Problem 1. (10 pt.) Packet-switching: store-and-forward

Assumptions:

• Assume no other delay source than transmission delay
• Packet length (L) = 4 MB
• Link bandwidth (R) = 100 Mbps
• Note that ‘B’ stands for bytes and ‘b’ stands for bits in the metrics above

• Calculate the end-to-end delay, assuming that source and destination directly connected thru a single link without any intermediate network device in between (i.e., Source —- Destination).
• Calculate the end-to-end delay, assuming that source and destination connected thru three intermediate links with two intermediate network devices in between (i.e., Source —- Network Device1 —- Network Device2 —- Destination).

Problem 2. (10 pt.) Circuit-switching

Consider the following circuit-switched network. Assume that there are 5 circuits on each link. Note that the circuit switching in the slide of “Alternative core; circuit switching” assumes four circuits on each link.

1

• Suppose that all connections are between the switch in the upper-left-hand corner and the switch in the lower-right-hand corner. What is the maximum number of simultaneous connections that can be in progress. Justify your answer.
• What is the maximum number of simultaneous connections (from any to any) that can be in progress at any one time in this network. Justify your answer.