i. When their communication starts, it will continue running for relatively longer period of time and at a steady rate. Would a packet switched network or a circuit switched network more appropriate for this kind of network? Why?

Ans:

A circuit-switched network would be more appropriate to the application, as the application involves long sessions. Since the transmission rate is known and not unpredictable, bandwidth can be utilized for each session. We had not to use packet switched network for such flexible requirements.

If a link connecting two end nodes can support a transmission rate of 100𝑀𝑏𝑝𝑠 and it can support up to 20 simultaneous connections. If circuit switching is used, what will be the available transmission rate to nodes 𝐴 and 𝐵.

Ans: As in circuit switching we have to reserve the resources, for each node so in this case transmission rate would be equally divided on each node, 50 Mbps approx. for each node i.e. 50Mbps for node A and 50Mbps for node B.

Suppose that a packet switched network is used and the only traffic in this network comes from these nodes as described above. What will be the available transmission rate to the link connecting nodes 𝐴 and 𝐵? Is some form of congestion control needed? Why?

Ans: In case when packet switching is used transmission rate will vary depending upon availability of the nodes, if one node is transmitting at a time it may transmit data at 100Mbps, I think that congestion control would be needed as packet data is being used and packet delay or loss may occur so for controlling that we must require congestion control for reliable data transfer

Suddenly other hosts also start communicating over the link being used by 𝐴 and 𝐵. How would your answers to (b) and (c) will change? For both circuit switched and packet switched cases, would the network delays experience by 𝐴 and 𝐵 be constant or time varying?

Ans: For other hosts in scenario of circuit switching 100Mbps would be equally distributed and reserved for all the hosts, whether they are active or not but in the case of packet switching the availability of the hosts would matter for allocating the transmission rate. No delay would be experienced by circuit switched network as its behaviour is guaranteed, and in case of packet data delays would be experienced and they would be varying , depending upon size of packet and transmission rate allocated to that node.

Suppose that a copper cable connects two nodes (devices) located 600km apart. Assume that propagation speed in the given cable is 2x10^8ms-1.

(a) What is the propagation delay at this link?

Ans: As we know Propagation delay = d/s, Where d = length of physical link s = propagation speed in medium

d=600km=600000 m =6X10^5s=2x10^8d/s= 6x10^5/2x10^8=0.003 secs

Suppose that nodes can transmit at a rate of 10Mbps. What is the transmission delay for packet of length 1250 bytes?

Ans: as we knowR=link bandwidth (bps)L=packet length (bits)time to send bits into link = L/R

R=10Mbps =10^7 bpsL=1250 bytes = 10000 bits

L/R = 10^7/10^4 =1000

Assuming that only these two nodes are using the link at a given time and there is negligible processing delay, what is the throughput that the destination node can obtain via this link?

Ans: As we know throughput is rate (bits/time unit) at which bits transferred between sender/receiver, so for our scenario throughput is

Total rate – total delay

Total delay

dnodal=dproc+d trans+dprop = neglecting+1000+0.03

=1000.03

Total rate

2x10^8 m/s

Throughput= 2X10^8-1000.03= 199998999.97 m/s rate ans