iperf slow loopback

Hi Zigotha,

first of all, I'm not that good in networking stuff ^^ So maybe anyone else might step in, but from what I see it's the network speed depend on a couple of facts. And it is always hard to tell what exactly is the issue.

You compare with "other" servers - are they the same build? 

You may encounter differences with different network cards and different operating systems.

Are all systems connected to the same switch?
Are the firewall settings correct or is it blocking some traffic?

If you have the exact same build but still differences in the speed, it could be that the NIC is the causing part and might be replaced.

Best regards,
Stefan

Hi, Stefan!

loopback trafic never hits physical network. it is all about hardware perfomance as i know.

i mean iperf -c 127.0.0.1

Hi,

thanks for clarification

You mentioned other servers with higher traffic, are those also R720xd and do they have the same hard ware config?

If yes, are you able to perform a cross test with the NIC?

Have you checked if there is a firmware update available for this NIC, maybe an update will solve it.

Thanks

Stefan

Hello, Stephan! Other servers are R720\R720xd to, but they has higher perfomance. And
iperf between servers is about 5 gbit/sec. the problem is only in loopback perfomance of
one server. Thats why i asked someone here - in dell community - to check iperf -c
127.0.0.1 on servers with same cpu's / ram

Hi Zigotha,

well, as mentioned, I'm not a big help when it comes to networking stuff.

I hope that someone in the community with such a configuration is able to answer right soon.

Cheers
Stefan