draft-ietf-idr-bgpls-segment-routing-epe-03.txt   draft-ietf-idr-bgpls-segment-routing-epe-04.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 22, 2016 S. Ray Expires: November 13, 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
March 21, 2016 May 12, 2016
Segment Routing BGP Peer Engineering BGP-LS Extensions Segment Routing BGP Egress Peer Engineering BGP-LS Extensions
draft-ietf-idr-bgpls-segment-routing-epe-03 draft-ietf-idr-bgpls-segment-routing-epe-04
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.
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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 22, 2016. This Internet-Draft will expire on November 13, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 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
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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 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 Peer Engineering (BGP-PE) policies and strategies. efficient BGP Egress Peer Engineering (BGP-EPE) 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 BGP Peer Engineering (BGP-PE) architecture is The Segment Routing BGP Egress Peer Engineering (BGP-EPE)
described in [I-D.ietf-spring-segment-routing-central-epe]. architecture is 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 BGP- As defined in [I-D.ietf-spring-segment-routing-central-epe], an BGP-
PE enabled Egress PE node MAY advertise segments corresponding to its EPE enabled Egress PE node MAY advertise segments corresponding to
attached peers. These segments are called BGP peering segments or its attached peers. These segments are called BGP peering segments
BGP Peering SIDs. In case of eBGP, they enable the expression of or BGP Peering SIDs. In case of eBGP, they enable the expression of
source-routed inter-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-PE policy applied at an ingress PE involves two minimum, a BGP-EPE policy applied at an ingress PE involves two
segments: the Node SID of the chosen egress PE and then the BGP segments: the Node SID of the chosen egress PE and then the BGP
Peering Segment for the chosen egress PE peer or peering interface. Peering Segment for the chosen egress PE peer or peering interface.
This document defines the BGP-PE Peering Segments: This document defines the BGP-EPE 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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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-PE 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-
PE 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.
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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 BGP-PE is used in the flags defined in Figure 2. For example, when BGP-EPE 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 a BGP-PE topology as defined in MUST 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 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 BGP-PE 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).
Peer ASN. Peer ASN.
o Link Descriptors Sub-TLVs, as defined in [RFC7752], contain the o Link Descriptors Sub-TLVs, as defined in [RFC7752], contain the
addresses used by the BGP session: addresses used by the BGP session:
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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 BGP-PE 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).
Peer ASN. Peer ASN.
o Link Descriptors Sub-TLVs, as defined in [RFC7752], MUST contain o Link Descriptors Sub-TLVs, as defined in [RFC7752], MUST contain
the following TLVs: the following TLVs:
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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
BGP-PE 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, 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 |\ +------+
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o LinkAttributes: see section 3.3.2 of [RFC7752] o LinkAttributes: see section 3.3.2 of [RFC7752]
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: BGP-PE. A new Protocol-ID: BGP-EPE.
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: |
+---------------------+--------------------------+-------------+ +---------------------+--------------------------+-------------+
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[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-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. Shakir, "Segment Routing Architecture", draft-ietf- and R. Shakir, "Segment Routing Architecture", draft-ietf-
spring-segment-routing-07 (work in progress), December spring-segment-routing-08 (work in progress), May 2016.
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 BGP Peer Engineering", draft-
draft-ietf-spring-segment-routing-central-epe-00 (work in ietf-spring-segment-routing-central-epe-01 (work in
progress), October 2015. progress), March 2016.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752, Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016, DOI 10.17487/RFC7752, March 2016,
<http://www.rfc-editor.org/info/rfc7752>. <http://www.rfc-editor.org/info/rfc7752>.
Authors' Addresses Authors' Addresses
Stefano Previdi (editor) Stefano Previdi (editor)
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