| [[sgs]] |
| == SGs interface |
| |
| OsmoMSC offers an SGs interface using the SGsAP protocol. The SGs interface is an |
| optional interface between a 2G (GERAN) / 3G (UTRAN) MSC and an 4G (EUTRAN) MME. |
| Its purpose is to facilitate both CSFB (Circuit-Switched Fall Back) and SMSoS |
| (SMS over SGs). It is used for Mobility management (MM) and paging procedures |
| between the EPS (Evolved Packet Services) and CS (Circuit Switched) domain. |
| |
| === VTY configuration |
| |
| The SGs interface implementation in OsmoMSC is automatically active and requires |
| only minimal configuration. When no specific configuration is provided OsmoMSC |
| will listen on 0.0.0.0:29118 (SCTP) for incoming connections. |
| |
| This is sufficient in the most configurations, but in larger installations, |
| where services are either tied to specific interfaces and/or more instances of |
| OsmoMSC run in parallel, a custom configuration is necessary. |
| |
| The user has the option to configure the IP address (`local-ip`) and the SCTP |
| port (`local-port`) and also the `vlr-name` that OsmoMSC uses to identify itself |
| towards the MME. It should be noted that the `vlr-name` is usually the DNS name |
| for the IP address of the VLR/MSC, so IP address used and the `vlr-name` should |
| match the DNS server entry. |
| |
| ---- |
| sgs |
| local-ip 127.0.0.1 |
| local-port 29118 |
| vlr-name vlr.example.net |
| ---- |
| |
| In order to fine tune the behavior of the SGs interface the user also has |
| control over the relevant timers (`ts5`, `ts6-2`, `ts7`, `ts11`, `ts14`, `ts15`) |
| and counters (`ns7`, `ns11`). Each timer and counter has to be configured |
| separately. In the following example we change the value of ts and ns11. |
| |
| ---- |
| sgs |
| timer ts7 23 |
| counter ns11 100 |
| ---- |
| |
| |
| [NOTE] |
| ==== |
| In case multiple instances of OsmoMSC run in parallel, it is advised to use a |
| different `vlr-name` for each instance. In any case it must be ensured that the |
| SGs interface of each instance is bound to a different IP address and/or port. |
| ==== |
| |
| === Connection monitoring |
| |
| The user can use the VTY command `show sgs-connections` to list the MMEs that |
| are currently connected to OsmoMSC. |