Troubleshotting 100% CPU usage

RouterOS General
1

Hello all,

almost every week (maximum 10 days) my mikrotik suddenly reach 100% CPU and network starts to become slow.
After a reboot everything returns back to 20-25% CPU usage, network delays vanish until the next time.

There is not excessive traffic to the network
Is there any way to troubleshoot this problem?

I am using 6.33.3 on RB433
The problem appears at least for 4-6 months randomly!
Thank you

2

Hi JJX,

Debugging this one can be a bit hit and miss but I’d take a look at a few things:

  1. RB433 isn’t the fasted device around - ie averaging more than 20-30Mbps is going to suffer imo
  2. Dynamic routing protocols like bgp can sometimes eat things alive if RAM is tight (check available RAM [/system resource print] - free memory
  3. If you have any firewall rule that dynamically adds items to an address list - check the list didn’t grow too big
  4. One I most often see on customer device – DNS server allows remote requests from outside the network … DDOS kills the device. Add a firewall rule that looks for new dns requests …

Hope that helps to start with

3

  1. Yes, but it should be enough to handle an 24 MBit DSL and 3 WiFi clients…
    If excessive traffic was the issue, the problem should be solved after a reboot or should reappear after the reboot (when all connections are re-established)

/system resource print
uptime: 21h2m22s
version: 6.33.3 (stable)
build-time: Dec/03/2015 16:08:10
free-memory: 33.8MiB
total-memory: 64.0MiB
cpu: MIPS 24Kc V7.4
cpu-count: 1
cpu-frequency: 300MHz
cpu-load: 27%
free-hdd-space: 42.4MiB
total-hdd-space: 64.0MiB
write-sect-since-reboot: 807
write-sect-total: 39812406
bad-blocks: 0%
architecture-name: mipsbe
board-name: RB433
platform: MikroTik

  1. I don’t have

  2. DNS is allowed only to internal network.
    Cache size is limited to 4096 KB

4

use tools profile to see who is consuming cpu

5

I will send an update the next time the problem reappears