< draft-ietf-lsvr-applicability-03.txt		draft-ietf-lsvr-applicability-04.txt >
	skipping to change at page 1, line 13 ¶		skipping to change at page 1, line 13 ¶
	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: May 5, 2020 Cisco Systems		Expires: May 5, 2020 Cisco Systems
	S. Zandi		S. Zandi
	G. Dawra		G. Dawra
	Linkedin		Linkedin
	November 2, 2019		November 2, 2019
	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-03		draft-ietf-lsvr-applicability-04
	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 2, line 26 ¶		skipping to change at page 2, line 26 ¶
	6.1. Usage of BGP-LS SPF SAFI . . . . . . . . . . . . . . . . 5		6.1. Usage of BGP-LS SPF SAFI . . . . . . . . . . . . . . . . 5
	6.1.1. Relationship to Other BGP AFI/SAFI Tuples . . . . . . 6		6.1.1. Relationship to Other BGP AFI/SAFI Tuples . . . . . . 6
	6.2. Peering Models . . . . . . . . . . . . . . . . . . . . . 6		6.2. Peering Models . . . . . . . . . . . . . . . . . . . . . 6
	6.2.1. Sparse Peering Model . . . . . . . . . . . . . . . . 6		6.2.1. Sparse Peering Model . . . . . . . . . . . . . . . . 6
	6.2.2. Bi-Connected Graph Heuristic . . . . . . . . . . . . 7		6.2.2. Bi-Connected Graph Heuristic . . . . . . . . . . . . 7
	6.3. BGP Spine/Leaf Topology Policy . . . . . . . . . . . . . 7		6.3. BGP Spine/Leaf Topology Policy . . . . . . . . . . . . . 7
	6.4. BGP Peer Discovery Requirements . . . . . . . . . . . . . 8		6.4. BGP Peer Discovery Requirements . . . . . . . . . . . . . 8
	6.5. BGP Peer Discovery . . . . . . . . . . . . . . . . . . . 9		6.5. BGP Peer Discovery . . . . . . . . . . . . . . . . . . . 9
	6.5.1. BGP Peer Discovery Alternatives . . . . . . . . . . . 9		6.5.1. BGP Peer Discovery Alternatives . . . . . . . . . . . 9
	6.5.2. Data Center Interconnect (DCI) Applicability . . . . 9		6.5.2. Data Center Interconnect (DCI) Applicability . . . . 9
	6.6. Non-Transit Node Capability . . . . . . . . . . . . . . . 10		7. Non-CLOS/FAT Tree Topology Applicability . . . . . . . . . . 10
	6.7. Non-CLOS/FAT Tree Topology Applicability . . . . . . . . 10		8. Non-Transit Node Capability . . . . . . . . . . . . . . . . . 10
	7. BGP Policy Applicability . . . . . . . . . . . . . . . . . . 10		9. BGP Policy Applicability . . . . . . . . . . . . . . . . . . 10
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10		10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 11		11. Security Considerations . . . . . . . . . . . . . . . . . . . 11
	10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11		12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
	11. References . . . . . . . . . . . . . . . . . . . . . . . . . 11		13. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
	11.1. Normative References . . . . . . . . . . . . . . . . . . 11		13.1. Normative References . . . . . . . . . . . . . . . . . . 11
	11.2. Informative References . . . . . . . . . . . . . . . . . 11		13.2. Informative References . . . . . . . . . . . . . . . . . 11
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
	1. Introduction		1. Introduction
	This document complements [I-D.ietf-lsvr-bgp-spf] by discussing the		This document complements [I-D.ietf-lsvr-bgp-spf] by discussing the
	applicability of the technology in a simple and fairly common		applicability of the technology in a simple and fairly common
	deployment scenario, which is described in Section 4.		deployment scenario, which is described in Section 4.
	After describing the deployment scenario, Section 5 will describe the		After describing the deployment scenario, Section 5 will describe the
	reasons for BGP modifications for such deployments.		reasons for BGP modifications for such deployments.
	skipping to change at page 10, line 5 ¶		skipping to change at page 10, line 5 ¶
	The BGP discovery mechanisms under consideration are		The BGP discovery mechanisms under consideration are
	[I-D.acee-idr-lldp-peer-discovery],		[I-D.acee-idr-lldp-peer-discovery],
	[I-D.xu-idr-neighbor-autodiscovery], and [I-D.ietf-lsvr-l3dl].		[I-D.xu-idr-neighbor-autodiscovery], and [I-D.ietf-lsvr-l3dl].
	6.5.2. Data Center Interconnect (DCI) Applicability		6.5.2. Data Center Interconnect (DCI) Applicability
	Since BGP SPF is to be used for the routing underlay and DCI gateway		Since BGP SPF is to be used for the routing underlay and DCI gateway
	boxes typically have direct or very simple connectivity, BGP external		boxes typically have direct or very simple connectivity, BGP external
	sessions would typically not include the BGP SPF SAFI.		sessions would typically not include the BGP SPF SAFI.
	6.6. Non-Transit Node Capability		7. Non-CLOS/FAT Tree Topology Applicability
			The BGP SPF extensions [I-D.ietf-lsvr-bgp-spf] can be used in other
			topologies and avail the inherent convergence improvements.
			Additionally, sparse peering techniques may be utilized Section 6.2.
			However, determining whether or to establish a BGP session is more
			complex and the heuristic described in Section 6.2.2 cannot be used.
			In such topologies, other techniques such as those described in
			[I-D.ietf-lsr-dynamic-flooding] may be employed. One potential
			deployment would be the underlay for a Service Provider (SP) backbone
			where usage of a single protocol, i.e., BGP, is desired.
			8. Non-Transit Node Capability
	In certain scenarios, a BGP node wishes to participate in the BGP SPF		In certain scenarios, a BGP node wishes to participate in the BGP SPF
	topology but never be used for transit traffic. These in include		topology but never be used for transit traffic. These in include
	situations where a server wants to make application services		situations where a server wants to make application services
	available to clients homed at subnets throughout the BGP SPF domain		available to clients homed at subnets throughout the BGP SPF domain
	but doesn't ever want to be used as a router (i.e., carry transit		but doesn't ever want to be used as a router (i.e., carry transit
	traffic). Another specific instance is where a controller is		traffic). Another specific instance is where a controller is
	resident on a server and direct connectivity to the controller is		resident on a server and direct connectivity to the controller is
	required throughout the entire domain. This can readily be		required throughout the entire domain. This can readily be
	accomplished using the BGP-LS Node NLRI Attribute SPF Status TLV as		accomplished using the BGP-LS Node NLRI Attribute SPF Status TLV as
	described in [I-D.ietf-lsvr-bgp-spf].		described in [I-D.ietf-lsvr-bgp-spf].
	6.7. Non-CLOS/FAT Tree Topology Applicability		9. BGP Policy Applicability
	The BGP SPF extensions [I-D.ietf-lsvr-bgp-spf] can be used in other
	topologies and avail the inherent convergence improvements.
	Additionally, sparse peering techniques may be utilized Section 6.2.
	However, determining whether or to establish a BGP session is more
	complex and the heuristic described in Section 6.2.2 cannot be used.
	In such topologies, other techniques such as those described in
	[I-D.ietf-lsr-dynamic-flooding] may be employed. One potential
	deployment would be the underlay for a Service Provider (SP) backbone
	where usage of a single protocol, i.e., BGP, is desired.
	7. BGP Policy Applicability
	Existing BGP policy including aggregation and prefix filtering may be		Existing BGP policy including aggregation and prefix filtering may be
	used in conjunction with the BGP-LS SPF SAFI. When aggregation		used in conjunction with the BGP-LS SPF SAFI. When aggregation
	policy is used, BGP-LS SPF prefix NLRI will be originated for the		policy is used, BGP-LS SPF prefix NLRI will be originated for the
	aggregate prefix and BGP-LS SPF prefix NLRI for components will be		aggregate prefix and BGP-LS SPF prefix NLRI for components will be
	filtered. Additionally, link and node NLRI may be filtered and the		filtered. Additionally, link and node NLRI may be filtered and the
	abstracted by the prefix NLRI.		abstracted by the prefix NLRI.
	When BGP policy is used with the BGP-LS SPF SAFI, BGP speakers in the		When BGP policy is used with the BGP-LS SPF SAFI, BGP speakers in the
	BGP-LS SPF routing domain will not all have the same set of NLRI and		BGP-LS SPF routing domain will not all have the same set of NLRI and
	will compute a different BGP local routing table. Consequently, care		will compute a different BGP local routing table. Consequently, care
	must be taken to assure routing is consistent and blackholes or		must be taken to assure routing is consistent and blackholes or
	routing loops do not ensue. However, this is no different than if		routing loops do not ensue. However, this is no different than if
	tradition BGP routing using the IPv4 and IPv6 address families were		tradition BGP routing using the IPv4 and IPv6 address families were
	used.		used.
	8. IANA Considerations		10. IANA Considerations
	No IANA updates are requested by this document.		No IANA updates are requested by this document.
	9. Security Considerations		11. Security Considerations
	This document introduces no new security considerations above and		This document introduces no new security considerations above and
	beyond those already specified in the [RFC4271] and		beyond those already specified in the [RFC4271] and
	[I-D.ietf-lsvr-bgp-spf].		[I-D.ietf-lsvr-bgp-spf].
	10. Acknowledgements		12. Acknowledgements
	The authors would like to thank Alvaro Retana and Yan Filyurin for		The authors would like to thank Alvaro Retana and Yan Filyurin for
	the review and comments.		the review and comments.
	11. References		13. References
	11.1. 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-06 (work in progress), September		draft-ietf-lsvr-bgp-spf-06 (work in progress), September
	2019.		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>.
	[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>.
	11.2. Informative References		13.2. Informative References
	[CLOS] "A Study of Non-Blocking Switching Networks", The Bell		[CLOS] "A Study of Non-Blocking Switching Networks", The Bell
	System Technical Journal, Vol. 32(2), DOI		System Technical Journal, Vol. 32(2), DOI
	10.1002/j.1538-7305.1953.tb01433.x, March 1953.		10.1002/j.1538-7305.1953.tb01433.x, March 1953.
	[I-D.acee-idr-lldp-peer-discovery]		[I-D.acee-idr-lldp-peer-discovery]
	Lindem, A., Patel, K., Zandi, S., Haas, J., and X. Xu,		Lindem, A., Patel, K., Zandi, S., Haas, J., and X. Xu,
	"BGP Logical Link Discovery Protocol (LLDP) Peer		"BGP Logical Link Discovery Protocol (LLDP) Peer
	Discovery", draft-acee-idr-lldp-peer-discovery-05 (work in		Discovery", draft-acee-idr-lldp-peer-discovery-05 (work in
	progress), July 2019.		progress), July 2019.
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