SGSN and GGSN

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THE GB INTERFACE

The GB interface used frame relay techniques to link the PCU function of the MFS and the SGSN. Physically, it can be routed in a variety of four ways:

1. A direct connection between the MFS and the SGSN.
2. Via a public frame relay data network.
3. Via the MSC.
4. Via the Ater-Mux interface through the TC to the MSC. In this case it carries a combination of PS and CS traffic and signaling.

Combinations of these methods are also possible. The Gb interface provide E2E signaling between the MFS and the SGSN, and serves as the BSS-GPRS backbone.

Here the principle function:

• Network services: * Transfer of BSSGP-PDUs between the BSS and the SGSN. * Allocation and load sharing of PDUs among VC. * Access to intermediate frame relay data network.
• BSS-GPRS protocol services: * Radio resource information. * Routing information. * Transfer of LLC-PDUs between the BSS and the SGSN. * Quality of service information. * Suspend and resume procedures for class B MS.

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