draft-ietf-isis-mpls-elc-07.txt		draft-ietf-isis-mpls-elc-08.txt
	Network Working Group X. Xu		Network Working Group X. Xu
	Internet-Draft Alibaba Inc		Internet-Draft Alibaba Inc
	Intended status: Standards Track S. Kini		Intended status: Standards Track S. Kini
	Expires: November 15, 2019		Expires: March 6, 2020
	P. Psenak		P. Psenak
	C. Filsfils		C. Filsfils
	Cisco		Cisco
	S. Litkowski		S. Litkowski
	Orange		Orange
	May 14, 2019		September 3, 2019
	Signaling Entropy Label Capability and Entropy Readable Label Depth		Signaling Entropy Label Capability and Entropy Readable Label Depth
	Using IS-IS		Using IS-IS
	draft-ietf-isis-mpls-elc-07		draft-ietf-isis-mpls-elc-08
	Abstract		Abstract
	Multiprotocol Label Switching (MPLS) has defined a mechanism to load-		Multiprotocol Label Switching (MPLS) has defined a mechanism to load-
	balance traffic flows using Entropy Labels (EL). An ingress Label		balance traffic flows using Entropy Labels (EL). An ingress Label
	Switching Router (LSR) cannot insert ELs for packets going into a		Switching Router (LSR) cannot insert ELs for packets going into a
	given Label Switched Path (LSP) unless an egress LSR has indicated		given Label Switched Path (LSP) unless an egress LSR has indicated
	via signaling that it has the capability of processing ELs, referred		via signaling that it has the capability to process ELs, referred to
	to as Entropy Label Capability (ELC), on that tunnel. In addition,		as Entropy Label Capability (ELC), on that tunnel. In addition, it
	it would be useful for ingress LSRs to know each LSR's capability of		would be useful for ingress LSRs to know each LSR's capability for
	reading the maximum label stack depth and performing EL-based load-		reading the maximum label stack depth and performing EL-based load-
	balancing, referred to as Entropy Readable Label Depth (ERLD). This		balancing, referred to as Entropy Readable Label Depth (ERLD). This
	document defines a mechanism to signal these two capabilities using		document defines a mechanism to signal these two capabilities using
	IS-IS. These mechanisms are particularly useful, where label		IS-IS. These mechanisms are particularly useful, where label
	advertisements are done via protocols like IS-IS.		advertisements are done via protocols like IS-IS.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	skipping to change at page 1, line 48 ¶		skipping to change at page 1, line 48 ¶
	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 November 15, 2019.		This Internet-Draft will expire on March 6, 2020.
	Copyright Notice		Copyright Notice
	Copyright (c) 2019 IETF Trust and the persons identified as the		Copyright (c) 2019 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 27 ¶		skipping to change at page 2, line 27 ¶
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3		2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Advertising ERLD Using IS-IS . . . . . . . . . . . . . . . . 3		3. Advertising ERLD Using IS-IS . . . . . . . . . . . . . . . . 3
	4. Advertising ELC Using IS-IS . . . . . . . . . . . . . . . . . 3		4. Advertising ELC Using IS-IS . . . . . . . . . . . . . . . . . 3
	5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4		5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
	6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4		6. BGP-LS Extension . . . . . . . . . . . . . . . . . . . . . . 4
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 4		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
	8. Normative References . . . . . . . . . . . . . . . . . . . . 4		8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
			9. Normative References . . . . . . . . . . . . . . . . . . . . 5
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
	1. Introduction		1. Introduction
	[RFC6790] describes a method to load-balance Multiprotocol Label		[RFC6790] describes a method to load-balance Multiprotocol Label
	Switching (MPLS) traffic flows using Entropy Labels (EL). "The Use		Switching (MPLS) traffic flows using Entropy Labels (EL). "The Use
	of Entropy Labels in MPLS Forwarding" [RFC6790] introduces the		of Entropy Labels in MPLS Forwarding" [RFC6790] introduces the
	concept of Entropy Label Capability (ELC) and defines the signalings		concept of Entropy Label Capability (ELC) and defines the signalings
	of this capability via MPLS signaling protocols. Recently,		of this capability via MPLS signaling protocols. Recently,
	mechanisms have been defined to signal labels via link-state Interior		mechanisms have been defined to signal labels via link-state Interior
	Gateway Protocols (IGP) such as IS-IS		Gateway Protocols (IGP) such as IS-IS
	[I-D.ietf-isis-segment-routing-extensions]. In such scenario, the		[I-D.ietf-isis-segment-routing-extensions]. In such scenarios, the
	defined signaling mechanisms are inadequate. This draft defines a		defined signaling mechanisms are inadequate. This draft defines a
	mechanism to signal the ELC using IS-IS. This mechanism is useful		mechanism to signal the ELC using IS-IS. This mechanism is useful
	when the label advertisement is also done via IS-IS.		when the label advertisement is also done via IS-IS.
	In addition, in the cases where stacked LSPs are used for whatever		In addition, in the cases where LSPs are used for whatever reasons
	reasons (e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it		(e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it would be
	would be useful for ingress LSRs to know each intermediate LSR's		useful for ingress LSRs to know each intermediate LSR's capability of
	capability of reading the maximum label stack depth and performing		reading the maximum label stack depth and performing EL-based load-
	EL-based load-balancing. This capability, referred to as Entropy		balancing. This capability, referred to as Entropy Readable Label
	Readable Label Depth (ERLD) as defined in		Depth (ERLD) as defined in [I-D.ietf-mpls-spring-entropy-label] may
	[I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to		be used by ingress LSRs to determine the position of the EL label in
	determine whether it's necessary to insert an EL for a given LSP in		the stack, and whether it's necessary to insert multiple ELs at
	the case where there has already been at least one EL in the label		different positions in the label stack.
	stack [I-D.ietf-mpls-spring-entropy-label].
	2. Terminology		2. Terminology
	This memo makes use of the terms defined in [RFC6790] and [RFC4971].		This memo makes use of the terms defined in [RFC6790] and [RFC4971].
	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.
	3. Advertising ERLD Using IS-IS		3. Advertising ERLD Using IS-IS
	A new MSD-type of the Node MSD sub-TLV [RFC8491], called ERLD is		A new MSD-type of the Node MSD sub-TLV [RFC8491], called ERLD is
	defined to advertise the ERLD of a given router. As shown in		defined to advertise the ERLD of a given router. As shown in
	Figure 2, it is formatted as described in [RFC8491] with a new MSD-		Figure 2, it is formatted as described in [RFC8491] with a new MSD-
	Type code to be assigned by IANA (the type code of 2 is desired) and		Type code to be assigned by IANA (the type code of 2 is desired) and
	the Value field is set to the ERLD in the range between 0 to 255.		the Value field is set to the ERLD in the range between 0 to 255.
	The scope of the advertisement depends on the application. If a		The scope of the advertisement depends on the application. If a
	router has multiple linecards with different capabilities of reading		router has multiple line-cards with different capabilities of reading
	the maximum label stack depth, the router MUST advertise the smallest		the maximum label stack depth, the router MUST advertise the smallest
	one.		one.
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| MSD-Type=TBD2 | ERLD |		| MSD-Type=TBD2 | ERLD |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 2: ERLD MSD-Type Format		Figure 2: ERLD MSD-Type Format
	4. Advertising ELC Using IS-IS		4. Advertising ELC Using IS-IS
	Even though ELC is a property of the node, in some cases it is		Even though ELC is a property of the node, in some cases it is
	advantageous to associate and advertise the ELC with a prefix. In a		advantageous to associate and advertise the ELC with a prefix. In a
	multi-area network, routers may not know the identity of the prefix		multi-area network, routers may not know the identity of the prefix
	originator in the remote area, or may not know the capabilities of		originator in a remote area, or may not know the capabilities of such
	such originator. Similarly in a multi-domain network, the identity		originator. Similarly in a multi-domain network, the identity of the
	of the prefix originator and its capabilities may not be known to the		prefix originator and its capabilities may not be known to the
	ingress LSR.		ingress LSR.
	One bit of the "Bit Values for Prefix Attribute Flags Sub-TLV"		One bit of the "Bit Values for Prefix Attribute Flags Sub-TLV"
	registry defined in [RFC7794] (Bit 3 is desired) is to be assigned by		registry defined in [RFC7794] (Bit 3 is desired) is to be assigned by
	the IANA for the ELC. If a router has multiple line cards, the		the IANA for the ELC. If a router has multiple line cards, the
	router MUST NOT announce the ELC for any prefixes that are locally		router MUST NOT announce the ELC for any prefixes that are locally
	attached unless all of its linecards are capable of processing ELs.		attached unless all of its line-cards are capable of processing ELs.
	If a router supports ELs on all of its linecards, it SHOULD set the		If a router supports ELs on all of its line-cards, it SHOULD set the
	ELC for every local host prefix it advertises in IS-IS.		ELC for every local host prefix it advertises in IS-IS.
	When a router leaks a prefix between two levels (upwards or		When a router leaks a prefix between two levels (upwards or
	downwards), it MUST preserve the ELC signalling for this prefix.		downwards), it MUST preserve the ELC signaling for this prefix.
	0 1 2 3 4 5 6 7...		0 1 2 3 4 5 6 7...
	+-+-+-+-+-+-+-+-+...		+-+-+-+-+-+-+-+-+...
	|X|R|N|E| ...		|X|R|N|E| ...
	+-+-+-+-+-+-+-+-+...		+-+-+-+-+-+-+-+-+...
	When redistributing a prefix between two IS-IS protocol instances or		When redistributing a prefix between two IS-IS protocol instances or
	redistributed from another protocol to an IS-IS protocol instance, a		redistributing from another protocol to an IS-IS protocol instance, a
	router SHOULD preserve the ELC signalling for that prefix. The exact		router SHOULD preserve the ELC signaling for that prefix. The exact
	mechanism on how to exchange ELC between protocol instances running		mechanism used to exchange ELC between protocol instances running on
	on an ASBR is outside of the scope of this document and is		an ASBR is outside of the scope of this document and is
	implementation specific.		implementation specific.
	5. Acknowledgements		5. Acknowledgements
	The authors would like to thank Yimin Shen, George Swallow, Acee		The authors would like to thank Yimin Shen, George Swallow, Acee
	Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura, Bruno Decraene		Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura, Bruno Decraene
	Carlos Pignataro, Wim Hendrickx, and Gunter Van De Velde for their		Carlos Pignataro, Wim Hendrickx, and Gunter Van De Velde for their
	valuable comments.		valuable comments.
	6. IANA Considerations		6. BGP-LS Extension
			The IS-IS extensions defined in this document can be advertised via
			BGP-LS [RFC7752] using existing BGP-LS TLVs.
			The ELC Flag included in the Prefix Attribute Flags sub-TLV, as
			defined in Section 4, is advertised using the Prefix Attribute Flags
			TLV (TLV 1170) of the BGP-LS IPv4/IPv6 Prefix NLRI Attribute as
			defined in section 2.3.2 of
			[I-D.ietf-idr-bgp-ls-segment-routing-ext].
			The ERLD MSD-type introduced for IS-IS in Section 3 is advertised
			using the Node MSD TLV (TLV 266) of the BGP-LS Node NLRI Attribute as
			defined in section 3 of [I-D.ietf-idr-bgp-ls-segment-routing-ext].
			7. IANA Considerations
	IANA is requested to allocate the E-bit (bit position 3 is desired)		IANA is requested to allocate the E-bit (bit position 3 is desired)
	from the "Bit Values for Prefix Attribute Flags Sub-TLV" registry.		from the "Bit Values for Prefix Attribute Flags Sub-TLV" registry.
	IANA is requested to allocate a MSD type (the type code of 2 is		IANA is requested to allocate a MSD type (the type code of 2 is
	desired) from the "IGP MSD Types" registry for ERLD.		desired) from the "IGP MSD Types" registry for ERLD.
	7. Security Considerations		8. Security Considerations
	The security considerations as described in [RFC4971] are applicable		The security considerations as described in [RFC4971] nd
	to this document. This document does not introduce any new security		[I-D.ietf-mpls-spring-entropy-label] are applicable to this document.
	risks.
	8. Normative References		Incorrectly setting the E flag (ELC capable) (during origination,
			leaking or redistribution) may lead to black-holing of the traffic on
			the egress node.
			9. Normative References
			[I-D.ietf-idr-bgp-ls-segment-routing-ext]
			Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H.,
			and M. Chen, "BGP Link-State extensions for Segment
			Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-16
			(work in progress), June 2019.
	[I-D.ietf-isis-segment-routing-extensions]		[I-D.ietf-isis-segment-routing-extensions]
	Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,		Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,
	Gredler, H., and B. Decraene, "IS-IS Extensions for		Gredler, H., and B. Decraene, "IS-IS Extensions for
	Segment Routing", draft-ietf-isis-segment-routing-		Segment Routing", draft-ietf-isis-segment-routing-
	extensions-24 (work in progress), April 2019.		extensions-25 (work in progress), May 2019.
	[I-D.ietf-mpls-spring-entropy-label]		[I-D.ietf-mpls-spring-entropy-label]
	Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,		Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
	Shakir, R., and J. Tantsura, "Entropy label for SPRING		Shakir, R., and J. Tantsura, "Entropy label for SPRING
	tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in		tunnels", draft-ietf-mpls-spring-entropy-label-12 (work in
	progress), July 2018.		progress), July 2018.
	[I-D.ietf-spring-segment-routing-mpls]		[I-D.ietf-spring-segment-routing-mpls]
	Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,		Bashandy, A., Filsfils, C., Previdi, S., Decraene, B.,
	Litkowski, S., and R. Shakir, "Segment Routing with MPLS		Litkowski, S., and R. Shakir, "Segment Routing with MPLS
	skipping to change at page 5, line 28 ¶		skipping to change at page 6, line 5 ¶
	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>.
	[RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed.,		[RFC4971] Vasseur, JP., Ed., Shen, N., Ed., and R. Aggarwal, Ed.,
	"Intermediate System to Intermediate System (IS-IS)		"Intermediate System to Intermediate System (IS-IS)
	Extensions for Advertising Router Information", RFC 4971,		Extensions for Advertising Router Information", RFC 4971,
	DOI 10.17487/RFC4971, July 2007,		DOI 10.17487/RFC4971, July 2007,
	<https://www.rfc-editor.org/info/rfc4971>.		<https://www.rfc-editor.org/info/rfc4971>.
	[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
	Engineering", RFC 5305, DOI 10.17487/RFC5305, October
	2008, <https://www.rfc-editor.org/info/rfc5305>.
	[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and		[RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and
	L. Yong, "The Use of Entropy Labels in MPLS Forwarding",		L. Yong, "The Use of Entropy Labels in MPLS Forwarding",
	RFC 6790, DOI 10.17487/RFC6790, November 2012,		RFC 6790, DOI 10.17487/RFC6790, November 2012,
	<https://www.rfc-editor.org/info/rfc6790>.		<https://www.rfc-editor.org/info/rfc6790>.
			[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
			S. Ray, "North-Bound Distribution of Link-State and
			Traffic Engineering (TE) Information Using BGP", RFC 7752,
			DOI 10.17487/RFC7752, March 2016,
			<https://www.rfc-editor.org/info/rfc7752>.
	[RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and		[RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and
	U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4		U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4
	and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794,		and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794,
	March 2016, <https://www.rfc-editor.org/info/rfc7794>.		March 2016, <https://www.rfc-editor.org/info/rfc7794>.
	[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
	Writing an IANA Considerations Section in RFCs", BCP 26,
	RFC 8126, DOI 10.17487/RFC8126, June 2017,
	<https://www.rfc-editor.org/info/rfc8126>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	[RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,		[RFC8491] Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg,
	"Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,		"Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491,
	DOI 10.17487/RFC8491, November 2018,		DOI 10.17487/RFC8491, November 2018,
	<https://www.rfc-editor.org/info/rfc8491>.		<https://www.rfc-editor.org/info/rfc8491>.
	Authors' Addresses		Authors' Addresses
End of changes. 22 change blocks.
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