What is a communication protocol?
- A communication protocol is a set of rules that govern the exchange of information in a network.
- Communications protocols define the manner in which peer processes communicate among various hardware devices.
- The protocols define the rules for function such as passing and extraction of messages and handling error conditions.
What are the reasons for using layered protocols? OR What is protocol layering?
- Many problems can arise when data is sent in form of “packets”. Some of these problems are: Link failure, Network congestion, Host failure, Packet delay or loss, Data corruption, Data duplication, Packets out of sync.
- It is not practical for a single protocol to take care of all these potential problems. Therefore we organize the protocol software into different layers, so that each layer can handle a particular set of problems.
- Networking functions which have related uses are grouped together to form layers.
- The purpose of each layer is to offer certain services to the higher layers.
Characteristics of a Layered Protocol:
- Each layer has a predefined set of functions.
- Layers provide services to their immediate upper layers.
- Peer layers communicate using a peer protocol.
- Layers are separated from each other with interfaces.
What are the Advantages of Layering?
- Data hiding and encapsulation: data structures and algorithms in one layer are not visible to other layers.
- Reduced complexity: Complex systems can be decomposed into more easily understood pieces. A layer or a sublayer can be simplified or omitted if some or all of its services are not needed.
- Increased evolution: Systems can evolve faster since layers can be changed while still integrating with existing systems.
- Easy extension: Alternate services can be offered at layer N+1 that share the services of layer N.
- Multi-vendor integration: Different vendors can provide different implementations.
- Easy testing: Each layer can be tested independently.
What is an open system?
- An open system is a set of protocols that allows any two different systems to communicate no matter what the underlying architecture is.
- The OSI model of networking is an open system as it allows the communication process between different systems without requiring changes to the logic of the underlying hardware or software.
(C) Mukesh N Tekwani, 2021