Simulation of two Queue Management techniques – Tail Drop and RED, for a mesh network. The results obtained are analysed over 3 parameters: Throughput, End-2-End delay and Packet Loss/Drop. The goal of the simulations performed using NS2, is to determine which Queueing mechanism, Taildrop or RED, is better for managing queues and thereby more effective for Congestion Control. These two mechanism are tried on a single network scheme and are compared on the basis of various performance parameters. RED came out as a queue management technique with the target to outperform the performance of Tail Drop.

Schematic of the network simulated A Mesh network with 3 wireless nodes, 3 static and 3 mobile nodes.

Description of the different flows/packets/protocols Routing protocol : AODV Interface queue type : Droptail and RED End to end link specs: 2Mb 10ms and 1.7Mb 20ms End to End protocol: TCP and UDP

Varying parameters

• Congestion control protocol (Taildrop/RED)
• Sent Data Rate
• Packet size

For Observations, refer to the observation directory in the repository. Overall Simulation Information:

Drop Tail Simulation length in seconds: 9.77363029 Number of nodes: 7 Number of sending nodes: 7 Number of receiving nodes: 4 Number of generated packets: 640 Number of sent packets: 316 Number of forwarded packets: 289 Number of dropped packets: 326 Number of lost packets: 4 Minimal packet size: 32 Maximal packet size: 1040 Average packet size: 870.7948 Number of sent bytes: 246072 Number of forwarded bytes: 244808 Number of dropped bytes: 330808 Packets dropping nodes: 0 1 2 5

RED Simulation length in seconds: 5.321942771 Number of nodes: 7 Number of sending nodes: 7 Number of receiving nodes: 4 Number of generated packets: 619 Number of sent packets: 285 Number of forwarded packets: 266 Number of dropped packets: 336 Number of lost packets: 1 Minimal packet size: 40 Maximal packet size: 1040 Average packet size: 875.2949 Number of sent bytes: 223204 Number of forwarded bytes: 222304 Number of dropped bytes: 339796 Packets dropping nodes: 0 1 2

Results Results for the observed parameters as per our simulation are following:

• Throughput analysis: As we can see from the fig. (iii) and fig. (iv), throughput of both the protocols are almost the same. But RED seems to have a slight advantage over Tail Drop protocol.
• Packet Loss: From the overall simulation information, it is clear that Drop Tail suffered from the loss of 4 packets while RED suffered from the loss of just 1 packet.
• End to End Delay: From the fig. (i) belonging to Tail Drop and fig. (ii) belonging to RED, it is clear that the avg. delay time for data in case of RED is less than Tail Drop. So, RED seems to perform better in case of E2E delay as well.

Conclusion Results shows that RED performs better than Tail Drop maintaining a low packet drop and higher throughput also maintaining a high packet delivery ratio(as clear from the overall information).