< draft-xu-lsr-isis-flooding-reduction-in-msdc-01.txt		draft-xu-lsr-isis-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
	IS-IS Flooding Reduction in MSDC		IS-IS Flooding Reduction in MSDC
	draft-xu-lsr-isis-flooding-reduction-in-msdc-01		draft-xu-lsr-isis-flooding-reduction-in-msdc-02
	Abstract		Abstract
	IS-IS is commonly used as an underlay routing protocol for MSDC		IS-IS is commonly used as an underlay routing protocol for MSDC
	(Massively Scalable Data Center) networks. For a given IS-IS router		(Massively Scalable Data Center) networks. For a given IS-IS 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 LSP from multiple IS-IS neighbors. In addition, two IS-IS		the same LSP from multiple IS-IS neighbors. In addition, two IS-IS
	neighbors may send each other the same LSP simultaneously. The		neighbors may send each other the same LSP simultaneously. The
	unneccessary link-state information flooding wastes the precious		unnecessary link-state information flooding wastes the precious
	process resource of IS-IS routers greatly due to the fact that there		process resource of IS-IS routers greatly due to the fact that there
	are too many IS-IS neighbors for each IS-IS router within the CLOS		are too many IS-IS neighbors for each IS-IS router within the CLOS
	topology. This document proposes some extensions to IS-IS so as to		topology. This document proposes some extensions to IS-IS so as to
	reduce the IS-IS flooding within MSDC networks greatly. The		reduce the IS-IS flooding within MSDC networks greatly. The
	reduction of the IS-IS flooding is much beneficial to improve the		reduction of the IS-IS flooding is much beneficial to improve the
	scalability of MSDC networks.		scalability of MSDC networks.
	Requirements Language		Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	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
	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 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
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	skipping to change at page 2, line 43 ¶		skipping to change at page 2, line 43 ¶
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 5		6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
	7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5		7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
	7.1. Normative References . . . . . . . . . . . . . . . . . . 5		7.1. Normative References . . . . . . . . . . . . . . . . . . 5
	7.2. Informative References . . . . . . . . . . . . . . . . . 6		7.2. Informative References . . . . . . . . . . . . . . . . . 6
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
	1. Introduction		1. Introduction
	IS-IS is commonly used as an underlay routing protocol for Massively		IS-IS 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 IS-IS router within the CLOS topology, it would		topology. For a given IS-IS router within the CLOS topology, it would
	receive multiple copies of exactly the same LSP from multiple IS-IS		receive multiple copies of exactly the same LSP from multiple IS-IS
	neighbors. In addition, two IS-IS neighbors may send each other the		neighbors. In addition, two IS-IS neighbors may send each other the
	same LSP simultaneously. The unnecessary link-state information		same LSP simultaneously. The unnecessary link-state information
	flooding wastes the precious process resource of IS-IS routers		flooding wastes the precious process resource of IS-IS routers
	greatly and therefore IS-IS could not scale very well in MSDC		greatly and therefore IS-IS could not scale very well in MSDC
	networks.		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
	skipping to change at page 3, line 45 ¶		skipping to change at page 3, line 45 ¶
	| / // \ | / -- \ |		| / // \ | / -- \ |
	| / // \ | / -- \ |		| / // \ | / -- \ |
	+-+- //* +\\+-/-+ +---\-++		+-+- //* +\\+-/-+ +---\-++
	|Router| |Router| |Router|		|Router| |Router| |Router|
	+------+ +------+ +------+		+------+ +------+ +------+
	Figure 1		Figure 1
	With the assistance of a controller acting as IS-IS Designated		With the assistance of a controller acting as IS-IS Designated
	Intermediate System (DIS) for the management LAN, IS-IS routers		Intermediate System (DIS) for the management LAN, IS-IS routers
	within the MSDC network don't need to exchange any IS-IS Protocl		within the MSDC network don't need to exchange any IS-IS Protocol
	Datagram Units (PDUs) other than Hello packets among them. In order		Datagram Units (PDUs) other than Hello packets among them. In order
	to obtain the full topology information (i.e., the fully synchronized		to obtain the full topology information (i.e., the fully synchronized
	link-state database) of the MSDC's network, these IS-IS routers would		link-state database) of the MSDC's network, these IS-IS routers would
	exchange the link-state information with the controller being elected		exchange the link-state information with the controller being elected
	as IS-IS DIS for the management LAN instead.		as IS-IS DIS for the management LAN instead.
	To further suppress the flooding of multicast IS-IS PDUs originated		To further suppress the flooding of multicast IS-IS PDUs originated
	from IS-IS routers over the management LAN, IS-IS routers would not		from IS-IS routers over the management LAN, IS-IS routers would not
	send multicast IS-IS Hello packets over the management LAN.		send multicast IS-IS Hello packets over the management LAN.
	Insteads, they just wait for IS-IS Hello packets originated from the		Instead, they just wait for IS-IS Hello packets originated from the
	controller being elected as IS-IS DIS initially. Once an IS-IS DIS		controller being elected as IS-IS DIS initially. Once an IS-IS DIS
	for the management LAN has been discovered, they start to send IS-IS		for the management LAN has been discovered, they start to send IS-IS
	Hello packets directly (as unicasts) to the IS-IS DIS periodically.		Hello packets directly (as unicasts) to the IS-IS DIS periodically.
	In addition, IS-IS routers would send IS-IS PDUs to the IS-IS DIS for		In addition, IS-IS routers would send IS-IS PDUs to the IS-IS DIS for
	the management LAN as unicasts as well. In contrast, the controller		the management LAN as unicasts as well. In contrast, the controller
	being elected as IS-IS DIS would send IS-IS PDUs as before. As a		being elected as IS-IS DIS would send IS-IS PDUs as before. As a
	result, IS-IS routers would not receive IS-IS PDUs from one another		result, IS-IS routers would not receive IS-IS PDUs from one another
	unless these IS-IS PDUs are forwarded as unknown unicasts over the		unless these IS-IS PDUs are forwarded as unknown unicasts over the
	management LAN. Through the above modifications to the current IS-IS		management LAN. Through the above modifications to the current IS-IS
	router behaviors, the IS-IS flooding is greatly reduced, which is		router behaviors, the IS-IS flooding is greatly reduced, which is
	skipping to change at page 4, line 50 ¶		skipping to change at page 4, line 50 ¶
	In other words, IS-IS routers would not send any IS-IS Hello packet		In other words, IS-IS routers would not send any IS-IS Hello packet
	over the management LAN until they have found an IS-IS DIS for the		over the management LAN until they have found an IS-IS DIS for the
	management LAN. Note that IS-IS routers SHOULD NOT be elected as IS-		management LAN. Note that IS-IS routers SHOULD NOT be elected as IS-
	IS DIS for the management LAN (This is done by setting the DIS		IS DIS for the management LAN (This is done by setting the DIS
	Priority of those IS-IS routers to zero). As a result, IS-IS routers		Priority of those IS-IS routers to zero). As a result, IS-IS routers
	would not see each other over the management LAN. In other word, IS-		would not see each other over the management LAN. In other word, IS-
	IS routers would not establish adjacencies with one other.		IS routers would not establish adjacencies with one other.
	Furthermore, IS-IS routers SHOULD send all the types of IS-IS PDUs to		Furthermore, IS-IS routers SHOULD send all the types of IS-IS PDUs to
	the controller being elected as IS-IS DIS as unicasts as well.		the controller being elected as IS-IS DIS as unicasts as well.
	To advoid the data traffic from being forwarded across the management		To avoid the data traffic from being forwarded across the management
	LAN, the cost of all IS-IS routers' interfaces to the management LAN		LAN, the cost of all IS-IS routers' interfaces to the management LAN
	SHOULD be set to the maximum value.		SHOULD be set to the maximum value.
	When a given IS-IS router lost its connection to the management LAN,		When a given IS-IS router lost its connection to the management LAN,
	it SHOULD actively establish adjacency with all of its IS-IS		it SHOULD actively establish adjacency with all of its IS-IS
	neighbors within the CLOS network. As such, it could obtain the full		neighbors within the CLOS network. As such, it could obtain the full
	LSDB of the CLOS network while flooding its self-originated LSPs to		LSDB of the CLOS network while flooding its self-originated LSPs to
	the remaining part of the whole CLOS network through these IS-IS		the remaining part of the whole CLOS network through these IS-IS
	neighbor.		neighbor.
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