draft-ietf-mpls-multicast-07.txt		draft-ietf-mpls-multicast-08.txt
	Network Working Group D. Ooms, B. Sales		Network Working Group D. Ooms, B. Sales
	Internet Draft Alcatel		Internet Draft Alcatel
	Expiration Date: July 2002 W. Livens		Expiration Date: October 2002 W. Livens
	Colt Telecom		Colt Telecom
	A. Acharya		A. Acharya
	IBM		IBM
	F. Griffoul		F. Griffoul
	Ulticom		Ulticom
	F. Ansari		F. Ansari
	Bell Labs		Bell Labs
	January 2002		April 2002
	Framework for IP Multicast in MPLS		Framework for IP Multicast in MPLS
	draft-ietf-mpls-multicast-07.txt		draft-ietf-mpls-multicast-08.txt
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
	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		Task Force (IETF), its areas, and its working groups. Note that
	other groups may also distribute working documents as Internet-		other groups may also distribute working documents as Internet-
	Drafts.		Drafts.
	skipping to change at page 22, line 25		skipping to change at page 22, line 25
	can be maintained but the label advertisement is duplicated in space.		can be maintained but the label advertisement is duplicated in space.
	Since LSPs are only rewarding if they have a long lifetime and since		Since LSPs are only rewarding if they have a long lifetime and since
	the number of LSRs on a shared link is limited the second approach		the number of LSRs on a shared link is limited the second approach
	seems advantageous.		seems advantageous.
	Another issue with multicast in multi-access networks is whether to		Another issue with multicast in multi-access networks is whether to
	use upstream or downstream label assignment. For multicast traffic,		use upstream or downstream label assignment. For multicast traffic,
	upstream label allocation is simpler since there can be only one		upstream label allocation is simpler since there can be only one
	upstream node per link that belongs to a multicast tree. This		upstream node per link that belongs to a multicast tree. This
	(upstream) node can assign a label without any contention. With		(upstream) node can assign a unique label for the FEC. With
	downstream allocation, there may be multiple downstream nodes for a		downstream allocation, there may be multiple downstream nodes for a
	given tree on a multi-access link; each node may propose a label		given tree on a multi-access link; each node may propose a different
	assignment leading to contention and a contention resolution scheme		label assignment for a FEC which would require some resolution
	is required to chose one of them as the label allocator.		process in order to come of with a single label per multicast FEC on
			the link.
	Once a label has been assigned, it is possible that the label		Once a label has been assigned, it is possible that the label
	assigner leaves the tree. With downstream label assignment, this		assigner leaves the tree. With downstream label assignment, this
	could happen when the label allocator leaves the group. With		could happen when the label allocator leaves the group. With
	upstream assignment this could happen when the upstream LSR changes		upstream assignment this could happen when the upstream LSR changes
	due to a unicast topology change.		due to a unicast topology change.
	10. More issues		10. More issues
	10.1. TTL field		10.1. TTL field
	skipping to change at page 25, line 29		skipping to change at page 25, line 29
	a) Easier label allocation in multi-access networks (see section 9).		a) Easier label allocation in multi-access networks (see section 9).
	b) The same label can be kept when the downstream LSR (which would		b) The same label can be kept when the downstream LSR (which would
	have been the label allocator in downstream mode in a multi-access		have been the label allocator in downstream mode in a multi-access
	network) leaves the group (see section 9).		network) leaves the group (see section 9).
	c) The upstream and implicit distribution mode allow a faster LSP		c) The upstream and implicit distribution mode allow a faster LSP
	setup when the LSP is traffic triggered.		setup when the LSP is traffic triggered.
			Whether to use upstream or downstream label distribution is outside
			the scope of this framework. The relative complexity between the
			necessary protocol extensions and the resolution mechanism needed,
			as well as the relative operational complexity, will influence which
			way to go.
	10.5. Explicit vs. Implicit Label Distribution		10.5. Explicit vs. Implicit Label Distribution
	Beside the explicit distribution modes (which use a signaling		Beside the explicit distribution modes (which use a signaling
	protocol), [ACHA] proposes an implicit label distribution method by		protocol), [ACHA] proposes an implicit label distribution method by
	using unknown labels. This method has all the advantages of the		using unknown labels. This method has all the advantages of the
	upstream label allocation method and is probably the fastest label		upstream label allocation method and is probably the fastest label
	advertisement method for traffic triggered LSPs.		advertisement method for traffic triggered LSPs.
	Implicit label distribution is not applicable if the FEC-to-label		Implicit label distribution is not applicable if the FEC-to-label
	binding has been advertised prior to traffic arrival, e.g. explicit		binding has been advertised prior to traffic arrival, e.g. explicit
End of changes.
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