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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.

1. Express the propagation delay, $d _{prop}$, in terms of m and s.
1. Determine the transmission time of the packet, $d _{trans}$, in terms of L and R
2. Ignoring processing and queuing delays, obtain an expression for the end-to-end delay.
3. Suppose Host A begins to transmit the packet at time t = 0. At time t = $d _{trans}$, where is the last bit of the packet?
4.  Suppose $d _{prop}$ is greater than $d _{trans}$ . At time t = $d _{trans}$, where is the first bit of the packet?
5. Suppose $d _{prop}$ is less than $d _{trans}$. At time t = $d _{trans}$, where is the first bit of the packet?
6. Suppose s = $2.5 \times 10^8$, L = 120 bits, and R = 56 kbps. Find the distance mso that $d _{prop}$ equals $d _{trans}$.
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