CS: 08 ACN

Which of the following best describes the role of Border Gateway Protocol (BGP) in computer networking?

• A) It is a protocol used for secure web browsing.

• B) It is a routing protocol used within a local area network (LAN).

• C) It is a protocol used to exchange routing information between different autonomous systems (ASes) on the internet.

• D) It is a protocol used to establish virtual private network (VPN) connections.

i) When a host 128.96.34.15 wishes to send the data packet to the 128.96.34.139, the packet may be lost during transmission. Where the lost packet resides and how do you recover it?

ii) What addressing being used to send a data packet to H1, H2, and H3 altogether? Find the number of hops from H1 through H3.

iii) Which layer’s responsibility is to find the source and destination address in a set prescribed time? Who generates the data packet in the network?

Answer explanation

i) When a packet is lost in the network the signal becomes zero and the lost packet cannot be recovered

ii) The broadcast address is used to send a data packet to H1, H2, and H3 altogether, and 3 hops are required from H1 through H3

iii) Network layer’s responsibility. Source node generates the data packet in the network

2. i) Backpressure and choke packet methods are vital for alleviating congestion. Yes/No. Validate

your answer with proper justification.

i) Examine how communication/exchange of data happens between source and destination. ii) Outline the process of encapsulation in the above diagram.

Answer the following questions: i) Discuss the four important flow characteristics for achieving good quality of service. ii) Identify the scheduling method in the diagram below. Illustrate the working of this method in scheduling the packets for the diagram given below. Give its advantages and disadvantages.

Answer explanation

i) Reliability, Delay, Jitter, Bandwidth

ii) Weighted Fair Queuing - In this technique, the packets are still assigned to different classes and admitted to different queues. The queues, however, are weighted based on the priority of the queues; higher priority means a higher weight. The system processes packets in each queue in a round-robin fashion with the number of packets selected from each queue based on the corresponding weight. For example, if the weights are 3, 2, and 1, three packets are processed from the first queue, two from the second queue, and one from the third queue. If the system does not impose priority on the classes, all weights can be equal. In this way, we have fair queuing with priority.