Hi Everyone,
Kind of new here, so please don't mind if I ask some absurd or stupid questions :)
We have a small problem for which we are Trying to find the solution. It involves following entities
1. HLR -> Vendor = NSN
2. STP -> Vendor = Huawie
3. USSD GW (This is us) -> SS7 stack Vendor = Tieto
Currently we are handing USSD requests coming from HLR. We have multiple nodes/machines each having it's own GT and PC.
The integration is such that HLR has our VGT [virtual GT: Virtual GT is mapped to the all USSDGW GTs , so that STP can load balance the traffic to USSGW] to which is sends the requests to STP. The STP then does the load balancing the sends the requests to USSGW with RI=SSN, this works fine till the USSD is not interactive. However when the requests are Interactive, i.e. involving multiple dialogues, the the above scenario fails because:
1. STP sends in calledPartyAddress RI= SSN and also sends GT which the VGT (not physical GT) of USSD GW
2. The USSDGW replies in callingPartyAddress with RI=GT and sends back the VGT; same one which is got from STP, does not replace it with physical GT.
3. The Next Dialogue of same session which HLR forwards to STP; STP send RI=SSN but ALSO does load balancing, and hence sends to other USSD GW, causing the dialogue to ABORT as that sessionID does not belong to that USSDGW node.
We have spoken to the Tieto support and they have said when RI=GT is sent, ONLY then the stack can return the physical GT in Callingparty Address forcing the HLR to send the next dialogue of the physical GT thus subsequent requests will land on same USSGW from which the initial response was given.
However, the operator is saying that they cannot sent RI=GT as then they cannot load Balance on STP end.
Can you some please guide here if this is possible on Huawei STP to load balance on GT rather than SSN & DPC?
Regards,
SFA
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