High link utilization

[mohammed hurais]

Hi all,

We are using a network monitoring tool and we are getting link utilization alerts on the following tool.

My query is what are the options i got manually to check the utilization via CLI.

please help me.

[mohammed hurais]

Or like what are the troubleshooting options i got from the CLI?

[kcnajaf · Accepted solution]

Hi Mohammed,

There are couple of parameters which you can try to verify this.

If you do sh interface "interface which is alerting heavy utilization" you should be able to verify below components.

1) txload, rxload and reliability. The reliability should be 255/255 and other two values should be <1-255>/255). If the numerator is high value that means heavy download or upload is happening on that interface.

2) 5 minute input and output rate:- This will display the currect traffic flowing on that interface and it represented as bits/sec

If the above two points you are seeing heavy usuage then you can enable ip accounting to check which end device is sending the data through that interface. IP accouting can be enabled as below command.

int fas x/x

ip accounting out-packets

The result can be viewed with "sh ip accounting"

Hope this helps.

Regards

Najaf

Please rate when applicable or helpful !!!

[bmcginn]

Hi Mohammed,

You'll need to provide more information.  Is it a router? is it a switch? is it an access-point? What model and IOS?

Without the above it is difficult for forum members to help.

You may be able to try something like:

show int | i is up|input rate|output rate

That will give you an idea.  To have that setting refresh more often you could put the following command into the interface itself.

load-interval 30

For troubleshooting you could look for errors on the interface, look for speed and duplex on the interface, run tdr cable diagnostics tool for layer 1 things.

If it is a switch, for layer 2 things look for Spanning tree issues such as root placement an so forth.  You can look at the device's CPU to see if its being hammered (show proc cpu).

Again, if its a switch you can do a SPAN port and run wireshark to see traffic.

You can run a boatload of debugs, but I'm wary with that as a debug ip packet may cause CPU overload   

good luck.

[mohammed hurais]

Its a live network.....And its a router connected at the remote site via MPLS

[InayathUlla Sharieff]

Hi Mohammed,

I agree with Najaf statements that clears all the basic things which we need to look at the interface utilization.

You will a noticed when the link is highly utilized there will be increased in Input/output drops occuring on that particular interface.  Just a note to remember.

Regards

Inayath

[mohammed hurais]

Thanks Najaf  ..that was really helpful...jazakallah