A network is a group of devices interconnected with each other in order to share information, files, and resources. In order to make these operations we must have an operating system controlling them.
In a distributed system, unlike a multiprocessor system, processors dont share either a memory nor a clock, they communicate through buses, telephone lines or some other communication networks. In this system processors can be also called host, site or nodes.
When a system has data to send to another system, the sending system segments the data and adds header bytes to each segment, the resulting packages of information are know as packets.
A protocol defines the format and the order of messages exchanges between two or more communicating entities, as well as the actions taken on the transmission and/or receipt of a message or other event.
Let´s suppose we have 3 processes in different systems: A, B and C in a network. They can be connected in different ways:
- Fully connected network: They are all directly linked
- Partially connected network: Only some of them are directly linked
- Hierarchical Network: They are in the form of a tree
- Star Network: One of the sites is connected to all of the other sites
- Ring Network: Each one of the site is connected to exactly two other sites
- Multiaccess bus network:They communicate directly with each other through a shared link
- Hybrid Networks: Different networks connected together
Computer Networking (Kurose Ross)