Lab6 - lab6 PDF

Preview

Summary

lab6...

Description

Exercise 1 Question 1: Why the throughput achieved by flow tcp2 is higher than tcp1 between time span 6 sec to 8 sec? Due to the larger bandwidth between n3 -> n2 compared to the lower bandwidth between n0 ->n2 there is more package arrived and after adjustment at 6sec the throughput of tcp is larger then tcp1. Also tcp2 has less rtt then tcp1 and gets a higher share of the bandwidth. Question 2: Why the throughput for flow tcp1 is fluctuating between time span 0.5 sec to 2 sec? Due to the slowstart in order to probe the bandwidth Question 3: Why is the maximum throughput achieved by any one flow capped at around 1.5Mbps? Due to node 2 dropping packages from node 0 and 3 when they try to send more packages, this results to windows size dropping to 1 which leads to slow start. Due to the entrance of tcp 2 , more bandwidth is consumed which results in tcp 1 not being able to achieve the highest throughput possible.

Exercise 2: Understanding IP Fragmentation Question 1: Which data size has caused fragmentation and why? Which host/router has fragmented the original datagram? How many fragments have been created when data size is specified as 2000? The data size 2000 and 3500, as in the maximum segment size in default is 1500 bytes. Router is 192.168.1.3 2 fragments have been created. Question 3: Give the ID, length, flag and offset values for all the fragments of the first packet sent by 192.168.1.103 with data size of 3500 bytes? id 7a7b 7a7b 7a7b

length 1514 1514 582

flag 0x2000, more fragments 0x20b9, more fragments 0x0172

offset 0 185 370

Question 4: Has fragmentation of fragments occurred when data of size 3500 bytes has been used? Why and why not? Yes as the maximum transmission unit is smaller than the data.

Question 5: What will happen if for our example one fragment of the original datagram from 192.168.1.103 is lost?

The datagram is disregarded and it will retransmit the whole package. Question 1: Which nodes communicate with which other nodes? Which route do the packets follow? Does it change over time?

Node 1 -> node 0 -> node 1 -> node 4 -> node 5 Node 2 -> node 3 -> node 5 Question 2: What happens at time 1.0 and at time 1.2? Does the route between the communicating nodes change as a result of that? Node1 -> node4 is down. No change. Question 3: Did you observe any additional traffic as compared to Step 3 above? How does the network react to the changes that take place at time 1.0 and time 1.2 now? Yes reroute the traffic to node 2 as node 4 is down....