< draft-ietf-idr-bgp-ls-segment-routing-msd-02.txt		draft-ietf-idr-bgp-ls-segment-routing-msd-03.txt >
	IDR Working Group J. Tantsura		IDR Working Group J. Tantsura
	Internet-Draft Nuage Networks		Internet-Draft Apstra, Inc.
	Intended status: Standards Track U. Chunduri		Intended status: Standards Track U. Chunduri
	Expires: February 14, 2019 Huawei USA		Expires: August 23, 2019 Huawei USA
	G. Mirsky		G. Mirsky
	ZTE Corp.		ZTE Corp.
	S. Sivabalan		S. Sivabalan
	Cisco		Cisco
	August 13, 2018		N. Triantafillis
			Apstra, Inc.
			February 19, 2019
	Signaling MSD (Maximum SID Depth) using Border Gateway Protocol Link-		Signaling MSD (Maximum SID Depth) using Border Gateway Protocol Link-
	State		State
	draft-ietf-idr-bgp-ls-segment-routing-msd-02		draft-ietf-idr-bgp-ls-segment-routing-msd-03
	Abstract		Abstract
	This document defines a way for a Border Gateway Protocol Link-State		This document defines a way for a Border Gateway Protocol Link-State
	(BGP-LS) speaker to advertise multiple types of supported Maximum SID		(BGP-LS) speaker to advertise multiple types of supported Maximum SID
	Depths (MSDs) at node and/or link granularity.		Depths (MSDs) at node and/or link granularity.
	Such advertisements allow logically centralized entities (e.g.,		Such advertisements allow logically centralized entities (e.g.,
	centralized controllers) to determine whether a particular SID stack		centralized controllers) to determine whether a particular SID stack
	can be supported in a given network.		can be supported in a given network.
	skipping to change at page 1, line 42 ¶		skipping to change at page 1, line 44 ¶
	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 https://datatracker.ietf.org/drafts/current/.		Drafts is at https://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 February 14, 2019.		This Internet-Draft will expire on August 23, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2019 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	Internet-DrafSignaling MSD (Maximum SID Depth) using BGP-LS August 2018
	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
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://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 . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Conventions used in this document . . . . . . . . . . . . 3		1.1. Conventions used in this document . . . . . . . . . . . . 3
	1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3		1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3
	1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3		1.1.2. Requirements Language . . . . . . . . . . . . . . . . 3
	2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3		2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
	3. MSD supported by a node . . . . . . . . . . . . . . . . . . . 3		3. MSD supported by a node . . . . . . . . . . . . . . . . . . . 4
	4. MSD supported on a link . . . . . . . . . . . . . . . . . . . 4		4. MSD supported on a link . . . . . . . . . . . . . . . . . . . 4
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 5		6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
	8.1. Normative References . . . . . . . . . . . . . . . . . . 5		8.1. Normative References . . . . . . . . . . . . . . . . . . 5
	8.2. Informative References . . . . . . . . . . . . . . . . . 6		8.2. Informative References . . . . . . . . . . . . . . . . . 6
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
	1. Introduction		1. Introduction
	skipping to change at page 3, line 4 ¶		skipping to change at page 3, line 9 ¶
	in SR PCE Capability TLV and METRIC Object. However, if PCEP is not		in SR PCE Capability TLV and METRIC Object. However, if PCEP is not
	supported/configured on the head-end of a SR tunnel or a Binding-SID		supported/configured on the head-end of a SR tunnel or a Binding-SID
	anchor node and controller does not participate in IGP routing, it		anchor node and controller does not participate in IGP routing, it
	has no way to learn the MSD of nodes and links which has been		has no way to learn the MSD of nodes and links which has been
	configured. BGP-LS [RFC7752] defines a way to expose topology and		configured. BGP-LS [RFC7752] defines a way to expose topology and
	associated attributes and capabilities of the nodes in that topology		associated attributes and capabilities of the nodes in that topology
	to a centralized controller.		to a centralized controller.
	Other types of MSD are known to be useful. For example,		Other types of MSD are known to be useful. For example,
	[I-D.ietf-ospf-mpls-elc] and [I-D.ietf-isis-mpls-elc] define Readable		[I-D.ietf-ospf-mpls-elc] and [I-D.ietf-isis-mpls-elc] define Readable
	Internet-DrafSignaling MSD (Maximum SID Depth) using BGP-LS August 2018
	Label Depth Capability (RLDC) that is used by a head-end to insert an		Label Depth Capability (RLDC) that is used by a head-end to insert an
	Entropy Label (EL) at a depth that can be read by transit nodes.		Entropy Label (EL) at a depth that can be read by transit nodes.
	1.1. Conventions used in this document		1.1. Conventions used in this document
	1.1.1. Terminology		1.1.1. Terminology
	BGP-LS: Distribution of Link-State and TE Information using Border		BGP-LS: Distribution of Link-State and TE Information using Border
	Gateway Protocol		Gateway Protocol
	skipping to change at page 3, line 45 ¶		skipping to change at page 3, line 47 ¶
	capitals, as shown here .		capitals, as shown here .
	2. Problem Statement		2. Problem Statement
	In existing technology only PCEP has extension to signal the MSD (SR		In existing technology only PCEP has extension to signal the MSD (SR
	PCE Capability TLV/ METRIC Object as defined in		PCE Capability TLV/ METRIC Object as defined in
	[I-D.ietf-pce-segment-routing],If PCEP is not supported by the node		[I-D.ietf-pce-segment-routing],If PCEP is not supported by the node
	(head-end of the SR tunnel) controller has no way to learn the MSD of		(head-end of the SR tunnel) controller has no way to learn the MSD of
	the node/link configured. OSPF and IS-IS extensions are defined in:		the node/link configured. OSPF and IS-IS extensions are defined in:
	[I-D.ietf-ospf-segment-routing-msd]		[RFC8476]
	[I-D.ietf-isis-segment-routing-msd]		[RFC8491]
	3. MSD supported by a node		3. MSD supported by a node
	Node MSD is encoded in a new Node Attribute TLV, as defined in		Node MSD is encoded in a new Node Attribute TLV, as defined in
	[RFC7752]		[RFC7752]
	Internet-DrafSignaling MSD (Maximum SID Depth) using BGP-LS August 2018
	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 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Sub-Type and Value ...		| Sub-Type and Value ...
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...
	Figure 1: Node attribute format		Figure 1: Node attribute format
	Type : A 2-octet field specifying code-point of the new TLV type.		Type : A 2-octet field specifying code-point of the new TLV type.
	Code-point:(TBD1) from BGP-LS Node Descriptor, Link Descriptor,		Code-point:(TBD1) from BGP-LS Node Descriptor, Link Descriptor,
	Prefix Descriptor, and Attribute TLVs registry		Prefix Descriptor, and Attribute TLVs registry
	Length: A 2-octet field that indicates the length of the value		Length: A 2-octet field that indicates the length of the value
	portion		portion
	Sub-Type and value fields are as defined in corresponding OSPF		Sub-Type and value fields are as defined in corresponding OSPF
	[I-D.ietf-ospf-segment-routing-msd] and IS-IS		[RFC8476] and IS-IS [RFC8491] extensions.
	[I-D.ietf-isis-segment-routing-msd] extensions.
	4. MSD supported on a link		4. MSD supported on a link
	Link MSD is encoded in a New Link Attribute TLV, as defined in		Link MSD is encoded in a New Link Attribute TLV, as defined in
	[RFC7752]		[RFC7752]
	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 |
	skipping to change at page 4, line 49 ¶		skipping to change at page 5, line 4 ¶
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...
	Figure 2: Link attribute format		Figure 2: Link attribute format
	Type : A 2-octet field specifying code-point of the new TLV type.		Type : A 2-octet field specifying code-point of the new TLV type.
	Code-point:(TBD2) from BGP-LS Node Descriptor, Link Descriptor,		Code-point:(TBD2) from BGP-LS Node Descriptor, Link Descriptor,
	Prefix Descriptor, and Attribute TLVs registry		Prefix Descriptor, and Attribute TLVs registry
	Length: A 2-octet field that indicates the length of the value		Length: A 2-octet field that indicates the length of the value
	portion		portion
	Sub-Type and value fields are as defined in corresponding OSPF		Sub-Type and value fields are as defined in corresponding OSPF
	[I-D.ietf-ospf-segment-routing-msd] and IS-IS		[RFC8476] and IS-IS [RFC8491] extensions.
	[I-D.ietf-isis-segment-routing-msd] extensions.
	Internet-DrafSignaling MSD (Maximum SID Depth) using BGP-LS August 2018
	5. IANA Considerations		5. IANA Considerations
	We request IANA assign code points from the registry BGP-LS Node		We request IANA assign code points from the registry BGP-LS Node
	Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs,		Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs,
	as follows: TLV Code Point Description IS-IS TLV/Sub-TLV Reference		as follows: TLV Code Point Description IS-IS TLV/Sub-TLV Reference
	TBD1 Node MSD 242/23 (this document) TBD2 Link MSD		TBD1 Node MSD 242/23 (this document) TBD2 Link MSD
	(22,23,25,141,222,223)/15 (this document)		(22,23,25,141,222,223)/15 (this document)
	6. Security Considerations		6. Security Considerations
	Advertisement of the additional information defined in this document		Advertisement of the additional information defined in this document
	that is false, e.g., an MSD that is incorrect, may result in a path		that is false, e.g., an MSD that is incorrect, may result in a path
	computation failing, having a service unavailable, or instantiation		computation failing, having a service unavailable, or instantiation
	of a path that can't be supported by the head-end (the node		of a path that can't be supported by the head-end (the node
	performing the imposition).		performing the imposition).
	This document does not introduce security issues beyond those		This document does not introduce security issues beyond those
	discussed in [RFC7752], [I-D.ietf-ospf-segment-routing-msd] and		discussed in [RFC7752], [RFC8476] and [RFC8491] extensions.
	[I-D.ietf-isis-segment-routing-msd]
	7. Acknowledgements		7. Acknowledgements
	We like to thank Nikos Triantafillis, Acee Lindem, Ketan Talaulikar,		We like to thank Acee Lindem, Ketan Talaulikar, Stephane Litkowski
	Stephane Litkowski and Bruno Decraene for their reviews and valuable		and Bruno Decraene for their reviews and valuable comments.
	comments.
	8. References		8. References
	8.1. Normative References		8.1. Normative References
	[I-D.ietf-isis-segment-routing-msd]
	Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
	"Signaling MSD (Maximum SID Depth) using IS-IS", draft-
	ietf-isis-segment-routing-msd-13 (work in progress), July
	2018.
	[I-D.ietf-ospf-segment-routing-msd]
	Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak,
	"Signaling MSD (Maximum SID Depth) using OSPF", draft-
	ietf-ospf-segment-routing-msd-15 (work in progress), July
	2018.
	[I-D.ietf-pce-segment-routing]		[I-D.ietf-pce-segment-routing]
	Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,		Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
	and J. Hardwick, "PCEP Extensions for Segment Routing",		and J. Hardwick, "PCEP Extensions for Segment Routing",
	draft-ietf-pce-segment-routing-12 (work in progress), June		draft-ietf-pce-segment-routing-15 (work in progress),
	2018.		February 2019.
	Internet-DrafSignaling MSD (Maximum SID Depth) using BGP-LS August 2018
	[I-D.ietf-spring-segment-routing-mpls]
	Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
	Litkowski, S., and R. Shakir, "Segment Routing with MPLS
	data plane", draft-ietf-spring-segment-routing-mpls-14
	(work in progress), June 2018.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[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,
	<https://www.rfc-editor.org/info/rfc7752>.		<https://www.rfc-editor.org/info/rfc7752>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
			[RFC8476] Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak,
			"Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476,
			DOI 10.17487/RFC8476, December 2018,
			<https://www.rfc-editor.org/info/rfc8476>.
			[RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
			"Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,
			DOI 10.17487/RFC8491, November 2018,
			<https://www.rfc-editor.org/info/rfc8491>.
	8.2. Informative References		8.2. Informative References
	[I-D.ietf-isis-mpls-elc]		[I-D.ietf-isis-mpls-elc]
	Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.		Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
	Litkowski, "Signaling Entropy Label Capability and Entropy		Litkowski, "Signaling Entropy Label Capability and Entropy
	Readable Label Depth Using IS-IS", draft-ietf-isis-mpls-		Readable Label Depth Using IS-IS", draft-ietf-isis-mpls-
	elc-05 (work in progress), July 2018.		elc-06 (work in progress), September 2018.
	[I-D.ietf-isis-segment-routing-extensions]		[I-D.ietf-isis-segment-routing-extensions]
	Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,		Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,
	Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura,		Gredler, H., and B. Decraene, "IS-IS Extensions for
	"IS-IS Extensions for Segment Routing", draft-ietf-isis-		Segment Routing", draft-ietf-isis-segment-routing-
	segment-routing-extensions-19 (work in progress), July		extensions-22 (work in progress), December 2018.
	2018.
	[I-D.ietf-ospf-mpls-elc]		[I-D.ietf-ospf-mpls-elc]
	Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.		Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
	Litkowski, "Signaling Entropy Label Capability and Entropy		Litkowski, "Signaling Entropy Label Capability and Entropy
	Readable Label-stack Depth Using OSPF", draft-ietf-ospf-		Readable Label-stack Depth Using OSPF", draft-ietf-ospf-
	mpls-elc-06 (work in progress), August 2018.		mpls-elc-07 (work in progress), September 2018.
	[I-D.ietf-ospf-segment-routing-extensions]		[I-D.ietf-ospf-segment-routing-extensions]
	Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,		Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
	Shakir, R., Henderickx, W., and J. Tantsura, "OSPF		Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
	Extensions for Segment Routing", draft-ietf-ospf-segment-		Extensions for Segment Routing", draft-ietf-ospf-segment-
	routing-extensions-25 (work in progress), April 2018.		routing-extensions-27 (work in progress), December 2018.
	Internet-DrafSignaling MSD (Maximum SID Depth) using BGP-LS August 2018		[I-D.ietf-spring-segment-routing-mpls]
			Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
			Litkowski, S., and R. Shakir, "Segment Routing with MPLS
			data plane", draft-ietf-spring-segment-routing-mpls-18
			(work in progress), December 2018.
	Authors' Addresses		Authors' Addresses
	Jeff Tantsura		Jeff Tantsura
	Nuage Networks		Apstra, Inc.
	Email: jefftant.ietf@gmail.com		Email: jefftant.ietf@gmail.com
	Uma Chunduri		Uma Chunduri
	Huawei USA		Huawei USA
	Email: uma.chunduri@huawei.com		Email: uma.chunduri@huawei.com
	Greg Mirsky		Greg Mirsky
	ZTE Corp.		ZTE Corp.
	Email: gregimirsky@gmail.com		Email: gregimirsky@gmail.com
	Siva Sivabalan		Siva Sivabalan
	Cisco		Cisco
	Email: msiva@cisco.com		Email: msiva@cisco.com
			Nikos Triantafillis
			Apstra, Inc.
			Email: nikos@apstra.com
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