1. Suppose users share a 2 Mbps link. Also suppose each user transmits continuously at 1Mbps when transmitting, but each user transmits only 20
About the IP protocol
a. Consider an IPv4 packet going through a router. Determine which fields in the header may be
changed, before the packet is forwarded.
b. Are there any fields from the header of an IPv4 packet that are no longer maintained in the
header of an IPv6 packet? Briefly explain the reasons.
5. Consider the network topology below.
26
2
30
10
20
40
15
1
2
4
3
5
The numbers listed next to the links are link costs.
a. Determine the shortest path from node 1 to node 5 using the Distance Vector algorithm and Dijkstra’s algorithm.
b. Now suppose that the link cost for link 14 changed to 45. Determine again the shortest path from node 1 to 5 using the Distance Vector algorithm and Dijkstra’s algorithm.
6. Consider the network topology in the previous problem. The numbers listed next to the links are assumed to be bandwidth. Determine the widest path from node 2 to node 5 using a variant of the Djkstra’s algorithm.
7. Consider a sevennode ring network.
a. If a distance vector protocol is used, determine how long it will take for all nodes to have the same routing information if updates are done every 10 seconds.
b. If a link state protocol is issued, how long will it take before every node has the identical linkstate database if flooding is done every 5 seconds. Determine how many linkstate messages in total are flooded till the time when all nodes have the identical database.
8. Solve the previous problem, now for a fully connected 7node network.
1. Suppose users share a 2 Mbps link. Also suppose each user transmits continuously at 1Mbps when transmitting, but each user transmits only 20 percent of the time. a. When circuit switching is used, how many users can be supported? b. For the remainder of this problem, suppose packet switching is used. Why will there be essentially no queuing delay before the link if two or fewer users transmit at the same time? Why will there be a queuing delay if three users transmit at the same time? c. Suppose now there are four users. Find the fraction of time during which the queue grows. 2. Define the following parameters for a switching network: N = number of hops between two given end systems L = message length in bits B = data rate, in bits per second (bps), on all links P = fixed packet size, in bits H = overhead (header) bits per packet S = call setup time (circuit switching or virtual circuit) in seconds D = propagation delay per hop in seconds For N = 4, L = 3200, B = 9600, P = 1024, H = 16, S = 0.2, D = 0.001, compute the endtoend delay for circuit switching, virtual circuit packet switching, and datagram packet switching. Assume that there are no acknowledgements. Ignore processing delay at the nodes. 3. Consider a subnet with prefix 128.119.40.128/26. Given an example of one IP address (of form xxx.xxx.xxx.xxx) that can be assigned to this network. Suppose an ISP owns the block of addresses of the form 128.119.40.64/25. Suppose it wants to create four subnets from this block, with each block having the same number of IP addresses. What are the prefixes (of form a.b.c.d/x) for the four subnets? 4. About the IP protocol a. Consider an IPv4 packet going through a router. Determine which fields in the header may be changed, before the packet is forwarded. b. Are there any fields from the header of an IPv4 packet that are no longer maintained in the header of an IPv6 packet? Briefly explain the reasons. 5. Consider the network topology below. 262301020401512435The numbers listed next to the links are link costs.
a. Determine the shortest path from node 1 to node 5 using the Distance Vector algorithm and Dijkstra’s algorithm. b. Now suppose that the link cost for link 14 changed to 45. Determine again the shortest path from node 1 to 5 using the Distance Vector algorithm and Dijkstra’s algorithm. 6. Consider the network topology in the previous problem. The numbers listed next to the links are assumed to be bandwidth. Determine the widest path from node 2 to node 5 using a variant of the Djkstra’s algorithm. 7. Consider a sevennode ring network. a. If a distance vector protocol is used, determine how long it will take for all nodes to have the same routing information if updates are done every 10 seconds. b. If a link state protocol is issued, how long will it take before every node has the identical linkstate database if flooding is done every 5 seconds. Determine how many linkstate messages in total are flooded till the time when all nodes have the identical database. 8. Solve the previous problem, now for a fully connected 7node network.
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