DLCI Allocation in Client/Server Applications 1

Original Post: This is regarding RFCOMM DLCI & server channel business (eGroups Msg. ) Date: 2000-08-16

Question

Say there are 2 separate connections established at the RFCOMM level ,say for DLCI = 2 and DLCI = 3.

Logically these 2 DLCI connections are mapped on the same server channel value (DLC) 1. So how will the RFCOMM knows to which connection it has to send data, if the Application wants to write some data on the server channel 1 ?.

Answer

Since application is communicating with RFCOMM only through DLC, DLCI = 2 and DLCI = 3 can not exist in the same direction.

For example, say server is giving one service on DLC = 1.Then any client accessing this service on DLC = 1 will be internally represent as DLCI=2 by the RFCOMM from client side to server side if the client is
established the RFCOMM session. But server will communicate to client on the same DLC will be internally represent as DLCI= 3. If the RFCOMM session is established by the server itself then it will be exactly opposite.

In simple terms server application on the non-initiating device are allocated DLCIs 2,4,6,…,60 (even numbers); and server applications on the initiating device are allocated DLCIs 3,5,7,…,61 (odd numbers). This DLCI value is valid only within the device itself.

Note : see also 'DLCI Allocation in Client/Server Applications 2'