CS 2302 Computer Networks Unit 4

11. What is meant by quality of service?

            The quality of service defines a set of attributes related to the performance of the connection. For each connection, the user can request a particular attribute each service class is associated with a set of attributes.

12.  What are the two categories of QoS attributes?

            The two main categories are,

·         User Oriented

·         Network Oriented

13.  List out the user related attributes?

            User related attributes are SCR – Sustainable Cell Rate PCR – Peak Cell Rate MCR- Minimum Cell Rate CVDT – Cell Variation Delay Tolerance.

14. What are the networks related attributes?

The network related attributes are, Cell loss ratio (CLR) Cell transfer delay (CTD) Cell delay variation (CDV) Cell error ratio (CER).    

15. What is RED?

            Random Early Detection in each router is programmed to monitor its own queue length and when it detects that congestion is imminent, to notify the source to adjust its congestion window.

CS 2302 Computer Networks Unit 4

1. Explain the main idea of UDP?

             The basic idea is for a source process to send a message to a port and for the destination process to receive the message from a port.

2. What are the different fields in pseudo header?

·         Protocol number

·         Source IP address

·         Destination IP addresses.

3. Define TCP?

               TCP guarantees the reliable, in order delivery of a stream of bytes. It is a full-duplex protocol, meaning that each TCP connection supports a pair of byte streams, one flowing in each direction.

4. Define Congestion Control?

               It involves preventing too much data from being injected into the network, thereby causing switches or links to become overloaded. Thus flow control is an end to an end issue, while congestion control is concerned with how hosts and networks interact.

5. State the two kinds of events trigger a state transition?

·         A segment arrives from the peer.

·         The local application process invokes an operation on TCP.