# Homework Solution: 1. The performance of a client-server system is strongly influenced by two major network characteristics: the bandwidth of the network (that i…

1. The performance of a client-server system is strongly influenced by two major network characteristics: the bandwidth of the network (that is, how many bits/sec it can transport) and the latency (that is, how many seconds it takes for the first bit to get from the client to the server). Give an example of a network that exhibits high bandwidth but also high latency. Then give an example of one that has both low bandwidth and low latency. 2. What are two reasons for using layered protocols? What is one possible disadvantage of using layered protocols? 3. What is the main difference between TCP and UDP? 4. An image is 1600 × 1200 pixels with 3 bytes/pixel. Assume the image is uncompressed. How long does it take to transmit it over a 56-kbps modem channel? Over a 1-Mbps cable modem? 5. Calculate the end-to-end transit time for a packet for both GEO (altitude: 35,800 km), MEO (altitude: 18,000 km) and LEO (altitude: 750 km) satellites. 6. Three packet-switching networks each contain n nodes. The first network has a star topology with a central switch, the second is a (bidirectional) ring, and the third is fully interconnected, with a wire from every node to every other node. What are the best-, average-, and worst-case transmission paths in hops?

## Expert Answer

1. Fiber links have both high bandwidth and high latency.

1. The deed of a client-server scheme is strongly influenced by brace elder network characteristics: the bandwidth of the network (that is, how numerous parts/sec it can ecstasy) and the latency (that is, how numerous remedys it catchs ce the primeval part to earn from the client to the server). Afford an in of a network that exhibits exalted bandwidth excluding besides exalted latency. Then afford an in of individual that has twain feeble bandwidth and feeble latency.

2. What are brace reasons ce using layered protocols? What is individual potential hindrance of using layered protocols?

3. What is the ocean variety between TCP and UDP?

4. An copy is 1600 × 1200 pixels with 3 bytes/pixel. Assume the copy is uncompressed. How covet does it catch to impel it balance a 56-kbps modem machine? Balance a 1-Mbps cable modem?

5. Calculate the end-to-end transit period ce a packet ce twain GEO (altitude: 35,800 km), MEO (altitude: 18,000 km) and LEO (altitude: 750 km) attendant.

6. Three packet-switching networks each hold n nodes. The primeval network has a something topology with a convenient switch, the remedy is a (bidirectional) ring, and the third is amply interconnected, with a wire from whole node to whole other node. What are the best-, average-, and worst-case transmission paths in hops?

## Expert Defense

1.

Fiber connects accept twain exalted bandwidth and exalted latency. Ce eg. A transcontinental fiber connect has numerous gigabits/sec of bandwidth. Excluding, its latency is besides exalted ascribable to the propagation of inadequate balance thousands of kilometres.

A 56-kbps modem connecting a computer in a persomal area network is an in of a network that has feeble bandwidth and feeble latency.