High cpu usage on 2921
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07-15-2019 03:08 AM
Hi, i have a problem with 2921 cisco router
The problem with high cpu load, but it appears only when somebody from office is downloading something big (downloading or updating various game clients)
command show processes cpu monitor interval | exclude 0.00 not show what exactly loads cpu to 100%. I can see it only with snmp monitoring
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07-15-2019 03:18 AM
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07-15-2019 03:22 AM
Hi there,
If the CPU utilisation value cannot be accounted for by IOS processes then it must be attributed to CPU interrupts.
Can you share the first few lines of sh proc cpu , this will show the split of interrupts / processes.
Also what is the output of sh interfaces switching
cheers,
Seb.
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07-15-2019 04:22 AM - edited 07-15-2019 04:28 AM
sh interfaces switching output in txt file
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07-15-2019 05:45 PM
Your overall process CPU is a bit more (relative to interrupt CPU) than I like to see, and I notice your IP Input is somewhat more than 2%. That too might bear some improvement, but overall you're likely just pushing more through your router than it was designed for.
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07-15-2019 03:48 AM
@Koks wrote:
The problem with high cpu load, but it appears only when somebody from office is downloading something big (downloading or updating various game clients)
That means the WAN bandwidth exceeds the capacity of the router.
What is the WAN bandwidth?
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07-15-2019 04:24 AM
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07-15-2019 11:30 PM
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07-16-2019 12:57 AM
Can you confirm your words somehow?
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07-16-2019 01:37 AM
The document in attach. confirms that it supports 200 Mbps. I want to know with a show interface WAN-int-id the statistics, bw and speed of the interface and a show cpu proc sorted to see what process consumes the most cpu. It could be bw overload. Traffic can be optimized with qos and acl's to block traffic to certain resources.
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07-16-2019 02:09 AM - edited 07-16-2019 02:13 AM
Are you running encryption/VPN?
And describe the WAN link: Is this a 200/200 link (upload/download) or 200 Mbps (upload &/or download)?
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07-16-2019 08:03 AM
Oh? Yes the 2921 can process more than 200 Mbps, as seen in table 1, but did you see figure 1 on the last page which Cisco recommends a 2921 for up to 50 Mbps WAN? Software based router performance varies much depending on the nature of your traffic and your configuration. Generally, process switched traffic consumes much more CPU, for the volume traffic, than interrupt switched traffic.
In other words, your CPU loading is likely to be expected with your traffic and configuration. Again, you might be able to reduce the load, a bit, by possibly adjusting your config and/or getting the amount of traffic going to IP Input reduced. However, likely a major decrease in CPU would require a more "powerful" ISR.
