rfc9692v8.txt		rfc9692.txt
	skipping to change at line 1412 ¶		skipping to change at line 1412 ¶
	possible to connect them together by interplane bidirectional rings		possible to connect them together by interplane bidirectional rings
	as illustrated in Figure 13. The rings will be used to exchange full		as illustrated in Figure 13. The rings will be used to exchange full
	north topology information between planes. All ToFs having the same		north topology information between planes. All ToFs having the same
	north topology allows, by the means of transitive, negative		north topology allows, by the means of transitive, negative
	disaggregation described in Section 6.5.2, to efficiently fix any		disaggregation described in Section 6.5.2, to efficiently fix any
	possible fallen leaf scenario. Somewhat as a side effect, the		possible fallen leaf scenario. Somewhat as a side effect, the
	exchange of information fulfills the requirement for a full view of		exchange of information fulfills the requirement for a full view of
	the fabric topology at the ToF level without the need to collate it		the fabric topology at the ToF level without the need to collate it
	from multiple points.		from multiple points.
	_______________________________________________________________________		(Artwork only available as SVG: see
	| [Plane A] . [Plane B] . [Plane C] . [Plane D] |		https://www.rfc-editor.org/rfc/rfc9692.html)
	|.....................................................................|
	| +------------------------------------------------------------+ |
	| | +---+ . +---+ . +---+ . +---+ | |
	| +-+ n +-------------+ n +-------------+ n +------------+ n +-+ |
	| +--++ . +-+++ . +-+++ . +--++ |
	| || . || . || . || |
	| +---------||---------------||----------------||--------------+ || |
	| | +---+ || . +---+ || . +---+ || . +---+ | || |
	| +-+ 1 +---||--------+ 1 +--||---------+ 1 +--||--------+ 1 +-+ || |
	| +--++ || . +-+++ || . +-+++ || . +-+++ || |
	| || || . || || . || || . || || |
	| || || . || || . || || . || || |
	Figure 13: Using Rings to Bring All Planes and Bind Them at the ToF		Figure 13: Using Rings to Bring All Planes and Bind Them at the ToF
	5.5. Addressing the Fallen Leaves Problem		5.5. Addressing the Fallen Leaves Problem
	One consequence of the "fallen leaf" problem is that some prefixes		One consequence of the "fallen leaf" problem is that some prefixes
	attached to the fallen leaf become unreachable from some of the ToF		attached to the fallen leaf become unreachable from some of the ToF
	nodes. RIFT defines two methods to address this issue, denoted as		nodes. RIFT defines two methods to address this issue, denoted as
	positive disaggregation and negative disaggregation. Both methods		positive disaggregation and negative disaggregation. Both methods
	flood corresponding types of South TIEs to advertise the impacted		flood corresponding types of South TIEs to advertise the impacted
	prefix(es).		prefix(es).
	skipping to change at line 3747 ¶		skipping to change at line 3735 ¶
	leaves. Such scenario cannot be addressed by positive disaggregation		leaves. Such scenario cannot be addressed by positive disaggregation
	only and needs a further mechanism.		only and needs a further mechanism.
	6.5.2.1. Cabling of Multiple ToF Planes		6.5.2.1. Cabling of Multiple ToF Planes
	Returning in this section to designs with multiple planes as shown		Returning in this section to designs with multiple planes as shown
	originally in Figure 3, Figure 18 highlights how the ToF is cabled in		originally in Figure 3, Figure 18 highlights how the ToF is cabled in
	case of two planes by the means of dual-rings to distribute all the		case of two planes by the means of dual-rings to distribute all the
	North TIEs within both planes.		North TIEs within both planes.
	_______________________________________________________________________		(Artwork only available as SVG: see
	| [Plane A] . [Plane B] . [Plane C] . [Plane D] |		https://www.rfc-editor.org/rfc/rfc9692.html)
	|.....................................................................|
	| +------------------------------------------------------------+ |
	| | +---+ . +---+ . +---+ . +---+ | |
	| +-+ n +-------------+ n +-------------+ n +------------+ n +-+ |
	| +--++ . +-+++ . +-+++ . +--++ |
	| || . || . || . || |
	| +---------||---------------||----------------||--------------+ || |
	| | +---+ || . +---+ || . +---+ || . +---+ | || |
	| +-+ 1 +---||--------+ 1 +--||---------+ 1 +--||--------+ 1 +-+ || |
	| +--++ || . +-+++ || . +-+++ || . +-+++ || |
	| || || . || || . || || . || || |
	| || || . || || . || || . || || |
	Figure 18: Topologically Connected Planes		Figure 18: Topologically Connected Planes
	Section 5.3 already describes how failures in multi-plane fabrics can		Section 5.3 already describes how failures in multi-plane fabrics can
	lead to traffic loss that normal positive disaggregation cannot fix.		lead to traffic loss that normal positive disaggregation cannot fix.
	The mechanism of negative, transitive disaggregation incorporated in		The mechanism of negative, transitive disaggregation incorporated in
	RIFT provides the corresponding solution, and the next section		RIFT provides the corresponding solution, and the next section
	explains the involved mechanisms in more detail.		explains the involved mechanisms in more detail.
	6.5.2.2. Transitive Advertisement of Negative Disaggregates		6.5.2.2. Transitive Advertisement of Negative Disaggregates
	A ToF node discovering that it cannot reach a fallen leaf SHOULD		A ToF node discovering that it cannot reach a fallen leaf SHOULD
	skipping to change at line 4411 ¶		skipping to change at line 4387 ¶
	the normative schema in Section 7.		the normative schema in Section 7.
	The initial state is ComputeBestOffer.		The initial state is ComputeBestOffer.
	Enter		Enter
	|		|
	v		v
	+------------------+		+------------------+
	| ComputeBestOffer |		| ComputeBestOffer |
	| |<----+		| |<----+
			| | | ChangeLocalHierarchyIndications
			| | | ChangeLocalConfiguredLevel
			| | | NeighborOffer
	| | | BetterHAL		| | | BetterHAL
	| | | BetterHAT		| | | BetterHAT
	| | | ChangeLocalConfiguredLevel
	| | | ChangeLocalHierarchyIndications
	| | | LostHAT		| | | LostHAT
	| | | NeighborOffer
	| | | ShortTic		| | | ShortTic
	| |-----+		| |-----+
	| |		| |
	| |<---------------------		| |<---------------------
	| |---------------------> (UpdatingClients)		| |---------------------> (UpdatingClients)
	| | ComputationDone		| | ComputationDone
	+------------------+		+------------------+
	^ |		^ |
	| | LostHAL		| | LostHAL
	| V		| V
	(HoldingDown)		(HoldingDown)
	(ComputeBestOffer)		(ComputeBestOffer)
	| ^		| ^
	| | ChangeLocalConfiguredLevel
	| | ChangeLocalHierarchyIndications		| | ChangeLocalHierarchyIndications
			| | ChangeLocalConfiguredLevel
	| | HoldDownExpired		| | HoldDownExpired
	V |		V |
	+------------------+		+------------------+
	| HoldingDown |		| HoldingDown |
	| |<----+		| |<----+
			| | | NeighborOffer
	| | | BetterHAL		| | | BetterHAL
	| | | BetterHAT		| | | BetterHAT
	| | | ComputationDone
	| | | LostHAL		| | | LostHAL
	| | | LostHat		| | | LostHat
	| | | NeighborOffer		| | | ComputationDone
	| | | ShortTic		| | | ShortTic
	| |-----+		| |-----+
	+------------------+		+------------------+
	^		^
	|		|
	(UpdatingClients)		(UpdatingClients)
	(ComputeBestOffer)		(ComputeBestOffer)
	| ^		| ^
			| | ChangeLocalHierarchyIndications
			| | ChangeLocalConfiguredLevel
	| | BetterHAL		| | BetterHAL
	| | BetterHAT		| | BetterHAT
	| | LostHAT		| | LostHAT
	| | ChangeLocalHierarchyIndications
	| | ChangeLocalConfiguredLevel
	V |		V |
	+------------------+		+------------------+
	| UpdatingClients |		| UpdatingClients |
	| |<----+		| |<----+
	| | |		| | |
	| | | NeighborOffer		| | | NeighborOffer
	| | | ShortTic		| | | ShortTic
	| |-----+		| |-----+
	+------------------+		+------------------+
	|		|
End of changes. 14 change blocks.
	38 lines changed or deleted		14 lines changed or added
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