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MPLS additions to RSVP

MPLS additions to RSVP. Tunnel identification Tunnel parameter negotiation Routing policy distribution Routing debugging information Scalability improvements LSP merging. Tunnel identification. New Session C-Type <Dest_Address>, <Tunnel ID>, <Extended_Tunnel_ID>

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MPLS additions to RSVP

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  1. MPLS additions to RSVP • Tunnel identification • Tunnel parameter negotiation • Routing policy distribution • Routing debugging information • Scalability improvements • LSP merging

  2. Tunnel identification New Session C-Type • <Dest_Address>, <Tunnel ID>, <Extended_Tunnel_ID> • Semantics are that the complete filter specification is the Label • Extended Tunnel ID can be used to scope session to a single source router (i.e. ensure globally unique tunnel identification)

  3. Tunnel identification (2) New Sender_Template • <Src_Address><LSP_ID> • LSP_ID allows a source to ‘share’ a session with itself. Useful for reroute and bandwidth change operations

  4. Tunnel parameter negotiation • LABEL_REQUEST object • Carries L3 protocol ID to describe contents of the tunnel • Range of acceptable label values • LABEL object • Carries selected label value • Session Attribute/Policy Object • Setup & hold priorities • Flags

  5. Routing policy distribution • EXPLICIT_ROUTE_OBJECT • List of IP addresses for loose or strict source route • Carries path for session

  6. Routing debugging information • RECORD_ROUTE_OBJECT • List of systems in the path • Useful for • loop detection & avoidance • debugging policy configuration • Subsequently pinning a route

  7. TE Setup R9 R8 R3 R4 R2 Pop R5 R1 32 49 R6 R7 17 22 Path : ERO (R1->R2->R6->R7->R4->R9) Tunnel ID 5, LSP_ID 1 Resv: Communicates labels and Establishes label Operations Reserves bandwidth on each link 0401_10F8_c1 UUnet-9803 40

  8. TE Rerouting - Alternate Path R9 R8 R3 R4 R2 Pop R5 R1 32 49 R6 R7 17 22 Setup: Path (R1->R2->R3->R4->R9) Tunnel ID 5, LSP_ID 2 Until R9 gets new Path Message, current Resv is refreshed 0401_10F8_c1 UUnet-9803 43

  9. TE - Switching Paths R9 R8 R3 R4 R2 Pop Pop 26 89 R5 R1 32 38 49 R6 R7 17 22 Resv: Allocates labels for both paths Reserves bandwidth once per link PathTear Can then be sent to remove old path (and release resources) 0401_10F8_c1 UUnet-9803 44

  10. RSVP scaling issues • Refresh packets scale linearly with the number of sessions • Sending lots of little packets has high overhead • Sessions need not be refreshed independently • Still need capacity to deal with peak signaling events (e.g., link failure)

  11. Possible approaches • Aggregate refresh messages verbatim • Decreases packet processing overhead • Provides substantial improvement • Trivial modification • Requires a capability bit

  12. Possible approaches (2) • Transmit a refresh digest (IS-IS model) • Decreases packet processing overhead • Decreases signaling bandwidth • Increased protocol complexity • Need a capability bit

  13. Possible approaches (3) • Run RSVP on top of TCP (BGP model) • Significant departure from ‘soft state’ model • Add router-to-router ‘keepalives’ to provide liveness • Reliability provided hop-by-hop • No refreshes necessary • Must explicitly tear down sessions

  14. LSP merging • Merging: multi-point to point LSPs • Work in progress • Automatic merging of ‘compatible’ LSPs • e.g. same ERO • Merging is ‘voluntary’ - can disable • Sources initiate LSPs, control compatibility • Input welcome

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