Design-Issues-of-Layers

• Design Issues of Layers - There are some key design issues that are to be considered in computer networks. Every layer needs a mechanism for identifying senders and receivers. As many computers are normally connected in networks, few of which have multiple processors. A means for a process on one machine is needed to specify with whom it wants to communicate to. Thus some form of addressing scheme is to be devised.

Another design issue is data transmission modes. It concerns the rules for the data transfer. The systems can use serial or parallel transmission, synchronous or Asynchronous transmission, simplex or duplex transmission. The protocol also must determine how many logical channels the connection corresponds to and what their priorities are.

Another major design issue is Error Control techniques as physical circuits are not perfect. Some of the error detecting or correcting codes are to be used at both the ends of the connection. At the same time we need to consider Flow Control techniques is necessary to keep a fast sender from swamping a slow receiver. Some systems use some kind of feedback from receiver, which is useful to limit the transmission rate.

It is convenient or expensive to set up separate connection for each pair of communicating processes. Same connection can be used by multiple & unrelated conversation. Thus we need to focus on Multiplexing and de-multiplexing techniques as one of the design issue. Multiplexing is needed in the physical layer, where all the traffic for all connections has to be sent over at most a few physical circuits.

When there are multiple paths between the source and destination the complexity lies in finding the best, optimum and shortest path. Hence to find optimum path we need Routing schemes. Apart from these some the design issues can be related to security, compression techniques and so on.