< draft-ietf-isis-segment-routing-msd-05.txt		draft-ietf-isis-segment-routing-msd-06.txt >
	skipping to change at page 1, line 14 ¶		skipping to change at page 1, line 14 ¶
	Internet-Draft Individual		Internet-Draft Individual
	Intended status: Standards Track U. Chunduri		Intended status: Standards Track U. Chunduri
	Expires: June 4, 2018 Huawei Technologies		Expires: June 4, 2018 Huawei Technologies
	S. Aldrin		S. Aldrin
	Google, Inc		Google, Inc
	L. Ginsberg		L. Ginsberg
	Cisco Systems		Cisco Systems
	December 01, 2017		December 01, 2017
	Signaling MSD (Maximum SID Depth) using IS-IS		Signaling MSD (Maximum SID Depth) using IS-IS
	draft-ietf-isis-segment-routing-msd-05		draft-ietf-isis-segment-routing-msd-06
	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 IS-IS		supported by a node at node and/or link granularity by an IS-IS
	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 impose the SID		by the head-end at node and/or link granularity to impose the SID
	stack of an appropriate depth. MSD is relevant to the head-end of a		stack of an appropriate depth. MSD is relevant to the head-end of a
	SR tunnel or Binding-SID anchor node where Binding-SID expansions		SR tunnel or Binding-SID anchor node where Binding-SID expansions
	skipping to change at page 2, line 23 ¶		skipping to change at page 2, line 23 ¶
	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
	1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3		1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
	3. Node MSD Advertisement . . . . . . . . . . . . . . . . . . . 4		3. Node MSD Advertisement . . . . . . . . . . . . . . . . . . . 4
	4. LINK MSD Advertisement . . . . . . . . . . . . . . . . . . . 4		4. Link MSD Advertisement . . . . . . . . . . . . . . . . . . . 4
	5. Node MSD vs Link MSD conflict resolution . . . . . . . . . . 5		5. Node MSD vs Link MSD conflict resolution . . . . . . . . . . 5
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 6		7. Security Considerations . . . . . . . . . . . . . . . . . . . 6
	8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6		8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
	9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6		9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7		10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
	10.1. Normative References . . . . . . . . . . . . . . . . . . 7		10.1. Normative References . . . . . . . . . . . . . . . . . . 7
	10.2. Informative References . . . . . . . . . . . . . . . . . 7		10.2. Informative References . . . . . . . . . . . . . . . . . 7
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
	1. Introduction		1. Introduction
	When Segment Routing tunnels are computed by a centralized		When Segment Routing tunnels are computed by a centralized
	controller, it is critical that the controller learns the MSD		controller, it is critical that the controller learns the MSD
	"Maximum SID Depth" of the node or link SR tunnel exits over, so the		"Maximum SID Depth" of the node or link SR tunnel exits over, so the
	skipping to change at page 4, line 45 ¶		skipping to change at page 4, line 45 ¶
	MSD of the router originating the Router Capability TLV. Node		MSD of the router originating the Router Capability TLV. Node
	Maximum MSD is a number in the range of 0-254. 0 represents lack of		Maximum MSD is a number in the range of 0-254. 0 represents lack of
	the ability to impose MSD stack of any depth; any other value		the ability to impose MSD stack of any depth; any other value
	represents that of the node. This value SHOULD represent the lowest		represents that of the node. This value SHOULD represent the lowest
	value supported by node.		value supported by node.
	Other Sub-types other than defined above are reserved for future		Other Sub-types other than defined above are reserved for future
	extensions. This sub-TLV is optional. The scope of the		extensions. This sub-TLV is optional. The scope of the
	advertisement is specific to the deployment.		advertisement is specific to the deployment.
	4. LINK MSD Advertisement		4. Link MSD Advertisement
	A new sub-TLV - Link MSD sub-TLV is defined for TLVs 22, 23, 141,		A new sub-TLV - Link MSD sub-TLV is defined for TLVs 22, 23, 141,
	222, and 223 to carry the provisioned MSD of the interface associated		222, and 223 to carry the provisioned MSD of the interface associated
	with the link.		with the link.
	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 | Sub-Type and Value |		| Type | Length | Sub-Type and Value |
	skipping to change at page 5, line 43 ¶		skipping to change at page 5, line 43 ¶
	This document includes a request to IANA to allocate sub-TLV type		This document includes a request to IANA to allocate sub-TLV type
	codes for the new sub TLV proposed in Section 3 of this document from		codes for the new sub TLV proposed in Section 3 of this document from
	IS-IS Router Capability TLV Registry as defined by [RFC7981].		IS-IS Router Capability TLV Registry as defined by [RFC7981].
	Following values have been allocated by IANA:		Following values have been allocated by IANA:
	Value Description Reference		Value Description Reference
	----- --------------- -------------		----- --------------- -------------
	23 Node MSD This document		23 Node MSD This document
	15 Link MSD This document
	Figure 3: MSD Types		Figure 3: Node MSD
	For the Link MSD, we request IANA to allocate new sub-TLV codes as		For the Link MSD, we request IANA to allocate new sub-TLV codes as
	defined in Section 4 from Sub-TLVs for TLVs 22, 23, 141, 222 and 223		defined in Section 4 from Sub-TLVs for TLVs 22, 23, 141, 222 and 223
	registry.		registry.
			Value Description Reference
			----- --------------- -------------
			15 Link MSD This document
			Figure 4: Link MSD
	Per TLV information where LINK MSD sub-TLV can be part of:		Per TLV information where LINK MSD sub-TLV can be part of:
	TLV 22 23 25 141 222 223		TLV 22 23 25 141 222 223
	--------------------		--- --------------------
	y y y y y y		y y y y y y
	Figure 4: TLVs where LINK MSD Sub-TLV can be present		Figure 5: TLVs where LINK MSD Sub-TLV can be present
	This document requests the creation of a new IANA managed registry to		This document requests the creation of a new IANA managed registry to
	identify MSD types as proposed in Section 3, Section 4. The		identify MSD types as proposed in Section 3, Section 4. The
	registration procedure is "Expert Review" as defined in [RFC8126].		registration procedure is "Expert Review" as defined in [RFC8126].
	Suggested registry name is "MSD Sub-types". Types are an unsigned 8		Suggested registry name is "MSD Sub-types". Types are an unsigned 8
	bit number. The following values are defined by this document		bit number. The following values are defined by this document
	Value Name Reference		Value Name Reference
	----- --------------------- -------------		----- --------------------- -------------
	0 Reserved This document		0 Reserved This document
	1 Base MSD This document		1 Base MSD This document
	2-250 Unassigned This document		2-250 Unassigned This document
	251-254 Experimental This document		251-254 Experimental This document
	255 Reserved This document		255 Reserved This document
	Figure 5: MSD Sub-type Codepoints Registry		Figure 6: MSD Sub-type Codepoints Registry
	7. Security Considerations		7. Security Considerations
	This document describes a mechanism to signal Segment Routing MSD		This document describes a mechanism to signal Segment Routing MSD
	supported at node and/or link granularity through IS-IS LSPs and does		supported at node and/or link granularity through IS-IS LSPs and does
	not introduce any new security issues.		not introduce any new security issues.
	8. Contributors		8. Contributors
	The following people contributed to this document:		The following people contributed to this document:
End of changes. 10 change blocks.
	11 lines changed or deleted		16 lines changed or added
This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/