Generalized MPLS SignalingSPVC Service
The problem
Requirements
Recovery
rules out simple splicing
Minimal or no change to ATM software
Simple solution needed soon
Terminology
MPLS
Solution Elements / Issues
MPLS / ATM Interface
PWE Identifiers
Two Identifiers for circuit
SAI - Source Attachment Identifier
TAI - Target Attachment Identifier
Structure of SAI, TAI
AGI - Attachment Group Identifier
AII - Attachment Individual Identifier
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Mismatched Identifiers
SPVC IE -> DLCI or VPI/VCI
PWE3
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NSAP Format
ESI
Mapping Identifiers
Mapping Identifiers (2)
SPVC IE carries DLCI or VPI / VCI
Two special AGIs are defined to indicate format of the TAII
AGIfr -> <ESI><DLCI>
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MPLS / ATM Interface
Interface between ATM and MPLS is AINI or UNI / IISP
MPLS network is modeled as a Multi-homed ATM Host (with lots of addresses)
All AEs advertise the same single NSAP prefix for the MPLS Network
Prefix ::= <IDP for IPv4><IP Net Prefix>
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Re-assembly & ATM / FR IWF
PNNI / Q.2931
Label Mapping
ATM / FR Interworking, FRF5, FRF 8.1 configured at PAE and/or PME
Pseudo-wire encapsulation selected on basis of Re-assembly
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Quality of Service (QoS)
Forward MPLS QoS inferred from ATM Signaling
Reverse MPLS QoS configured at PME because LDP is uniditectional
Forward & Reverse ATM QoS carried in ATM Signaling
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Configuration
PMEs: AGIs and (T)AII (note AII indicates both interface and DLCI or VPI/VCI)
PAEs: NSAP and DLCI or VPI/VCI
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SPVC Setup
Called Party address
Interface encoded in ESI
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ATM Setup: PAE to ME
PAE uses normal procedures
Setup message formatted and sent
Call is routed through a UNI to a ME
ME terminates ATM call
ATM Setup: PAE to ME
MPLS
PNNI / Q.2931
MPLS Setup: ME to MPE
LDP session created to MPE loopback (if not already setup)
TAII created by formatting ESI + DLCI or ESI + VPI/VCI
SAII mapped based on incoming Port & VPI/VCI
Signals L2VPN FEC with AGI + TAII
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MPLS Setup: MPE to ME
MPLS
Label Mapping
Label Mapping
of SAI and TAI reversed
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SPVC Setup Completion
PME uses TAII to identify interface and DLCI or VPI/VCI (could be literal or symbolic)
PME responds with reverse setup
ME then completes the ATM call
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ATM Setup: ME to PAE
MPLS
Q.2931 / PNNI
Recovery
MPLS
X
Conclusions
Wide deployment of PWE3 will not happen without a tractable transition plan
Proposal places all functions within boxes in PSN (don’t expect ATM vendors to be highly motivated to assist in the transition)
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Thank You
