The generic term node or host refers to any device on a network. A file server is a computer that stores and manages files for multiple users on a network. A web server is an application dedicated to responding to requests for web pages from web browsers on client machines.
Types of Networks
Local area network - LAN
A network that connects a relatively small number of machines in a relatively close geographical area. Various configurations are used to administrate LANs (called topologies)
- Ring - A configuration that connects all nodes in a closed loop on which messages travel in one direction
- Star - A configuration that centers around one node to which all others are connected and through which all messages are sent
- Bus - All nodes are connected to a single communication line that carries messages in both directions
Wide area network - WAN
A network that connected two or more local area networks over a potentially large geographical distance. Often one particular node on a LAN is set up to serve as a gateway to handle communications going between that particular LAN and other networks.
Internet backbone - A set of high speed networks that carry Internet traffic. These are provided by large companies such as AT&T.
Internet server provider (ISP) - A company that provides other companies or individuals with access to the Internet
Used in Ethernet. The protocol does not work with radio.
The process is as follows:
- Listen to channel
- If idle then transmit
- Else wait until the channel is idle, then transmit
- During transmission, listen in on transmission for collisions
- If a collision is detected, then stop transmitting
- Jam signal
- Wait random amount of time
- Restart from beginning
Used in WiFi. The process is as follows:
- Listen to channel
- If idle
- Wait short time
- If still idle then start transmission
- Wait until end of other transmission
- Wait random time
- Go to step 1
The hidden terminal problem
When end systems cannot hear each other, but can each communicate with a single AP.
|Repeater||Repeats everything regardless of the destination|
|Bridge||Allows for some control and efficiency, as a signal is only repeated to the other side if the desination is on the other side|
|Switch||Similar to a bridge, but can connect many networks together|
One continuously executing server serves many clients, whom initiate the communication.
Two processes communicating as equals on a one-to-one basis. Peer process are usually short lived.