iperf test on cat5e Gb network, 177Mbits/sec...Why?

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BigBadAl

Limp Gawd
Joined
Sep 16, 2010
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Ok, iperf test between 2 machines on a cat5e gigabit network with HP 1810G 24 switch...

Machine 1: Server, win7 pro x64, dell dimension, dual core 3.4Ghz pentium d, 8GB ram, intel pro 1000 MT nic
Machine 2: Client, win7 home prem x64, samsung laptop, core i3, 8GB ram onboard Gb nic.

did a handful of tests both directions (dell as server, then with the samsung lappy as the server) and it seems quicker with the dell as the server (177Mbits/sec), with the samsung as the server i get around 159Mbits/sec.

I would have expected to see more from this network, anyone have any ideas? something glaringly obvious? something to try?

many thanks!
 
onboard NIC on the client box will slow it down normally. Intel NIC's are great but that crappy nic will slow it down. Also Hard drive read/write speeds will show things slowed down too. What are the speeds of the HD's you have?
 
That's brutal. I easily get ~ 115 MB/s with my 1810-24G with Intel NICs using CAT5E.

Were the firewalls on? What brand is the Samsung NIC? Usually desktop to desktop will be faster than desktop to laptop due to the hard drive speed. Tried different cable? Using the drivers from Microsoft or from the actual NIC manufacturers?
 
What transfer sizes are you using.... are you doing this via command line? What options?
 
I thought the whole point of this iperf was to test performance of the network and eliminate such variables as hard drive speed!? I assumed it 'cached' some data in memory and shoved it straight out of the nic!?

Firewalls were on but I allowed the test through. Not sure of the brand of the onboard nic, battery gone flat now:p.

HDD in the dell desktop is a 3GB/sec sata jobbie, recently upgraded from a hell slow sata something or other.

I'll try between two desktops tomorrow and report back.

How sure are we that iperf transfers from disk?
 
Mackintire said:
What transfer sizes are you using.... are you doing this via command line? What options?
Click to expand...

ummm all default i think used iperf -s on server and iperf -c <server ip> on client.

Update: the samsungs onboard nic is a realtek... bummer!
 
Last edited:
177 Mbps = ~22 MB per sec. That's atrocious, even for a laptop hard drive, and even a "crappy" NIC will do better than that.

I'd be looking for a duplex mismatch somewhere on the network or the like.
 
iperf doesn't use your hdd; mostly network with a little bit of CPU.

what's the latency between devices? You can try increasing your TCP window size; when I do iperf test I usually bump it up to 64k or so (iperf -w 64k)

C:\>iperf -w 65k -c 192.168.220.87
------------------------------------------------------------
Client connecting to wh-mon06, TCP port 5001
TCP window size: 65.0 KByte
------------------------------------------------------------
[280] local 127.0.0.1 port 61765 connected with 192.168.220.87 port 5001
[ ID] Interval Transfer Bandwidth
[280] 0.0-10.0 sec 945 MBytes 791 Mbits/sec
 
BigBadAl said:
Machine 1: Server, win7 pro x64, dell dimension, dual core 3.4Ghz pentium d, 8GB ram, intel pro 1000 MT nic
Machine 2: Client, win7 home prem x64, samsung laptop, core i3, 8GB ram onboard Gb nic.
Click to expand...

That's why
 
Ok, with one thing and another, i've not had chance yet to play with another machine on the network.

Rumour has it I'm getting an early finish tomorrow so will play then, I'm thinking/hoping the intel nic in the laptop too.

If my memory serves me :)eek:) all switch ports are 1000 fd as are the nics on the two systems I've used so far. Obviously that's the first thing I'm going to check on tomorrow.
 
Laptops, especially consumer laptops tend to have very poor network speeds even when at 1gbit.

Even my "business" model Dell E4310 gets crappy iperf speeds.

All my desktops perform well though.
 
okey dokey...

Another test on the LAN with another machine (Win7 Pro x64, 4GB ram, pentium e6500 @2.93Ghz, onboard pcie Gb Realtek) the server machine is the same as before....

this client machine with the same stock settings (iperf -c <server ip>) gave me 245Mbits/sec but when I used What Fint suggested I get 654Mbit/sec (81 MB/sec) so there`s an improvement there over the laptop nic and another onboard realtek and again with the modified tcp window....

Now to find an intel that`ll go in this machine.....
 
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