< draft-xu-lsr-ospf-flooding-reduction-in-msdc-01.txt		draft-xu-lsr-ospf-flooding-reduction-in-msdc-02.txt >
	Network Working Group X. Xu		Network Working Group X. Xu
	Internet-Draft Alibaba Inc		Internet-Draft Alibaba, Inc
	Intended status: Standards Track L. Fang		Intended status: Standards Track L. Fang
	Expires: April 21, 2019 Expedia, Inc		Expires: October 24, 2019 Expedia, Inc
	J. Tantsura		J. Tantsura
	Apstra, Inc.		Apstra, Inc.
	S. Ma		S. Ma
	Juniper		Juniper
	October 18, 2018		April 22, 2019
	OSPF Flooding Reduction in MSDC		OSPF Flooding Reduction in MSDC
	draft-xu-lsr-ospf-flooding-reduction-in-msdc-01		draft-xu-lsr-ospf-flooding-reduction-in-msdc-02
	Abstract		Abstract
	OSPF is commonly used as an underlay routing protocol for MSDC		OSPF is commonly used as an underlay routing protocol for MSDC
	(Massively Scalable Data Center) networks. For a given OSPF router		(Massively Scalable Data Center) networks. For a given OSPF router
	within the CLOS topology, it would receive multiple copies of exactly		within the CLOS topology, it would receive multiple copies of exactly
	the same LSA from multiple OSPF neighbors. In addition, two OSPF		the same LSA from multiple OSPF neighbors. In addition, two OSPF
	neighbors may send each other the same LSA simultaneously. The		neighbors may send each other the same LSA simultaneously. The
	unneccessary link-state information flooding wastes the precious		unnecessary link-state information flooding wastes the precious
	process resource of OSPF routers greatly due to the fact that there		process resource of OSPF routers greatly due to the fact that there
	are too many OSPF neighbors for each OSPF router within the CLOS		are too many OSPF neighbors for each OSPF router within the CLOS
	topology. This document proposes some extensions to OSPF so as to		topology. This document proposes some extensions to OSPF so as to
	reduce the OSPF flooding within MSDC networks greatly. The reduction		reduce the OSPF flooding within MSDC networks greatly. The reduction
	of the OSPF flooding is much beneficial to improve the scalability of		of the OSPF flooding is much beneficial to improve the scalability of
	MSDC networks. These modifications are applicable to both OSPFv2 and		MSDC networks. These modifications are applicable to both OSPFv2 and
	OSPFv3.		OSPFv3.
	Requirements Language		Requirements Language
	skipping to change at page 2, line 7 ¶		skipping to change at page 2, line 7 ¶
	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
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	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 April 21, 2019.		This Internet-Draft will expire on October 24, 2019.
	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
	publication of this document. Please review these documents		publication of this document. Please review these documents
	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
	skipping to change at page 2, line 43 ¶		skipping to change at page 2, line 43 ¶
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 6		6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
	7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6		7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
	7.1. Normative References . . . . . . . . . . . . . . . . . . 6		7.1. Normative References . . . . . . . . . . . . . . . . . . 6
	7.2. Informative References . . . . . . . . . . . . . . . . . 6		7.2. Informative References . . . . . . . . . . . . . . . . . 6
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
	1. Introduction		1. Introduction
	OSPF is commonly used as an underlay routing protocol for Massively		OSPF is commonly used as an underlay routing protocol for Massively
	Scalable Data Center (MSDC) networks where CLOS is the most popular		Scalable Data Center (MSDC) networks where CLOS is the most popular
	toplogy. For a given OSPF router within the CLOS topology, it would		topology. For a given OSPF router within the CLOS topology, it would
	receive multiple copies of exactly the same LSA from multiple OSPF		receive multiple copies of exactly the same LSA from multiple OSPF
	neighbors. In addition, two OSPF neighbors may send each other the		neighbors. In addition, two OSPF neighbors may send each other the
	same LSA simultaneously. The unnecessary link-state information		same LSA simultaneously. The unnecessary link-state information
	flooding wastes the precious process resource of OSPF routers greatly		flooding wastes the precious process resource of OSPF routers greatly
	and therefore OSPF could not scale very well in MSDC networks.		and therefore OSPF could not scale very well in MSDC networks.
	To simplify the network management task, centralized controllers are		To simplify the network management task, centralized controllers are
	becoming fundamental network elements in most MSDCs. One or more		becoming fundamental network elements in most MSDCs. One or more
	controllers are usually connected to all routers within the MSDC		controllers are usually connected to all routers within the MSDC
	network via a Local Area Network (LAN) which is dedicated for network		network via a Local Area Network (LAN) which is dedicated for network
	skipping to change at page 4, line 9 ¶		skipping to change at page 4, line 9 ¶
	bidirectional communication between OSPF neighbors, and even the DR/		bidirectional communication between OSPF neighbors, and even the DR/
	BDR election purpose in the case where those OSPF routers are		BDR election purpose in the case where those OSPF routers are
	connected to a broadcast network. In order to obtain the full		connected to a broadcast network. In order to obtain the full
	topology information (i.e., the fully synchronized link-state		topology information (i.e., the fully synchronized link-state
	database) of the MSDC's network, these OSPF routers just need to		database) of the MSDC's network, these OSPF routers just need to
	exchange the link-state information with the controllers being		exchange the link-state information with the controllers being
	elected as OSPF DR/BDR for the management LAN instead.		elected as OSPF DR/BDR for the management LAN instead.
	To further suppress the flooding of multicast OSPF packets originated		To further suppress the flooding of multicast OSPF packets originated
	from OSPF routers over the management LAN, OSPF routers would not		from OSPF routers over the management LAN, OSPF routers would not
	send multicast OSPF Hello packets over the management LAN. Insteads,		send multicast OSPF Hello packets over the management LAN. Instead,
	they just wait for OSPF Hello packets originated from the controllers		they just wait for OSPF Hello packets originated from the controllers
	being elected as OSPF DR/BDR initially. Once OSPF DR/BDR for the		being elected as OSPF DR/BDR initially. Once OSPF DR/BDR for the
	management LAN have been discovered, they start to send OSPF Hello		management LAN have been discovered, they start to send OSPF Hello
	packets directly (as unicasts) to OSPF DR/BDR periodically. In		packets directly (as unicasts) to OSPF DR/BDR periodically. In
	addition, OSPF routers would send other types of OSPF packets (e.g.,		addition, OSPF routers would send other types of OSPF packets (e.g.,
	Database Descriptor packet, Link State Request packet, Link State		Database Descriptor packet, Link State Request packet, Link State
	Update packet, Link State Acknowledgment packet) to OSPF DR/BDR for		Update packet, Link State Acknowledgment packet) to OSPF DR/BDR for
	the management LAN as unicasts as well. In contrast, the controllers		the management LAN as unicasts as well. In contrast, the controllers
	being elected as OSPF DR/BDR would send OSPF packets as specified in		being elected as OSPF DR/BDR would send OSPF packets as specified in
	[RFC2328]. As a result, OSPF routers would not receive OSPF packets		[RFC2328]. As a result, OSPF routers would not receive OSPF packets
	skipping to change at page 6, line 35 ¶		skipping to change at page 6, line 35 ¶
	7.2. Informative References		7.2. Informative References
	[RFC4136] Pillay-Esnault, P., "OSPF Refresh and Flooding Reduction		[RFC4136] Pillay-Esnault, P., "OSPF Refresh and Flooding Reduction
	in Stable Topologies", RFC 4136, DOI 10.17487/RFC4136,		in Stable Topologies", RFC 4136, DOI 10.17487/RFC4136,
	July 2005, <https://www.rfc-editor.org/info/rfc4136>.		July 2005, <https://www.rfc-editor.org/info/rfc4136>.
	Authors' Addresses		Authors' Addresses
	Xiaohu Xu		Xiaohu Xu
	Alibaba Inc		Alibaba, Inc
	Email: xiaohu.xxh@alibaba-inc.com		Email: xiaohu.xxh@alibaba-inc.com
	Luyuan Fang		Luyuan Fang
	Expedia, Inc		Expedia, Inc
	Email: luyuanf@gmail.com		Email: luyuanf@gmail.com
	Jeff Tantsura		Jeff Tantsura
	Apstra, Inc.		Apstra, Inc.
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