2d) ANALYSIS OF CSMA-CA PROTOCOL USING LAN TRAINER KIT

AIM

To Implement the CSMA/CA protocol for packet communication using Benchmark LAN Trainer Kit between a numbers of nodes connected to a common bus.

APPARATUS REQUIRED

1. Benchmark LAN Trainer kit

2. Two number of computers (nodes).

ALGORITHM

REFERENCES

 http //en.wikipedia.org/wiki/Carrier_sense_multiple_access_with_collision_avoidance

  

PROCEDURE

Steps to configure receiver

1.Click on the CSMA/CA icon from the desktop on one PC.

2.Click the configuration button.

Steps to configure client nodes

1.Click on CSMA/CA icon from the desktop on second PC.

2.Click the configuration button in the window in the second PC.

3.Click OK button and download the driver to the NIU using BOOT button command.Booting from any one of the applications is enough.

4.Run the experiment by RUN Start from each application.Follow the same procedure in the client side also.

5.Set the back-off time as 40ms simultaneously in both the windows.

6.Set the carrier back off time as 40ms simultaneously in the windows.

7.Set the control signal handshake equal to packet length simultaneously in both the windows.

8.Set the data signal handshake equal to twice the packet length.

9.After 100s,both the nodes stop Tx.

10.Once the sender stops,press OK button in the receiver node and press the stop button.

11.Repeat the above steps for various values of ta.

12.Calculate the practical offered load from the formula and plot the graph.

13.Repeat the experiment for various values of packet length,node and data rate.

SETTING THE CONFIGURATION MENU

PC1(Access Point) PC2(Client Nodes)Node ID 0 0 on config menu1 & 1 on menu2Protocol ALOHA ALOHABaud Rate 8kbps(config& NEU) 8kbps(config& NEU)Duration 100s 100sPacket Length 100 100Bit Delay 0(at NEU) 0(at NEU)Direction Receiver SenderMy Address 1 1

THEORY

Carrier sense multiple access with collision avoidance  (CSMA/CA) in computer networking, is a network multiple access method in which carrier sensing is used, but nodes attempt to avoid collisions by transmitting only when the channel is sensed to be "idle". CSMA/CA is a protocol that operates in the Data Link Layer (Layer 2) of the  OSI model. Collision avoidance is used to improve the performance of the CSMA method by attempting to divide the channel somewhat equally among all transmitting nodes within the collision domain. Although CSMA/CA has been used in a variety of wired communication systems, it is particularly beneficial in a wireless LAN due to a common problem of multiple stations being able to see the Access Point, but not each other.

PERFORMANCE ANALYSIS PARAMETERS OF CSMA-CA

CALCULATION OF PRACTICAL THROUGHPUT

CALCULATION OF PRACTICAL OFFERED LOAD FOR CSMA/CA

CALCULATION OF PRACTICAL THROUGHPUT(X) FROM OBTAINED READINGS

CALCULATION OF PRACTICAL OFFERED LOAD

G = Generated Load

N = Number of nodes

P = Packet Length

C = Data Rate

ta = Inter-Packet Delay

MODEL GRAPH

TABULATION

IPD TX2 C2 TX3 C3 G-PRACTICAL

OFFERED LOAD

X-PRACTICAL THROUGHPUT

ACK G-COUNT

IPD TX1 C1 TX2 C2 TX3 C3 TX4 C4

G-OFFERED LOAD X-PRACTICAL THROUGHPUT AVERAGE DELAY

RESULT

Thus CSMA/CA protocol analysis using Benchmark LAN Trainer Kit for packet communication between a number of nodes connected to a common bus is implemented.