I am hitting a SIP issue with CUCM 8.6.2 integrated with Exchange 2010 UM using TLS.
About 10% of calls fail and just keep ringing when dialling the pilot.
We found SIP is entering a race condition as it does not receive a DNS reply in time in between the Ringing and 200 OK received.
TAC recommended to try and configure Exchange to delay the 200 OK if possible.
Does anyone know if this can be done?
What dns query is CUCM waiting on at that stage of the call? The only dns requirement I'm aware of is if the trunk is configured with a fqdn as the destination address rather than an IP address, at which point the dns query would need to be resolved before the invite is sent.
Sent from Cisco Technical Support iPad App
Trunks have IP's as destination but we found with TAC SIP is doing a DNS lookup on the hostname in the 'Contact' Field of both the 'Ringing and 200 OK' receives from Exchange UM, which TAC mentioned is like a security check.
Eg below, (i have X'd out the hostname)
15:09:24.394 |//SIP/Stack/Event/0x0/Queued event from SIP SPI : SIPSPI_EV_DNS_RESOLVE|2,100,63,1.20765994^10.60.11.18^*
15:09:24.394 |//SIP/Stack/States/0xfdf1040/0xfdf1040 : State change from (STATE_RECD_PROCEEDING, SUBSTATE_PROCEEDING_PROCEEDING) to (STATE_RECD_PROCEEDING, SUBSTATE_SENT_DNS)|2,100,63,1.20765994^10.60.11.18^*
15:09:24.394 |//SIP/Stack/States/0xfdf1040/0xfdf1040 : State change from (STATE_RECD_PROCEEDING, SUBSTATE_SENT_DNS) to (STATE_RECD_PROCEEDING, SUBSTATE_SENT_DNS)|2,100,63,1.20765994^10.60.11.18^*
15:09:24.394 |//SIP/Stack/Info/0xfdf1040/Transaction Complete. Lock on Facilities released.|2,100,63,1.20765994^10.60.11.18^*
15:09:24.394 |//SIP/Stack/Info/0xfdf1040/No cached request event|2,100,63,1.20765994^10.60.11.18^*
15:09:24.394 |//SIP/SIPD(2,73,71)/ccbId=0/scbId=0/getKeyBasedOnCiAndBranch: AddressingElement branch is 0 and ci is 33622859 mapKey is 33622859|2,100,63,1.20765994^10.60.11.18^*
15:09:24.394 |//SIP/SIPD(2,73,71)/ccbId=0/scbId=0/getCdpcPidGivenCcbidAndCi: found Cdpc Pid (2,100,74,287797) for mapKey 33622859|2,100,63,1.20765994^10.60.11.18^*
15:09:24.394 |//SIP/SIPDns(2,72,1)/convertQueryType: Converted Query ReqType 1|2,100,63,1.20765994^10.60.11.18^*
15:09:24.394 |//SIP/SIPDns(2,72,1)/copySpiToSdl: DNS req type 3, query preferred type 0|2,100,63,1.20765994^10.60.11.18^*
5:09:24.398 |//SIP/SIPDns(2,72,1)/wait_SdlDnsSrvRecordRsp: Received SdlDnsSrvRecordRsp ReqCode is 0|0,0,0,0.0^*^*
15:09:24.398 |//SIP/SIPDns(2,72,1)/printRRlist: A Record: 10.60.11.18|0,0,0,0.0^*^*
15:09:24.398 |//SIP/SIPDns(2,72,1)/selectElementFromQueryResult: Query Result ReqType 1|0,0,0,0.0^*^*
15:09:24.398 |//SIP/SIPDns(2,72,1)/copySdlDnsSrvRecordRspToSpi: ReqType is 1|0,0,0,0.0^*^*
15:09:24.398 |//SIP/SIPDns(2,72,1)/wait_SdlDnsSrvRecordRsp: (IpAddress):hostname=XXXXXXXXXXXX,IP=10.60.11.18:0,next query=0|0,0,0,0.0^*^*
15:09:24.398 |//SIP/SIPHandler/ccbId=0/scbId=0/addHostToHostSet: IP addr=10.60.11.18, hostname=XXXXXXXXXXX|0,0,0,0.0^*^*
15:09:24.398 |//SIP/Stack/Info/0x0/ccsip_spi_get_msg_type returned: 2 for event 44|0,0,0,0.0^*^*
15:09:24.398 |//SIP/Stack/States/0xfdf1040/0xfdf1040 : State change from (STATE_RECD_PROCEEDING, SUBSTATE_SENT_DNS) to (STATE_RECD_PROCEEDING, SUBSTATE_NONE)|0,0,0,0.0^*^*
Since this DNS lookup on the 'Contact' field is really a security check, does anyone know if it can be disabled on CUCM?