draft-ietf-ospf-mpls-elc-07.txt		draft-ietf-ospf-mpls-elc-08.txt
	OSPF Working Group X. Xu		OSPF 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: March 29, 2019		Expires: November 14, 2019
	S. Sivabalan		P. Psenak
	C. Filsfils		C. Filsfils
	Cisco		Cisco
	S. Litkowski		S. Litkowski
	Orange		Orange
	September 25, 2018		May 13, 2019
	Signaling Entropy Label Capability and Entropy Readable Label-stack		Signaling Entropy Label Capability and Entropy Readable Label-stack
	Depth Using OSPF		Depth Using OSPF
	draft-ietf-ospf-mpls-elc-07		draft-ietf-ospf-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 tunnel unless an egress LSR has indicated via signaling that it		given tunnel unless an egress LSR has indicated via signaling that it
	has the capability of processing ELs, referred to as Entropy Label		has the capability of processing ELs, referred to as Entropy Label
	Capability (ELC), on that tunnel. In addition, it would be useful		Capability (ELC), on that tunnel. In addition, it would be useful
	for ingress LSRs to know each LSR's capability of reading the maximum		for ingress LSRs to know each LSR's capability of reading the maximum
	label stack depth and performing EL-based load-balancing, referred to		label stack depth and performing EL-based load-balancing, referred to
	as Entropy Readable Label Depth (ERLD), in the cases where stacked		as Entropy Readable Label Depth (ERLD), in the cases where stacked
	LSPs are used for whatever reasons. This document defines mechanisms		LSPs are used. This document defines a mechanisms to signal these
	to signal these two capabilities using OSPF. These mechanisms are		two capabilities using OSPF and OSPFv3. These mechanisms are
	useful when the label advertisement is also done via OSPF. In		particularly useful in the environment where Segment Routing (SR) is
	addition, this document introduces the Non-IGP Functional		used, where label advertisements are done via protocols like OSPF and
	Capabilities TLV for advertising OSPF router's actual non-IGP		OSPFv3.
	functional capabilities. ELC is one of such non-IGP functional
	capabilities.
	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", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	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
	skipping to change at page 2, line 12 ¶		skipping to change at page 2, line 10 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
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	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
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	Copyright Notice		Copyright Notice
	Copyright (c) 2018 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
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	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	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. Non-OSPF Functional Capabilities TLV . . . . . . . . . . . . 3		3. Advertising ELC Using OSPF . . . . . . . . . . . . . . . . . 3
	4. Advertising ELC Using OSPF . . . . . . . . . . . . . . . . . 4		3.1. Advertising ELC Using OSPFv2 . . . . . . . . . . . . . . 4
	5. Advertising ERLD Using OSPF . . . . . . . . . . . . . . . . . 4		3.2. Advertising ELC Using OSPFv3 . . . . . . . . . . . . . . 4
	6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5		4. Advertising ERLD Using OSPF . . . . . . . . . . . . . . . . . 4
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 5		6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5		7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
	9.1. Normative References . . . . . . . . . . . . . . . . . . 5		8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
	9.2. Informative References . . . . . . . . . . . . . . . . . 6		8.1. Normative References . . . . . . . . . . . . . . . . . . 5
			8.2. Informative References . . . . . . . . . . . . . . . . . 6
	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). [RFC6790]		Switching (MPLS) traffic flows using Entropy Labels (EL). It also
	introduces the concept of Entropy Label Capability (ELC) and defines		introduces the concept of Entropy Label Capability (ELC) and defines
	the signalings of this capability via MPLS signaling protocols.		the signalings of this capability via MPLS signaling protocols.
	Recently, mechanisms are being defined to signal labels via link-		Recently, mechanisms are being defined to signal labels via link-
	state Interior Gateway Protocols (IGP) such as OSPF		state Interior Gateway Protocols (IGP) such as OSPF
	[I-D.ietf-ospf-segment-routing-extensions]. In such scenario, the		[I-D.ietf-ospf-segment-routing-extensions]. In such scenario, the
	signaling mechanisms defined in [RFC6790] are inadequate. This draft		signaling mechanisms defined in [RFC6790] are inadequate. This draft
	defines a mechanism to signal the ELC [RFC6790] using OSPF. This		defines a mechanism to signal the ELC using OSPF. This mechanism is
	mechanism is useful when the label advertisement is also done via		useful when the label advertisement is also done via OSPF.
	OSPF.
	In addition, in the cases where stacked LSPs are used for whatever		In addition, in the cases where stacked LSPs are used for whatever
	reasons (e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it		reasons (e.g., SR-MPLS [I-D.ietf-spring-segment-routing-mpls]), it
	would be useful for ingress LSRs to know each intermediate LSR's		would be useful for ingress LSRs to know each intermediate LSR's
	capability of reading the maximum label stack depth and performing		capability of reading the maximum label stack depth and performing
	EL-based load-balancing. This capability, referred to as Entropy		EL-based load-balancing. This capability, referred to as Entropy
	Readable Label Depth (ERLD) as defined in		Readable Label Depth (ERLD) as defined in
	[I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to		[I-D.ietf-mpls-spring-entropy-label] may be used by ingress LSRs to
	determine whether it's necessary to insert an EL for a given LSP of		determine whether it's necessary to insert an EL for a given LSP of
	the stacked LSP tunnel in the case where there has already been at		the stacked LSP tunnel in the case where there has already been at
	least one EL in the label stack [I-D.ietf-mpls-spring-entropy-label].		least one EL in the label stack [I-D.ietf-mpls-spring-entropy-label].
	2. Terminology		2. Terminology
	This memo makes use of the terms defined in [RFC6790] and [RFC7770].		This memo makes use of the terms defined in [RFC6790] and [RFC7770].
	3. Non-OSPF Functional Capabilities TLV		3. Advertising ELC Using OSPF
	This document defines the Router Non-IGP Functional Capabilities TLV
	with TLV type code of TBD1 within the body of the OSPF Router
	Information LSA. An OSPF router advertising an OSPF RI LSA MAY
	include the Router Non-IGP Functional Capabilities TLV. If included,
	it MUST be included in the first instance of the LSA. Additionally,
	the TLV MUST reflect the advertising OSPF router's actual non-IGP
	functional capabilities in the flooding scope of the containing OSPF
	RI LSA.
	The format of the Router Non-OSPF Functional Capabilities TLV is as		Even though ELC is a property of the node, in some cases it is
	follows:		advantageous to associate and advertise the ELC with the prefix. In
			multi-area network, routers may not know the identity of the prefix
			originator in the remote area, or may not know the capabilities of
			such originator. Similarly in the multi domain network, the identity
			of the prefix originator and its capabilities may not be known to the
			ingress LSR.
	0 1 2 3		If a router has multiple line cards, the router MUST NOT announce ELC
	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		unless all of its linecards are capable of processing ELs.
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type=TBD1 | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Non-IGP Functional Capabilities |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	Figure 1: Non-OSPF Functional Capabilities TLV Format
	Type: TBD1.		If the router support ELs on all of its line cards, it SHOULD
			advertise the ELC with every local host prefix it advertises in OSPF.
	Length: Indicates the length of the value portion in octets and		When an OSPF Area Border Router (ABR) advertises the prefix to the
	will be a multiple of 4 octets dependent on the number of		connected area based on the intra-area or inter-area prefix that is
	capabilities advertised. Initially, the length will be 4,		reachable in some other area, it MUST preserve the ELC signalling for
	denoting 4 octets of Non-IGP Functional Capabilities Bits as		such prefix.
	defined in [I-D.ietf-isis-mpls-elc].
	Value: contains the Non-IGP Functional Capabilities Bits as		When an OSPF Autonomous System Boundary Router (ASBR) redistributes
	defined in [I-D.ietf-isis-mpls-elc].		the prefix from other instance of the OSPF or from some other
			protocol, it SHOULD preserve the ELC signalling for the prefix.
			Exact mechanism on how to exchange ELC between protocol instances on
			the ASBR is outside of the scope of this document and is
			implementation specific.
	The Non-IGP Functional Capabilities TLV MAY be followed by optional		3.1. Advertising ELC Using OSPFv2
	TLVs that further specify a non-OSPF functional capability. In
	contrast to the OSPF Router Functional Capabilities TLV, the non-OSPF
	functional capabilities advertised in this TLV have no impact on the
	OSPF protocol operation. The specifications for non-IGP functional
	capabilities advertised in this TLV MUST describe protocol behavior
	and address backwards compatibility.
	4. Advertising ELC Using OSPF		[RFC7684] defines the OSPFv2 Extended Prefix TLV to advertise
			additional attributes associated with the prefix. The OSPFv2
			Extended Prefix TLV includes a one octet Flags field. A new bit in
			the Flags field is used to signal the ELC for the prefix:
	One bit of the Non-IGP Functional Capability Bits for is used to		0x20 - E-Flag (ELC Flag): Set by the advertising router to
	indicate the ELC.		indicate that the prefix originator is capable of processing ELs
	Assignment of a Non-IGP Functional Capability Bit for the ELC is		3.2. Advertising ELC Using OSPFv3
	defined in [I-D.ietf-isis-mpls-elc].
	If a router has multiple line cards, the router MUST NOT announce the		[RFC5340] defines the OSPFv3 PrefixOptions that is advertised along
	ELC [RFC6790] unless all of its linecards are capable of processing		with the prefix. A new bit in the OSPFV3 PrefixOptions is used to
	ELs.		signal the ELC for the prefix:
	How to apply the ELC advertisement to the inter-area, inter-AS and		0x04 - E-Flag (ELC Flag): Set by the advertising router to
	inter-protocol scenarios is outside the scope of this document.		indicate that the prefix originator is capable of processing ELs
	5. Advertising ERLD Using OSPF		4. Advertising ERLD Using OSPF
	A new MSD-type of the Node MSD sub-TLV		A new MSD-type of the Node MSD sub-TLV
	[I-D.ietf-isis-segment-routing-msd], called ERLD is defined to		[I-D.ietf-isis-segment-routing-msd], called ERLD is defined to
	advertise the ERLD of a given router. The scope of the advertisement		advertise the ERLD of a given router. The scope of the advertisement
	depends on the application.		depends on the application.
	Assignment of a MSD-Type for ERLD is defined in		Assignment of a MSD-Type for ERLD is defined in
	[I-D.ietf-isis-mpls-elc].		[I-D.ietf-isis-mpls-elc].
	If a router has multiple linecards with different capabilities of		If a router has multiple linecards with different capabilities of
	reading the maximum label stack deepth, the router MUST advertise the		reading the maximum label stack deepth, the router MUST advertise the
	smallest one.		smallest one.
	6. 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		Lindem, Les Ginsberg, Ketan Talaulikar, Jeff Tantsura , Bruno
	Decraene and Carlos Pignataro for their valuable comments.		Decraene and Carlos Pignataro for their valuable comments.
	7. IANA Considerations		6. IANA Considerations
	This document requests IANA to allocate one TLV type from the OSPF RI		This document requests IANA to allocate one bit from the OSPFv2
	TLVs registry for the Non-IGP Functional CapabilitiesTLV.		Extended Prefix TLV Flags registry:
	8. Security Considerations		0x20 - E-Flag (ELC Flag)
			This document requests IANA to allocate one bit from the OSPFv3
			Prefix Options registry:
			0x04 - E-Flag (ELC Flag)
			7. Security Considerations
	The security considerations as described in [RFC7770] is applicable		The security considerations as described in [RFC7770] is applicable
	to this document. This document does not introduce any new security		to this document. This document does not introduce any new security
	risk.		risk.
	9. References		8. References
	9.1. Normative References		8.1. Normative References
	[I-D.ietf-isis-mpls-elc]		[I-D.ietf-isis-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 Depth Using IS-IS", draft-ietf-isis-mpls-		Readable Label Depth Using IS-IS", draft-ietf-isis-mpls-
	elc-05 (work in progress), July 2018.		elc-06 (work in progress), September 2018.
	[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-16 (work in progress),		ietf-isis-segment-routing-msd-19 (work in progress),
	September 2018.		October 2018.
	[I-D.ietf-ospf-segment-routing-extensions]		[I-D.ietf-ospf-segment-routing-extensions]
	Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,		Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
	Shakir, R., Henderickx, W., and J. Tantsura, "OSPF		Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
	Extensions for Segment Routing", draft-ietf-ospf-segment-		Extensions for Segment Routing", draft-ietf-ospf-segment-
	routing-extensions-25 (work in progress), April 2018.		routing-extensions-27 (work in progress), December 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
	data plane", draft-ietf-spring-segment-routing-mpls-14		data plane", draft-ietf-spring-segment-routing-mpls-22
	(work in progress), June 2018.		(work in progress), May 2019.
	[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>.
	[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic		[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
	Engineering", RFC 5305, DOI 10.17487/RFC5305, October		Engineering", RFC 5305, DOI 10.17487/RFC5305, October
	2008, <https://www.rfc-editor.org/info/rfc5305>.		2008, <https://www.rfc-editor.org/info/rfc5305>.
			[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
			for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
			<https://www.rfc-editor.org/info/rfc5340>.
	[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>.
			[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
			Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
			Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
			2015, <https://www.rfc-editor.org/info/rfc7684>.
	[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and		[RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
	S. Shaffer, "Extensions to OSPF for Advertising Optional		S. Shaffer, "Extensions to OSPF for Advertising Optional
	Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,		Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
	February 2016, <https://www.rfc-editor.org/info/rfc7770>.		February 2016, <https://www.rfc-editor.org/info/rfc7770>.
	9.2. Informative References		8.2. Informative References
	[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.
	Authors' Addresses		Authors' Addresses
	Xiaohu Xu		Xiaohu Xu
	Alibaba Inc		Alibaba Inc
	Email: xiaohu.xxh@alibaba-inc.com		Email: xiaohu.xxh@alibaba-inc.com
	Sriganesh Kini		Sriganesh Kini
	Email: sriganeshkini@gmail.com		Email: sriganeshkini@gmail.com
	Siva Sivabalan		Peter Psenak
	Cisco		Cisco
	Email: msiva@cisco.com		Email: ppsenak@cisco.com
	Clarence Filsfils		Clarence Filsfils
	Cisco		Cisco
	Email: cfilsfil@cisco.com		Email: cfilsfil@cisco.com
	Stephane Litkowski		Stephane Litkowski
	Orange		Orange
	Email: stephane.litkowski@orange.com		Email: stephane.litkowski@orange.com
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