Cellular Network Infrastructure » Core Network (CN) » OsmoMSC

This is basically the same as #3102, so lets reject it.

Sorry, it's not the same: the one is the a_reset FSM in OsmoBSC, while this here is in OsmoMSC.
True, both MSC and BSC currently kind of don't touch their a_reset implementations in a similar way,
but tracking each side should be separate, depending on what each side should be doing.

neels: Both parts were intended to be generalized and put in a library somehow. Maybe we should fix that. Possibly libosmo-sigtran is a good place?

Note: Neels and me agree that it might make sense to send a reset immediately when there is some connection attempt from a BSC. Just blocking every connection attempts from not yet known BSCs until the BSC sends a reset is fine, however, responding with a reset to a connection attempt from an unknown BSC is better and it speeds up the process of re-negotiation.

I have checked the a_iface.c. When we receive a connection request in sccp_sap_up() we lookup the BSC context information. If we can not find a a context, we allocate a new one and we also send an BSSMAP RESET back immediately. This means this part works also as expected.

So if the MSC restarts and if we loose all context we will re-learn the context on the next connection attempt and send a reset immediately. I think we have no problem here.

Please clarify:

• is a_reset.c currently used in osmo-msc?
• do we use the part of it designed to detect stale connections?
• Any actions required to get rid of dead code?

• is a_reset.c currently used in osmo-msc?
  Yes

• do we use the part of it designed to detect stale connections?
  No

• Any actions required to get rid of dead code?
  We have two options: We can remove the unused parts of the code locally or we
  move the whole FSM over to a library (but which one?). I think the first option
  would be the simplest and it would not hurt to much. I could do that now if you
  agree.

dexter wrote:

• is a_reset.c currently used in osmo-msc?
  Yes

ok. Which part? (I think you showed me before, but I forgot. We can discuss it personally next week. not urgent.)

• Any actions required to get rid of dead code?
  We can remove the unused parts of the code locally

yes, I don't think it's worth the trouble to move it around.

I have now stripped all unnecessary code, please see:

https://gerrit.osmocom.org/8054 a_reset: cleanup + remove dead code

Ok, nice. Took the opportunity to read the rest of it again and added some general comments about the rest of the code at that same gerrit patch (even though it's not strictly related to that patch)

The patch (https://gerrit.osmocom.org/8054) is now merged and the cleanups to a_reset.c are now done.