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ATM OAM (Operation And Maintenance Principles and Functions)

ATM OAM (Operation And Maintenance Principles and Functions). S. Y. Yang. Contents. ATM OAM Recommendation , I.610. History & Reference. I.610 (03/93) UNI3.1 (1994) I.610 (11/95) I.610 (02/99) I.630 (02/99) B-ISDN Workshop 97,98 by D.Y. Kwak. I.610 Seminar(97) TP by S.Y. Yang.

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ATM OAM (Operation And Maintenance Principles and Functions)

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  1. ATM OAM(Operation And Maintenance Principles and Functions) S. Y. Yang

  2. Contents • ATM OAM Recommendation , I.610.

  3. History & Reference • I.610 (03/93) • UNI3.1 (1994) • I.610 (11/95) • I.610 (02/99) • I.630 (02/99) • B-ISDN Workshop 97,98 by D.Y. Kwak. • I.610 Seminar(97) TP by S.Y. Yang.

  4. OAM principles • Performance Monitoring • Defect and Failure Detection • Defect : Interruption of the capability • Failure : Termination of the capability • System Protection • Defect Information • Fault Localization

  5. OAM functions are performed by the layer management. The results may be provided to the plane management or to the adjacent higher layer. Relationship of OAM functions with B-ISDN PRM

  6. OAM levels and flows • OAM levels in the B-ISDN • Virtual channel level • Virtual path level • Transmission path level • Digital section level • Regenerator section level • The OAM functions of a missing level are performed at the next higher level.

  7. OAM Hierarchy

  8. Physical Layer F1 : regenerator section level F2 : digital section level F3 : transmission path level ATM Layer F4 : virtual path level F5 : virtual channel level OAM flows are bidirectional. The entire ATM VPC/VCC VPC/VCC segment Mechanisms for OAM flows SDH: G.707 to 709,G782,G783, Cell-based:I.432, PDH: G.702,G.804, G.832

  9. VPC/VCC Segment • one single VP/VC bidirectional link connection; • one single VP/VC bidirectional matrix connection; • a concatenation of VP/VC bidirectional link connections and VP/VC bidirectional matrix connections.

  10. Possible segment configurations.

  11. End-to-end F4 flow Segment F4 flow End-to-end F5 flow Segment F5 flow OAM Flows(1)

  12. OAM Flows (2) • One or more segment may be defined along a VPC/VCC. • Neither overlapped nor embedded VPC/VCC segments can be defined. • Any CP can be configured as a source/sink of a segment.

  13. ATM layer OAM functions

  14. AIS : End-to-end AIS • The ATM NE which detects VPC/VCC defect shall generate and send e-t-e AIS cells on all affected active VPC/VCCs. • Receiving low level defect indications; • detecting LOC at segment sink endpoint.

  15. AIS : End-to-end AIS • E-t-e AIS cells are generated and transmitted ASAP after detection of a defect, and are transmitted periodically (1 cell/s) during the defect condition. • E-t-e AIS cell generation shall be stopped as soon as the defect indications are removed. • E-t-e AIS cells are detected at the VPC/VCC sink-point. • E-t-e AIS cells may be non-intrusively monitored at CPs along the VPC/VCC. • E-t-e AIS state is declared at the VPC/VCC endpoint or intermediate CPs along the VPC/VCC as soon as a e-t-e AIS cell is received or lower level defect or LOC is detected. • E-t-e AIS state is release when a user cell or e-t-e CC cell is received. • E-t-e AIS state is also released if e-t-e AIS cells are absent for 2.5 +/- 0.5 sec. ( If CC activated, 3.5 +/- 0.5 sec).

  16. Example

  17. AIS : Segment AIS • Network Operator Option. • The ATM NE which detects the VPC/VCC defect within an OAM segment shall generate and send seg AIS cells in addition to e-t-e AIS cells on all affected active VPC/VCCs. • Segment endpoints and CPs outside of an OAM segment should not generate seg AIS cells. • Each CP can be configured by TMN as either being within a segment or not within a segment. • The default value for each CP of the node is within a segment.

  18. RDI : End-to-end (Seg) RDI • E-t-e RDI is sent to the far end from VPC/VCC endpoint as soon as it has declared a e-t-e AIS state.(1 cell/s) • E-t-e RDI cell generation shall be stopped as soon as the e-t-e AIS state released. • E-t-e RDI cells are detected at the VPC/VCC endpoint and e-t-e RDI state is declared after the reception of one e-t-e RDI cell. • E-t-e RDI cells may be non-intrusively monitored at CPs along the VPC/VCC. • E-t-e RDI state is released at the VPC/VCC endpoint when no e-t-e RDI cell is received during a nominally 2.5 +/- 0.5 sec.

  19. Continuity Check • CC can be simultaneously carried out end-to-end or at segment level on a certain number of selected active VPC/VCCs. • Two alternative mechanisms. • CC cells are sent when no user cells have been sent for a 1 sec. • CC cells are sent repetitively with a periodicity of 1 cell/s independent of the user cell flow. • When the VPC/VCC sink-point with CC activated does not receive any user cell or CC cell with in 3.5 +/- 0.5 sec, it will declare the AIS state due to a LOC defect. • When the VPC/VCC segment sink-point does not receive any user cell or CC cell with in 3.5 +/- 0.5 sec, it will declare a LOC defect and start transmitting e-t-e AIS cells in the forward direction. • During a LOC defect, to avoid a duplication of e-t-e AIS cell flows , the segment sink point shall not insert additional e-t-e AIS cells if it already is receiving and forwarding e-t-e AIS cells.

  20. Loopback(PING) • LB cells can be inserted at CPs, segment endpoints, connection endpoints. • Seg LB cells can be looped back at CPs. • The waiting time is 5 secs. • E-t-e LB cells shall not be looped back at CPs.

  21. Loopback(PING)

  22. Loopback Applications

  23. Loopback Applications

  24. Loopback Applications

  25. Loopback Applications

  26. Multiple Loopback

  27. Performance Monitoring • PM of a VPC/VCC or segment is performed by inserting monitoring cells at the ends of the VPC/VCC or segment, respectively. • PM shall be done by monitoring blocks of user cells. • The block size N may have value 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768.

  28. PM/CC Activation/Deactivation • Activation Procedure

  29. PM/CC Activation/Deactivation • Deactivation Procedure

  30. ATM layer OAM cell format

  31. ATM layer OAM cell format

  32. ATM layer OAM cell format : LID(Location ID)

  33. ATM layer OAM cell format

  34. ATM layer OAM cell format : FPM & BR MCSN : Monitoring Cell Sequence Number TUC0+1 : Total User Cell number related to the CLP0+1 BEDC0+1 : Block Error Detection Code related to the CLP0+1 TUC0 : Total User Cell number related to the CLP0 TSTP : Time Stamp SECBC : Severely Errored Cell Block Count TRCC0 : Total Received Cell Count related to the CLP0 BLER0+1 : Block Error Result

  35. ATM layer OAM cell format :Act/Deact

  36. Feasible Implementation CAC should take care of the presence of OAM flows.

  37. Summary • ATM OAM Recommendation, I.610.

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