Virtual Circuit Switching and Circuit Switching

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• Published : September 19, 2012

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HW1

1.Describe the common points between virtual circuit switching and circuit switching, and the common points between virtual circuit switching and datagram switching.

Answer: Virtual circuit switching and circuit switching: Both require a link to be established before data is transferred and torn off once the transmission is over. Both have bandwidth efficiency.

Virtual Circuit switching and datagram switching: Both transmit data using packet multiplexing. The packets are stored and then forwarded from each node in the path.

2.List the major advantages and disadvantages with the layered approach to protocols.

Answer: Advantages: The system is divided into different sub systems according to different functions hence, simplifying the system. This way each layer is independent and it can be upgraded independently.

Disadvantages: Many layers perform the same function which decreases the efficiency. Also the design of many layers is complex..

3.Suppose station A and B are interconnected through two parallel unreliable links, where each link has a failure probability of 0.1. Calculate the average seconds per day when A and B lose communication.

Answer: Probability of failure = 0.1*0.1=0.01=1%
Average seconds in a day when they loose communication = 24*60*60*1% = 864 seconds.

4.Suppose you are running a home business and want a very reliable Internet connection (say, you have 4 computers and you don’t want a disruption of more than 1 minute). Explain how you would design this home network. (hint, consider the following potential failures: your Internet Service Provider (ISP), your router)

Answer: Since,the failure of ISP and router has to be taken care of we can have two ISP and routers.Whenever one ISP fails the network switches to the other ISP.This results in the use of two routers..Also ,since it is a home network we can use a star topology and link all home computers to the ISP and router.Because...