We are seeing a problem where a second SIP session causes the nf conntrack expectation table to be flushed. It looks like for SIP some reference counting is needed. The traces all look like the following. The important part seems to be the second INVITE happening over the same session pair. This is all over UDP, and is using 2.6.32 kernel. . . 10.128.00.62 204.9.06.06 204.9.06.05 10.128.00.120 | | | | | INVITE SDP | | | |------------------------------>| | | | | | | | 100 Trying | | | |<------------------------------| | | | | | | | 180 Ringing | | | |<------------------------------| | | | | | | | 200 OK SDP (telephone-event | | | |<------------------------------| | | | | | | | ACK | | | |------------------------------>| | | | | | RTP | | | |<=============>| | | | | | INVITE SDP | | | |------------------------------>| | | | | | | | 100 Trying | | | |<------------------------------| | | | | | | | 180 Ringing | | | |<------------------------------| | | | | | | | BYE | | | |------------------------------>| | | | | | | | 481 Call Does Not Exist | | | |<------------------------------| | | | | | | | 200 OK SDP | | | |------------------------------>| | | | | | | | ACK | | | |------------------------------>| | | | | | | | BYE | | | |------------------------------>| | | | | | | | 200 OK SDP | | | |------------------------------>| | | | | | | -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html