echanisms, the entire LLC-PDU is delivered to the network services for transmission to the BSS. The flow control parameters sent by the BSS to the SGSN consist of the following information: The bucket size (Bmax) for a given BVC or mobile station in the downlink direction The bucket leak rate (R) for a given BVC or mobile station in the downlink direction The bucket full ratio for a given BVC or mobile station in the downlink direction, if the current bucket level (CBL) feature is negotiated The SGSN performs flow control on an individual mobile station using SGSN determined values of Bmax and R unless it receives a FLOW- CONTROL-MS message from the BSS regarding that mobile station. The SGSN continues to perform flow control for a particular mobile station using the Bmax and R values received from the BSS for at least T(h) sec- onds after receiving a FLOW-CONTROL-MS message from the BSS regarding that mobile station. When timer T(h) has expired or when the mobile station changes cells, the SGSN may reinitialize the SGSN internal flow control variables for that mobile station and begin to use SGSN gen- erated values for Bmax and R. Currently, the use of Frame Relay makes sense because the GPRS net- works operate at speeds of up to 2 Mbps. In the future as the per-user speeds increase (such as with EDGE or 3G), the use of ATM will most likely be required. The greater the speed per mobile station, the greater the data- carrying capacity of the network to support the multitude of simultaneous users. ETSI was very clear that they intended this evolution to be a consid- eration in their decision to select the various protocols. In fact, many ven- dors' SGSN products may be a form of ATM switch already in preparation for this evolution. One thing is certain: low-latency, high-speed, and highly reliable data transfer is a requirement to meet the demands of a mobile user. Frame Relay brings a good portion of the requirements to the table in its existing state. This will satisfy the network for the near term, or may be an