Thursday, May 3, 2012

SG (SIGNALLING GATEWAY)





Ericsson :

Ericsson MGW works as SG(W) as well.

They interface HSL/TDM links at one end and SIGTRAN on the other side and perform the signaling transfer over traditional/SIGTRAN networks.

The issue is since SIGTRAN don't carry any SLS bit and MGW performs MTP3 functionality (i.e. reads the message and routes to MSC if the DPC is MSC-Server, Ex : POI Links-ISUP / BSSAP/RANAP ), it looses the balancing control and loads SLS -0 to 7 and leaves SLS-8 to 15 on the TDM Side in the ratio of 75% to 25% of total traffic.



Huawei :


When I observed the same in HUAWEI, they do MTP2 analysis at MGW. All signaling messages are sent to MSC-Server. For GCP protocol huawei uses specific interfaces and never mixes any other traffic like ISUP/SCCP on the same HW.
So their software focuses on the end to end analysis rather than do everything. The outcome there is perfect load balancing at TDM Links side.

A Practical Example of SG(W) Functionality:
The following traces and screenshots show the practical involvement SG(W) functionality.
 

 A Mobil Terminating Call Coming from PSTN to Mobile Network where MGW acts as SG(W) (Logical Call Control) :


A Mobil Terminating Call Coming from PSTN to Mobile Network where MGW acts as SG(W) (Phyical Message Flow) :


Note :  Since SGW is an important element in LTE Network, I have updated this post with SG(W) as for Signalling Gateway.


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