draft-ietf-idr-bgp-ls-segment-routing-rld-01.txt		draft-ietf-idr-bgp-ls-segment-routing-rld-02.txt
	IDR Working Group G. Van de Velde, Ed.		IDR Working Group G. Van de Velde, Ed.
	Internet-Draft W. Henderickx		Internet-Draft W. Henderickx
	Intended status: Standards Track M. Bocci		Intended status: Standards Track M. Bocci
	Expires: June 21, 2018 Nokia		Expires: December 14, 2018 Nokia
	K. Patel		K. Patel
	Arrcus		Arrcus
	December 18, 2017		June 12, 2018
	Signalling ERLD using BGP-LS		Signalling ERLD using BGP-LS
	draft-ietf-idr-bgp-ls-segment-routing-rld-01		draft-ietf-idr-bgp-ls-segment-routing-rld-02
	Abstract		Abstract
	This document defines the attributes to use for BGP-LS to expose ERLD		This document defines the attribute encoding to use for BGP-LS to
	"Entropy capable Readable Label Depth" from a node or link to a		expose ERLD "Entropy capable Readable Label Depth" from a node to a
	centralised controller (PCE/SDN).		centralised controller (PCE/SDN).
	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 [1].		document are to be interpreted as described in RFC 2119 [1].
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 41 ¶		skipping to change at page 1, line 41 ¶
	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-
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	This Internet-Draft will expire on June 21, 2018.		This Internet-Draft will expire on December 14, 2018.
	Copyright Notice		Copyright Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2018 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
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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. Conventions used in this document . . . . . . . . . . . . . . 3		2. Conventions used in this document . . . . . . . . . . . . . . 3
	2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3		2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
	3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3		3. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
	4. ERLD support by a node . . . . . . . . . . . . . . . . . . . 3		4. Origination of ERLD in BGP-LS . . . . . . . . . . . . . . . . 3
	5. ERLD support by a link . . . . . . . . . . . . . . . . . . . 4		5. ERLD support by a node . . . . . . . . . . . . . . . . . . . 4
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 5		6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
	7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
	9.1. Normative References . . . . . . . . . . . . . . . . . . 5		9.1. Normative References . . . . . . . . . . . . . . . . . . 5
	9.2. Informative References . . . . . . . . . . . . . . . . . 5		9.2. Informative References . . . . . . . . . . . . . . . . . 5
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
	1. Introduction		1. Introduction
	When Segment Routing tunnels are computed by a centralised		When Segment Routing tunnels are computed by a centralised
	controller, it is beneficial that the controller knows the ERLD		controller, it is beneficial that the controller knows the ERLD
	(Entropy capable Readable Label Depth) of each node or link a tunnel		(Entropy capable Readable Label Depth) of each node or link a tunnel
	traverses. A network node signalling an ERLD MUST support the		traverses. A network node signalling an ERLD MUST support the
	ability to read the signalled number of labels before any action is		ability to read the signalled number of labels before any action is
	done upon the packet and SHOULD support entropy awareness found		done upon the packet and SHOULD support entropy awareness found
	within the signalled ERLD depth.		within the signalled ERLD depth.
	ERLD awareness of each node and link will allow a network SDN		ERLD awareness of each node will allow a network SDN controller to
	controller to influence the path used for each tunnel. The SDN		influence the path used for each tunnel. The SDN controller may for
	controller may for example only create tunnels with a label stack		example only create tunnels with a label stack smaller or equal as
	smaller or equal as the ERLD of each node and link on the path. This		the ERLD of each node on the path. This will allow the network to
	will allow the network to behave accordingly (e.g. make use of		behave accordingly (e.g. make use of Entropy Labels to improve ECMP)
	Entropy Labels to improve ECMP) upon the imposed Segment Routing		upon the imposed Segment Routing label stack on each packet.
	label stack on each packet.
	This document describes how to use BGP-LS to expose the ERLD of a		This document describes how to use BGP-LS to expose the ERLD of a
	node.		node.
	2. Conventions used in this document		2. Conventions used in this document
	2.1. Terminology		2.1. Terminology
	BGP-LS: Distribution of Link-State and TE Information using Border		BGP-LS: Distribution of Link-State and TE Information using Border
	Gateway Protocol		Gateway Protocol
	skipping to change at page 3, line 28 ¶		skipping to change at page 3, line 28 ¶
	PCEP: Path Computation Element Protocol		PCEP: Path Computation Element Protocol
	SID: Segment Identifier		SID: Segment Identifier
	SR: Segment routing		SR: Segment routing
	3. Problem Statement		3. Problem Statement
	In existing technology both ISIS [4] and OSPF [3] have proposed		In existing technology both ISIS [4] and OSPF [3] have proposed
	extensions to signal the RLD (Readable Label Depth) and ELC (Entropy		extensions to signal the RLD (Readable Label Depth) and ELC (Entropy
	Label Capability) of a node or link. However, if a network SDN		Label Capability) of a node. However, if a network SDN controller is
	controller is connected to the network through a BGP-LS session and		connected to the network through a BGP-LS session and not through
	not through ISIS or OSPF technology, then both RLD and ELC needs to		ISIS or OSPF technology, then both RLD and ELC needs to be signalled
	be signaled in BGP-LS accordingly. This document describes the		using BGP-LS encoding. This document describes the extension BGP-LS
	extension BGP-LS requires to transport the combination of RLD and ELC		requires to transport the combined RLD and ELC into an ERLD (Entropy
	into according ERLD attributes for nodes and links.		capable Readable Label Depth) attribute.
	A network SDN controller having awareness of the ERLD Entropy capable		A network SDN controller having awareness of the ERLD can for example
	Readable Label Depth can for example use it as a constraint on path		use it as a constraint on path computation to make sure that high
	computation so that it can make sure that high bandwidth LSPs are not		bandwidth LSPs are not placed on LAG (Link Aggregation Group),
	placed on LAG (Link Aggregation Group) links with smaller member		containing links with smaller member bandwidth, if they know the
	bandwidths if they know the Entropy Label cannot be processed by the		Entropy Label cannot be processed by the node at the ingress to the
	node at the ingress to the link.		link.
	4. ERLD support by a node		4. Origination of ERLD in BGP-LS
			Both ISIS [4] and OSPF [3] have proposed extensions to signal the RLD
			(Readable Label Depth) and ELC (Entropy Label Capability) for a node.
			A BGP-LS router exporting the IGP LSDB, MUST NOT encode the IGP RLD
			value in an BGP-LS ERLD attribute, if the associated node ELC is not
			signalled.
			5. ERLD support by a node
	Node ERLD is encoded in a new Node Attribute TLV, as defined in		Node ERLD is encoded in a new Node Attribute TLV, as defined in
	RFC7752 [2].		RFC7752 [2].
	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 |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| ERLD |		| ERLD |
	skipping to change at page 4, line 26 ¶		skipping to change at page 4, line 31 ¶
	Code-point: TBA from BGP-LS Node Descriptor, Link Descriptor,		Code-point: TBA from BGP-LS Node Descriptor, Link Descriptor,
	Prefix Descriptor, and Attribute TLVs registry		Prefix Descriptor, and Attribute TLVs registry
	Length: A 2-octet field that indicates the length of the value		Length: A 2-octet field that indicates the length of the value
	portion		portion
	ERLD: Node ERLD is a number in the range of 0-254. The value of 0		ERLD: Node ERLD is a number in the range of 0-254. The value of 0
	represents lack of ability to read a label stack of any depth, any		represents lack of ability to read a label stack of any depth, any
	other value represents the readable label depth of the node.		other value represents the readable label depth of the node.
	5. ERLD support by a link
	Link ERLD is encoded in a new Link Attribute TLV, as defined in
	RFC7752 [2].
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| ERLD |
	+-+-+-+-+-+-+-+-+
	Figure 2
	Type : A 2-octet field specifying code-point of the new TLV type.
	Code-point: TBA from BGP-LS Node Descriptor, Link Descriptor,
	Prefix Descriptor, and Attribute TLVs registry
	Length: A 2-octet field that indicates the length of the value
	portion
	ERLD: Link ERLD is a number in the range of 0-254. The value of 0
	represents lack of ability to read a label stack of any depth, any
	other value represents the readable label depth of the link.
	6. Security Considerations		6. Security Considerations
	This document does not introduce security issues beyond those		This document does not introduce security issues beyond those
	discussed in RFC7752 [2]		discussed in RFC7752 [2]
	7. Acknowledgements		7. Acknowledgements
	Thanks to discussions with Acee Lindem, Jeff Tantsura, Stephane		Thanks to discussions with Acee Lindem, Jeff Tantsura, Stephane
	Litkowski, Bruno Decraene, Kireeti Kompella, John E. Drake and		Litkowski, Bruno Decraene, Kireeti Kompella, John E. Drake and
	Carlos Pignataro to bring the concept of combining ELC and RLD into a		Carlos Pignataro to bring the concept of combining ELC and RLD into a
	single ERLD signalled parameter more suitable for SDN controller		single ERLD signalled parameter more suitable for SDN controller
	based networks.		based networks.
	8. IANA Considerations		8. IANA Considerations
	This document requests assigning 2 new code-points from the BGP-LS		This document requests assigning a new code-points from the BGP-LS
	Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute		Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
	TLVs registry as specified in sections 4 and 5.		TLVs registry as specified in section 5.
			Note: placeholder IANA request
			Request Node ERLD codepoint
			BGP-LS TLV Code Point: TBD1
			ISIS TLV 242/TBD2
			Note: There is nothing in IANA from draft draft-ietf-isis-mpls-elc
			Note: Draft talks only about ELC/RLD and that is mismatch with ERLD
			OSPF RI TLV TBD5
			OSPF ELC in Non-OSPF functionality Capability Bits (TBD6)
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[1] Bradner, S., "Key words for use in RFCs to Indicate		[1] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997,		Requirement Levels", BCP 14, RFC 2119, March 1997,
	<http://xml.resource.org/public/rfc/html/rfc2119.html>.		<http://xml.resource.org/public/rfc/html/rfc2119.html>.
	[2] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and		[2] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
	S. Ray, "North-Bound Distribution of Link-State and		S. Ray, "North-Bound Distribution of Link-State and
	Traffic Engineering (TE) Information Using BGP", RFC 7752,		Traffic Engineering (TE) Information Using BGP", RFC 7752,
	DOI 10.17487/RFC7752, March 2016,		DOI 10.17487/RFC7752, March 2016,
	<https://www.rfc-editor.org/info/rfc7752>.		<https://www.rfc-editor.org/info/rfc7752>.
	9.2. Informative References		9.2. Informative References
	[3] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.		[3] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
	Litkowski, "draft-ietf-ospf-mpls-elc", October 2016.		Litkowski, "draft-ietf-ospf-mpls-elc", January 2018.
	[4] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.		[4] Xu, X., Kini, S., Sivabalan, S., Filsfils, C., and S.
	Litkowski, "draft-ietf-isis-mpls-elc", October 2016.		Litkowski, "draft-ietf-isis-mpls-elc", January 2018.
	Authors' Addresses		Authors' Addresses
	Gunter Van de Velde (editor)		Gunter Van de Velde (editor)
	Nokia		Nokia
	Antwerp		Antwerp
	BE		BE
	Email: gunter.van_de_velde@nokia.com		Email: gunter.van_de_velde@nokia.com
	Wim Henderickx		Wim Henderickx
	Nokia		Nokia
	Belgium		Belgium
	Email: wim.henderickx@nokia.com		Email: wim.henderickx@nokia.com
	Matthew Bocci		Matthew Bocci
	Nokia		Nokia
	Shoppenhangers Road		Shoppenhangers Road
	Maidenhead, Berks		Maidenhead, Berks
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