draft-ietf-mpls-crldp-unnum-02.txt		draft-ietf-mpls-crldp-unnum-03.txt
	Network Working Group Kireeti Kompella		Network Working Group Kireeti Kompella
	Internet Draft Juniper Networks		Internet Draft Juniper Networks
	Expiration Date: March 2002 Yakov Rekhter		Expiration Date: June 2002 Yakov Rekhter
	Juniper Networks		Juniper Networks
	Alan Kullberg		Alan Kullberg
	NetPlane Systems		NetPlane Systems
	Signalling Unnumbered Links in CR-LDP		Signalling Unnumbered Links in CR-LDP
	draft-ietf-mpls-crldp-unnum-02.txt		draft-ietf-mpls-crldp-unnum-03.txt
	1. Status of this Memo		1. 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 2, line 20		skipping to change at page 2, line 20
	OSPF), and (b) the ability to specify unnumbered links in MPLS TE		OSPF), and (b) the ability to specify unnumbered links in MPLS TE
	signalling. The former is covered in [ISIS-TE, OSPF-TE]. The focus		signalling. The former is covered in [ISIS-TE, OSPF-TE]. The focus
	of this document is on the latter.		of this document is on the latter.
	Current signalling used by MPLS TE doesn't provide support for		Current signalling used by MPLS TE doesn't provide support for
	unnumbered links because the current signalling doesn't provide a way		unnumbered links because the current signalling doesn't provide a way
	to indicate an unnumbered link in its Explicit Route Objects. This		to indicate an unnumbered link in its Explicit Route Objects. This
	document proposes simple procedures and extensions that allow CR-LDP		document proposes simple procedures and extensions that allow CR-LDP
	signalling [CR-LDP] to be used with unnumbered links.		signalling [CR-LDP] to be used with unnumbered links.
	4. Interface Identifiers		4. Link Identifiers
	Since unnumbered links are not identified by an IP address, then for		An unnumbered link has to be a point-to-point link. An LSR at each
	the purpose of MPLS TE they need some other identifier. We assume		end of an unnumbered link assigns an identifier to that link. This
	that each unnumbered link on a Label Switched Router (LSR) is given a		identifier is a non-zero 32-bit number that is unique within the
	unique 32-bit identifier. The scope of this identifier is the LSR to		scope of the LSR that assigns it. The IS-IS and/or OSPF and RSVP
	which the link belongs; moreover, the IS-IS and/or OSPF and CR-LDP		modules on an LSR must agree on the identifiers.
	modules on an LSR must agree on interface identifiers.
	Note that links are directed, i.e., a link l is from some LSR A to		There is no a priori relationship between the identifiers assigned to
	some other LSR B. LSR A chooses the interface identifier for link l.		a link by the LSRs at each end of that link.
	To be completely clear, we call this the "outgoing interface
	identifier from LSR A's point of view". If there is a reverse link		LSRs at the two end points of an unnumbered link exchange with each
	from LSR B to LSR A (for example, a point-to-point SONET interface		other the identifiers they assign to the link. Exchanging the
	connecting LSRs A and B would be represented as two links, one from A		identifiers may be accomplished by configuration, by means of a
	to B, and another from B to A), B chooses the outgoing interface		protocol such as LMP ([LMP]), by means of RSVP/CR-LDP (especially in
	identifier for the reverse link; we call this the link's "incoming		the case where a link is a Forwarding Adjacency, see below), or by
	interface identifier from A's point of view". There is no a priori		means of IS-IS or OSPF extensions ([ISIS-GMPLS], [OSPF-GMPLS]).
	relationship between the two interface identifiers.
			Consider an (unnumbered) link between LSRs A and B. LSR A chooses an
			idenfitier for that link. So is LSR B. From A's perspective we refer
			to the identifier that A assigned to the link as the "link local
			identifier" (or just "local identifier"), and to the identifier that
			B assigned to the link as the "link remote identifier" (or just
			"remote identifier"). Likewise, from B's perspective the identifier
			that B assigned to the link is the local identifier, and the
			identifier that A assigned to the link is the remote identifier.
			This section is equally applicable to the case of unnumbered
			component links (see [LINK-BUNDLE]).
	5. Unnumbered Forwarding Adjacencies		5. Unnumbered Forwarding Adjacencies
	If an LSR that originates an LSP advertises this LSP as an unnumbered		If an LSR that originates an LSP advertises this LSP as an unnumbered
	Forwarding Adjacency in IS-IS or OSPF (see [LSP-HIER]), or the LSR		Forwarding Adjacency in IS-IS or OSPF (see [LSP-HIER]), or the LSR
	uses the Forwarding Adjacency formed by this LSP as an unnumbered		uses the Forwarding Adjacency formed by this LSP as an unnumbered
	component link of a bundled link (see [BUNDLE]), the LSR MUST		component link of a bundled link (see [LINK-BUNDLE]), the LSR MUST
	allocate an interface identifier to that Forwarding Adjacency (just		allocate an identifier to that Forwarding Adjacency (just like for
	like for any other unnumbered link). Moreover, the Request message		any other unnumbered link). Moreover, the REQUEST message used for
	used for establishing the LSP that forms the Forwarding Adjacency		establishing the LSP that forms the Forwarding Adjacency MUST contain
	MUST contain an LSP_TUNNEL_INTERFACE_ID object (described below),		an LSP_TUNNEL_INTERFACE_ID TLV (described below), with the LSR's
	with the LSR's Router ID set to the head end's Router ID, and the		Router ID set to the head end's Router ID, and the Interface ID set
	Interface ID set to the interface identifier that the LSR allocated		to the identifier that the LSR allocated to the Forwarding Adjacency.
	to the Forwarding Adjacency.
	If the LSP is bidirectional, and the tail-end LSR (of the forward		If the REQUEST message contains the LSP_TUNNEL_INTERFACE_ID TLV, then
	LSP) advertises the reverse LSP as an unnumbered Forwarding		the tail-end LSR MUST allocate an identifier to that Forwarding
	Adjacency, the tail-end LSR MUST allocate an interface identifier to		Adjacency (just like for any other unnumbered link). Furthermore,
	the reverse Forwarding Adjacency. Furthermore, the MAPPING message		the MAPPING message for the LSP MUST contain an
	for the LSP MUST contain an LSP_TUNNEL_INTERFACE_ID object, with the		LSP_TUNNEL_INTERFACE_ID TLV, with the LSR's Router ID set to the
	LSR's Router ID set to the tail end's router ID, and the Interface ID		tail-end's Router ID, and the Interface ID set to the identifier
	set to the interface identifier allocated by the tail-end LSR.		allocated by the tail-end LSR.
	5.1. LSP_TUNNEL_INTERFACE_ID Object		For the purpose of processing the ERO and the Interface ID TLV, an
			unnumbered Forwarding Adjacency is treated as an unnumbered (TE) link
			or an unnumbered component link as follows. The LSR that originates
			the Adjacency sets the link local identifier for that link to the
			value that the LSR allocates to that Forwarding Adjacency, and the
			link remote identifier to the value carried in the Interface ID field
			of the Reverse Interface ID TLV (for the definition of Reverse
			Interface ID TLV see below). The LSR that is a tail-end of that
			Forwarding Adjacency sets the link local identifier for that link to
			the value that the LSR allocates to that Forwarding Adjacency, and
			the link remote identifier to the value carried in the Interface ID
			field of the Forward Interface ID TLV (for the definition of Forward
			Interface ID see below).
	The LSP_TUNNEL_INTERFACE ID object has Type to be determined by IETF		5.1. LSP_TUNNEL_INTERFACE_ID TLV
			The LSP_TUNNEL_INTERFACE ID TLV has Type to be determined by IETF
	consensus and length 8. The format is given below.		consensus and length 8. The format is given below.
	Figure 1: Interface ID TLV		This TLV can optionally appear in either a REQUEST message or a
			MAPPING message. In the former case, we call it the "Forward
			Interface ID" for that LSP; in the latter case, we call it the
			"Reverse Interface ID" for the LSP.
			Figure 1: LSP_TUNNEL_INTERFACE_ID TLV
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| Type | Length |		|0|0| Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| LSR's Router ID |		| LSR's Router ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Interface ID (32 bits) |		| Interface ID (32 bits) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	This object can optionally appear in either a REQUEST message or a
	MAPPING message. In the former case, we call it the "Forward
	Interface ID" for that LSP; in the latter case, we call it the
	"Reverse Interface ID" for the LSP.
	6. Signalling Unnumbered Links in EROs		6. Signalling Unnumbered Links in EROs
	A new subobject of the Explicit Route Object (ERO) is used to specify		A new subobject of the Explicit Route Object (ERO) is used to specify
	unnumbered links. This subobject has the following format:		unnumbered links. This subobject has the following format:
	Figure 2: Unnumbered Interface ID Subobject		Figure 2: Unnumbered Interface ID Subobject
	0 1 2 3		0 1 2 3
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	|0|0| Type | Length |		|0|0| Type | Length |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Router ID |		| Router ID |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| Interface ID (32 bits) |		| Interface ID (32 bits) |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	This subobject is strict. The Type is 0x0805 (Unnumbered Interface		The Type is 0x0805 (Unnumbered Interface ID) and the Length is 8.
	ID) and the Length is 8.
	The Interface ID is the outgoing interface identifier with respect to
	the LSR specified by the router ID.
	6.1. Processing the Unnumbered Interface ID Subobject
	First of all, the receiving LSR must validate that it received the		The Interface ID is the identifier assigned to the link by the LSR
	Request message correctly. If the first subobject in the ERO is an		specified by the router ID.
	Unnumbered Interface subobject, the check is done as follows (for
	other types of ERO subobjects, the rules in [CR-LDP] apply).
	The IF_ID TLV ([GMPLS-SIG], [GMPLS-CRLDP]), if present in the		6.1. Processing the IF_ID TLV
	message, MUST contain the same Router ID (IP Address) as the Router
	ID carried in the Unnumbered Interface ID subobject. If not, the
	receiving LSR MUST return a "Bad Initial ER-Hop" error. If IF_ID TLV
	is present, and it carries the IF_INDEX TLV, the receiving LSR SHOULD
	check that the value carried in this TLV is the same as carried in
	the Interface ID field of the Unnumbered Interface ID subobject. If
	the value is different, the receiving LSR MUST return a "Bad Initial
	ER-Hop" error.
	If the above checks are passes, the LSR checks whether the tuple		When an LSR receives a REQUEST message containing the IF_ID TLV with
	<Router ID, Interface ID> from the Unnumbered Interface subobject		the IF_INDEX TLV, the LSR processes this TLV as follows. The LSR
	matches the tuple <Router ID, Forward Interface ID> of any of the		must have information about the identifiers assigned by its neighbors
	LSPs for which the LSR is a tail-end. If a match is found, the match		to the unnumbered links between the neighbors and the LSR. The LSR
	identifies the Forwarding Adjacency for which the LSR has to perform		uses this information to find a link with tuple <Router ID, local
	label allocation.		identifier> matching the tuple <IP Address, Interface ID> carried in
			the IF_INDEX TLV. If the matching tuple is found, the match
			identifies the link for which the LSR has to perform label
			allocation.
	Otherwise, the LSR MUST check whether the tuple <Router ID, Interface		Otherwise, the LSR SHOULD return an error.
	ID> from the Unnumbered Interface subobject matches the tuple <Router
	ID, Reverse Interface ID> of any of the bidirectional LSPs for which
	the LSR is the head-end. If a match is found, the match identifies
	the Forwarding Adjacency for which the LSR has to perform label
	allocation, namely, the reverse Forwarding Adjacency for the LSP
	identified by the match.
	Otherwise, the LSR must have information about the identifiers		6.2. Processing the ERO object
	assigned by its neighbors to the unnumbered links (i.e., incoming
	interface identifiers from LSR's point of view). The LSR uses this
	information to find a link with tuple <Router ID, incoming interface
	identifier> matching the tuple <Router ID, Interface ID> from the
	Unnumbered Interface subobject. If the matching tuple is found, and
	the link is not a bundled link, the match identifies the link for
	which the LSR has to perform label allocation. If the matching tuple
	is found, and the link is a bundled link, the LSR follows the
	procedures for label allocation as described in [LINK-BUNDLE].
	6.2. Selecting the Next Hop		The Unnumbered Interface ID subobject is defined to be a part of a
			particular abstract node if that node has the Router ID that is equal
			to the Router ID field in the subobject, and if the node has an
			(unnumbered) link or an (unnumbered) Forwarding Adjacency whose local
			identifier (from that node's point of view) is equal to the value
			carried in the Interface ID field of the subobject.
	Once an LSR determines the link for which the LSR has to perform		With this in mind, the ERO processing in the presence of the
	label allocation, the LSR removes the initial subobject in the ERO,		Unnumbered Interface ID subobject follows the rules specified in
	and computes the next hop. The next hop for an Unnumbered Interface		section 4.8.1 of [CR-LDP].
	ID subobject is determined as follows. The Interface ID MUST refer
	to an outgoing interface identifier that this node allocated; if not,
	the node SHOULD return a "Bad Strict Node" error. The next hop is
	the LSR at the other end of the link that the Interface ID refers to.
	If this is the LSR itself, the subobject is removed, and the process
	repeated. If the next node is some other LSR, this is the next hop
	to which a Request message must be sent.
	When sending a Request message to the next hop, if the message		As part of the ERO processing, or to be more precise, as part of the
	carries the IF_ID object, then this object MUST contain the IF_INDEX		next hop selection, if the outgoing link is unnumbered, the REQUEST
	TLV, with IP Address in that TLV set to the LSR's Router ID, and		message that the node sends to the next hop MUST include the IF_ID
	Interface ID set to the Interface ID carried in the first subobject		TLV, with the IP address field of that TLV set to the Router ID of
	of the ERO.		the node, and the Interface ID field of that TLV set to the
			identifier assigned to the link by the node.
	7. Security Considerations		7. Security Considerations
	This document raises no new security concerns for CR-LDP.		This document raises no new security concerns for CR-LDP.
	8. Acknowledgments		8. Acknowledgments
	Thanks to Rahul Aggarwal for his comments on the text. Thanks too to		Thanks to Rahul Aggarwal for his comments on the text. Thanks too to
	Bora Akyol and Vach Kompella.		Bora Akyol and Vach Kompella.
	9. References		9. References
	[BUNDLE] Kompella, K., Rekhter, Y., and Berger, L., "Link Bundling in		[LINK-BUNDLE] Kompella, K., Rekhter, Y., and Berger, L., "Link
	MPLS Traffic Engineering", draft-kompella-mpls-bundle-05.txt (work in		Bundling in MPLS Traffic Engineering", draft-kompella-mpls-
	progress)		bundle-05.txt (work in progress)
	[CR-LDP] Jamoussi, B., editor, "Constraint-Based LSP Setup using		[CR-LDP] Jamoussi, B., editor, "Constraint-Based LSP Setup using
	LDP", draft-ietf-mpls-cr-ldp-04.txt (work in progress)		LDP", draft-ietf-mpls-cr-ldp-04.txt (work in progress)
	[GMPLS-SIG] Ashwood, P., et al., "Generalized MPLS - Signalling		[GMPLS-SIG] Ashwood, P., et al., "Generalized MPLS - Signalling
	Functional Description", draft-ietf-generalized-mpls-		Functional Description", draft-ietf-generalized-mpls-
	signalling-05.txt		signalling-05.txt
	[GMPLS-CRLDP] Ashwood, P., et al., "Generalized MPLS Signaling - CR-		[GMPLS-CRLDP] Ashwood, P., et al., "Generalized MPLS Signaling - CR-
	LDP Extensions", draft-ietf-mpls-generalized-cr-ldp-04.txt		LDP Extensions", draft-ietf-mpls-generalized-cr-ldp-04.txt
	[ISIS-TE] Smit, H., and Li, T., "IS-IS extensions for Traffic		[ISIS-TE] Smit, H., and Li, T., "IS-IS extensions for Traffic
	Engineering", draft-ietf-isis-traffic-02.txt (work in progress)		Engineering", draft-ietf-isis-traffic-02.txt (work in progress)
	[LSP-HIER] Kompella, K., and Rekhter, Y., "LSP Hierarchy with MPLS		[LSP-HIER] Kompella, K., and Rekhter, Y., "LSP Hierarchy with MPLS
	TE", draft-ietf-mpls-lsp-hierarchy-02.txt (work in progress)		TE", draft-ietf-mpls-lsp-hierarchy-02.txt (work in progress)
	[OSPF-TE] Katz, D., and Yeung, D., "Traffic Engineering Extensions to		[OSPF-TE] Katz, D., and Yeung, D., "Traffic Engineering Extensions to
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