Cellular Network Infrastructure » Core Network (CN) » OsmoSTP

I think this has long been resolved? We are using M3UA in ASP mode from osmo-bsc and osmo-msc. Please confirm.

I am not sure. We never tried it or even thought about it. When I get it correct, this would be a configuration where e.g. two OsmoSTP are connecting to each other. This means that one of them must take the client role. The topology could be something like this:

osmo-bsc (ASP) <------> (STP) OsmoSTP (ASP) <------> (STP) OsmoSTP (STP) <------> (ASP) osmo-msc

I think this is something we have to test in order to be sure that it really works.

The M3UA protocol defines various roles of M3UA endpoints: SGW, ASP and IPSP.

osmo-stp currently implements only the SGW (Signaling Gateway) role, allowing external M3UA entities in ASP role to connect to it. It does not permit the SGW to operate in ASP role to connect to external SGWs

1. Extension of the VTY interface to operate the osmo-stp send of the M3UA link in ASP mode
2. Extension of the osmo-stp internal implementation to behave accordingly
3. Implementation of automatic test cases in TTCN-3

I've made an initial implementation as part of laforge/wip, but it requires thorough testing before pushing for inclusion. There are two new VTY commands for specifying the SCTP role (client / server) and the xUA role (sg / asp).

Initial testing shows that the ASP transitions through ASPUP and ASPAC as expected. However, both the ASP and the SG are sending NOTIFY to each other, which is probably not how it's supposed to be. We need to suppress NOTIFY generation if we're not in SG role.

NOTIFY problem has been fixed. They are now suppressed when operating in ASP role.

Attaching a new pcap file.

The ASP side config looked like this:

cs7 instance 0
 point-code format 24
 asp asp-sender 2905 9999 m3ua
  local-ip 127.0.0.1
  remote-ip 127.0.0.1
  role asp
  sctp-role client
 as as-sender m3ua
  asp asp-sender
  routing-key 1023 23
 route-table system
  update route 23 16777215 linkset as-sender

while the SG side looked like that:

cs7 instance 0
 point-code format 24
 asp asp-sender 9999 2905 m3ua
  local-ip 127.0.0.1
  remote-ip 127.0.0.1
 as as-sender m3ua
  asp asp-sender
  routing-key 1023 23
 route-table system
  update route 23 16777215 linkset as-sender
 listen m3ua 2905
  accept-asp-connections dynamic-permitted

the routing doesn't yet make sense in the above configs, I'm just pasting them to illustrate how to use the 'role' and 'sctp-role' commands to switch a given section into operating as client/ASP towards another SG.

This is implemented in https://gerrit.osmocom.org/#/c/libosmo-sccp/+/15974/ and https://gerrit.osmocom.org/#/c/libosmo-sccp/+/15975/ - automatic tests (all passing) are in the laforge/wip branch of osmo-ttcn3-hacks.git.

Once it passes code review, it will be in master.

all code / patches in master; tests are executed automatically and pass, see those including clnt in the name at https://jenkins.osmocom.org/jenkins/job/ttcn3-stp-test/test_results_analyzer/