< draft-ietf-pim-anycast-rp-06.txt		draft-ietf-pim-anycast-rp-07.txt >
	Network Working Group Dino Farinacci		Network Working Group Dino Farinacci
	INTERNET-DRAFT Yiqun Cai		INTERNET-DRAFT Yiqun Cai
	Expiration Date: August 2006 cisco Systems		Expiration Date: August 2006 cisco Systems
	February 4, 2006		February 7, 2006
	Anycast-RP using PIM		Anycast-RP using PIM
	<draft-ietf-pim-anycast-rp-06.txt>		<draft-ietf-pim-anycast-rp-07.txt>
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that other		Task Force (IETF), its areas, and its working groups. Note that other
	skipping to change at page 4, line 13 ¶		skipping to change at page 4, line 13 ¶
	consistently configured in all RPs in the set.		consistently configured in all RPs in the set.
	3.0 Mechanism		3.0 Mechanism
	The following diagram illustrates a domain using 3 RPs where		The following diagram illustrates a domain using 3 RPs where
	receivers are joining to the closest RP according to where unicast		receivers are joining to the closest RP according to where unicast
	routing metrics take them and 2 sources sending packets to their		routing metrics take them and 2 sources sending packets to their
	respective RPs.		respective RPs.
	The rules described in this section do not override the rules in		The rules described in this section do not override the rules in
	[N1]. They are intended to blend with the rules in [N1]. If there is		[N1]. They are intended to blend with the rules in [N1]. If there is
	any question on the interpretation, precedent is given to [N1].		any question on the interpretation, precedent is given to [N1].
	S1-----RP1 RP2 RP3------S3		S1-----RP1 RP2 RP3------S3
	/ \ |		/ \ |
	/ \ |		/ \ |
	R1 R1’ R2		R1 R1' R2
	Assume the above scenario is completely connected where R1, R1’, and		Assume the above scenario is completely connected where R1, R1', and
	R2 are receivers for a group, and S1 and S3 send to that group.		R2 are receivers for a group, and S1 and S3 send to that group.
	Assume RP1, RP2 and RP3 are all assigned the same IP address which is		Assume RP1, RP2 and RP3 are all assigned the same IP address which is
	used as the Anycast-RP address (let’s say the IP address is RPA).		used as the Anycast-RP address (let's say the IP address is RPA).
	Note, the address used for the RP address in the domain (the Anycast-		Note, the address used for the RP address in the domain (the
	RP address) needs to be different than the addresses used by the		Anycast-RP address) needs to be different than the addresses used by
	Ancyast-RP routers to communicate with each other.		the Anycast-RP routers to communicate with each other.
	The following procedure is used when S1 starts sourcing traffic:		The following procedure is used when S1 starts sourcing traffic:
	o S1 sends a multicast packet.		o S1 sends a multicast packet.
	o The DR directly attached to S1 will form a PIM Register		o The DR directly attached to S1 will form a PIM Register
	message to send to the Anycast-RP address (RPA). The unicast		message to send to the Anycast-RP address (RPA). The unicast
	routing system will deliver the PIM Register message to the		routing system will deliver the PIM Register message to the
	nearest RP, in this case RP1.		nearest RP, in this case RP1.
	o RP1 will receive the PIM Register message, decapsulate it, send the		o RP1 will receive the PIM Register message, decapsulate it, send the
	packet down the shared-tree to get the packet to receivers R1 and		packet down the shared-tree to get the packet to receivers R1 and
	R1’.		R1'.
	o RP1 is configured with RP2 and RP3’s IP address. Since the		o RP1 is configured with RP2 and RP3's IP address. Since the
	Register message did not come from one of the RPs in the		Register message did not come from one of the RPs in the
	anycast-RP set, RP1 assumes the packet came from a DR. If the		anycast-RP set, RP1 assumes the packet came from a DR. If the
	Register is not addressed to the Anycast-RP address, an error		Register is not addressed to the Anycast-RP address, an error
	has occurred and it should be rate-limited logged.		has occurred and it should be rate-limited logged.
	o RP1 will then send a copy of the Register message from S1’s		o RP1 will then send a copy of the Register message from S1's
	DR to both RP2 and RP3. RP1 will use its own IP address as		DR to both RP2 and RP3. RP1 will use its own IP address as
	the source address for the PIM Register message.		the source address for the PIM Register message.
	o RP1 MAY join back to the source-tree by triggering a (S1,G) Join		o RP1 MAY join back to the source-tree by triggering a (S1,G) Join
	message toward S1. However, RP1 MUST create (S1,G) state.		message toward S1. However, RP1 MUST create (S1,G) state.
	o RP1 sends a Register-Stop back to the DR. If, for some reason,		o RP1 sends a Register-Stop back to the DR. If, for some reason,
	the Register messages to RP2 and RP3 are lost, then when the		the Register messages to RP2 and RP3 are lost, then when the
	Register suppression timer expires in the DR, it will resend		Register suppression timer expires in the DR, it will resend
	Registers to allow another chance for all RPs in the Anycast-RP		Registers to allow another chance for all RPs in the Anycast-RP
	skipping to change at page 5, line 42 ¶		skipping to change at page 5, line 42 ¶
	o RP3 sends a Register-Stop back to the RP1.		o RP3 sends a Register-Stop back to the RP1.
	o RP3 creates (S1,G) state so when a receiver joins after S1 starts		o RP3 creates (S1,G) state so when a receiver joins after S1 starts
	sending, RP3 can join quickly to the source-tree for S1.		sending, RP3 can join quickly to the source-tree for S1.
	o RP1 processes the Register-Stop from each of RP2 and RP3. There		o RP1 processes the Register-Stop from each of RP2 and RP3. There
	is no specific action taken when processing Register-Stop messages.		is no specific action taken when processing Register-Stop messages.
	The procedure for S3 sending follows the same as above but it is RP3		The procedure for S3 sending follows the same as above but it is RP3
	which sends a copy of the Register originated by S3’s DR to RP1 and		which sends a copy of the Register originated by S3's DR to RP1 and
	RP2. Therefore, this example shows how sources anywhere in the		RP2. Therefore, this example shows how sources anywhere in the
	domain, associated with different RPs, can reach all receivers, also		domain, associated with different RPs, can reach all receivers, also
	associated with different RPs, in the same domain.		associated with different RPs, in the same domain.
	4.0 Observations and Guidelines about this Proposal		4.0 Observations and Guidelines about this Proposal
	o An RP will send a copy of a Register only if the Register is		o An RP will send a copy of a Register only if the Register is
	received from an IP address not in the Anycast-RP list (i.e. the		received from an IP address not in the Anycast-RP list (i.e. the
	Register came from a DR and not another RP). An implementation		Register came from a DR and not another RP). An implementation
	MUST safeguard against inconsistently configured anycast-RP sets		MUST safeguard against inconsistently configured anycast-RP sets
	in each RP by copying the TTL from a Register message to the		in each RP by copying the TTL from a Register message to the
	Register messages it copies and sends to other RPs.		Register messages it copies and sends to other RPs.
	o Each DR that PIM registers for a source will send the message to		o Each DR that PIM registers for a source will send the message to
	the anycast-RP address (which results in the packet getting to the		the anycast-RP address (which results in the packet getting to the
	closest physical RP). Therefore there are no changes to the DR		closest physical RP). Therefore there are no changes to the DR
	logic.		logic.
	o Packets flow to all receivers no matter what RP they have joined		o Packets flow to all receivers no matter what RP they have joined
	to.		to.
	o The source gets Registered to a single RP by the DR. It’s the		o The source gets Registered to a single RP by the DR. It's the
	responsibility of the RP that receives the PIM Register		responsibility of the RP that receives the PIM Register
	messages from the DR (the closest RP to the DR based on routing		messages from the DR (the closest RP to the DR based on routing
	metrics) to get the packet to all other RPs in the Anycast-RP		metrics) to get the packet to all other RPs in the Anycast-RP
	set.		set.
	o Logic is changed only in the RPs. The logic change is for		o Logic is changed only in the RPs. The logic change is for
	sending copies of Register messages. Register-Stop processing is		sending copies of Register messages. Register-Stop processing is
	unchanged. However, an implementation MAY suppress sending		unchanged. However, an implementation MAY suppress sending
	Register-Stop messages in response to a Register received from		Register-Stop messages in response to a Register received from
	an RP.		an RP.
	skipping to change at page 6, line 39 ¶		skipping to change at page 6, line 39 ¶
	end-to-end. That is from DR -> RP1 -> {RP2 and RP3}. There is no		end-to-end. That is from DR -> RP1 -> {RP2 and RP3}. There is no
	need for specific rate-limiting logic between the RPs.		need for specific rate-limiting logic between the RPs.
	o When topology changes occur, the existing source-tree adjusts		o When topology changes occur, the existing source-tree adjusts
	as it does today according to [N1]. The existing shared-trees,		as it does today according to [N1]. The existing shared-trees,
	as well, adjust as it does today according to [N1].		as well, adjust as it does today according to [N1].
	o Physical RP changes are as fast as unicast route convergence.		o Physical RP changes are as fast as unicast route convergence.
	Retaining the benefit of [I1].		Retaining the benefit of [I1].
	o An RP that doesn’t support this specification can be mixed with		o An RP that doesn't support this specification can be mixed with
	RPs that do support this specification. However, the non-supporter		RPs that do support this specification. However, the non-supporter
	RPs should not have sources registering to it but may have		RPs should not have sources registering to it but may have
	receivers joined to it.		receivers joined to it.
	o If Null Registers are sent (Registers with an IP header and no IP		o If Null Registers are sent (Registers with an IP header and no IP
	payload), they MUST be replicated to all of the RPs in the Anycast-		payload), they MUST be replicated to all of the RPs in the Anycast-
	RP set so that source state remains alive for active sources.		RP set so that source state remains alive for active sources.
	o The number of RPs in the Anycast-RP set should remain small so the		o The number of RPs in the Anycast-RP set should remain small so the
	amount of non-native replication is kept to a minimum.		amount of non-native replication is kept to a minimum.
	skipping to change at page 9, line 4 ¶		skipping to change at page 9, line 4 ¶
	domains together by using Anycast-PIM inside a transit domain.		domains together by using Anycast-PIM inside a transit domain.
	6.0 IANA Considerations		6.0 IANA Considerations
	This document makes no request to IANA.		This document makes no request to IANA.
	Note to RFC Editor: this section may be removed on publication as an		Note to RFC Editor: this section may be removed on publication as an
	RFC.		RFC.
	7.0 Security Consideration		7.0 Security Consideration
	This section describes the security consideration for Register and		This section describes the security consideration for Register and
	Register-Stop messages between Anycast-RPs. For PIM messages between DR		Register-Stop messages between Anycast-RPs. For PIM messages between
	and RP, please see [N1].		DR and RP, please see [N1].
	7.1 Attack Based On Forged Messages		7.1 Attack Based On Forged Messages
	An attacker may forge a Register message using one of the addresses		An attacker may forge a Register message using one of the addresses
	in the Anycast-RP list in order to achieve one or more of the		in the Anycast-RP list in order to achieve one or more of the
	following effects:		following effects:
	1. Overwhelm the target RP in a denial-of-service attack		1. Overwhelm the target RP in a denial-of-service attack
	2. Inject unauthorized data to receivers served by the RP		2. Inject unauthorized data to receivers served by the RP
	3. Inject unauthorized data and create bogus SA entries in other		3. Inject unauthorized data and create bogus SA entries in other
End of changes. 14 change blocks.
	19 lines changed or deleted		19 lines changed or added
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