What is s11 interface ?
Earlier we have discussed some interfaces (e.g s6a ) in EPC. Here we will discuss about the s11 interface. S11 interface is between MME and the SGW. Both MME and SGW are in roaming network. The protocol over s11 interface is GTP . GTP is a tunneling protocol which is used to setup a data tunnel for internet to a mobile subscriber. GTP runs over UDP . So s11 interface used UDP as the network protocol. The interface uses signaling for setup pdp session for internet. SGW in turns does signaling towards the PGW on another interface. When a mobile phone attaches it does signaling with HSS over S6a interface and then on s11 interface. Following are the messages name exchanges on s11 interface.
- Create session request/response.
- Delete session request/response.
- Modify bearer request/response.