In addition, the Bluetooth baseband protocol provides authentication and encryption controlled at the physical layer. Management of the secret keys is left to software at a higher layer. The FEC is intended to reduce the number of retransmitted data packets and is always used to protect the packet headers that contain the link information. From this mode, any device can initiate a connection and become the master. The maximum delay for a master to establish a connection with a slave is 2.56 seconds.
Active modes occur after connections are established and a piconet is formed.
The active modes are either the connected mode or the transmit data mode. Low-power modes include the hold, sniff, and park modes. A master unit can put slave units in a hold mode, or slave units can demand to be placed in hold mode when there is no data to be transmitted. The hold mode is typically used when connecting several piconets or managing low-power devices. In sniff mode, the device listens to the piconet at a reduced rate, which is programmable.