Write down the functions of Gateway, Routers, Repeaters, Bridges, Hubs and Switches.

Subject Computer Network
NU Year Set: 3.(b) Marks: 6 Year: 2017

The gateway functions allow data exchange between all available communication technologies. This is accomplished by using “connections” which connect data points of different technologies with each other. Both “1-to-n” and “m-to-1” connections are supported. Connections can contain simple or complex calculations. Different engineering units of connected data points are automatically converted. Connections can easily be created using templates. They are distinguished into local and global connections. Connections can be created manually or automatically using the Smart Auto-Connect™ feature of the Configurator tool. Especially the automated creation of connections reduces engineering effort and helps preventing configuration errors.
The two major types of routers are:
  • Static Static routers require an administrator to manually set up and configure the routing table and to specify each route.
  • Dynamic Dynamic routers are designed to discover routes automatically and therefore require a minimal amount of setting up and configuration. More sophisticated than static routers, they examine information from other routers and make packet-by-packet decisions about how to send data across the network.
Routers communicate with each other to share information about available paths and directly connected routes.
A Static route can be manually programmed to create a routing table. This means that all data will follow the same route. This is also known as non-adaptive routing. Each node on the WAN has a fixed routing table. All messages for a particular destination must follow a predetermined path this is good for determining secure routes.
If a node is faulty, added or removed the tables will have to be altered manually. This method does not cope well with unplanned events such as breakdown or congestion although it does use less router processor overhead.

Most routers are dynamic with the capability of being statically configured.
Dynamic routers automatically create dynamic routing tables based on the data that is provided from other routers. Dynamic routing is designed to cope with unplanned events. Routers respond to changes in the network status by automatically updating the routing table
In digital communication systems, a repeater is a device that receives a digital signal on an electromagnetic or optical transmission medium and regenerates the signal along the next leg of the medium. In electromagnetic media, repeaters overcome the attenuation caused by free-space electromagnetic-field divergence or cable loss. A series of repeaters make possible the extension of a signal over a distance.

bridge is a device that connects and passes packets between two network segments that use the same communications protocol. Bridges operate at the data link layer (layer 2) of the OSI reference model. A bridge will filter, forward or flood an incoming frame based on the MAC address of that frame.

Hubs and switches function as a common connection point for the workstations, printers, file servers and other devices that make up a network. The main difference between hubs and switches is the way in which they communicate with the network. A hub functions as the central connection point of a network.

A network switch (also called switching hub, bridging hub, officially MAC bridge) is a computer networking device that connects devices together on a computer network by using packet switching to receive, process, and forward data to the destination device.

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