An Investigation into Transport Protocols and Data Transport ...

8.3. Results 174
10
100
Total Throughput (mbit/sec)
9
8
7
6
StandardTCP
BicTCP
5
FAST
HSTCP
HTCP
ScalableTCP
4
10 100
RTT (msec)
(a) 10Mbit/sec Bottleneck Capacity
Total Throughput (mbit/sec)
95
90
85
80
75
70
StandardTCP
BicTCP
FAST
65
HSTCP
HTCP
ScalableTCP
60
10 100
RTT (msec)
(b) 100Mbit/sec Bottleneck Capacity
240
Total Throughput (mbit/sec)
220
200
180
160
StandardTCP
BicTCP
FAST
HSTCP
HTCP
ScalableTCP
10 100
RTT (msec)
(c) 250Mbit/sec Bottleneck Capacity
Figure 8.27: Aggregate Goodput of two competing TCP flows with asymmetric
network conditions. The first flow is set to 162ms RTT and the second flow to
that as shown (Bottleneck Queuesize set to 20% BDP of the high latency flow).
flows is shown in Figure 8.29. In both cases the long latency flow is severely
handicapped by the aggressiveness of the second flow.
H-TCP is much more fair with bandwidth allocation between flows as
shown in Figure 8.30. It shows that even with large latency differences between
flows, the longer, and hence less responsive flow is able to maintain
a sufficiently large cwnd to enable high throughput transport, and hence
achieve fairness. As the bandwidth is inversely proportional to the latency
of the flow, a larger cwnd is required by a longer latency flow in order to
remain fair. This is shown in Figure 8.30(b).