ce a connection is established, a device can be in one of the Chapter Ten Table 10-4: Bluetooth Connection States State Description Active Devices in an active state participate in the channel. The active master schedules transmissions including regular transmissions to keep slaves synchronised. Active slaves listen for packets during ACL time slots. An active slave may sleep until the next ACL transmission if it is not addressed. Sniff Devices in the sniff state conserve power by listening for transmissions at a reduced rate. The inactive interval is programmable and will depend on the specific device type and application. A data transfer can be put on hold as a power saving measure either at the request of the slave device or under the direction of the master device. In the hold state only an internal timer will be running in the slave device. The data transfer will resume immediately after the slave device returns to active mode. Devices in the park state are still synchronised but do not participate in piconet traffic. Slaves give up their 3-bit active member device address when entering this state and take on an 8-bit parked member address. Parked devices will continue occasionally to listen to transmissions in order to re-synchronise and check on other broadcast messages. four states; active, sniff, hold, and park - in order of decreasing power consumption. Table 10-4 provides a brief description. Higher Layer Protocols Link Manager Protocol The link manager protocol (LMP) is used to set up and manage Baseband connections, including link configuration, authentication and power management functions. This is achieved by exchanging protocol data units (PDUs) between the Link Managers of two paired devices. PDUs include control of pairing, authentication, initiation of sniff, hold and park modes, power increase or decrease requests and selection of preferred packet coding and size to optimise data throughput. Host Controller Interface The host controller interface (HCI) provides a uniform command interface to t