Effect of MTU on TCP performance

Hardware Used:

        Processors:     Dual Intel Pentium Processors (1 GHz)
        Memroy:         1 GB
        Network:        Two 1 GigE cards, one 100 MB FastE card, 32 bit PCI card

	OS:             Linux 2.4.19 with Web100
Network Path Information:
        Path:     PSC to ISI-East
	RTT:      about 10 msec
	WAN Link: 1 GigE
NOTE: The end-2-end path is GigE

Data transfer rates at various MTUs was measured using iperf. Five tests were done for each MTU size.

Effect of locking down an interrupt to a particular CPU (John Heffner's suggestion to get maximum performance):

Default                 966 881 927 875 876 919 901 833    (Avg: 897)
Fixing irq 20 to CPU1   922 912 946 921 872 915 916 886    (Avg: 911)
Please see http://www.psc.edu/~mathis/MTU/ for additional information on MTU issues.
Please see http://www.web100.org for additional information on Web100.

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