HCI Connection_Handle to L2CAP CID Translation
Original Post: Questions - Connection handle and Channel Identifier
(SIG Forum ) Date: 2000-08-18
HCI data packets are passed (upward) on to the
L2CAP layer. However it is not apparently clear how the L2CAP layer
decides which Channel Identifier (CID) to route the L2CAP packet too. It
does this by using the HCI packet Connection_Handle field , which uniquely
identifies a data pipe that connects two bluetooth devices.
When the packet is passed up to the L2CAP layer, the
HCI header (including the Connection_Handle field) is stripped to give the
future L2CAP packet payload data. The L2CAP keeps track which
Connection_Handle every CID is related to , and then when the upper layer
wants to send data through the L2CAP layer, the L2CAP layer looks up what
Connection_Handle the CID corresponds to and tells the HCI layer to send
data on that Connection_Handle.
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