Important Questions and Answers: Routing

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.

6. What are the properties in star topology?

·        Even though a switch has a fixed number of inputs and outputs, which limits the number of hosts that can be connected to a single switch , large networks can be built by interconnecting a number of switches.

·        We can connect switches to each other and to hosts using point-to point links, which typically means that we can build networks of large geographic scope.

7. What is VCI?

A Virtual Circuit Identifier that uniquely identifies the connection at this switch, and which will be carried inside the header of the packets that belongs to this connection.

8. What is hop-by-hop flow control?

Each node is ensured of having the buffers it needs to queue the packets that arrive on that circuit. This basic strategy is usually called hop-by-hop flow control.

9. Explain the term best-effort?

If something goes wrong and the packet gets lost, corrupted, misdelivered, or in any way fails to reach its intended destination, the network does nothing.

10. What is maximum transmission unit?

MTU- which is the largest IP datagram that it can carry in a frame .

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.

16. Define Reliable flooding?

It is the process of making sure that all the nodes participating in the routing protocol get a copy of the link state information from all the other nodes.

17.            What are the features in OSPF?

·        Authentication of routing messages.

·        Additional hierarchy.

·        Load balancing.

18.            Define Subnetting?

Subnetting provides an elegantly simple way to reduce the total number of network numbers that are assigned. The idea is to take a single IP network number and allocate the IP address with that network to several physical networks, which are now referred to as subnets.

19.            What are the different types of AS?

·        Stub AS

·        Multi homed AS

·        Transit AS

20.            What is an Area?

An Area is a set of routers that are administratively configured to exchange link-state information with each other. There is one special area- the backbone area, also known as area 0.

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.            What is LSP?

In link state routing, a small packet containing routing information sent by a router to all other router by a packet called link state packet.