A2 computing - networking

[Ravichandran]

Dear Munir and Hakim

 

         Please look into this link for more details on network topics. http://homepages.uel.ac.uk/u0116771/

Please read the content and share how you can differenciate between routers, hubs, bridges, switches and ethernet cards.

 

Ravi

[M.H.Jr]

1) Ethernet card, or widely known as Network Interface Card (NIC), is a piece of hardware connected to the computer to enable the computers to communicate with each other. 

 

2) A hub is used to connect many computers together using NIC. Hub transmits the data it received to all of its ports hence slowing down the connection.

 

3) A switch is similar to hub but it speeds up the network and makes it faster compared with hub. This is because a switch reads the MAC address of the frames and directly transfer the signal to the destination.

 

4) A bridge is a piece of hardware which connects two LANs together. It is protocol independent and forwards packets without re-analysing and re-routing the messages.

 

5) Router is any device which connects any number of LAN of any types, topologies or protocols.

[Ravichandran]

ISDN Versus MODEM

 

1. A single ISDN line can support a wire speed up to 128K bit/sec, which is more than four times faster than a V.34 modem running at its highest possible speed.
2. Another important consideration in comparing modems and ISDN is the use of compression. Compression can double this to approximately 250K bit/sec for many files. ISDN does this with much higher reliability and much faster connection times than a modem.
3. ISDN supports 64K or 56K bit/sec synchronous connections. The serial interfaces on most personal computers are not capable of this.
4. ISDN is an end-to-end digital connection, which provides cleaner data and   

      clearer voice. Analog telephone sets convert the sound waves of voice to analog

electrical waves (analog transmission).ISDN sets convert voice into voltages representing a string of 0s and 1s (digital transmission),similar to those on a compact disc recording. In both cases, these converted electrical signals are sent over the telephone network.

[Ravichandran]

what is the different between the modem and router . Both can used for isdn connection .

Modem and router are two very different equipment and doing different jobs!!

1. A modem turns analog singals to digital signals. A router routes traffic between networks.
2. Modems establish and maintain analog/digital link and then receive&transmit data on this link.Router receive tcp/udp packets, may filter/encrypt/prioritize them, and transmit them to best path on the network.
3. A modem converts between two signaling types. For example, between the cable that cable television runs over and Ethernet, or between a DSL line and a USB port. A modem connects exactly two endpoints.
   A router keeps track of where information needs to go and forwards it in the right direction, translating it if necessary.
   Typically you only need a modem if you only want to connect one computer to your Internet access. If you want to connect more than one, you will need a router to steer traffic to the correct machine.
4. Router will not modulate or demodulate the signals but modem(modulator and demodulor) does the work of modulating the signal while sending the
   signal and demodulate while recieve the signal.
   Router will route the signal or the packet to the particular destination and no limits for router like other sub networks it can route the signal without limits.
5. In most cases routers and modems are either connected together on combined in one equipment.
6. A good many ISDN modems just don't work. Big headaches.
7. A router tells you exactly what is wrong while a modem hides it's problems.

[Ravichandran]