draft-ietf-idr-bgp-ls-segment-routing-msd-03.txt		draft-ietf-idr-bgp-ls-segment-routing-msd-04.txt
	skipping to change at page 1, line 17 ¶		skipping to change at page 1, line 17 ¶
	G. Mirsky		G. Mirsky
	ZTE Corp.		ZTE Corp.
	S. Sivabalan		S. Sivabalan
	Cisco		Cisco
	N. Triantafillis		N. Triantafillis
	Apstra, Inc.		Apstra, Inc.
	February 19, 2019		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-03		draft-ietf-idr-bgp-ls-segment-routing-msd-04
	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 3, line 47 ¶		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:
	[RFC8476]		[RFC8476], [RFC8491]
	[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]
	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 5, line 17 ¶		skipping to change at page 5, line 17 ¶
	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		The advertisement of an incorrect MSD value may have negative
	that is false, e.g., an MSD that is incorrect, may result in a path		consequences. If the value is smaller than supported, path
	computation failing, having a service unavailable, or instantiation		computation may fail to compute a viable path. If the value is
	of a path that can't be supported by the head-end (the node		larger than supported, an attempt to instantiate a path that can't be
	performing the imposition).		supported by the head-end (the node performing the SID imposition)
			may occur. The presence of this information may also inform an
			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] extensions.		discussed in [RFC7752], [RFC8476] and [RFC8491]
	7. Acknowledgements		7. Acknowledgements
	We like to thank Acee Lindem, Ketan Talaulikar, Stephane Litkowski		We like to thank Acee Lindem, Ketan Talaulikar, Stephane Litkowski
	and Bruno Decraene for their reviews and valuable comments.		and Bruno Decraene for their reviews and valuable comments.
	8. References		8. References
	8.1. Normative References		8.1. Normative References
End of changes. 4 change blocks.
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