1. 1 MPLS –TP Fault OAM draft-ietf-mpls-tp-fault-03 George Swallow swallow@cisco.com IETF79 November 2010

2. 2 Changes  Restricted Range on Timer values  New section on minimum implementation requirements Basically what is expected of a pure transport box  Clarified text on setting LDI flag  General editing

3. 3  Issue arises when a fault times out but BFD does not come back up When do you cease suppressing alarms?  Consider an LSP from A to D Timer Values ABCD

4. 4 Scenario ABCD Link B-C fails BFD goes down B sends AIS/LDI to A (not necessarily in that order) A raises a yellow alarm Link C-D fails C “sends” AIS/LDI to A with a long timeout Link B-C comes up B clears AIS (or AIS times out) BFD does not come up When does A raise a red alarm? X X

5. 5 Solution  To bound the time that A needs to wait limit maximum time between successive AIS messages  Proposed max value is 20 seconds If you allow for three periods this bounds it at 1 minutes  For comparison Y.1731 allow a max value of 1 minute

6. 6 Minimum Implementation Requirements 1.Sending AIS and LKR messages at a rate of 1 per second. In particular other values of the Refresh Timer and setting the R flag to value other than zero need not be supported. 2.Support of setting the LDI flag. 3.Receiving AIS and LKR messages with any allowed Refresh Timer value

7. 7 1.Support of receiving the LDI flag. 2.Support of receiving the R flag. 3.All TLVs. Items optional to implement

8. 8 Next Steps  Request last call