Performance Evaluation on Buddy-TCP By Felix

Simulation Setup S C1C1 CNCN … … T_Sink1 T_SinkN … T1T1 TNTN U U_Sink 4N Mbps 50 ms L Types of traffic: S -> C i  {1..N} : Joint-TCP flows T i  {1..N} ->T_Sink i  {1..N} : Ordinary TCP Reno flows U -> U_Sink : Background Poison UDP traffic at the rate of 40x2xN kbps Others: TCP MSS: 1460bytes TCP advertised window: 64Kbytes UDP Pkt Size: 500 bytes Queuing Decipline: DropTail N : # of Joint-TCP flows Links: All links except link L have bandwidth of 100Mbps and propagation delay of 10ms

Performance Metrics Allocation Accuracy w i  {1..N} : weights ; r i  {1..N} : Average throughputs AR i = NR i / NW i Allocation Accuracy = where

Performance Metrics Impact Ratio –Measure the impact to other TCP Reno traffic –Repeat each simulation with those Joint-TCP streams running Ordinary TCP Reno. Impact Ratio = Ravg_new / Ravg_ord where Ravg_new : average throughput of all interfering TCP flows when Coordinated Congestion Control is adopted on the Joint-TCP flows Ravg_ord : average throughput of all the interfering TCP flows when TCP Reno is adopted on the Joint-TCP flows

Allocation Accuracy Allocation Accuracy when allocation ratio is (1:2:3)

Allocation Accuracy (Cont’) Allocation Accuracy when allocation ratio is (1:4:8)

Allocation Accuracy (Con’t) Summary: –The allocation accuracy of MulTCP (with or without SACK) degrades when the allocation ratio increases (e.g. from 1:2:3 to 1:4:8). –Buddy-TCP maintains high allocation accuracy (>0.98) regardless of the number of Joint-TCP streams and the allocation ratio –The performance difference when RED is adopted is negligible.

Impact Ratio Impact Ratio for Droptail

Impact Ratio (Cont’) Impact Ratio for RED

Impact Ratio (Cont’) Summary: –MulTCP (with and without SACK) causes an decrease in the average throughput of the competing ordinary TCP traffic. The decrease can be upto 70% when SACK is used. –Buddy-TCP causes an increase (10 – 20%) in the average throughput of the competing ordinary TCP traffic. –RED has negligible effect on the Impact Ratio

Effect of Random Packet Loss S C1C1 CNCN … … T_Sink1 T_SinkN … T1T1 TNTN U U_Sink 4N Mbps 50 ms L -Random packet loss is introduced in the bottleneck link L -N = 3

Effect of Random Packet Loss (Cont’) Allocation Accuracy for the allocation ratio (1:2:3)

Effect of Random Packet Loss (Cont’) Allocation Accuracy for the allocation ratio (1:4:8)

Effect of Random Packet Loss (Cont’) Impact Ratio for different loss probability

Effect of Random Packet Loss (Cont’) Summary –When random packet loss probability is increased at the bottleneck link, the allocation accuracy will be increased, and the impact ratio will approach to 1. The effect is more apparent for MulTCP (with and without SACK) –Reason: When random packet loss probability increase to certain level, the total throughput is NOT limited by the bottleneck bandwidth anymore. Probability of TCP Timeout due to burst of packet losses at the bottleneck node is reduced.

What’s Next? Convergence of bandwidth allocation –Vs RTT Application on adaptive video streaming (some preliminary results)