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  1. OAM Procedures for VPWS Interworkingdraft-aissaoui-l2vpn-vpws-iw-oam-00Mustapha Aïssaoui, Matthew Bocci, David Watkinson, AlcatelHamid Ould-Brahim, Mike Loomis, NortelThomas D. Nadeau, Monique Morrow, Cisco SystemsJohn Z. Yu, Hammerhead SystemsHimanshu Shah, CienaPaul Doolan, Mangrove SystemsPeter Busschbach, Lucent Technologies Mustapha Aïssaoui

  2. Objective and Scope • Provide OAM procedures for the Virtual Private Wire Service (VPWS) • An outstanding deliverable of the L2 VPN WG (item 5 in charter) • Draft covers the following VPWS: • Homogeneous VPWS of ATM, FR, and Ethernet types • This part will be moved to draft-nadeau-pwe3-oam-msg-map-04 as both drafts converged on many aspects • Heterogeneous VPWS • IP interworking VPWS (ARP-mediation) • FR-ATM Interworking VPWS • Ethernet interworking VPWS • Draft builds on PWE3 encapsulation and control procedures Mustapha Aïssaoui

  3. Terminology… • An end-to-end virtual circuit in a VPWS consists of a 3 segment set: <AC, PW, AC> • Ref. Section 3.3 of L2 VPN Framework • A VPWS is homogeneous if AC and PW types are the same • E.g., ATM VPWS: <ATM AC, ATM PW, ATM AC> • A VPWS is heterogeneous if any two segments of the circuit are of different type • E.g., IP interworking VPWS: <ATM AC, IP PW, ATM AC>, or <ATM AC, IP PW, FR AC> Mustapha Aïssaoui

  4. a d b e b a e d c c c f f Defect Locations Attachment Circuit (AC) PSN Tunnel Attachment Circuit (AC) Pseudowire PE 1 PE 2 CE 1 CE 2 NSP PWE PWE NSP (L2N1) (L2N2) Emulated Service Defect in the L2 network Defect on a PE PSN interface Defect on a PE AC interface Defect in the PSN network Mustapha Aïssaoui

  5. VPWS OAM Interworking Models • Homogeneous VPWS • AC link layer not terminated at PE • Native service OAM must run inband transparently over PSN tunnel: • it is used for both AC and PW defect indication • Referred to as homogeneous VPWS OAM model • Exceptions: FR and Ethernet VPWS for a lack of inband OAM • Heterogeneous VPWS • AC link layer terminated at PE • Native service OAM always terminates at the AC endpoint in a PE • requires PW specific defect indication • Out-of-band PW status signaling is used • Referred to as heterogeneous VPWS OAM model • Exception: FR-ATM interworking VPWS when PW is of ATM type Mustapha Aïssaoui

  6. b d a e c c f Homogeneous VPWS OAM Model Attachment Circuit (AC) PSN Tunnel Attachment Circuit (AC) Pseudowire PE 1 PE 2 CE 1 CE 2 NSP PWE PWE NSP (L2N1) (L2N2) Native Service OAM PW OAM PSN OAM PW OAM is a segment of the end-to-end native service OAM Mustapha Aïssaoui

  7. b d a e c c f Heterogeneous VPWS OAM Model Attachment Circuit (AC) PSN Tunnel Attachment Circuit (AC) Pseudowire PE 1 PE 2 CE 1 CE 2 NSP PWE PWE NSP (L2N1) (L2N2) Native Service OAM Native Service OAM PW OAM PSN OAM Native service OAM segments and PW OAM segment are independent Mustapha Aïssaoui

  8. PW Status A PW is declared DOWN if any of the following conditions are met: • A physical layer alarm is detected on the PSN interface • The status of the PSN tunnel is DOWN as a result of: • A defect in a PSN tunnel OAM connectivity verification (e.g., LSP-Ping, Y.1711 CV) • A PE receiving Y.1711 FDI/BDI over a MPLS tunnel • A PE receiving a RSVP-TE PathErr message • A remote PW status message is received indicating that one or both directions of the PW are down • An inband PW OAM connectivity verification, such as VCCV or Y.1711 CV, indicates that one or both directions of the PW are down. Mustapha Aïssaoui

  9. FR AC Status • FR OAM in Deployment Networks: • PVC management, Q.933 Annex A, widely used over UNI • FRF.19 specifies a more extensive inband OAM capability but has little known deployments • A FR AC is declared DOWN if any of the following conditions are met: • A PVC is not ‘deleted’ from the Frame Relay network and the Frame Relay network explicitly indicates in a full status report (and optionally by the asynchronous status message) that this Frame Relay PVC is ‘inactive’. In this case, this status maps across the PE to the corresponding PW only. • The LIV indicates that the link from the PE1 to the Frame Relay network is down. In this case, the link down indication maps across the PE to all corresponding PWs. • A physical layer alarm is detected on the FR interface. In this case, this status maps across the PE to all corresponding PWs. Mustapha Aïssaoui

  10. ATM AC Status • ATM OAM in Deployment Networks: • I.610 provides a complete set of OAM capabilities • Defect indication (AIS/RDI), continuity checking (CC), and loopback verification (LB) widely used • Performance monitoring becoming a carrier’s requirement • An ATM AC is declared DOWN if any of the following conditions are met: • A physical layer alarm is detected on the ATM interface • A PE receives an F4/F5 AIS/RDI OAM cell indicating that the ATM VP/VC is down in the adjacent L2 ATM network (e.g., L2N1 for PE1) Mustapha Aïssaoui

  11. Ethernet AC Status • Ethernet link layer management and service OAM standards are at their early development stage • An Ethernet AC is declared DOWN if any of the following conditions are met: • A physical layer alarm is detected on the Ethernet interface Mustapha Aïssaoui

  12. 1 2 a OAM Procedures Example 1: Homogeneous VPWS PSN Tunnel ATM AC ATM AC ATM PW PE 1 PE 2 CE 1 CE 2 NSP PWE PWE NSP (L2N1) (L2N2) AIS RDI Mustapha Aïssaoui

  13. 1 2 a 3 4 5 OAM Procedures Example 2: Heterogeneous VPWS PSN Tunnel ATM AC ATM AC IP PW PE 1 PE 2 CE 1 CE 2 NSP PWE PWE NSP (L2N1) (L2N2) AIS PW Status AIS RDI RDI Mustapha Aïssaoui

  14. Performance and Scalability Considerations • A flooding of alarms on the ACs may result in a large number of PW status signaling messages generated by a PE • could impact performance of MPLS control plane • A method for aggregating PW status messages is one possible solution Mustapha Aïssaoui

  15. Next Step • Align homogeneous VPWS OAM in this draft and in draft-nadeau-pwe3-oam-msg-map-04 • present to both PWE3 and L2VPN WGs • Progress heterogeneous VPWS OAM in the L2 VPN working group • aligned with work in the MPLS and FR Alliance • Discuss status in PWE3 Mustapha Aïssaoui