< draft-ietf-ospf-segment-routing-msd-02.txt		draft-ietf-ospf-segment-routing-msd-03.txt >
	OSPF Working Group J. Tantsura		OSPF Working Group J. Tantsura
	Internet-Draft Individual		Internet-Draft Individual
	Intended status: Standards Track U. Chunduri		Intended status: Standards Track U. Chunduri
	Expires: September 9, 2017 Huawei Technologies		Expires: September 29, 2017 Huawei Technologies
	S. Aldrin		S. Aldrin
	Google, Inc		Google, Inc
	P. Psenak		P. Psenak
	Cisco Systems		Cisco Systems
	March 8, 2017		March 28, 2017
	Signaling MSD (Maximum SID Depth) using OSPF		Signaling MSD (Maximum SID Depth) using OSPF
	draft-ietf-ospf-segment-routing-msd-02		draft-ietf-ospf-segment-routing-msd-03
	Abstract		Abstract
	This document proposes a way to signal Maximum SID Depth (MSD)		This document proposes a way to signal Maximum SID Depth (MSD)
	supported by a node at node and/or link granularity by an OSPF		supported by a node at node and/or link granularity by an OSPF
	Router. In a Segment Routing (SR) enabled network a centralized		Router. In a Segment Routing (SR) enabled network a centralized
	controller that programs SR tunnels needs to know the MSD supported		controller that programs SR tunnels needs to know the MSD supported
	by the head-end at node and/or link granularity to push the SID stack		by the head-end at node and/or link granularity to push the SID stack
	of an appropriate depth. MSD is relevant to the head-end of a SR		of an appropriate depth. MSD is relevant to the head-end of a SR
	tunnel or Binding-SID anchor node where Binding-SID expansions might		tunnel or Binding-SID anchor node where Binding-SID expansions might
	skipping to change at page 1, line 43 ¶		skipping to change at page 1, line 43 ¶
	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 9, 2017.		This Internet-Draft will expire on September 29, 2017.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 3, line 14 ¶		skipping to change at page 3, line 14 ¶
	necessarily act as head-ends. In order, for BGP-LS to signal MSD for		necessarily act as head-ends. In order, for BGP-LS to signal MSD for
	the all nodes and links in the network MSD is relevant, MSD		the all nodes and links in the network MSD is relevant, MSD
	capabilites SHOULD be distributed to every OSPF router in the		capabilites SHOULD be distributed to every OSPF router in the
	network.		network.
	[I-D.ietf-ospf-mpls-elc] defines Readable Label Depth Capability		[I-D.ietf-ospf-mpls-elc] defines Readable Label Depth Capability
	(RLDC) that is used by a head-end to insert Entropy Label (EL) at		(RLDC) that is used by a head-end to insert Entropy Label (EL) at
	appropriate depth, so it could be read by transit nodes. MSD in		appropriate depth, so it could be read by transit nodes. MSD in
	contrary signals ability to push SID's stack of a particular depth.		contrary signals ability to push SID's stack of a particular depth.
	MSD of type 1 (IANA Registry) is used to signal the number of SIDs a		MSD of type 1 (IANA Registry) is used to signal the total number of
	node is capable of imposing, to be used by a path computation		SIDs a node is capable of imposing, to be used by a path computation
	element/controller and is only relevant to the part of the stack		element/controller. In case, there are additional labels (e.g.
	created as the result of the computation. In case, there are		service) that are to be pushed to the stack - this would be signaled
	additional labels (e.g. service) that are to be pushed to the stack -		with an another MSD type (TBD), MSD SHOULD be adjusted to reflect
	MSD SHOULD be adjusted to reflect that. In the future, new MSD types		that. In the future, new MSD types could be defined to signal
	could be defined to signal additional capabilities: entropy labels,		additional capabilities: entropy labels, labels that can be pushed
	labels that can be pushed thru recirculation, or another dataplane		thru recirculation, or another dataplane e.g IPv6.
	e.g IPv6.
	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
	OSPF: Open Shortest Path First		OSPF: Open Shortest Path First
	skipping to change at page 7, line 40 ¶		skipping to change at page 7, line 40 ¶
	Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E.,		Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E.,
	Raszuk, R., Lopez, V., Tantsura, J., Henderickx, W., and		Raszuk, R., Lopez, V., Tantsura, J., Henderickx, W., and
	J. Hardwick, "PCEP Extensions for Segment Routing", draft-		J. Hardwick, "PCEP Extensions for Segment Routing", draft-
	ietf-pce-segment-routing-08 (work in progress), October		ietf-pce-segment-routing-08 (work in progress), October
	2016.		2016.
	[I-D.tantsura-idr-bgp-ls-segment-routing-msd]		[I-D.tantsura-idr-bgp-ls-segment-routing-msd]
	Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan,		Tantsura, J., Chunduri, U., Mirsky, G., and S. Sivabalan,
	"Signaling Maximum SID Depth using Border Gateway Protocol		"Signaling Maximum SID Depth using Border Gateway Protocol
	Link-State", draft-tantsura-idr-bgp-ls-segment-routing-		Link-State", draft-tantsura-idr-bgp-ls-segment-routing-
	msd-02 (work in progress), January 2017.		msd-03 (work in progress), March 2017.
	[RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and		[RFC5838] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and
	R. Aggarwal, "Support of Address Families in OSPFv3",		R. Aggarwal, "Support of Address Families in OSPFv3",
	RFC 5838, DOI 10.17487/RFC5838, April 2010,		RFC 5838, DOI 10.17487/RFC5838, April 2010,
	<http://www.rfc-editor.org/info/rfc5838>.		<http://www.rfc-editor.org/info/rfc5838>.
	[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,		[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
	Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute		Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
	Advertisement", RFC 7684, DOI 10.17487/RFC7684, November		Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
	2015, <http://www.rfc-editor.org/info/rfc7684>.		2015, <http://www.rfc-editor.org/info/rfc7684>.
End of changes. 6 change blocks.
	14 lines changed or deleted		13 lines changed or added
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