This problem begins to explore propagation delay and transmission delay, two central concepts

in data networking. Consider 2 hosts, A and B, connected by a single link of rate R bps. Suppose that the 2 hosts

are separated by m meters, and suppose the propagation speed s along the link is in meters/sec. Host A is to

send a packet of size L bits to Host B.

a.

Express the propagation delay, d

prop

, in terms of m and s.

b. Determine the transmission time of the packet, d

trans

, in terms of L and R.

c.

Ignoring processing and queuing delays, obtain an expression for the end-to-end delay.

Now suppose that there are (2) WAN links separating hosts A and B using (3) routers. The first WAN links

transmission rate is 2 Mbps; the second is 4 Mbps. The propagation speed s=2.5*10

8

m/sec. The distance of the

first WAN link is 4000 Kilometers and the distance of the second WAN link is 600 Kilometers.

d. Draw the network between A and B; include hosts A and B in your picture. Label each WAN link with its

transmission rate.

e. Compute the propagation delay for sending (1) 1400 byte packet from over the WAN from A to B. Show

your answer in seconds out to at least 4 decimal places.