< draft-ietf-ospf-segment-routing-msd-20.txt		draft-ietf-ospf-segment-routing-msd-21.txt >
	OSPF Working Group J. Tantsura		OSPF Working Group J. Tantsura
	Internet-Draft Nuage Networks		Internet-Draft Nuage Networks
	Intended status: Standards Track U. Chunduri		Intended status: Standards Track U. Chunduri
	Expires: March 4, 2019 Huawei Technologies		Expires: March 29, 2019 Huawei Technologies
	S. Aldrin		S. Aldrin
	Google, Inc		Google, Inc
	P. Psenak		P. Psenak
	Cisco Systems		Cisco Systems
	August 31, 2018		September 25, 2018
	Signaling MSD (Maximum SID Depth) using OSPF		Signaling MSD (Maximum SID Depth) using OSPF
	draft-ietf-ospf-segment-routing-msd-20		draft-ietf-ospf-segment-routing-msd-21
	Abstract		Abstract
	This document defines a way for an Open Shortest Path First (OSPF)		This document defines a way for an Open Shortest Path First (OSPF)
	Router to advertise multiple types of supported Maximum SID Depths		Router to advertise multiple types of supported Maximum SID Depths
	(MSDs) at node and/or link granularity. Such advertisements allow		(MSDs) at node and/or link granularity. Such advertisements allow
	entities (e.g., centralized controllers) to determine whether a		entities (e.g., centralized controllers) to determine whether a
	particular SID stack can be supported in a given network. This		particular SID stack can be supported in a given network. This
	document defines only one type of MSD, but defines an encoding that		document defines only one type of MSD, but defines an encoding that
	can support other MSD types. Here the term OSPF means both OSPFv2		can support other MSD types. Here the term OSPF means both OSPFv2
	skipping to change at page 1, line 42 ¶		skipping to change at page 1, line 42 ¶
	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 March 4, 2019.		This Internet-Draft will expire on March 29, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2018 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 ¶
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3		1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
	1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4		1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
	2. Node MSD Advertisement . . . . . . . . . . . . . . . . . . . 4		2. Node MSD Advertisement . . . . . . . . . . . . . . . . . . . 4
	3. Link MSD sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5		3. Link MSD sub-TLV . . . . . . . . . . . . . . . . . . . . . . 5
	4. Using Node and Link MSD Advertisements . . . . . . . . . . . 6		4. Using Node and Link MSD Advertisements . . . . . . . . . . . 6
	5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7		5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 7		6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
	7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7		7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8
	8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8		8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
	9.1. Normative References . . . . . . . . . . . . . . . . . . 8		9.1. Normative References . . . . . . . . . . . . . . . . . . 8
	9.2. Informative References . . . . . . . . . . . . . . . . . 8		9.2. Informative References . . . . . . . . . . . . . . . . . 9
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
	1. Introduction		1. Introduction
	When Segment Routing (SR) paths are computed by a centralized		When Segment Routing (SR) paths are computed by a centralized
	controller, it is critical that the controller learns the Maximum SID		controller, it is critical that the controller learns the Maximum SID
	Depth (MSD) that can be imposed at each node/link on a given SR path		Depth (MSD) that can be imposed at each node/link on a given SR path
	to insure that the SID stack depth of a computed path doesn't exceed		to insure that the SID stack depth of a computed path doesn't exceed
	the number of SIDs the node is capable of imposing.		the number of SIDs the node is capable of imposing.
	skipping to change at page 7, line 10 ¶		skipping to change at page 7, line 10 ¶
	advertisement of that MSD type. However, in some cases the lack of		advertisement of that MSD type. However, in some cases the lack of
	advertisement might imply that the functionality associated with the		advertisement might imply that the functionality associated with the
	MSD type is not supported. The correct interpretation MUST be		MSD type is not supported. The correct interpretation MUST be
	specified when an MSD type is defined.		specified when an MSD type is defined.
	5. IANA Considerations		5. IANA Considerations
	This document requests IANA to allocate TLV type (TBD1) from the OSPF		This document requests IANA to allocate TLV type (TBD1) from the OSPF
	Router Information (RI) TLVs Registry as defined by [RFC7770]. IANA		Router Information (RI) TLVs Registry as defined by [RFC7770]. IANA
	has allocated the value 12 through the early assignment process.		has allocated the value 12 through the early assignment process.
			Value Description Reference
			----- --------------- -------------
			12 Node MSD This document
			Figure 3: RI Node MSD
	Also, this document requests IANA to allocate a sub-TLV type (TBD2)		Also, this document requests IANA to allocate a sub-TLV type (TBD2)
	from the OSPFv2 Extended Link TLV Sub-TLVs registry. IANA has		from the OSPFv2 Extended Link TLV Sub-TLVs registry. IANA has
	allocated the value 6 through the early assignment process. Finally,		allocated the value 6 through the early assignment process.
	this document requests IANA to allocate a sub-TLV type (TBD3) from
	the OSPFv3 Extended-LSA Sub-TLV registry.		Value Description Reference
			----- --------------- -------------
			6 OSPFv2 Link MSD This document
			Figure 4: OSPFv2 Link MSD
			Finally, this document requests IANA to allocate a sub-TLV type
			(TBD3) from the OSPFv3 Extended-LSA Sub-TLV registry.
			Value Description Reference
			----- --------------- -------------
			TBD3 OSPFv3 Link MSD This document
			Figure 5: OSPFv3 Link MSD
	6. Security Considerations		6. Security Considerations
	Security concerns for OSPF are addressed in [RFC7474], [RFC4552] and		Security concerns for OSPF are addressed in [RFC7474], [RFC4552] and
	[RFC7166]. Further security analysis for OSPF protocol is done in		[RFC7166]. Further security analysis for OSPF protocol is done in
	[RFC6863]. Security considerations, as specified by [RFC7770],		[RFC6863]. Security considerations, as specified by [RFC7770],
	[RFC7684] and [RFC8362] are applicable to this document.		[RFC7684] and [RFC8362] are applicable to this document.
	Implementations MUST assure that malformed TLV and Sub-TLV defined in		Implementations MUST assure that malformed TLV and Sub-TLV defined in
	this document are detected and do not provide a vulnerability for		this document are detected and do not provide a vulnerability for
	skipping to change at page 8, line 4 ¶		skipping to change at page 8, line 30 ¶
	gain intelligence about devices in the network.		gain intelligence about devices in the network.
	There's no Denial of Service risk specific to this extension, and it		There's no Denial of Service risk specific to this extension, and it
	is not vulnerable to replay attacks.		is not vulnerable to replay attacks.
	7. Contributors		7. Contributors
	The following people contributed to this document:		The following people contributed to this document:
	Les Ginsberg		Les Ginsberg
	Email: ginsberg@cisco.com		Email: ginsberg@cisco.com
	8. Acknowledgments		8. Acknowledgments
	The authors would like to thank Acee Lindem, Ketan Talaulikar, Tal		The authors would like to thank Acee Lindem, Ketan Talaulikar, Tal
	Mizrahi, Stephane Litkowski and Bruno Decraene for their reviews and		Mizrahi, Stephane Litkowski and Bruno Decraene for their reviews and
	valuable comments.		valuable comments.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[I-D.ietf-isis-segment-routing-msd]		[I-D.ietf-isis-segment-routing-msd]
	Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,		Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
	"Signaling MSD (Maximum SID Depth) using IS-IS", draft-		"Signaling MSD (Maximum SID Depth) using IS-IS", draft-
	ietf-isis-segment-routing-msd-13 (work in progress), July		ietf-isis-segment-routing-msd-16 (work in progress),
	2018.		September 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>.
	[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, <https://www.rfc-editor.org/info/rfc7684>.		2015, <https://www.rfc-editor.org/info/rfc7684>.
	skipping to change at page 9, line 15 ¶		skipping to change at page 9, line 41 ¶
	[I-D.ietf-idr-bgp-ls-segment-routing-msd]		[I-D.ietf-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 MSD (Maximum SID Depth) using Border Gateway		"Signaling MSD (Maximum SID Depth) using Border Gateway
	Protocol Link-State", draft-ietf-idr-bgp-ls-segment-		Protocol Link-State", draft-ietf-idr-bgp-ls-segment-
	routing-msd-02 (work in progress), August 2018.		routing-msd-02 (work in progress), August 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-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-12 (work in progress), June
	2018.		2018.
	[RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality		[RFC4552] Gupta, M. and N. Melam, "Authentication/Confidentiality
	for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006,		for OSPFv3", RFC 4552, DOI 10.17487/RFC4552, June 2006,
	<https://www.rfc-editor.org/info/rfc4552>.		<https://www.rfc-editor.org/info/rfc4552>.
End of changes. 11 change blocks.
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