draft-ietf-idr-bgp-ls-segment-routing-msd-04.txt		draft-ietf-idr-bgp-ls-segment-routing-msd-05.txt
	IDR Working Group J. Tantsura		IDR Working Group J. Tantsura
	Internet-Draft Apstra, Inc.		Internet-Draft Apstra, Inc.
	Intended status: Standards Track U. Chunduri		Intended status: Standards Track U. Chunduri
	Expires: August 23, 2019 Huawei USA		Expires: December 3, 2019 Futurewei Technologies
			K. Talaulikar
			Cisco Systems
	G. Mirsky		G. Mirsky
	ZTE Corp.		ZTE Corp.
	S. Sivabalan
	Cisco
	N. Triantafillis		N. Triantafillis
	Apstra, Inc.		Apstra, Inc.
	February 19, 2019		June 1, 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-04		draft-ietf-idr-bgp-ls-segment-routing-msd-05
	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 entities (e.g., centralized controllers) to
	centralized controllers) to determine whether a particular SID stack		determine whether a particular Segment Identifier (SID) stack can be
	can be supported in a given network.		supported in a given network.
	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
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 August 23, 2019.		This Internet-Draft will expire on December 3, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 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.
	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
	skipping to change at page 2, line 25 ¶		skipping to change at page 2, line 25 ¶
	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 . . . . . . . . . . . . . . . . 4
	2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3		2. Advertisement of MSD via BGP-LS . . . . . . . . . . . . . . . 4
	3. MSD supported by a node . . . . . . . . . . . . . . . . . . . 4		3. Node MSD TLV . . . . . . . . . . . . . . . . . . . . . . . . 4
	4. MSD supported on a link . . . . . . . . . . . . . . . . . . . 4		4. Link MSD TLV . . . . . . . . . . . . . . . . . . . . . . . . 5
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 5		6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5		7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5		8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
	8.1. Normative References . . . . . . . . . . . . . . . . . . 5		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
	8.2. Informative References . . . . . . . . . . . . . . . . . 6		9.1. Normative References . . . . . . . . . . . . . . . . . . 7
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7		9.2. Informative References . . . . . . . . . . . . . . . . . 7
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
	1. Introduction		1. Introduction
	When Segment Routing tunnels are computed by a centralized		When Segment Routing (SR) [RFC8402] paths are computed by a
	controller, it is critical that the controller learns the MSD		centralized controller, it is critical that the controller learns the
	"Maximum SID Depth" of the node or link SR tunnel exits over, so the		Maximum SID Depth (MSD) that can be imposed at each node/link on a
	SID stack depth of a path computed doesn't exceed the number of SIDs		given SR path. This ensures that the Segment Identifier (SID) stack
	the node is capable of imposing. This document describes how to use		depth of a computed path doesn't exceed the number of SIDs the node
	BGP-LS to signal the MSD of a node or link to a centralized		is capable of imposing.
	controller.
	PCEP SR extensions draft [I-D.ietf-pce-segment-routing] signals MSD		[I-D.ietf-pce-segment-routing] defines how to signal MSD in the Path
	in SR PCE Capability TLV and METRIC Object. However, if PCEP is not		Computation Element Protocol (PCEP). The OSPF and IS-IS extensions
	supported/configured on the head-end of a SR tunnel or a Binding-SID		for signaling of MSD are defined in [RFC8476] and [RFC8491]
	anchor node and controller does not participate in IGP routing, it		respectively.
	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		However, if PCEP is not supported/configured on the head-end of a SR
	associated attributes and capabilities of the nodes in that topology		tunnel or a Binding-SID anchor node, and controller does not
	to a centralized controller.		participate in IGP routing, it has no way of learning the MSD of
			nodes and links. BGP-LS [RFC7752] defines a way to advertise
			topology and associated attributes and capabilities of the nodes in
			that topology to a centralized controller. This document defines
			extensions to BGP-LS to advertise one or more types of MSDs at node
			and/or link granularity.
	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
	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.
			In the future, it is expected that new MSD-Types will be defined to
			signal additional capabilities, e.g., ELs, SIDs that can be imposed
			through recirculation, or SIDs associated with another data plane
			such as IPv6. MSD advertisements MAY be useful even if SR itself is
			not enabled. For example, in a non-SR MPLS network, MSD defines the
			maximum label depth.
	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
	MSD: Maximum SID Depth		MSD: Maximum SID Depth
	PCC: Path Computation Client		PCC: Path Computation Client
	PCE: Path Computation Element		PCE: Path Computation Element
	PCEP: Path Computation Element Protocol		PCEP: Path Computation Element Protocol
	SID: Segment Identifier		SID: Segment Identifier
	SR: Segment routing		SR: Segment routing
			Label Imposition: Imposition is the act of modifying and/or adding
			labels to the outgoing label stack associated with a packet. This
			includes:
			o replacing the label at the top of the label stack with a new
			label.
			o pushing one or more new labels onto the label stack The number of
			labels imposed is then the sum of the number of labels that are
			replaced and the number of labels that are pushed. See [RFC3031]
			for further details.
	1.1.2. Requirements Language		1.1.2. 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", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here .		capitals, as shown here .
	2. Problem Statement		2. Advertisement of MSD via BGP-LS
	In existing technology only PCEP has extension to signal the MSD (SR		This document describes extensions that enable BGP-LS speakers to
	PCE Capability TLV/ METRIC Object as defined in		signal the MSD capabilities of nodes and their links in a network to
	[I-D.ietf-pce-segment-routing],If PCEP is not supported by the node		a BGP-LS consumer of network topology such as a centralized
	(head-end of the SR tunnel) controller has no way to learn the MSD of		controller. The centralized controller can leverage this information
	the node/link configured. OSPF and IS-IS extensions are defined in:		in computation of SR paths and their instantiation on network nodes
			based on their MSD capabilities. When a BGP-LS speaker is
			originating the topology learnt via link-state routing protocols like
			OSPF or IS-IS, the MSD information for the nodes and their links is
			sourced from the underlying extensions as defined in [RFC8476] and
			[RFC8491] respectively. The BGP-LS speaker may also advertise the
			MSD information for the local node and its links when not running any
			link-state IGP protocol e.g. when running BGP as the only routing
			protocol.
	[RFC8476], [RFC8491]		The extensions introduced in this document allow for advertisement of
			different MSD-Types. This document does not define these MSD-Types
			but leverages the definition, guidelines and the code-point registry
			specified in [RFC8491]. This enables sharing of MSD-Types that may
			be defined in the future by the IGPs in BGP-LS.
	3. MSD supported by a node		3. Node MSD TLV
	Node MSD is encoded in a new Node Attribute TLV, as defined in		Node MSD is encoded in a new Node Attribute TLV [RFC7752] using the
	[RFC7752]		following format:
	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 ...		| MSD-Type | MSD-Value | MSD-Type... | MSD-Value... |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 1: Node attribute format		Figure 1: Node MSD TLV Format
	Type : A 2-octet field specifying code-point of the new TLV type.		Where:
	Code-point:(TBD1) from BGP-LS Node Descriptor, Link Descriptor,
	Prefix Descriptor, and Attribute TLVs registry
	Length: A 2-octet field that indicates the length of the value		o Type: 266
	portion
	Sub-Type and value fields are as defined in corresponding OSPF		o Length: variable (multiple of 2); represents the total length of
	[RFC8476] and IS-IS [RFC8491] extensions.		the value field in octets.
	4. MSD supported on a link		o Value : consists of one or more pairs of a 1-octet MSD-Type and
			1-octet MSD-Value.
	Link MSD is encoded in a New Link Attribute TLV, as defined in		* MSD-Type : one of the values defined in the IANA registry
	[RFC7752]		titled "IGP MSD-Types" under the "Interior Gateway Protocol
			(IGP) Parameters" registry created by [RFC8491].
			* MSD-Value : a number in the range of 0-255. For all MSD-Types,
			0 represents the lack of ability to impose an MSD stack of any
			depth; any other value represents that of the node. This value
			MUST represent the lowest value supported by any link
			configured for use by the advertising protocol instance.
			4. Link MSD TLV
			Link MSD is encoded in a new Link Attribute TLV [RFC7752] using the
			following format:
	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 ...		| MSD-Type | MSD-Value | MSD-Type... | MSD-Value... |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ...		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 2: Link attribute format		Figure 2: Link MSD TLV Format
	Type : A 2-octet field specifying code-point of the new TLV type.		Where:
	Code-point:(TBD2) from BGP-LS Node Descriptor, Link Descriptor,
	Prefix Descriptor, and Attribute TLVs registry
	Length: A 2-octet field that indicates the length of the value		o Type: 267
	portion		o Length: variable (multiple of 2); represents the total length of
	Sub-Type and value fields are as defined in corresponding OSPF		the value field in octets.
	[RFC8476] and IS-IS [RFC8491] extensions.
			o Value : consists of one or more pairs of a 1-octet MSD-Type and
			1-octet MSD-Value.
			* MSD-Type : one of the values defined in the IANA registry
			titled "IGP MSD-Types" under the "Interior Gateway Protocol
			(IGP) Parameters" registry created by [RFC8491].
			* MSD-Value : a number in the range of 0-255. For all MSD-Types,
			0 represents the lack of ability to impose an MSD stack of any
			depth; any other value represents that of the link when used as
			an outgoing interface.
	5. IANA Considerations		5. IANA Considerations
	We request IANA assign code points from the registry BGP-LS Node		This document requests assigning code-points from the registry "BGP-
	Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs,		LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
	as follows: TLV Code Point Description IS-IS TLV/Sub-TLV Reference		TLVs" based on table below. Early allocation for these code-points
	TBD1 Node MSD 242/23 (this document) TBD2 Link MSD		have been done by IANA.
	(22,23,25,141,222,223)/15 (this document)
			+------------+-----------------+---------------------------+
			| Code Point | Description | IS-IS TLV/Sub-TLV |
			+------------+-----------------+---------------------------+
			| 266 | Node MSD | 242/23 |
			| 267 | Link MSD | (22,23,25,141,222,223)/15 |
			+------------+-----------------+---------------------------+
	6. Security Considerations		6. Security Considerations
	The advertisement of an incorrect MSD value may have negative		The advertisement of an incorrect MSD value may have negative
	consequences. If the value is smaller than supported, path		consequences. If the value is smaller than supported, path
	computation may fail to compute a viable path. If the value is		computation may fail to compute a viable path. If the value is
	larger than supported, an attempt to instantiate a path that can't be		larger than supported, an attempt to instantiate a path that can't be
	supported by the head-end (the node performing the SID imposition)		supported by the head-end (the node performing the SID imposition)
	may occur. The presence of this information may also inform an		may occur. The presence of this information may also inform an
	attacker of how to induce any of the aforementioned conditions.		attacker of how to induce any of the aforementioned conditions.
	This document does not introduce security issues beyond those		This document does not introduce security issues beyond those
	discussed in [RFC7752], [RFC8476] and [RFC8491]		discussed in [RFC7752], [RFC8476] and [RFC8491]
	7. Acknowledgements		7. Contributors
			Siva Sivabalan
			Cisco Systems Inc.
			Canada
	We like to thank Acee Lindem, Ketan Talaulikar, Stephane Litkowski		Email: msiva@cisco.com
	and Bruno Decraene for their reviews and valuable comments.
	8. References		8. Acknowledgements
	8.1. Normative References		We like to thank Acee Lindem, Stephane Litkowski and Bruno Decraene
			for their reviews and valuable comments.
	[I-D.ietf-pce-segment-routing]		9. References
	Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
	and J. Hardwick, "PCEP Extensions for Segment Routing",		9.1. Normative References
	draft-ietf-pce-segment-routing-15 (work in progress),
	February 2019.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[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,
	skipping to change at page 6, line 25 ¶		skipping to change at page 7, line 44 ¶
	[RFC8476] Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak,		[RFC8476] Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak,
	"Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476,		"Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476,
	DOI 10.17487/RFC8476, December 2018,		DOI 10.17487/RFC8476, December 2018,
	<https://www.rfc-editor.org/info/rfc8476>.		<https://www.rfc-editor.org/info/rfc8476>.
	[RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,		[RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
	"Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,		"Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,
	DOI 10.17487/RFC8491, November 2018,		DOI 10.17487/RFC8491, November 2018,
	<https://www.rfc-editor.org/info/rfc8491>.		<https://www.rfc-editor.org/info/rfc8491>.
	8.2. Informative References		9.2. 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., Psenak, P., 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-06 (work in progress), September 2018.		elc-07 (work in progress), May 2019.
	[I-D.ietf-isis-segment-routing-extensions]
	Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,
	Gredler, H., and B. Decraene, "IS-IS Extensions for
	Segment Routing", draft-ietf-isis-segment-routing-
	extensions-22 (work in progress), December 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., Psenak, P., 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-07 (work in progress), September 2018.		mpls-elc-08 (work in progress), May 2019.
	[I-D.ietf-ospf-segment-routing-extensions]		[I-D.ietf-pce-segment-routing]
	Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,		Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W.,
	Shakir, R., Henderickx, W., and J. Tantsura, "OSPF		and J. Hardwick, "PCEP Extensions for Segment Routing",
	Extensions for Segment Routing", draft-ietf-ospf-segment-		draft-ietf-pce-segment-routing-16 (work in progress),
	routing-extensions-27 (work in progress), December 2018.		March 2019.
	[I-D.ietf-spring-segment-routing-mpls]		[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
	Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,		Label Switching Architecture", RFC 3031,
	Litkowski, S., and R. Shakir, "Segment Routing with MPLS		DOI 10.17487/RFC3031, January 2001,
	data plane", draft-ietf-spring-segment-routing-mpls-18		<https://www.rfc-editor.org/info/rfc3031>.
	(work in progress), December 2018.
			[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
			Decraene, B., Litkowski, S., and R. Shakir, "Segment
			Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
			July 2018, <https://www.rfc-editor.org/info/rfc8402>.
	Authors' Addresses		Authors' Addresses
	Jeff Tantsura		Jeff Tantsura
	Apstra, Inc.		Apstra, Inc.
	Email: jefftant.ietf@gmail.com		Email: jefftant.ietf@gmail.com
	Uma Chunduri		Uma Chunduri
	Huawei USA		Futurewei Technologies
	Email: uma.chunduri@huawei.com		Email: umac.ietf@gmail.com
			Ketan Talaulikar
			Cisco Systems
			Email: ketant@cisco.com
	Greg Mirsky		Greg Mirsky
	ZTE Corp.		ZTE Corp.
	Email: gregimirsky@gmail.com		Email: gregimirsky@gmail.com
	Siva Sivabalan
	Cisco
	Email: msiva@cisco.com
	Nikos Triantafillis		Nikos Triantafillis
	Apstra, Inc.		Apstra, Inc.
	Email: nikos@apstra.com		Email: nikos@apstra.com
End of changes. 43 change blocks.
	112 lines changed or deleted		171 lines changed or added
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