On 04/12/2019 20:46, Harald Welte wrote:
We don't envisage a separation between MSC and HLR over unreliable back-haul, but I think I'm missing something here. (I still need to actually implement a local setup and observe)
In an inbound roaming situation, you have the MSC (VPLMN) in one village and the "authoritative" HLR for that subscriber (HPLMN) in another village.
Ah, indeed. I do need to setup and play with this. In my head, I was imagining that an IMSI attach request triggers an mslookup (broadcast) and that the response message contains what the VLR (msc) needs. I wasn't imagining TCP connections relating to core GSM over the unreliable IP network.
I'm wary of TCP. I'm no expert in all the things that can be tuned, so maybe there's a solution I'm unaware of?
If not, I don't like tcp over tinc-vpn at all where the underlying IP connection is unreliable. Things tend to stall for a long time. This is precisely the main problem I was seeing with multi-master distributed databases. They work fine in theory in a data centre, but add severe packet loss and it all falls down.
I'm quite possibly still missing something?
Thanks!
k.