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BigSky
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CRS112 switch low throughput

Thu Sep 09, 2021 12:45 am

I'm seeing performance issues with a few CRS112-8P-4S I've installed this summer. I've never used these switches before, but thought I'd try them.

I'm not using any vlans or routing, just using them as a PoE switch. In the setup I'll talk about here, I have the CRS112 switch (6.48.3) connected to a hEX S router (6.48.3) through the SFP ports on both. There's 6 AP being power up from this switch (48V PoE). The CPU load is running between 15-20% constantly, without much traffic running through the switch.

I'm using the default bridge configuration, that has hardware offload enabled on the ports and fast forward enabled on the bridge.
Screenshot 2021-09-08 153021.png
When I run a bandwidth test between the switch & the router, it maxs out at 30Mbps x 19Mbps.

I'm getting the same results from setups at different locations with ethernet connections between the router & switch, and also with wireless PtP connections between the router and switch.

Is this the limitation of this model? Or is there a programming issue?
Screenshot 2021-09-08 154148.png
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biomesh
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Re: CRS112 switch low throughput

Thu Sep 09, 2021 1:06 am

1) Don't run a speedtest / bandwidth test directly on the devices themselves. These are very slow CPU - 400Mhz. Instead run iperf tests on two devices connected to the switches/routers.

2) If you just connect via winbox, and don't have any interface window open, CPU utilization is under 10%. if you open a window with the interface stats/counters, it will increase the CPU by 10%. I have a ticket open on this, but it probably won't go anywhere. When you disconnect the CPU will run normally.

If you still have issues, post your config.
 
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BigSky
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Re: CRS112 switch low throughput

Thu Sep 09, 2021 1:14 am

Thank you biomesh. I'm only running the bandwidth because this particular site is far away. The customer is complaining about performance issues, so I log in via Winbox to "see" what's going on. I'll seeing this same issue on a few other installations I've done this summer, like I said. I'll try to get on-site to do further testing.
 
cdemers
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Re: CRS112 switch low throughput

Thu Sep 09, 2021 4:07 am

Config export would really help. But from the looks of it, if it's only running as a switch and getting 100% cpu, the bridge is mis-configured not having hardware offload enabled. Or you have enabled 'use ip firewall' in bridge settings, which will also run much of the traffic though the cpu.
 
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mkx
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Re: CRS112 switch low throughput

Thu Sep 09, 2021 10:48 am

To rule out winbox as culprit for CPU load, connect to the switch via ssh and run /tool profile cpu=all for a while to see if a) CPU is high or normal and b) what process is consuming the CPU.
 
mada3k
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Re: CRS112 switch low throughput

Thu Sep 09, 2021 6:39 pm

Sounds like your running everything through the CPU. Post complete /interface ethernet configuration and. /interface bridge port print .
 
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BigSky
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Re: CRS112 switch low throughput  [SOLVED]

Thu Sep 09, 2021 10:28 pm

Thank you all.

To rule out winbox as culprit for CPU load, connect to the switch via ssh and run /tool profile cpu=all for a while to see if a) CPU is high or normal and b) what process is consuming the CPU.

Per @mkx suggestion, I looked at the CPU usage through SSH instead of Winbox. It looks like Winbox adds 3-5% to the CPU load.

I was able to go on-site to a similar setup and test directly through a CRS-112, and the switch performed as it should. Easily handling tests of this 100Mbps circuit to Internet. Like @biomesh suggested, the onboard Bandwidth test maxed out the switch's CPU which capped speeds at around 30Mbps.

These switches are not the source of my customer's issue after all.

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