In the OSI model, the physical layer is the lowest layer which comes below the data link layer. The communication channel which is, most of the time cables, is connected to this layer. The physical layer is responsible for transmitting the raw bits over this channel.
In my previous articles on network design issues, I talked about the key issues concerned with the designing of these layers in a network model. When it comes to the physical layer, the design issue is concerning the bit transfer. In computer communication all data is in binary form (0 or 1). The challenge is that if we send a 1 bit, then it must be received at the other end as a 1 itself and not as 0.
Some of the concerns in the physical layer
- With how many volts would 0 and 1 be represented while communicating?
- Is the transmission full duplex or half duplex?
- The number of pins in the connector and the functions of each pin
- How a connection is established?
- The lifetime of a bit in microseconds
- How the connection will be terminated once the communication is over?
