CSGSN & CCN communication probem

	Network: GSM
	Service: GPRS
	Node: WPP CGSN 4.0
	CAMEL Subscribers cannot perform PDP context activation
	PDP context activation request failure
	Requested service option not subscribed
	Timeout waiting for CCN to reply
	SS7TRACE: TCAP:1 mIETtcap.c 15014
	TCAP: ERROR IN DIALOGUE IDENTITY A continue or abort message has been received from a remote node for a non-existing dialogue.
	Integrating CAMEL version 3 and CCN
	The communication between the SGSN and GGSN is working fine. Once the PDP tunnel is set up, the SGSN will send a sent_camel_gprs_pdp_context_est_ack to the CCN that the session is established. Unfortunately there is a timeout waiting for the CCN to respond.   The CCN sends the ss7 reply message with routing on GT of the CGSN. But since it uses routing on GT to the CGSN, it will match the GT rule which uses ssn 149. There is no GT rule for ssn 146. Since the dialogue for ssn 149 does not exist, you will see the following alarm in ss7trace.log; ****  TCAP:1 mIETtcap.c  2532    1   21    1  107  15014 TCAP: ERROR IN DIALOGUE IDENTITY A continue or abort message has been received from a remote node for a non-existing dialogue. Instead the CCN should use routing on ssn when routing towards the CGSN. This can be achieved by enabling termination indication for the ss7 sccp route to the CGSN.
	SOLUTION:   CONDITIONS: Camel interface is configured between the CGSN and the CCN PROCEDURE: In the CCN configure the ss7 route towards the CCN to use termination indication (ie termination indicator = yes).
	PDP context activation was failing with;   2006-07-21 16:37:24 Camel_test Event name: activate_pdp_failed_event ; Event details: – ; Cause Value: #requested_service_option_not_subscribed (33) ; IMSI: 413010239000002 ; MSISDN: 94716758432 ; NSAPI: 5 ; Routing Area Code: 1 ; Cell Global Identity: 413-1-1000 0-273 The communication between the SGSN and GGSN is working fine. Once the PDP tunnel is set up, the SGSN will send a sent_camel_gprs_pdp_context_est_ack to the CCN that the session is established. Unfortunately there is a timeout waiting for the CCN to respond. Erlang tracing was done on the camel erlang modules; trace:start([return,caller,subscriber]). trace:activate_imsi(413010239000002). trace:activate(["^cmd","^cga","^gsf","^gdm","^ssf","^cas"]). trace:activate(["^msm","^map"]). You will see the following from the erlang trace; call msmad:dp_release(undef_l,5,’application-timer-expired’) from nsfwos_dyn:handle_cast/2 07:45:55,275: (2_20,gss_ConServP,Cid 4414224) return gdmhan:gd_transmit_rq/4 -> {noreply,undef_l} 07:45:59,269: (2_20,gss_ConServP,Cid 4414224) call gdmhan:tc_l_cancel_ind(undef_l,146,15121,1) from nsfwos_dyn:handle_cast/2 07:46:05,275: (2_20,gss_ConServP,Cid 4414224) call gsfssf_s2:timeout(undef_l,{timerRef,#Ref<0.0.132.259827>,<0.26321.1>}) from nsfwos_dyn:handle_cast/2
	When activating sccp tracing we can see the following. The camel req msg goes like this;   CGSN——>STP———–>CCN 2976      2988          3008 called addr = 3008, routing on ssn 146 calling addr = 947100006, routing on GT The CCN accepts this message and replies to the CGSN; CCN—————>CGSN 3008              2976 called addr = 947100006, routing on GT calling addr = 2976, routing on ssn 146 #NOTE the ss7 return route doesn’t go through the original route, but this doesn’t matter. #NOTE gsh create_ss7_sccp_gtrule -rn GtRule77 -tn GtTranslator1 -addr 947100053 -ti 1 -tis 0 -en EntitySet3, the termination indication here is set to yes – route on ssn because the CCN uses ssn 11 and 146 for same addr 947100053. But since it uses routing on GT to 947100006, it will match the gtrule gsh create_ss7_sccp_gtrule -rn GtRule3 -tn GtTranslator1 -addr 947100006 -ti 0 -tis 0 -en EntitySet2 gsh create_ss7_sccp_entityset_local -en EntitySet2 -opc 2976 -ssn 149 But since ssn 149 is configured, the ss7 stack will send it on ssn 149 to the SGSN application. But no dialogue exists for ssn 149, the dialogue is for 146. Then you will see the following alarm in ss7trace.log; ****  TCAP:1 mIETtcap.c  2532    1   21    1  107  15014 TCAP: ERROR IN DIALOGUE IDENTITY A continue or abort message has been received from a remote node for a non-existing dialogue. SOLUTION ———- The way to solve this is to configure the CCN to use termination indicator set to YES when routing to the CGSN. This will force it to route on SSN instead of GT. Therefore it will not match GtRule3 anymore, but it will match (N1 section); gsh create_ss7_sccp_local_sap -opc 2976 -ssn 146 -nocon 0 Since the CGSN is a live node, we didn’t make any changes on the CGSN, we changed the CCN instead (CCN is not live). Now PDPCA is working and SMS over GPRS is too.

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Tags: ccn, SGSN