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slow 2.5 gbit performance with hardkernel odroid h2+

Fri Jul 24, 2020 10:20 pm

Dear MikroTik team and community,

I have a MikroTik CRS317-1G-16S+RM and have connected two H2+ devices from Hardkernel via RJ45 and some MikroTik S+RJ10 Revision 2.16. In the WebUI of SwOS in the "link" tab I can see that the devices are connected with the speed of 2.5Gbits. Great :-). But when I started testing I noticed that receiving data from the H2+ was good with a speed of 2.34Gbit/s and sending data to the H2+ was not. The speed was around 200Mbits. A quick look at the Error tab of SwOS revealed that there are RX pauses on the Ports where the H2+ are connected to. When I connect the two H2+ directly to each other I get full performance. And now I do not know what to do and wanted to ask for some help. (I tested a little bit around with flow control to see if that changes something, but it did not). What further information can I provide to help solve this? (don't know if this helps but the discussion started here ... 53#p300553

Thanks in advance.
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Re: slow 2.5 gbit performance with hardkernel odroid h2+

Sat Jul 25, 2020 12:36 pm

Did you try SwOS 2.12? They fixed quite a few data flow issues.
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Re: slow 2.5 gbit performance with hardkernel odroid h2+

Sat Jul 25, 2020 1:09 pm

In the hardkernel thread which OP started, he stated he's already running SwOS 2.12.

However, I'll make a comment on the discussion in that thread ... the comment won't make OP's life any easier, but still ...
Back in time when 1Gbps ethernet was coming to mainstream, Realtek NICs were pretty unpopular in linux universe. RTL hardware was not exactly the best (it lacked some advanced features) and linux drivers were sub-par (which seems to be the case still - manual config options not being supported). All in all that meant that networking using Realtek on linux was frequently problematic and many admins were explictly requesting Intel Gbps NICs in their hardware. And that's sometimes still the case, for example supported NICs by checkpoint firewall software are all Intel-based.
Could be that things are completely different in post-Gbps era but I haven't heard any praises of Realtek either (other than their networking hardware to be price-effective). There are a few Routerboards featuring RTL switch chips (e.g. RB4011) and none are known to be without problems regarding ethernet (including VLANs).
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Re: slow 2.5 gbit performance with hardkernel odroid h2+

Mon Aug 17, 2020 8:35 pm


I had the same problem. But after testing kernel 5.9.0RC1 on Ubuntu 20.04-1, iperf showed full speed.

Best regards

Brian W Andersen.

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