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Bug #6189

closed

SCCPLite: Support mgw pool feature

Added by pespin 5 months ago. Updated 5 months ago.

Status:
Resolved
Priority:
Normal
Assignee:
Category:
-
Target version:
-
Start date:
09/22/2023
Due date:
% Done:

100%

Spec Reference:

Description

Right now the mgw pool feature (with more than 1 configured/ready MGW) only works with AoIP.

The expalantion can be found in this commit description:
https://gitea.osmocom.org/cellular-infrastructure/osmo-bsc/commit/da4af65a51ee8b8d7b380330c0301de293347563

The failing scenario described there can be found by running TTCN3 test BSC_Tests.TC_mgwpool_all_used in the ttcn3-bsc-test-sccplite testsuite.
The first call properly does everything through first MGW (port 2427). The second call starts properly using second MGW (port 2428) to set up the BTS-side connection, but then, when the MSC sends the IPA-encapsulated MGCP to osmo-bsc, it forwards it to the first MGW (port 2427), which is wrong, since it should be forwarded to the second MGW.

So in summary, what happens:
  1. BSC <- MSC: AssignmentRequest(CIC=1) // This CIC indicated by the MSC to the BSC the MGW endpoint to use, which means its unique per MSC
  2. (BSC selects an MGW from the pool, sets up the BTS-side conn on MGW endpoint=CIC=1)
  3. BSC -> MSC: ASsignmentCompelte
  4. BSC <-> MSC: IPA
  5. BSC should be able to remember CIC=1 from that MSC links to a specific MGW it selected previously, and submit the MGCP to it.

I attacha sample run of BSC_Tests.TC_mgwpool_all_used to show the problem.


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