# This elementary problem begins to explore propagation delay and transmission delay, two central concepts in data networking. Consider two hosts,

## Question:

This elementary problem begins to explore propagation delay and transmission delay, two central concepts in data networking. Consider two hosts, A and B, connected by a single link of rate R bps. Suppose that the two hosts are separated by m meters, and suppose the propagation speed along the link is s meters/sec. Host A is to send a packet of size L bits to Host B.
a. Express the propagation delay, dprop ' in terms of In and s.
b. Determine the transmission time of the packet, dtrans,> in terms of Land R.
c. Ignoring processing and queuing delays, obtain an expression for the end -to-end delay.
d. Suppose Host A begins to transmit the packet at time t =O. At time t =dtrans '
where is the last bit of the packet?
e. Suppose dprop is greater than ddrop At time t =dtrans where is the first bit of the packet?
f. Suppose dprop is less than dtrans. At time t =dtrans' where is the first bit of the packet?
g. Suppose s =2.5· 108, L = 120 bits, and R =56 kbps. Find the distance m so that dprop equals dtrans.