< draft-dizhou-pim-umf-problem-statement-00.txt		draft-dizhou-pim-umf-problem-statement-01.txt >
	Internet Engineering Task Force D. Zhou, Ed.		Internet Engineering Task Force D. Zhou, Ed.
	Internet-Draft Hangzhou H3C Tech. Co., Ltd.		Internet-Draft Hangzhou H3C Tech. Co., Ltd.
	Intended status: Informational H. Deng		Intended status: Informational H. Deng
	Expires: January 2, 2011 China Mobile Research Institute		Expires: April 22, 2011 China Mobile Research Institute
	Y. Shi		Y. Shi
	Hangzhou H3C Tech. Co., Ltd.		Hangzhou H3C Tech. Co., Ltd.
	H. Liu		H. Liu
	Huawei Technologies Co., Ltd.		Huawei Technologies Co., Ltd.
	17 August 2010		I. Bhattacharya
			Cisco Systems
			October 19, 2010
	Unnecessary Multicast Flooding Problem Statement		Unnecessary Multicast Flooding Problem Statement
	draft-dizhou-pim-umf-problem-statement-00		draft-dizhou-pim-umf-problem-statement-01
	Abstract		Abstract
	This document describes the unnecessary multicast stream flooding		This document describes the unnecessary multicast stream flooding
	problem in the link layer switches between multicast source and PIM		problem in the link layer switches between multicast source and PIM
	First Hop Router (FHR). The IGMP-Snooping Switch will forward		First Hop Router (FHR). The IGMP-Snooping Switch will forward
	multicast streams to router ports, and the PIM FHR must receive all		multicast streams to router ports, and the PIM FHR must receive all
	multicast streams even if there is no request from receiver. This		multicast streams even if there is no request from receiver. This
	often leads to waste of switchs' cache and link bandwidth when the		often leads to waste of switchs' cache and link bandwidth when the
	multicast streams are not actually required. This document details		multicast streams are not actually required. This document details
	skipping to change at page 1, line 43 ¶		skipping to change at page 1, line 45 ¶
	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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	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
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	This Internet-Draft will expire on January 2, 2011.		This Internet-Draft will expire on April 22, 2011.
	Copyright Notice		Copyright Notice
	Copyright (c) 2010 IETF Trust and the persons identified as the		Copyright (c) 2010 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
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://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 7, line 47 ¶		skipping to change at page 7, line 47 ¶
	For the second problem of PIM FHR host simulation, the switch		For the second problem of PIM FHR host simulation, the switch
	directly connected to source can simulate IGMP Querier.		directly connected to source can simulate IGMP Querier.
	But when there are two or more switches simulating IGMP Queriers, the		But when there are two or more switches simulating IGMP Queriers, the
	phenomenon of unnecessary multicast streams flooding still exists.		phenomenon of unnecessary multicast streams flooding still exists.
	5.4. Replacing link layer switches with Routers		5.4. Replacing link layer switches with Routers
	Replacing link layer switches directly connected to sources with		Replacing link layer switches directly connected to sources with
	Routers is not a perfect solution either. Note that this solution		Routers is not a perfect solution either. It will limit the
	will lead to waste of ip address seriously if there are many sources.		flexibility of networking, and will further lead to waste of ip
	It will also bring about so many ip address segments and then		address and many ip address segments seriously if there are many
	complicated network management. After all, this solution will put		sources. It will also bring about many ip address segments and then
	some multicast sources and receivers in some different ip address		complicate network management.
	segment.
	6. some potential solutions		6. some potential solutions
	6.1. solution based on PIM and PIM-Snooping		6.1. solution based on PIM and PIM-Snooping
	The key points of it are as follows:		The key points of it are as follows:
	o When the PIM FHR receives a multicast stream, it creates an entry		o When the PIM FHR receives a multicast stream, it creates an entry
	of (S,G) if the entry did not exist. And it judges whether the		of (S,G) if the entry did not exist. And it judges whether the
	(S,G) entry has out interfaces. If the (S,G) has no out		(S,G) entry has out interfaces. If the (S,G) has no out
	interface, the PIM router sends out an unicast PIM prune message		interface, the PIM router sends out an unicast PIM prune message
	towards multicast source. The upstream neighbor address in the		towards the multicast source. The upstream neighbor address in
	message is the source address.		the message is the source address.
	o The switch between multicast sources and PIM FHR runs PIM snooping		o The switch between multicast sources and PIM FHR runs PIM snooping
	and IGMP snooping. When it intercepts the unicast PIM prune		and IGMP snooping. When it intercepts the unicast PIM prune
	message by ip protocol field identification and finds out that the		message by ip protocol field identification and finds out that the
	upstream neighbor address of the message is not in its PIM		upstream neighbor address of the message is not in its PIM
	neighbor lists, it creates a (S,G) entry with a pruned port and an		neighbor lists, it creates a (S,G) entry with a pruned port and an
	upstream port. The upstream port is found by looking up the		upstream port if not created before. The upstream port is found
	unicast mac table. That (S,G) entry is punched with a specific		by looking up the unicast mac table. That (S,G) entry is punched
	sign which means that entry is different from traditional PIM-		with a specific sign which means that entry is different from
	Snooping entry. The pruned port has a lifetime which is 1/3 of		traditional PIM-Snooping entry. The pruned port SHALL NOT forward
	the lifetime of PIM FHR's (S,G) entry, so that the multicast		multicast stream and has a lifetime which is 1/3 of that of PIM
	stream will arrive at PIM FHR before its (S,G) entry dies out.		FHR's (S,G) entry, then converted to be a downstream port, so that
			the multicast stream will arrive at PIM FHR to refresh the (S,G)
			entry.
	o By the information from IGMP-snooping entry and PIM-snooping		o Looking up IGMP-snooping entry and PIM-snooping entry, if the
	entry, the switch can decide whether it shall forward the unicast		switch find there is no need to forward the multicast stream, it
	PIM prune message towards multicast source.		SHALL forward the unicast PIM prune message towards multicast
			source.
	o When the switch receives an IGMP membership report, it shall		o When the switch receives an IGMP membership report, it shall
	forward the message through its router ports and upstream port.		forward the message through its router ports and upstream port.
	o When PIM FHR creates an out interface for a (S,G) entry that had		o When PIM FHR creates an out interface for a (S,G) entry that had
	no out interface before, it shall send unicast PIM join message		no out interface before, it shall send unicast PIM join message
	towards multicast source. The upstream neighbor address of the		towards multicast source. The upstream neighbor address of the
	message is the source address.		message is the source address.
	o When the switch receives the unicast PIM join message and finds		o When the switch receives the unicast PIM join message and finds
	out that the upstream neighbor address of the message is not in		out that the upstream neighbor address of the message is not in
	its PIM neighbor lists, it will change the pruned port to be		its PIM neighbor lists, it will convert the pruned port to be
	downstream port. When the (S,G) entry with specific sign has no		downstream port. When the (S,G) entry with specific sign has no
	pruned ports, it should be deleted in order to save the entry		pruned ports, it should be deleted in order to save the entry
	space.		space.
	o By the information from IGMP-snooping entry and PIM-snooping		o By the information from IGMP-snooping entry and PIM-snooping
	entry, the switch can decide whether it shall forward the unicast		entry, the switch can decide whether it shall forward the unicast
	PIM join message towards multicast source.		PIM join message towards multicast source.
	o The role of membership port is prior than that of pruned port, and		o The role of membership port is prior than that of pruned port, and
	the role of pruned port is prior than that of router port.		the role of pruned port is prior than that of router port or
			downstream port.
	o If two or more switches or PIM FHRs are connected by one port		o If two or more switches or PIM FHRs are connected by one port
	directly, or through HUB or normal switch, some query mechanism		directly, or through HUB or normal switch, some query mechanism
	shall be implemented.		shall be implemented.
	6.2. solution based on IGMP and IGMP-Snooping		6.2. solution based on IGMP and IGMP-Snooping
	The key points of it are as follows:		The key points of it are as follows:
	o When the PIM FHR receives a multicast stream, it creates an entry		o When the PIM FHR receives a multicast stream, it creates an entry
	skipping to change at line 397 ¶		skipping to change at page 16, line 4 ¶
	Email: young@h3c.com		Email: young@h3c.com
	Hui Liu		Hui Liu
	Huawei Technologies Co., Ltd.		Huawei Technologies Co., Ltd.
	Huawei Bld., No.3 Xinxi Rd.		Huawei Bld., No.3 Xinxi Rd.
	Shang-Di Information Industry Base, Hai-Dian Distinct,		Shang-Di Information Industry Base, Hai-Dian Distinct,
	Beijing		Beijing
	China(100085)		China(100085)
	Email: Liuhui47967@huawei.com		Email: Liuhui47967@huawei.com
			Indranil Bhattacharya
			Cisco Systems
			India(560037)
			Email: myselfindranil@gmail.com
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