The Real Time Frame Drop-Insert function listens to the channel and catches the frames. Each frame consists of a suite of header, one for any passed protocol layer, and of data.

The tested Network Element are: the BSC and a generic Network Element. Typical scenarios may be:
1) BSC and SGSN to test the Frame Relay protocol layer;
2) BSC and BTSM to test the LAPD protocol layer;
3) BSC and TRAU to test the LAPB protocol layer;
4) BSC and MSC to test the MTP protocol layer.

This application is protocol stack indipendent. One can indicate the at what interface level the Real Time Frame Drop-Insert must be executed, programming the LSU+ appropriately.

The Real Time Frame Drop-Insert function:
a) removes some message portions or the whole message (field by field) - Both the bit stream and the octects are managed. In order to control the BSC behaviour, this application may be programmed to remove the information field and the only suite of headers is exchanged (first, second and third scenarios).
b) allows that old and new version of an application could do testing operation - It catches each frame and removes some of its portions, these ones that cannot be managed because different in the two version, then, after the testing process, they are added again (fourth scenario).
 

For this application the minimum configuration includes: 

• Line Server Unit Plus;
• Drop-Insert Module.