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MPLS Signaling Extensions for Upstream Label Assignment

This document presents the extensions to MPLS signaling protocols for supporting upstream label assignment, allowing for efficient support of multipoint interfaces and P2MP hierarchy. It provides a mechanism for advertising, requesting, and distributing upstream assigned labels.

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MPLS Signaling Extensions for Upstream Label Assignment

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  1. MPLS signaling extensions for Upstream Label Assignment draft-raggarwa-mpls-ldp-upstream-00.txt draft-raggarwa-mpls-rsvp-upstream-00.txtRahul Aggarwal (Juniper Netwroks) Jean-Louis Le Roux (France Telecom) IETF 64, Vancouver, MPLS WG, 11/08/2005

  2. Background (1) • Architecture for upstream label assignment is defined in draft-raggarwa-mpls-upstream • MPLS Multicast encapsulation defined in draft-rosen-mpls-multicast-encaps • If for a given FEC F, Ru is the upstream LSR and Rd the downstream LSR • Downstream Assigned label = The label is distributed by Rd to Ru • Upstream Assigned label = The label is distributed by Ru to Rd • Upstream assigned label are looked up in a context specific ILM • The context can be, e.g., the Upstream Neighbor or the tunnel over which MPLS packets may be received • Various applications such as: Multicast VPN, avoiding branch LSR replication on multipoint interfaces (LAN, IP Multicast tunnel), and P2MP MPLS Hierarchy

  3. Background (2) • Extensions to MPLS signaling protocols are required to support upstream label assignment • Need for a mechanism allowing an LSR to advertise to its neigbours whether it supports upstream label assignment • Need for a mechanism to request & distribute upstream assigned labels • A P2MP LSP may be encapsulated in an IP Multicast tunnel or another P2MP LSP =>This requires to signal the id of the underlying IP or MPLS tunnel • draft-raggarwa-mpls-ldp-upstream & draft-raggarwa-mpls-rsvp-upstream define respectively LDP and RSVP extensions to support these functions • This is a result of a split of draft-raggarwa-mpls-rsvp-ldp-upstream that was presented in Paris • These are companion documents to the Upstream label assignment Architecture and Encapsulation drafts

  4. draft-raggarwa-mpls-ldp-upstream • Advertisement of Upstream Label assignment capability • Definition of a capability TLV, and Upstream Label Assignment sub-TLV to be carried in the Initialization message • Request & Distribution of Upstream Assigned Labels • Definition of an Upstream Assigned Label Request TLV to be carried within a Label Request message • Definition of an Upstream Assigned Label TLV to be carried within a Label Mapping/Release/Withdraw message • A LDP P2MP LSP maybe tunneled in a RSVP-TE P2MP LSP • A new RSVP-TE P2MP tunnel sub-TLV is defined for the Interface ID TLV • It carries the P2MP session and sender objects of the outer RSVP-TE P2MP tunnel

  5. draft-raggarwa-mpls-rsvp-upstream • Advertisement of Upstream Label assignment capability • A new capability bit is defined in the CAPABILIY object carried in an Hello message • Distribution of Upstream Assigned Labels • Definition of an UPSTREAM_ASSIGNED_LABEL object, to be carried within a Path • A RSVP-TE P2MP LSP maybe tunneled in another RSVP-TE P2MP LSP • A new RSVP-TE P2MP tunnel TLV is defined for the IF_ID RSVP-HOP object • It carries the P2MP session and senders objects of the outer RSVP-TE P2MP LSP • Allow binding the inner and outer RSVP-TE P2MP LSPs • This mechanism extends LSP hierarchy to P2MP LSPs

  6. Path Resv Path UAL 25 Path Resv Resv Lbl 40 Resv Lbl 33 Resv Lbl 18 Path Path UAL 25 40 33 18 25 25 25 draft-raggarwa-mpls-rsvp-upstreamRSVP-TE P2MP LSPs on LAN interfaces RSVP-TE P2MP LSP From R1 to {L1, L2) • Upstream Label assignment allows a branch LSR to send a single copy of a packet on a LAN interface of a P2MP LSP => bandwidth savings • Encapsulation follows procedure in draft-rosen-mpls-multicast-encaps L1 R2 B1 B1 ILM to NHLFE 25-> if 2, lbl 40 R1 ILM-to-NHLFE 18-> if 2, lbl 25 R3 L2 B1 ILM-to-NHLFE 25-> if 2, lbl 33

  7. Next steps • Straightforward LDP and RSVP-TE extensions for Upstream Label Assignment • Allows for efficient support of multipoint interfaces and P2MP Hierarchy • Need for WG feedback • WG doc?

  8. ThanksQuestions?

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