Which of the following statements is true concerning TCP’s congestion control?Question 24AnswerIt is used by ISPs to control the traffic in the networkIt changes the sending rate dynamically according to indicators of the network’s traffic conditionsIt is a mechanism used by routers to reduce the network trafficIt allows the sender to slow down so that the receiver is not overwhelmed.

A node of a data communication network which can transmit data at 4 different rates r, 2r, 3r& 4r uses the mechanism described below to control congestion: At any given time the nodeis transmitting data at one of the above rates. It is assumed that data is always available fortransmission. There is a congestion indication flag which is assumed to be independent of thestate of the node but indicates congestion in the whole network. The data transmission rate isrevised in regular intervals keeping to following rules:1. If the congestion flag is on, the data rate is reduced by two steps or to the lowest step (i.e.rate r) whatever the higher.2. If the flag is off, the rate is increased by one step or remains in the highest step.a) Draw the Markov chain indicating the states and transitions assuming that the flag ison with probability p. [30 marks]b) What happens if p=0 and if p=1? [10 marks]c) Calculate the state probabilities for p=0.6. [30 marks]d) What is the average transmission rate? [20 marks]e) Comment on the validity of the results in c) & d) if p varies with time. [10 marks]Q2.a) Jobs arrive at the rate of 1 job per unit time into an M/M/1-FIFO queue. What is themean queue length if the mean service time is 0.55 time units? [20 marks]b) Another M/M/1-FIFO queue has a server identical to that in a) and the same arrivalrate, but a longer mean service time of 0.85 time units. What is the mean queue lengthof this queue? [10 marks]c) Now, both streams of jobs are diverted to a third queue of type M/H2/1-FIFO with asingle server working at double the rate of those in a) and b).a. What is the total arrival rate? [10 marks]b. What is the mean service time of the jobs in this queue? [10 marks]c. What is the mean queue length of this queue? [30 marks]d. Analyse the pros and cons of this queue against the combination of queues ina) and b). [20 marks]

When an application uses a TCP socket, what transport services are provided to the application by TCP?  Check all that apply.Group of answer choicesThroughput guarantee. The socket can be configured to provide a minimum throughput guarantee between sender and receiver.Loss-free data transfer. The service will reliably transfer all data to the receiver, recovering from packets dropped in the network due to router buffer overflow.Congestion control.  The service will control senders so that the senders do not collectively send more data than links in the network can handle.Flow Control. The provided service will ensure that the sender does not send so fast as to overflow receiver buffers.Best effort service.  The service will make a best effort to deliver data to the destination but makes no guarantees that any particular segment of data will actually get there.Real-time delivery. The service will guarantee that data will be delivered to the receiver within a specified time bound.

Explain TCP Congestion Control in 5 short points

tcp segment congestion control (transport layer)

Which one of the following algorithm is not used for congestion control? a) traffic aware routing b) admission control c) load shedding d) routing information protocol