Hi all, We have a problem observed with sipXecs 4.0 and a beta version of the CounterPath client. The CounterPath client uses the (recently) randomized Expires: value from the 202 Accepted response as the Expires: value in its re-subscribe. This eventually results in the CounterPath client ratcheting the requested Expires: value down to a value that is below the minimum supported.
This triggers XECS-2182: Invalid Min-Expires: value in 423 Subscription Too Brief response, violates RFC 3261 The problem here is that sipXecs supplies a Min-Expires: value that is actually too low. The CounterPath client (reSIProcate stack) uses exactly this value, since it believes the value is acceptable. This causes XTRN-364: Flood of BLF SUBSCRIBEs with Expires: 32 (which is too brief to be accepted) The CounterPath client goes into a loop of sending invalid SUBSCRIBE requests ~8ms apart. If we simply fix XECS-2182 (I think we must) then the XTRN-364 "flood" problem will be alleviated. However, the CounterPath client will still ratchet the re-SUBSCRIBE Expires: value down to the minimum value. This minimum value will become the fixed refresh interval, which will cause unnecessary traffic and un-randomize the expiration. It is clear that the CounterPath client must be fixed to stop ratcheting down its Expires: value. However, it would seem that this problem is in the reSIProcate stack, and CounterPath probably won't be able to quickly deliver a fix. CounterPath has suggested that we workaround the problem with a sipXecs change to return an artificially high Min-Expires: 1800 in the 423 Subscription Too Brief response. This will cause the CounterPath to "reset" its requested Expires: value each time the ratcheting down reaches the minimum supported value. Not ideal, but still an improvement. Does anyone have a strong objection to doing this in the short term? Thanks. -Paul [email protected]
_______________________________________________ sipx-dev mailing list [email protected] List Archive: http://list.sipfoundry.org/archive/sipx-dev Unsubscribe: http://list.sipfoundry.org/mailman/listinfo/sipx-dev
