1. IETF 59, March 2004Mustapha AïssaouiSlide 1 OAM Procedures for VPWS Interworking draft-aissaoui-l2vpn-vpws-iw-oam-00 Mustapha Aïssaoui, Matthew Bocci, David Watkinson, Alcatel Hamid Ould-Brahim, Mike Loomis, Nortel Thomas D. Nadeau, Monique Morrow, Cisco Systems John Z. Yu, Hammerhead Systems Himanshu Shah, Ciena Paul Doolan, Mangrove Systems Peter Busschbach, Lucent Technologies

2. IETF 59, March 2004Mustapha AïssaouiSlide 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

3. IETF 59, March 2004Mustapha AïssaouiSlide 3 Terminology… An end-to-end virtual circuit in a VPWS consists of a 3 segment set: –Ref. Section 3.3 of L2 VPN Framework A VPWS is homogeneous if AC and PW types are the same –E.g., ATM VPWS: A VPWS is heterogeneous if any two segments of the circuit are of different type –E.g., IP interworking VPWS:, or

4. IETF 59, March 2004Mustapha AïssaouiSlide 4 Defect Locations PE 1PE 2 Attachment Circuit (AC) Attachment Circuit (AC) Emulated Service NSP Pseudowire PSN Tunnel CE 2CE 1 PWE NSP a (L2N1)(L2N2) ebc d cf ae bf c d Defect in the L2 network Defect on a PE AC interface Defect on a PE PSN interface Defect in the PSN network

5. IETF 59, March 2004Mustapha AïssaouiSlide 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

6. IETF 59, March 2004Mustapha AïssaouiSlide 6 Homogeneous VPWS OAM Model PE 1PE 2 Attachment Circuit (AC) Attachment Circuit (AC) NSP Pseudowire PSN Tunnel CE 2CE 1 PWE NSP a (L2N1)(L2N2) eb d f PW OAM is a segment of the end-to-end native service OAM PSN OAM Native Service OAM PW OAM cc

7. IETF 59, March 2004Mustapha AïssaouiSlide 7 Heterogeneous VPWS OAM Model PE 1PE 2 Attachment Circuit (AC) Attachment Circuit (AC) NSP Pseudowire PSN Tunnel CE 2CE 1 PWE NSP a (L2N1)(L2N2) eb d f Native service OAM segments and PW OAM segment are independent PSN OAM PW OAM Native Service OAM Native Service OAM cc

8. IETF 59, March 2004Mustapha AïssaouiSlide 8 PW Status A PW is declared DOWN if any of the following conditions are met: 1.A physical layer alarm is detected on the PSN interface 2.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 3.A remote PW status message is received indicating that one or both directions of the PW are down 4.An inband PW OAM connectivity verification, such as VCCV or Y.1711 CV, indicates that one or both directions of the PW are down.

9. IETF 59, March 2004Mustapha AïssaouiSlide 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: 1.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. 2.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. 3.A physical layer alarm is detected on the FR interface. In this case, this status maps across the PE to all corresponding PWs.

10. IETF 59, March 2004Mustapha AïssaouiSlide 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: 1.A physical layer alarm is detected on the ATM interface 2.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)

11. IETF 59, March 2004Mustapha AïssaouiSlide 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: 1.A physical layer alarm is detected on the Ethernet interface

12. IETF 59, March 2004Mustapha AïssaouiSlide 12 OAM Procedures Example 1: Homogeneous VPWS PE 1PE 2 ATM AC NSP ATM PW PSN Tunnel CE 2CE 1 PWE NSP (L2N1)(L2N2) AIS 2RDI a 1

13. IETF 59, March 2004Mustapha AïssaouiSlide 13 OAM Procedures Example 2: Heterogeneous VPWS PE 1PE 2 ATM AC NSP IP PW PSN Tunnel CE 2CE 1 PWE NSP (L2N2) AIS RDI a 1 2 3PW StatusAIS4 RDI5 (L2N1)

14. IETF 59, March 2004Mustapha AïssaouiSlide 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

15. IETF 59, March 2004Mustapha AïssaouiSlide 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