CS 2302 Computer Networks Unit 3

21. What is Source Specific Multicast?      

            SSM , a receiving host specifies both a multicast group and a specific host .the receiving host would then receive multicast addressed to the specified group, but only if they are from the special sender.

22. What is meant by congestion?

            Congestion in a network occurs if user sends data into the network at a rate greater than that allowed by network resources.

23. Why the congestion occurs in network?

            Congestion occurs because the switches in a network have a limited buffer size to store arrived packets.

24. What are the rules of non boundary-level masking?

·         The bytes in the IP address that corresponds to 255 in the mask will be  repeated in the sub network address 

·         The bytes in the IP address that corresponds to 0 in the mask will change to  0 in the sub network address 

·         For other bytes, use the bit-wise AND operator.

25 . explain the relationship of IEEE Project to the OSI model?

The IEEE has subdivided the data link layer into two sub layers:

* Logical link control (LLC)

* Medium access control (MAC)

LLC is non-architecture specific. The MAC sub layer contains a number of distinct modules, each carries proprietary information specific to the LAN product being used.

CS 2302 Computer Networks Unit 3

11. Define Routing?

            It is the process of building up the tables that allow thwe collect output for a packet to be determined.

12. Define ICMP?    

            Internet Control Message Protocol is a collection of error messages that are sent back to the source host whenever a router or host is unable to process an IP datagram successfully

13. Write the keys for understanding the distance vector routing?

The three keys for understanding the algorithm are,

·         Knowledge about the whole networks

·         Routing only to neighbors

·         Information sharing at regular intervals

14. Write the keys for understanding the link state routing?

The three keys for understanding the algorithm are,

·         Knowledge about the neighborhood. 

·         Routing to all neighbors.

·         Information sharing when there is a range.

15. How the packet cost referred in distance vector and link state routing?

In distance vector routing, cost refer to hop count while in case of link state routing, cost is a weighted value based on a variety of factors such as security levels, traffic or the state of the link.

CS 2302 Computer Networks Unit 3

1. Define packet switching?

            A packet switch is a device with several inputs and outputs leading to and from  the hosts that the switch interconnects.

2. What is a virtual circuit?

            A logical circuit made between the sending and receiving computers. The connection is made after both computers do handshaking. After the connection, all packets follow the same route and arrive in sequence.

3. What are data grams?

In datagram approach, each packet is treated independently from all others. Even when one packet represents just a place of a multi packet transmission, the network treats it although it existed alone. Packets in this technology are referred to as datagram.

4. What is meant by switched virtual circuit?

Switched virtual circuit format is comparable conceptually to dial-up line in circuit switching. In this method, a virtual circuit is created whenever it is needed and exits only for the duration of specific exchange.

5. What is meant by Permanent virtual circuit?

Permanent virtual circuits are comparable to leased lines in circuit switching.  In this method, the same virtual circuit is provided between two uses on a continuous basis. The circuit is dedicated to the specific uses.