Question

Problem 2 For a given network, the average packet length L = 1024 bytes, packets are arriving with an average rate = 8 pakets/s, the network is used to support voice call services which can tolerate a maximum end-to-end delay of 150 ms, the average end-to-end distance between any two connected nodes in the network is 1000 km, the average phase velocity for signal travelling throughout the network links is 0.1 speed of light in free space and the call setup time takes on average 2 s. Assuming the system has no queueing delay and has zero processing delay, answer the following. (1) Find the end-to-end propagation delay in this network. (2) What is the maximum allowable transmission delay to meet the QoS requirements? (3) Calculate the minimum required transmission rate in bits/s. (4) If the connection between the source and the destination is composed of 2 links in series, the first has speed speed 100 kb/s and the second has 150 kb/s, what is the output rate (throughput from the last link?

Answer 1

Soln given : Dist. blw nodes (d) = 10 km = 100m. Avg. phase velocity = 0.1 x3x108 m/s QoS = 150 ms Length of packet (L) = 1024 bytes = 1024x8 bits I Co End to End propagation delay = Distance b/w nodes (d) - Avg phase velocity (v.). 100 m 0.1X3x108 msec = 100 3x107 sec = - = 0.33x10 sec 0.033 seconds 33 ms - (2) Maximum Tolerable delay = QoS Hence, Oos = Transmission Delay + - (TE) (Maximum) Quality of service) Propagation Delo - C Tp . Hence, Tt = = Qos - TP 150 ms - 330S Chrom () 117 ms - = Length of parker@ ® Minimum Transmission rare (md ) = Min b/w) Maximum Transmission dolay

mtd = 1024×8 bits 1178103 seconds = 0.07 bits/sec Linki Linka Link2 Source (best) nation Throughput = minimum (throughputa, thay = mein (100kbls, 150 kb/s - 3 100 lbs

Summary : Propagation delay = distance between nodes / Link Velocity

Total end to end communication time = Transmission time + Propagation time between nodes

Maximum tolerable delay = Maximum Transmission Delay + Maximum propagation delay

Minimum Transmission Rate = Minimum Bandwidth = Length of Packet/Maximum Transmission Delay