An Investigation into Transport Protocols and Data Transport ...

9.1. Transfer Tests Across Dedicated Private Wide Area Networks 201
Normalised Goodput (mbit/sec)
2.6
2.4
2.2
2
1.8
1.6
1.4
1.2
1
0.8
Mean Goodput
500
450
400
350
300
250
200
150
100
50
Mean TCP Flow Goodput (mbit/sec)
Normalised Goodput (mbit/sec)
2.6
2.4
2.2
2
1.8
1.6
1.4
1.2
1
0.8
Mean Goodput
500
450
400
350
300
250
200
150
100
50
Mean TCP Flow Goodput (mbit/sec)
0.6
2 3 5 9 17 25 33
Number of Flows
0
0.6
2 3 5 9 17 25 33
Number of Flows
0
(a) HSTCP
(b) ScalableTCP
Normalised Goodput (mbit/sec)
2.6
2.4
2.2
2
1.8
1.6
1.4
1.2
1
0.8
Mean Goodput
500
450
400
350
300
250
200
150
100
50
Mean TCP Flow Goodput (mbit/sec)
Normalised Goodput (mbit/sec)
2.6
2.4
2.2
2
1.8
1.6
1.4
1.2
1
0.8
Mean Goodput
500
450
400
350
300
250
200
150
100
50
Mean TCP Flow Goodput (mbit/sec)
0.6
2 3 5 9 17 25 33
Number of Flows
0
0.6
2 3 5 9 17 25 33
Number of Flows
0
(c) H-TCP
(d) Standard TCP
Figure 9.8: Fairness between various number of concurrent parallel New-TCP flows
on MB-NG.
PCs.
Figure 9.7 shows the achieved aggregate goodput of n flows of each stack.
A slight increase in the total achieved goodput of all flows on MB-NG was
observed with an increase in the number of ‘parallel’ flows. All New-TCP
algorithms on MB-NG also exhibit similar aggregate goodputs, with ScalableTCP
and H-TCP achieving a greater goodput than that of HSTCP.
This is unsurprising due to the relatively large queue size allocations of the
network which facilitates high utilisation of the network.
On the DataTAG link, it was observed that Standard TCP bulk goodput
scales poorly on the long latency link, with an almost linear increase in
performance with the number of flows up to about 10 flows. Beyond this
value, the differences in the aggregate goodput between HSTCP, H-TCP and
Standard TCP are less apparent, showing a maximum utilisation of about