draft-ietf-lsr-isis-srv6-extensions-12.txt		draft-ietf-lsr-isis-srv6-extensions-13.txt
	Networking Working Group P. Psenak, Ed.		Networking Working Group P. Psenak, Ed.
	Internet-Draft C. Filsfils		Internet-Draft C. Filsfils
	Updates: 7370 (if approved) Cisco Systems		Updates: 7370 (if approved) Cisco Systems
	Intended status: Standards Track A. Bashandy		Intended status: Standards Track A. Bashandy
	Expires: October 10, 2021 Individual		Expires: October 14, 2021 Individual
	B. Decraene		B. Decraene
	Orange		Orange
	Z. Hu		Z. Hu
	Huawei Technologies		Huawei Technologies
	April 8, 2021		April 12, 2021
	IS-IS Extension to Support Segment Routing over IPv6 Dataplane		IS-IS Extension to Support Segment Routing over IPv6 Dataplane
	draft-ietf-lsr-isis-srv6-extensions-12		draft-ietf-lsr-isis-srv6-extensions-13
	Abstract		Abstract
	The Segment Routing (SR) allows for a flexible definition of end-to-		The Segment Routing (SR) allows for a flexible definition of end-to-
	end paths by encoding paths as sequences of topological sub-paths,		end paths by encoding paths as sequences of topological sub-paths,
	called "segments". Segment routing architecture can be implemented		called "segments". Segment routing architecture can be implemented
	over an MPLS data plane as well as an IPv6 data plane. This document		over an MPLS data plane as well as an IPv6 data plane. This document
	describes the IS-IS extensions required to support Segment Routing		describes the IS-IS extensions required to support Segment Routing
	over an IPv6 data plane.		over an IPv6 data plane.
	This documents updates [RFC7370] by modifying an existing registry.		This documents updates RFC 7370 by modifying an existing registry.
	Requirements Language		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.
	Status of This Memo		Status of This Memo
	skipping to change at page 2, line 4 ¶		skipping to change at page 2, line 4 ¶
	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 October 10, 2021.		This Internet-Draft will expire on October 14, 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2021 IETF Trust and the persons identified as the		Copyright (c) 2021 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 36 ¶		skipping to change at page 2, line 36 ¶
	4. Advertising Maximum SRv6 SID Depths . . . . . . . . . . . . . 4		4. Advertising Maximum SRv6 SID Depths . . . . . . . . . . . . . 4
	4.1. Maximum Segments Left MSD Type . . . . . . . . . . . . . 5		4.1. Maximum Segments Left MSD Type . . . . . . . . . . . . . 5
	4.2. Maximum End Pop MSD Type . . . . . . . . . . . . . . . . 5		4.2. Maximum End Pop MSD Type . . . . . . . . . . . . . . . . 5
	4.3. Maximum H.Encaps MSD Type . . . . . . . . . . . . . . . . 5		4.3. Maximum H.Encaps MSD Type . . . . . . . . . . . . . . . . 5
	4.4. Maximum End D MSD Type . . . . . . . . . . . . . . . . . 5		4.4. Maximum End D MSD Type . . . . . . . . . . . . . . . . . 5
	5. SRv6 SIDs and Reachability . . . . . . . . . . . . . . . . . 6		5. SRv6 SIDs and Reachability . . . . . . . . . . . . . . . . . 6
	6. Advertising Anycast Property . . . . . . . . . . . . . . . . 7		6. Advertising Anycast Property . . . . . . . . . . . . . . . . 7
	7. Advertising Locators and End SIDs . . . . . . . . . . . . . . 8		7. Advertising Locators and End SIDs . . . . . . . . . . . . . . 8
	7.1. SRv6 Locator TLV Format . . . . . . . . . . . . . . . . . 8		7.1. SRv6 Locator TLV Format . . . . . . . . . . . . . . . . . 8
	7.2. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . . . 10		7.2. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . . . 10
	8. Advertising SRv6 Adjacency SIDs . . . . . . . . . . . . . . . 11		8. Advertising SRv6 Adjacency SIDs . . . . . . . . . . . . . . . 12
	8.1. SRv6 End.X SID sub-TLV . . . . . . . . . . . . . . . . . 12		8.1. SRv6 End.X SID sub-TLV . . . . . . . . . . . . . . . . . 12
	8.2. SRv6 LAN End.X SID sub-TLV . . . . . . . . . . . . . . . 13		8.2. SRv6 LAN End.X SID sub-TLV . . . . . . . . . . . . . . . 14
	9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 15		9. SRv6 SID Structure Sub-Sub-TLV . . . . . . . . . . . . . . . 16
	10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 16		10. Advertising Endpoint Behaviors . . . . . . . . . . . . . . . 17
	11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16		11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
	11.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 16		11.1. SRv6 Locator TLV . . . . . . . . . . . . . . . . . . . . 17
	11.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 17		11.1.1. SRv6 End SID sub-TLV . . . . . . . . . . . . . . . . 18
	11.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 17		11.1.2. Revised sub-TLV table . . . . . . . . . . . . . . . 18
	11.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 18		11.2. SRv6 Capabilities sub-TLV . . . . . . . . . . . . . . . 19
	11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 18		11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs . . . . . 19
	11.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 19		11.4. MSD Types . . . . . . . . . . . . . . . . . . . . . . . 20
	11.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 19		11.5. Sub-Sub-TLVs for SID Sub-TLVs . . . . . . . . . . . . . 20
	11.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 20		11.6. Prefix Attribute Flags Sub-TLV . . . . . . . . . . . . . 21
	12. Security Considerations . . . . . . . . . . . . . . . . . . . 20		12. Security Considerations . . . . . . . . . . . . . . . . . . . 21
	13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 20		13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 21
	14. References . . . . . . . . . . . . . . . . . . . . . . . . . 21		14. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
	14.1. Normative References . . . . . . . . . . . . . . . . . . 21		14.1. Normative References . . . . . . . . . . . . . . . . . . 22
	14.2. Informative References . . . . . . . . . . . . . . . . . 24		14.2. Informative References . . . . . . . . . . . . . . . . . 25
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
	1. Introduction		1. Introduction
	With Segment Routing (SR) [RFC8402], a node steers a packet through		With Segment Routing (SR) [RFC8402], a node steers a packet through
	an ordered list of instructions, called segments.		an ordered list of instructions, called segments.
	Segments are identified through Segment Identifiers (SIDs).		Segments are identified through Segment Identifiers (SIDs).
	Segment Routing can be directly instantiated on the IPv6 data plane		Segment Routing can be directly instantiated on the IPv6 data plane
	through the use of the Segment Routing Header defined in [RFC8754].		through the use of the Segment Routing Header defined in [RFC8754].
	skipping to change at page 3, line 45 ¶		skipping to change at page 3, line 45 ¶
	Several new sub-TLVs are defined to advertise various SRv6 Maximum		Several new sub-TLVs are defined to advertise various SRv6 Maximum
	SID Depths.		SID Depths.
	The SRv6 End SID sub-TLV, the SRv6 End.X SID sub-TLV, and the SRv6		The SRv6 End SID sub-TLV, the SRv6 End.X SID sub-TLV, and the SRv6
	LAN End.X SID sub-TLV are used to advertise which SIDs are		LAN End.X SID sub-TLV are used to advertise which SIDs are
	instantiated at a node and what Endpoint behavior is bound to each		instantiated at a node and what Endpoint behavior is bound to each
	instantiated SID.		instantiated SID.
	This documents updates [RFC7370] by modifying an existing registry		This documents updates [RFC7370] by modifying an existing registry
	Section 11.1.2.		(Section 11.1.2).
	2. SRv6 Capabilities sub-TLV		2. SRv6 Capabilities sub-TLV
	A node indicates that it supports the SR Segment Endpoint Node		A node indicates that it supports the SR Segment Endpoint Node
	functionality as specified in [RFC8754] by advertising a new SRv6		functionality as specified in [RFC8754] by advertising a new SRv6
	Capabilities sub-TLV of the router capabilities TLV [RFC7981].		Capabilities sub-TLV of the router capabilities TLV [RFC7981].
	The SRv6 Capabilities sub-TLV may contain optional sub-sub-TLVs. No		The SRv6 Capabilities sub-TLV may contain optional sub-sub-TLVs. No
	sub-sub-TLVs are currently defined.		sub-sub-TLVs are currently defined.
	skipping to change at page 5, line 7 ¶		skipping to change at page 5, line 7 ¶
	for Maximum SID Depths (MSD) of various types. Node MSDs are		for Maximum SID Depths (MSD) of various types. Node MSDs are
	advertised in a sub-TLV of the Router Capabilities TLV [RFC7981].		advertised in a sub-TLV of the Router Capabilities TLV [RFC7981].
	Link MSDs are advertised in a sub-TLV of TLVs 22, 23, 141, 222, and		Link MSDs are advertised in a sub-TLV of TLVs 22, 23, 141, 222, and
	223.		223.
	This document defines the relevant SRv6 MSDs and requests MSD type		This document defines the relevant SRv6 MSDs and requests MSD type
	assignments in the MSD Types registry created by [RFC8491].		assignments in the MSD Types registry created by [RFC8491].
	4.1. Maximum Segments Left MSD Type		4.1. Maximum Segments Left MSD Type
	The Maximum Segments Left MSD Type specifies the maximum value of the		The Maximum Segments Left MSD Type signals the maximum value of the
	"Segments Left" field [RFC8754] in the SRH of a received packet		"Segments Left" field [RFC8754] in the SRH of a received packet
	before applying the Endpoint behavior associated with a SID.		before applying the Endpoint behavior associated with a SID.
	SRH Max Segments Left Type: 41		SRH Max Segments Left Type: 41
	If no value is advertised the supported value is 0.		If no value is advertised the supported value is 0.
	4.2. Maximum End Pop MSD Type		4.2. Maximum End Pop MSD Type
	The Maximum End Pop MSD Type signals the maximum number of SIDs in		The Maximum End Pop MSD Type signals the maximum number of SIDs in
	skipping to change at page 5, line 47 ¶		skipping to change at page 5, line 47 ¶
	inserting any SRH header.		inserting any SRH header.
	A non-zero SRH Max H.encaps MSD indicates that the headend can insert		A non-zero SRH Max H.encaps MSD indicates that the headend can insert
	an SRH up to the advertised value.		an SRH up to the advertised value.
	4.4. Maximum End D MSD Type		4.4. Maximum End D MSD Type
	The Maximum End D MSD Type specifies the maximum number of SIDs		The Maximum End D MSD Type specifies the maximum number of SIDs
	present in an SRH when performing decapsulation. These includes, but		present in an SRH when performing decapsulation. These includes, but
	not limited to, End.DX6, End.DT4, End.DT46, End with USD, End.X with		not limited to, End.DX6, End.DT4, End.DT46, End with USD, End.X with
	USD as defined in [RFC8986]).		USD as defined in [RFC8986].
	SRH Max End D Type: 45		SRH Max End D Type: 45
	If the advertised value is zero or no value is advertised		If the advertised value is zero or no value is advertised
	then the router cannot apply any behavior that results in		then the router cannot apply any behavior that results in
	decapsulation and forwarding of the inner packet if the		decapsulation and forwarding of the inner packet if the
	other IPv6 header contains an SRH.		other IPv6 header contains an SRH.
	5. SRv6 SIDs and Reachability		5. SRv6 SIDs and Reachability
	skipping to change at page 6, line 34 ¶		skipping to change at page 6, line 34 ¶
	SRv6 Locator TLV MUST be installed in the forwarding plane of		SRv6 Locator TLV MUST be installed in the forwarding plane of
	receiving SRv6 capable routers when the associated topology/algorithm		receiving SRv6 capable routers when the associated topology/algorithm
	is supported by the receiving node. The processing of the prefix		is supported by the receiving node. The processing of the prefix
	advertised in the SRv6 Locator TLV, the calculation of its		advertised in the SRv6 Locator TLV, the calculation of its
	reachability and the installation in the forwarding plane follows the		reachability and the installation in the forwarding plane follows the
	process defined for the Prefix Reachability TLV 236 [RFC5308], or TLV		process defined for the Prefix Reachability TLV 236 [RFC5308], or TLV
	237 [RFC5120].		237 [RFC5120].
	Locators associated with algorithm 0 and 1 (for all supported		Locators associated with algorithm 0 and 1 (for all supported
	topologies) SHOULD be advertised in a Prefix Reachability TLV (236 or		topologies) SHOULD be advertised in a Prefix Reachability TLV (236 or
	237) so that legacy routers (i.e., routers which do NOT support SRv6)		237) so that legacy routers (i.e., routers which do not support SRv6)
	will install a forwarding entry for algorithm 0 and 1 SRv6 traffic.		will install a forwarding entry for algorithm 0 and 1 SRv6 traffic.
	In cases where a locator advertisement is received in both a Prefix		In cases where a locator advertisement is received in both a Prefix
	Reachability TLV and an SRv6 Locator TLV - (e.g. prefix, prefix-		Reachability TLV and an SRv6 Locator TLV - (e.g. prefix, prefix-
	length, MTID all being equal and Algorithm being 0 in Locator TLV),		length, MTID all being equal and Algorithm being 0 in Locator TLV),
	the Prefix Reachability advertisement MUST be preferred when		In case where the same prefix, with the same prefix-length, MTID, and
	installing entries in the forwarding plane. This is to prevent		algorithm is received in both a Prefix Reachability TLV and an SRv6
			Locator TLV, the Prefix Reachability advertisement MUST be preferred
			when installing entries in the forwarding plane. This is to prevent
	inconsistent forwarding entries between SRv6 capable and SRv6		inconsistent forwarding entries between SRv6 capable and SRv6
	incapable routers. Such preference of Prefix Reachability		incapable routers. Such preference of Prefix Reachability
	advertisement does not have any impact on the rest of the data		advertisement does not have any impact on the rest of the data
	advertised in the SRv6 Locator TLV.		advertised in the SRv6 Locator TLV.
	Locators associated with Flexible Algorithms (see Section 4 of		Locators associated with Flexible Algorithms (see Section 4 of
	[I-D.ietf-lsr-flex-algo]) SHOULD NOT be advertised in Prefix		[I-D.ietf-lsr-flex-algo]) SHOULD NOT be advertised in Prefix
	Reachability TLVs (236 or 237). Advertising the Flexible Algorithm		Reachability TLVs (236 or 237). Advertising the Flexible Algorithm
	locator in regular Prefix Reachability TLV (236 or 237) would make		locator in regular Prefix Reachability TLV (236 or 237) would make
	the forwarding for it to follow algo 0 path.		the forwarding for it to follow algo 0 path.
	skipping to change at page 18, line 32 ¶		skipping to change at page 19, line 32 ¶
	Type: 25		Type: 25
	Description: SRv6 Capabilities sub-TLV.		Description: SRv6 Capabilities sub-TLV.
	Reference: This document (Section 2).		Reference: This document (Section 2).
	This document requests the creation of a new IANA managed registry,		This document requests the creation of a new IANA managed registry,
	under "IS-IS TLV Codepoints" registry - sub-sub-TLVs of the SRv6		under "IS-IS TLV Codepoints" registry - sub-sub-TLVs of the SRv6
	Capability sub-TLV. The registration procedure is "Expert Review" as		Capability sub-TLV. The registration procedure is "Expert Review" as
	defined in [RFC8126]. Guidance for the Designated Experts is		defined in [RFC8126]. Guidance for the Designated Experts is
	provided in [RFC7370]. Suggested registry name is "sub-sub-TLVs for		provided in the [RFC7370]. Suggested registry name is "sub-sub-TLVs
	SRv6 Capability sub-TLV". No sub-sub-TLVs are defined by this		for SRv6 Capability sub-TLV". No sub-sub-TLVs are defined by this
	document except for the reserved value.		document except for the reserved value.
	0: Reserved		0: Reserved
	1-255: Unassigned		1-255: Unassigned
	11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs		11.3. SRv6 End.X SID and SRv6 LAN End.X SID sub-TLVs
	This document makes the following registrations in the "Sub-TLVs for		This document makes the following registrations in the "Sub-TLVs for
	TLVs 22, 23, 25, 141, 222, and 223 (Extended IS reachability, IS		TLVs 22, 23, 25, 141, 222, and 223 (Extended IS reachability, IS
	skipping to change at page 19, line 23 ¶		skipping to change at page 20, line 23 ¶
	43 y y y y y y		43 y y y y y y
	44 y y y y y y		44 y y y y y y
	11.4. MSD Types		11.4. MSD Types
	This document makes the following registrations in the IGP MSD-Types		This document makes the following registrations in the IGP MSD-Types
	registry:		registry:
	Value Name Reference		Value Name Reference
	------------------		------------------
	41 SRH Max SL Section 4.1		41 SRH Max SL [This Document]
	42 SRH Max End Pop Section 4.2		42 SRH Max End Pop [This Document]
	44 SRH Max H.encaps Section 4.3		44 SRH Max H.encaps [This Document]
	45 SRH Max End D Section 4.4		45 SRH Max End D [This Document]
	11.5. Sub-Sub-TLVs for SID Sub-TLVs		11.5. Sub-Sub-TLVs for SID Sub-TLVs
	This document requests a new IANA registry be created under the IS-IS		This document requests a new IANA registry be created under the IS-IS
	TLV Codepoints Registry to control the assignment of sub-TLV types		TLV Codepoints Registry to control the assignment of sub-TLV types
	for the SID Sub-TLVs specified in this document - Section 7.2,		for the SID Sub-TLVs specified in this document - Section 7.2,
	Section 8.1, Section 8.2. The suggested name of the new registry is		Section 8.1, Section 8.2. The suggested name of the new registry is
	"sub-sub-TLVs for SRv6 End SID (5) (sub-TLV of TLVs 27, 135, 235, 236		"sub-sub-TLVs for SRv6 End SID (5) (sub-TLV of TLVs 27, 135, 235, 236
	and 237) and SRv6 End.X SID (43)/SRv6 LAN End.X SID (44) (sub-TLVs of		and 237) and SRv6 End.X SID (43)/SRv6 LAN End.X SID (44) (Sub-TLVs
	TLVs 27, 135, 235, 236 and 237)". The registration procedure is		for TLVs 22, 23, 25, 141, 222, and 223)". The registration procedure
	"Expert Review" as defined in [RFC8126]. Guidance for the Designated		is "Expert Review" as defined in [RFC8126]. Guidance for the
	Experts is provided in [RFC7370]The following assignments are made by		Designated Experts is provided in [RFC7370]. The following
	this document:		assignments are made by this document:
	Type Description Encoding		Type Description Encoding
	Reference		Reference
	---------------------------------------------------------		---------------------------------------------------------
	0 Reserved		0 Reserved
	1 SRv6 SID Structure Sub-Sub-TLV Section 9		1 SRv6 SID Structure Sub-Sub-TLV [This Document]
	2-255 Unassigned		2-255 Unassigned
	Type 5 43 44		Type 5 43 44
	1 y y y		1 y y y
	11.6. Prefix Attribute Flags Sub-TLV		11.6. Prefix Attribute Flags Sub-TLV
	This document adds a new bit in the "Bit Values for Prefix Attribute		This document adds a new bit in the "Bit Values for Prefix Attribute
	Flags Sub-TLV" registry:		Flags Sub-TLV" registry:
End of changes. 16 change blocks.
	42 lines changed or deleted		44 lines changed or added
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