Network Speeds

Last night I needed to transfer a vmware image from a linux host to a windows laptop. I was surprised it took over an hour to do so considering it was on a wired network, so I decided to do some testing on my network.

I have two ubuntu linux hosts which I will be calling linux1, linux2. I also have a mac laptop (apple1), a windows laptop (win1), plus a windows vm running on the mac (win1-vm). All have onboard gigabit network interface cards and are connect to a single 10/100 24 port switch in the basement.

So the first thing to do is benchmark the network and get a baseline
linux1 to linux2

linux1:$ iperf -t 60 -c linux2
------------------------------------------------------------
Client connecting to linux2, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 10.1.1.50 port 45045 connected with 10.1.1.136 port 5001
[ 3] 0.0-60.1 sec 674 MBytes 94.1 Mbits/sec

and apple1 to linux2

apple1:$ iperf -t 60 -c linux2
------------------------------------------------------------
Client connecting to linux2, TCP port 5001
TCP window size: 129 KByte (default)
------------------------------------------------------------
[ 3] local 10.1.1.125 port 64143 connected with 1.1.1.136 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-60.0 sec 664 MBytes 92.9 Mbits/sec

Here is the output from the endpoint linux2

linux2:$ iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 10.1.1.136 port 5001 connected with 10.1.1.50 port 45045
[ 4] 0.0-60.2 sec 674 MBytes 93.8 Mbits/sec
[ 5] local 10.1.1.136 port 5001 connected with 10.1.1.125 port 64143
[ 5] 0.0-60.0 sec 664 MBytes 92.9 Mbits/sec

This gives us a baseline of 92.9 Megabits to 93.8 Megabits per second, which look pretty good for a 10/100 Megabit per second switch.

Now to do some real world testing with scp
Transfer from linux2 to apple1

apple1:$ scp user@linux2:/usr/local/vm/test.vmdk .
user@linux2's password:
test.vmdk 100% 3549MB 10.5MB/s 05:39

Transfer from linux2 to linux1

linux1:$ scp user@linux2:/usr/local/vm/test.vmdk .
user@linux2's password:
test.vmdk 100% 3549MB 11.2MB/s 05:18

so we are getting 84 and 89.6 Megbits/s which are acceptable apple1's lower number might be related to having vmware fusion running on the same machine.

Now we test the same situation I had last night of transferring a file form linux2 to a windows host. I am using pscp V0.60

(win1-vm):\>pscp user@linux2:/usr/local/vm/test.vmdk .
test@linux2's password:
test.vmdk | 176000 kB | 936.2 kB/s | ETA: 01:01:34 | 4%

That gives us 0.914 Megabytes/s or 7.31 Megabits per second which is a far cry from 93.8 Megabits recorded by iperf

Putty also has a beta snapshot Version 2009-01-04:r8377 so I tried that

(win1-vm):>\pscp-b user@linux2:/usr/local/vm/test.vmdk .
user@linux2's password:
test.vmdk | 3634240 kB | 6975.5 kB/s | ETA: 00:00:00 | 100%

That gives us 6.812 Megabytes/s or 54.49 Megabits/s which is a lot better than V0.60 but still not as good as native scp to scp. The above pscp tests were on a windows vm on a mac so that might account for some of the slowness. The final test is for a transfer from linux2 to a dedicated Windows XP machine.


test.vmdk | 3634240 kB | 9665.5 kB/s | ETA: 00:00:00 | 100%

Which resulted in a respectable 9.44 Megabytes/s or 75.5 Megabits/s, still not quite as good as linux scp to scp but bearable.

So to conclude pscp V0.60 has some serious issues and should be avoided.

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