# CS601 Data Communication Assignment No 1 Solution Fall 2012

Q. 1. Different topologies behave differently when a connection fails. You are required to discuss the effect on the network when only one device connection fails in the following cases:  [2 x 6 = 12 Marks]

1. Seven devices are connected through a ring topology.
2. Six devices are connected through a dual ring topology.
3. Four devices are connected through a mesh topology.
4. Twelve devices are connected through a star topology (Note: Do not consider the hub failure).
5. Fifteen devices are connected through a star topology and only the hub is failed.
6. Eight devices are connected through a bus topology.

Note: Your answer for Q.1 should be in the same order as given in the question statements.

Solution:

Q. 1. Different topologies behave differently when a connection fails. You are required to discuss the effect on the network when only one device connection fails in the following cases:  [2 x 6 = 12 Marks]

1) Seven devices are connected through a ring topology.

Ans: In this case the whole network will go down because in ring topology failure of one computer affects whole network.

2) Six devices are connected through a dual ring topology.

Ans: Dual ring is based on channels so if one channel fails the 2nd channel will continue transmitting data. Suppose 3 computers are one channel and 3 on 2nd channel then failure of one computer will bring down only 1 channel and computers with it. 3 computers will go down in network and 3 will be working.

3) Four devices are connected through a mesh topology.

Ans: In mesh topology every computer is directly connected to another computer so, if one computer fails it will not affect the whole network. 3 devices will keep up the network.

4) Twelve devices are connected through a star topology (Note: Do not consider the hub failure).

Ans: In star topology we use a specialized device called the hub. If one computer fails then the remaining 11 will not be affected.

5) Fifteen devices are connected through a star topology and only the hub is failed.

Ans: Star topology fails and whole network goes down if network hub fails.

6) Eight devices are connected through a bus topology.

Ans: In bus topology if one computer fails then the remaining computers can still transmit data through backbone cable. 7 computers will be still functional.

Q. 2. Suppose a small company wants to develop a computer network of 18 computers in its main office. Due to limited resources the company wants a network architecture where a single communication medium can be shared among all other nodes. Considering this scenario, you are required to suggest the suitable line configuration and name all the possible ways through which your suggested line configuration can be implemented. [3 Marks]

Solution: I suggest Multiple line configuration in this situation. Star topology is the best solution for the small company of 18 computers. In this scenario the network hub can connect all computers and all computers can share data and resources efficiently.  And above all this is the cheaper network topology..