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MPLS additions to RSVP

Tunnel identification

Tunnel parameter negotiation

Routing policy distribution

Routing debugging information

Scalability improvements LSP merging

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Tunnel identification

New Session C-Type

, ,

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)

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Tunnel identification (2)

New Sender_Template

LSP_ID allows a source to share a session

with itself. Useful for reroute and

bandwidth change operations

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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 ObjectSetup & hold priorities

Flags

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Routing policy distribution

EXPLICIT_ROUTE_OBJECT

List of IP addresses for loose or strict source

route

Carries path for session

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Routing debugging information

RECORD_ROUTE_OBJECT

List of systems in the path

Useful for

loop detection & avoidance

debugging policy configuration

Subsequently pinning a route

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TE Setup

Path : ERO (R1->R2->R6->R7->R4->R9) Tunnel ID 5, LSP_ID 1

Resv: Communicates labels and Establishes label OperationsReserves bandwidth on each link

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TE Rerouting - Alternate Path

Setup: Path (R1->R2->R3->R4->R9) Tunnel ID 5, LSP_ID 2

Until R9 gets new Path Message, current Resv is refreshed

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TE - Switching Paths

PopPop

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3849 17

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Resv: Allocates labels for both pathsReserves bandwidth once per link

PathTear Can then be sent to remove old path (and release

resources)

8926

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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)

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Possible approaches

Aggregate refresh messages verbatim

Decreases packet processing overhead

Provides substantial improvement

Trivial modification

Requires a capability bit

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Possible approaches (2)

Transmit a refresh digest (IS-IS model)

Decreases packet processing overhead

Decreases signaling bandwidth

Increased protocol complexity

Need a capability bit

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Possible approaches (3)

Run RSVP on top of TCP (BGP model)

Significant departure from soft state model

Add router-to-router keepalives to provideliveness

Reliability provided hop-by-hop

No refreshes necessaryMust explicitly tear down sessions

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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