SYBSC IT COMPUTER NETWORKS UNIT III Connecting LANs, Backbone Networks, and Virtual
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This document summarizes key networking devices: - A repeater regenerates signals to extend transmission distances but does not amplify signals. It operates at the physical layer. - A hub connects multiple ports but cannot filter data, sending all data to all connected devices, maintaining a single collision domain. - A bridge can read MAC addresses to filter and forward data selectively between LANs on the same protocol, dividing collision domains but maintaining a single broadcast domain. It operates at the data link layer. - A switch is like a multi-port bridge but can boost efficiency by forwarding only valid data to the correct port, dividing both collision and broadcast domains.
SYBSC IT COMPUTER NETWORKS UNIT III Connecting LANs, Backbone Networks, and Virtual
- 1. UNIT III
- 5. 1. Repeater A repeater operates at the physical layer. Its job is to regenerate the signal over the same network before the signal becomes too weak or corrupted so as to extend the length to which the signal can be transmitted over the same network. An important point to be noted about repeaters is that they do no amplify the signal. When the signal becomes weak, they copy the signal bit by bit and regenerate it at the original strength. It is a 2 port device.
- 9. 2. Hub – A hub is basically a multiport repeater. A hub connects multiple wires coming from different branches, for example, the connector in star topology which connects different stations. Hubs cannot filter data, so data packets are sent to all connected devices. In other words, collision domain of all hosts connected through Hub remains one. Also, they do not have intelligence to find out best path for data packets which leads to inefficiencies and wastage.
- 13. 3. Bridge – A bridge operates at data link layer. A bridge is a repeater, with add on functionality of filtering content by reading the MAC addresses of source and destination. It is also used for interconnecting two LANs working on the same protocol. It has a single input and single output port, thus making it a 2 port device.
- 15. 5. Routers – A router is a device like a switch that routes data packets based on their IP addresses. Router is mainly a Network Layer device. Routers normally connect LANs and WANs together and have a dynamically updating routing table based on which they make decisions on routing the data packets. Router divide broadcast domains of hosts connected through it.
- 17. 4. Switch – A switch is a multi port bridge with a buffer and a design that can boost its efficiency(large number of ports imply less traffic) and performance. Switch is data link layer device. Switch can perform error checking before forwarding data, that makes it very efficient as it does not forward packets that have errors and forward good packets selectively to correct port only. In other words, switch divides collision domain of hosts, but broadcast domain remains same.
- 18. 6. Gateway – A gateway, as the name suggests, is a passage to connect two networks together that may work upon different networking models. They basically works as the messenger agents that take data from one system, interpret it, and transfer it to another system. Gateways are also called protocol converters and can operate at any network layer. Gateways are generally more complex than switch or router.