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MS-PW Signaling draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

Explore the benefits of extending PW control, using a modified form of LDP, and enabling controlled path discovery in multi-segment PW setups for efficient network path optimization and signaling. This solution addresses various requirements such as architecture, resiliency, QoS, traffic engineering, and security.

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MS-PW Signaling draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

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  1. MS-PW Signalingdraft-shah-bocci-pwe3-ms-pw-signaling-01.txt Matthew Bocci, Mustapha Aissaoui, Jason Rusmisel, Alcatel Himanshu Shah, Ciena Corp Nabil Bitar, Verizon Yetik Serbest, SBC draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  2. Why extend PW control? • Reuse existing PW signaling as far as possible • Use a modified form of LDP – Downstream Unsolicited today • Lightweight protocol to minimize complexity in U-PE and S-PE • LDP already used for L2VPN applications • Tunnel and PW signalling are separate issues • PWs are not regular LSPs draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  3. Guiding Assumptions • Can’t assume U-PEs have full S-PE/U-PE reachability info • Signalling launched by downstream U-PE • For PWs, can’t know full path until label mapping has reached T-UPE • Informed selection of PW path by upstream U-PE who has service knowledge and view of network path/resources • L2VPN service depends on selection of underlying PW network resources • Each hop selects next hop, either: • Controlled path discovery (not flooding) • Blind path search (mandates “crankback”) • Crank back to the source vs. Hop-by hop crank back • Requires source routing to be effective, but don’t have full path info • Objective is to minimise crank back • Same forward and reverse path for OAM • Ability to auto-provision backup path draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  4. Overview of Solution • U-PEs / S-PEs establish T-LDP adjacencies to build PW overlay • U-PEs assume role as active or passive to initiate signaling • MS-PW TLV provides unique key to process MS-PW signaling • <SU-PE, MS-PW-ID, TU-PE> • Peer PW ID: backward compatibility, eliminates need for global PW id • MS-PW established through LDP by sending LM to one or more T-LDP peers in succeeding direction • Controlled path discovery enables T-UPE to choose path with full service knowledge (See later slides) • Intelligent choice of next S-PE through local policies, BGP or other topology information • Only TU-PE can retain multiple labels for backup paths • Unused labels at S-PEs are released immediately for already installed FEC • Release unused labels after primary/backup paths selected draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  5. MS-PW Requirements Addressed by Draft • Architecture • Enables intra and inter-domain PWs with partial tunnel mesh • Resiliency • Tunnel protection with standard PSN mechanisms • S-PE protection • Automatically creates a backup path • T-UPE can choose a backup path that is disjoint • Quality of Service and Class of Service • Supports signaling of PW traffic parameters • Supports forward and reverse CAC at PEs • Traffic Engineering • Next hop selection can be based on end to end knowledge (but not mandated) • MS-PW Setup Mechanisms. • PW Routing: supports both static and dynamic path selection • Can work in a mixed static / dynamic MS-PW environment • Operations and Maintenance (OAM) • Ensures forward/reverse directions take same path • Fully supports existing PW status messaging etc • Security • Supports security mechanisms applicable to LDP draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  6. Main Changes to PW Control • We went with controlled path discovery as opposed to crank-back to source to minimise changes to PW control • Needs concept of active/passive U-PE behaviour • Local impact only • Needs a few additional TLVs: • MS-PW TLV, QoS TLV • Label release if no resources available draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  7. Multi Segment PW – Controlled Path Discovery S-PE:4 S-PE:1 MS-PW FEC TU-PE SU-PE S-PE:2 S-PE:3 • SU-PE does not knowbest path to TU-PE • Downstream • Inter-AS draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  8. Multi Segment PW - Controlled Path Discovery FEC installed Forward/reverse CAC S-PE:4 S-PE:1 Label mappinglaunched to subset of S-PEs TU-PE SU-PE S-PE:2 S-PE:3 • Next hop choice based on: • IP Reachability • Local policy • Static config draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  9. Multi Segment PW - Controlled Path Discovery Unused labels released S-PEs may install one MH-PW FEC if multiplereceived based on e.g. policy S-PE:4 S-PE:1 TU-PE SU-PE S-PE:2 S-PE:3 draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  10. Multi Segment PW - Controlled Path Discovery TU-PE makes primary /backup path choice Uses LDP path trace toensure disjoint paths S-PE:4 S-PE:1 TU-PE SU-PE S-PE:2 S-PE:3 draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

  11. Multi Segment PW – Controlled Path Discovery S-PE:4 S-PE:1 TU-PE SU-PE S-PE:2 S-PE:3 Label mappings launchedin reverse directions S-Pes use bindings from MH-PW FEC draft-shah-bocci-pwe3-ms-pw-signaling-01.txt

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