I think I've seen this problem with cheap switches - but now Im seeing it on Mikrotik not in switched environment.

960 with one port linked at 100mbps, and one port linked at 1000mbps.



Why would one port maxing out a 100mbps slow another port down? Neither port are related to each other - both feed from upstream core port - but this happens even when using bandwidth test to generate traffic. If 100mb port is sending 99mbps its not slowing down the other port, but as soon as it hits the max the other port slows down and packets are lost / latent.

Is this the same problem that switches have when everything isnt at gigabit?

6.46.8
No flow control / OFF

I think some call this "back pressure"? Flow control on or off doesnt change anything as the traffic sources are unrelated. It just seems as though when one port hits 100mbps the other ports that were going faster can no longer go as fast as they should. CPU is still around 15%. Packets start dropping across the gigabit port when the 100mb port is filled up.

Not sure if buffer on switch is per-port or is it common for while switch chip. If it's later, then a slow port can exhaust buffer making faster ports suffer.

Might want to try updating your mikrotik from version 6.44.6 to version 6.48.1

Using winbox
System --> Packages --> Check For Updates
Download and reboot

When the Mikrotik comes back after reboot
Using winbox
New Terminal --> type in "system" [ENTER] type in "routerboard" [ENTER] type in "print" [ENTER] type in "upgrade" [ENTER] type in "y" [ENTER]
Then still using winbox
System --> Reboot

That's all it takes to update/upgrade the software/firmware on your Mikroitk.

After your updates , see if the problem you are having is still there ...

North idaho Tom Jones

Thanks Tom. I did do the upgrade before posting and it did not help. Next I will try putting a gigabit switch in the middle to see if just changing the port speed to match will fix it. I had no idea this would happen and now wonder out of the 500+ mikrotik 960s I have in the field how many have this problem.