An Investigation into Transport Protocols and Data Transport ...

9.3. Internet Transfers 237
Fraction Bytes Retransmitted per Mbit/sec
10 −4
10 −6
10 −8
10 −10
10 −12
Standard TCP HSTCP ScalableTCP HTCP FAST BicTCP
New−TCP
Figure 9.32: Overhead from CERN to Dublin.
the increased stability of FAST suggest that the delayed based congestion
control algorithm of FAST is functioning well. Similarly, the large coefficient
of variation of Standard TCP is consistent with its large decrease values of
cwnd upon loss.
Overhead
FAST has the clear advantage in terms of lowering the overhead as shown
in Figure 9.32. This correlates well with previous results suggesting that the
inability of FAST to stabilise will result in large overheads.
Even though FAST has the largest inter-quartile range of overhead of all
the New-TCP algorithms, it is consistently below that of the other New-TCP
algorithms which show very similar results.
9.3.4 Results: CERN to LBL
Goodput
Figure 9.33 shows the goodput results to LBL. The performance boost by
the New-TCP protocols is clearly visible, with FAST having the highest
median goodput - with about a 10 times improvement over that of Standard