< draft-ietf-lsvr-applicability-06.txt		draft-ietf-lsvr-applicability-07.txt >
	LSVR K. Patel		LSVR K. Patel
	Internet-Draft Arrcus, Inc.		Internet-Draft Arrcus, Inc.
	Intended status: Informational A. Lindem		Intended status: Informational A. Lindem
	Expires: January 27, 2021 Cisco Systems		Expires: March 25, 2021 Cisco Systems
	S. Zandi		S. Zandi
	G. Dawra		G. Dawra
	Linkedin		Linkedin
	July 26, 2020		September 21, 2020
	Usage and Applicability of Link State Vector Routing in Data Centers		Usage and Applicability of Link State Vector Routing in Data Centers
	draft-ietf-lsvr-applicability-06		draft-ietf-lsvr-applicability-07
	Abstract		Abstract
	This document discusses the usage and applicability of Link State		This document discusses the usage and applicability of Link State
	Vector Routing (LSVR) extensions in data center networks utilizing		Vector Routing (LSVR) extensions in data center networks utilizing
	CLOS or Fat-Tree topologies. The document is intended to provide a		CLOS or Fat-Tree topologies. The document is intended to provide a
	simplified guide for the deployment of LSVR extensions.		simplified guide for the deployment of LSVR extensions.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 37 ¶		skipping to change at page 1, line 37 ¶
	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 January 27, 2021.		This Internet-Draft will expire on March 25, 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2020 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 6, line 40 ¶		skipping to change at page 6, line 40 ¶
	6.2.1. Sparse Peering Model		6.2.1. Sparse Peering Model
	Alternately, BFD [RFC5580] can be used to swiftly determine the		Alternately, BFD [RFC5580] can be used to swiftly determine the
	availability of links and the BGP peering model can be significantly		availability of links and the BGP peering model can be significantly
	sparser than the data center fabric. BGP SPF sessions only need to		sparser than the data center fabric. BGP SPF sessions only need to
	be established with enough peers to provide a bi-connected graph. If		be established with enough peers to provide a bi-connected graph. If
	IEBGP is used, then the BGP routers at tier N-1 will act as route-		IEBGP is used, then the BGP routers at tier N-1 will act as route-
	reflectors for the routers at tier N.		reflectors for the routers at tier N.
	The obvious usage of sparse peering is to avoid parallel sessions on		The obvious usage of sparse peering is to avoid parallel BGP sessions
	links between the same two BGP speakers in the data center fabric.		on links between the same two switches in the data center fabric.
	However, this use case is not very useful since parallel layer-3		However, this use case is not very useful since parallel layer-3
	links between the same two BGP routers are rare in CLOS or Fat-Tree		links between the same two BGP routers are rare in CLOS or Fat-Tree
	topologies. Two more interesting scenarios are described below.		topologies. Additionally, when there are multiple links, they are
			often aggregated at the link layer rather than the IP layer. Two
			more interesting scenarios are described below.
	In current data center topologies, there is often a very dense mesh		In current data center topologies, there is often a very dense mesh
	of links between levels, e.g., leaf and spine, providing 32-way,		of links between levels, e.g., leaf and spine, providing 32-way,
	64-way, or more Equal-Cost Multi-Path (ECMP) paths. In these		64-way, or more Equal-Cost Multi-Path (ECMP) paths. In these
	topologies, it is desirable not to have a BGP session on every link		topologies, it is desirable not to have a BGP session on every link
	and techniques such as the one described in Section 6.2.2 can be used		and techniques such as the one described in Section 6.2.2 can be used
	establish sessions on some subset of northbound links. For example,		establish sessions on some subset of northbound links. For example,
	in a Spine-Leaf topology, each leaf switch would only peer with a		in a Spine-Leaf topology, each leaf switch would only peer with a
	subset of the spines dependent on the flooding redundancy required to		subset of the spines dependent on the flooding redundancy required to
	be reasonably certain that every node within the BGP-LS SPF routing		be reasonably certain that every node within the BGP-LS SPF routing
	skipping to change at page 11, line 46 ¶		skipping to change at page 11, line 46 ¶
	The authors would like to thank Alvaro Retana, Yan Filyurin, and		The authors would like to thank Alvaro Retana, Yan Filyurin, and
	Boris Hassanov for their review and comments.		Boris Hassanov for their review and comments.
	13. References		13. References
	13.1. Normative References		13.1. Normative References
	[I-D.ietf-lsvr-bgp-spf]		[I-D.ietf-lsvr-bgp-spf]
	Patel, K., Lindem, A., Zandi, S., and W. Henderickx,		Patel, K., Lindem, A., Zandi, S., and W. Henderickx,
	"Shortest Path Routing Extensions for BGP Protocol",		"Shortest Path Routing Extensions for BGP Protocol",
	draft-ietf-lsvr-bgp-spf-09 (work in progress), May 2020.		draft-ietf-lsvr-bgp-spf-11 (work in progress), August
			2020.
	[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>.
	[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>.
	skipping to change at page 12, line 35 ¶		skipping to change at page 12, line 40 ¶
	(work in progress), June 2019.		(work in progress), June 2019.
	[I-D.ietf-lsr-dynamic-flooding]		[I-D.ietf-lsr-dynamic-flooding]
	Li, T., Psenak, P., Ginsberg, L., Chen, H., Przygienda,		Li, T., Psenak, P., Ginsberg, L., Chen, H., Przygienda,
	T., Cooper, D., Jalil, L., Dontula, S., and G. Mishra,		T., Cooper, D., Jalil, L., Dontula, S., and G. Mishra,
	"Dynamic Flooding on Dense Graphs", draft-ietf-lsr-		"Dynamic Flooding on Dense Graphs", draft-ietf-lsr-
	dynamic-flooding-07 (work in progress), June 2020.		dynamic-flooding-07 (work in progress), June 2020.
	[I-D.ietf-lsvr-l3dl]		[I-D.ietf-lsvr-l3dl]
	Bush, R., Austein, R., and K. Patel, "Layer 3 Discovery		Bush, R., Austein, R., and K. Patel, "Layer 3 Discovery
	and Liveness", draft-ietf-lsvr-l3dl-05 (work in progress),		and Liveness", draft-ietf-lsvr-l3dl-06 (work in progress),
	May 2020.		July 2020.
	[I-D.xu-idr-neighbor-autodiscovery]		[I-D.xu-idr-neighbor-autodiscovery]
	Xu, X., Talaulikar, K., Bi, K., Tantsura, J., and N.		Xu, X., Talaulikar, K., Bi, K., Tantsura, J., and N.
	Triantafillis, "BGP Neighbor Discovery", draft-xu-idr-		Triantafillis, "BGP Neighbor Discovery", draft-xu-idr-
	neighbor-autodiscovery-12 (work in progress), November		neighbor-autodiscovery-12 (work in progress), November
	2019.		2019.
	[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,		[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
	DOI 10.17487/RFC2328, April 1998,		DOI 10.17487/RFC2328, April 1998,
	<https://www.rfc-editor.org/info/rfc2328>.		<https://www.rfc-editor.org/info/rfc2328>.
End of changes. 8 change blocks.
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