
Type: TBA (suggested value 516). Type: TBA (suggested value 516).
Length: 4 octets Length: 4 octets
skipping to change at page 6, line 16 skipping to change at page 6, line 16
o Confederation Member ASN (Member-ASN) o Confederation Member ASN (Member-ASN)
Type: TBA (suggested value 517). Type: TBA (suggested value 517).
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. EPE Node Descriptors 4.2. BGP-PE 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 node. PE 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 The following Node Descriptors Sub-TLVs MAY appear in the Link NLRI
as Local Node Descriptors: as Local 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 [I-D.ietf-idr-ls-distribution]. 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.
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 o Node Descriptors as defined in defined in [RFC7752].
[I-D.ietf-idr-ls-distribution].
4.3. Link Attributes 4.3. 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)| |
| 1102 | Peer Adjacency Segment | variable | | 1102 | Peer Adjacency Segment | variable |
| | Identifier (Peer-Adj-SID) | | | | Identifier (Peer-Adj-SID) | |
| 1103 | Peer Set Segment | variable | | 1103 | Peer Set Segment | variable |
| | Identifier (Peer-Set-SID) | | | | Identifier (Peer-Set-SID) | |
+----------+---------------------------+----------+ +----------+---------------------------+----------+
Figure 1: TLV code points for BGP-LS EPE Figure 1: BGP-LS TLV code points for BGP-PE
Peer-Node-SID, Peer-Adj-SID and Peer-Set-SID have all the same format Peer-Node-SID, Peer-Adj-SID and Peer-Set-SID have all the same format
defined here below: defined here 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 |
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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
case described in [I-D.ietf-spring-segment-routing-central-epe] and case described in [I-D.ietf-spring-segment-routing-central-epe] and
MAY be omitted for other use cases. MAY be omitted for other use cases.
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
[I-D.ietf-idr-ls-distribution]MAY be inserted in order to advertise [RFC7752] MAY be inserted in order to advertise the characteristics
the characteristics of the link. of the link.
5. Peer Node and Peer Adjacency Segments 5. Peer Node and Peer Adjacency Segments
In this section the following Peer Segments are defined: In this section the following Peer Segments are defined:
Peer Node Segment (Peer-Node-SID) Peer Node Segment (Peer-Node-SID)
Peer Adjacency Segment (Peer-Adj-SID) Peer Adjacency Segment (Peer-Adj-SID)
Peer Set Segment (Peer-Set-SID) Peer Set Segment (Peer-Set-SID)
The Peer Node, Peer Adjacency and Peer Set segments can be either a The Peer Node, Peer Adjacency and Peer Set segments can be either a
local or a global segment (depending on the setting of the V and L local or a global segment (depending on the setting of the V and L
flags defined in Figure 2. For example, when EPE is used in the flags defined in Figure 2. For example, when BGP-PE is used in the
context of a SR network over the IPv6 dataplane, it is likely the context of a SR network over the IPv6 dataplane, it is likely the
case that the IPv6 addresses used as SIDs will be global. case that the IPv6 addresses used as SIDs will be global.
5.1. Peer Node Segment (Peer-Node-SID) 5.1. Peer Node Segment (Peer-Node-SID)
The Peer Node Segment describes the BGP session peer (neighbor). It The Peer Node Segment describes the BGP session peer (neighbor). It
MUST be present when describing an EPE topology as defined in MUST be present when describing a BGP-PE 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 Segment
is encoded within the BGP-LS Link NLRI specified in Section 4. is 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 Segment, at the BGP node advertising it, has the
following semantic: following 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 Segment is advertised with a Link NLRI, where:
o Local Node Descriptors contains o Local Node Descriptors contains
Local BGP Router ID of the EPE enabled egress PE. Local BGP Router ID of the BGP-PE 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).
Peer ASN. Peer ASN.
o Link Descriptors Sub-TLVs, as defined in o Link Descriptors Sub-TLVs, as defined in [RFC7752], contain the
[I-D.ietf-idr-ls-distribution], contain the addresses used by the addresses used by the BGP session:
BGP session:
* IPv4 Interface Address (Sub-TLV 259) contains the BGP session * IPv4 Interface Address (Sub-TLV 259) contains the BGP session
IPv4 local address. IPv4 local address.
* 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 4.3.
o In addition, BGP-LS Link Attributes, as defined in o In addition, BGP-LS Link Attributes, as defined in [RFC7752], MAY
[I-D.ietf-idr-ls-distribution], MAY be inserted in order to be inserted in order to advertise the characteristics of the link.
advertise the characteristics of the link.
5.2. Peer Adjacency Segment (Peer-Adj-SID) 5.2. Peer Adjacency Segment (Peer-Adj-SID)
The Peer Adjacency Segment, at the BGP node advertising it, has the The Peer Adjacency Segment, at the BGP node advertising it, has the
following semantic: following 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 Adjacency Segment is advertised with a Link NLRI, where:
o Local Node Descriptors contains o Local Node Descriptors contains
Local BGP Router ID of the EPE enabled egress PE. Local BGP Router ID of the BGP-PE 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).
Peer ASN. Peer ASN.
o Link Descriptors Sub-TLVs, as defined in o Link Descriptors Sub-TLVs, as defined in [RFC7752], MUST contain
[I-D.ietf-idr-ls-distribution], MUST contain the following TLVs: the following TLVs:
* Link Local/Remote Identifiers (Sub-TLV 258) contains the * Link Local/Remote Identifiers (Sub-TLV 258) contains the
4-octet Link Local Identifier followed by the 4-octet value 0 4-octet Link Local Identifier followed by the 4-octet value 0
indicating the Link Remote Identifier in unknown [RFC5307]. indicating the Link Remote Identifier in unknown [RFC5307].
o In addition, Link Descriptors Sub-TLVs, as defined in o In addition, Link Descriptors Sub-TLVs, as defined in [RFC7752],
[I-D.ietf-idr-ls-distribution], MAY contain the following TLVs: MAY contain the following TLVs:
* 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 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 4.3.
In addition, BGP-LS Link Attributes, as defined in In addition, BGP-LS Link Attributes, as defined in [RFC7752], MAY be
[I-D.ietf-idr-ls-distribution], MAY be inserted in order to advertise inserted in order to advertise the characteristics of the link.
the characteristics of the link.
5.3. Peer Set Segment 5.3. Peer Set Segment
The Peer Adjacency Segment, at the BGP node advertising it, has the The Peer Adjacency Segment, at the BGP node advertising it, has the
following semantic: following 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
skipping to change at page 12, line 11 skipping to change at page 12, line 11
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 4.3 identifying the set of which the Peer Node Segment or
Peer Adjacency Segment is a member. Peer Adjacency Segment 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 IPv4 with MPLS-based segments and the The solution is illustrated for IPv4 with MPLS-based segments and the
EPE topology is based on eBGP sessions between external peers. BGP-PE 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, H, and E are in the same AS and also applies to the case where C, D, H, and E are in the same AS and
run iBGP sessions between each other. run iBGP sessions between each other.
+------+ +------+
| | | |
+---D F +---D F
+---------+ / | AS 2 |\ +------+ +---------+ / | AS 2 |\ +------+
skipping to change at page 14, line 21 skipping to change at page 14, line 21
o Remote Node Descriptors (BGP Router-ID, peer ASN): 4.4.4.4, AS2 o Remote Node Descriptors (BGP Router-ID, peer ASN): 4.4.4.4, AS2
o Link Descriptors (BGP session IPv4 local address, BGP session IPv4 o Link Descriptors (BGP session IPv4 local address, BGP session IPv4
neighbor address): 1.0.1.1, 1.0.1.2 neighbor address): 1.0.1.1, 1.0.1.2
Attributes: Attributes:
o Peer-Node-SID: 1012 o Peer-Node-SID: 1012
o Link Attributes: see section 3.3.2 of o Link Attributes: see section 3.3.2 of [RFC7752]
[I-D.ietf-idr-ls-distribution]
6.3. Peer Node Segment for Node H 6.3. Peer Node Segment for Node H
Descriptors: Descriptors:
o Local Node Descriptors (BGP Router-ID, ASN, BGPL Identifier): o Local Node Descriptors (BGP Router-ID, ASN, BGPLS Identifier):
3.3.3.3 , AS1, 10000 3.3.3.3 , AS1, 10000
o Remote Node Descriptors (BGP Router-ID ASN): 6.6.6.6, AS3 o Remote Node Descriptors (BGP Router-ID ASN): 6.6.6.6, AS3
o Link Descriptors (BGP session IPv4 local address, BGP session IPv4 o Link Descriptors (BGP session IPv4 local address, BGP session IPv4
peer address): 1.0.2.1, 1.0.2.2 peer address): 1.0.2.1, 1.0.2.2
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 o Link Attributes: see section 3.3.2 of [RFC7752]
[I-D.ietf-idr-ls-distribution]
6.4. Peer Node Segment for Node E 6.4. Peer Node Segment 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):
3.3.3.3 , AS1, 10000 3.3.3.3 , AS1, 10000
o Remote Node Descriptors (BGP Router-ID, ASN): 5.5.5.5, AS3 o Remote Node Descriptors (BGP Router-ID, ASN): 5.5.5.5, AS3
o Link Descriptors (BGP session IPv4 local address, BGP session IPv4 o Link Descriptors (BGP session IPv4 local address, BGP session IPv4
skipping to change at page 15, line 29 skipping to change at page 15, line 29
o Remote Node Descriptors (BGP Router-ID, ASN): 5.5.5.5, AS3 o Remote Node Descriptors (BGP Router-ID, ASN): 5.5.5.5, AS3
o Link Descriptors (local interface identifier, IPv4 peer interface o Link Descriptors (local interface identifier, IPv4 peer interface
address): 0.0.0.1.0.0.0.0 , 1.0.3.2 address): 0.0.0.1.0.0.0.0 , 1.0.3.2
Attributes: Attributes:
o Peer-Adj-SID: 1032 o Peer-Adj-SID: 1032
o LinkAttributes: see section 3.3.2 of o LinkAttributes: see section 3.3.2 of [RFC7752]
[I-D.ietf-idr-ls-distribution]
6.6. Peer Adjacency Segment for Node E, Link 2 6.6. Peer Adjacency Segment 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):
3.3.3.3 , AS1, 10000 3.3.3.3 , AS1, 10000
o Remote Node Descriptors (BGP Router-ID, ASN): 5.5.5.5, AS3 o Remote Node Descriptors (BGP Router-ID, ASN): 5.5.5.5, AS3
o Link Descriptors (local interface identifier, IPv4 peer interface o Link Descriptors (local interface identifier, IPv4 peer interface
address): 0.0.0.2.0.0.0.0 , 1.0.4.2 address): 0.0.0.2.0.0.0.0 , 1.0.4.2
Attributes: Attributes:
o Peer-Adj-SID: 1042 o Peer-Adj-SID: 1042
o LinkAttributes: see section 3.3.2 of o LinkAttributes: see section 3.3.2 of [RFC7752]
[I-D.ietf-idr-ls-distribution]
7. IANA Considerations 7. IANA Considerations
This document defines: This document defines:
Two new Node Descriptors Sub-TLVs: BGP-Router-ID and BGP Two new Node Descriptors Sub-TLVs: BGP-Router-ID and BGP
Confederation Member. Confederation Member.
A new Protocol-ID for EPE: BGP-EPE. A new Protocol-ID: BGP-PE.
Three new BGP-LS Attribute Sub-TLVs: Peer-Node-SID, Peer-Adj-SID Three new BGP-LS Attribute Sub-TLVs: Peer-Node-SID, Peer-Adj-SID
and Peer-Set-SID. and Peer-Set-SID.
The codepoints are to be assigned by IANA. The following are the The codepoints are to be assigned by IANA. The following are the
suggested values: suggested values:
+---------------------+--------------------------+-------------+ +---------------------+--------------------------+-------------+
| Suggested Codepoint | Description | Defined in: | | Suggested Codepoint | Description | Defined in: |
+---------------------+--------------------------+-------------+ +---------------------+--------------------------+-------------+
| 7 | Protocol-ID | Section 4 | | 7 | Protocol-ID | Section 4 |
| 516 | BGP Router ID | Section 4.1 | | 516 | BGP Router ID | Section 4.1 |
| 517 | BGP Confederation Member | Section 4.1 | | 517 | BGP Confederation Member | Section 4.1 |
| 1101 | Peer-Node-SID | Section 4.3 | | 1101 | Peer-Node-SID | Section 4.3 |
| 1102 | Peer-Adj-SID | Section 4.3 | | 1102 | Peer-Adj-SID | Section 4.3 |
| 1103 | Peer-Set-SID | Section 4.3 | | 1103 | Peer-Set-SID | Section 4.3 |
+---------------------+--------------------------+-------------+ +---------------------+--------------------------+-------------+
Table 1: Summary Table of BGP-LS EPE Codepoints Table 1: Summary Table of BGP-LS Codepoints for BGP-PE
8. Manageability Considerations 8. Manageability Considerations
TBD TBD
9. Security Considerations 9. Security Considerations
[I-D.ietf-idr-ls-distribution] defines BGP-LS NLRIs to which the [RFC7752] defines BGP-LS NLRIs to which the extensions defined in
extensions defined in this document apply. this document apply.
The Security Section of [I-D.ietf-idr-ls-distribution] also applies The Security Section of [RFC7752] also applies to:
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.
10. Contributors 10. Contributors
Acee Lindem gave a substantial contribution to this document. Acee Lindem gave a substantial contribution to this document.
skipping to change at page 17, line 45 skipping to change at page 17, line 45
in Support of Generalized Multi-Protocol Label Switching in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008,
<http://www.rfc-editor.org/info/rfc5307>. <http://www.rfc-editor.org/info/rfc5307>.
[RFC6286] Chen, E. and J. Yuan, "Autonomous-System-Wide Unique BGP [RFC6286] Chen, E. and J. Yuan, "Autonomous-System-Wide Unique BGP
Identifier for BGP-4", RFC 6286, DOI 10.17487/RFC6286, Identifier for BGP-4", RFC 6286, DOI 10.17487/RFC6286,
June 2011, <http://www.rfc-editor.org/info/rfc6286>. June 2011, <http://www.rfc-editor.org/info/rfc6286>.
12.2. Informative References 12.2. Informative References
[I-D.ietf-idr-ls-distribution]
Gredler, H., Medved, J., Previdi, S., Farrel, A., and S.
Ray, "North-Bound Distribution of Link-State and TE
Information using BGP", draft-ietf-idr-ls-distribution-13
(work in progress), October 2015.
[I-D.ietf-spring-segment-routing] [I-D.ietf-spring-segment-routing]
Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., Filsfils, C., Previdi, S., Decraene, B., Litkowski, S.,
and r. rjs@rob.sh, "Segment Routing Architecture", draft- and R. Shakir, "Segment Routing Architecture", draft-ietf-
ietf-spring-segment-routing-07 (work in progress), spring-segment-routing-07 (work in progress), December
December 2015. 2015.
[I-D.ietf-spring-segment-routing-central-epe] [I-D.ietf-spring-segment-routing-central-epe]
Filsfils, C., Previdi, S., Ginsburg, D., and D. Afanasiev, Filsfils, C., Previdi, S., Ginsburg, D., and D. Afanasiev,
"Segment Routing Centralized Egress Peer Engineering", "Segment Routing Centralized Egress Peer Engineering",
draft-ietf-spring-segment-routing-central-epe-00 (work in draft-ietf-spring-segment-routing-central-epe-00 (work in
progress), October 2015. progress), October 2015.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<http://www.rfc-editor.org/info/rfc7752>.
Authors' Addresses Authors' Addresses
Stefano Previdi (editor) Stefano Previdi (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
Via Del Serafico, 200 Via Del Serafico, 200
Rome 00142 Rome 00142
Italy Italy
Email: sprevidi@cisco.com Email: sprevidi@cisco.com
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