EEM for interface load monitoring on VSS

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May 11th, 2009
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I am researching the possibility of using EEM to accomplish the following:

on a VSS chassis pair, i want a syslog alarm when the load of any physical interface reaches a value "THRESHOLD1", expressed in percentage.

On portchannel interfaces is want a syslog alarm when the load of the channel reaches 50% or more (50 = THRESHOLD2).

Both threshold should be configurable outside the script (using env variables ?)

I am think of using the "counter event" for this. Any suggestions ?



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Joe Clarke Mon, 05/11/2009 - 09:13
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EEM can certainly do what you want. However, the counter ED is probably not what you want. You want to use either the timer ED because you will need to check a slew of interfaces at once (I'm assuming). If you want the ability to configure the event parameters using environment variables, a Tcl script will be required.

Essentially, you will run your policy periodically, then check a show command for each interface, then do the math.

You could also use SNMP here as well (still using a timer ED, though). That is, run the command "show snmp mib ifmib ifindex" then for each ifIndex, get the ifSpeed and ifHighSpeed objects. If the interface is a high-speed interface (i.e. ifSpeed > 100 Mbps), then poll the ifHCInOctets and ifHCOutOctets, and build the utilization based on that.

Let me know if you need more advice on this.

gnijs Mon, 05/11/2009 - 23:37
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I really want the overhead of the script to be minimum, yet, still react rather quickly to traffic peaks, so start polling and calculating interface loads myself makes me already hesitant to go that direction...

Maybe i can just base myself on the rx and tx load indications (rx/255 and tx/255) in the show interface command. This way i don't have to poll he "ifSpeed" objects and calculate the load myself. Need to make some time free to test it on a lab switch...

Thanks for the advice,

Joe Clarke Tue, 05/12/2009 - 09:10
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Yes, you can do that. However, you will have to adjust your initial environment variables for percentage to reflect the fraction of 255 instead of 100. If that's something you're willing to live with, the policy will be pretty straight forward.


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