[c-nsp] SNMP question

[Sam Stickland]

Gert Doering wrote:
> Hi,
>
> On Mon, Apr 02, 2007 at 06:17:06PM +0100, Sam Stickland wrote:
>   
>> Can anyone answer this question from a college of mine?
>>
>> "Afternoon all. Does anyone know anything about the minimum poll period 
>> for an OID on a Cisco box? For example, I'm polling a 6500 for the in 
>> and out octets for a layer 2 interface and I periodically get a response 
>> of 0. Even with a period of 5 seconds this still happens. I know that 
>> this isn't a true reading of the in/out octets as the port connects to a 
>> market-data firewall which is continuously streaming market -data.
>>     
>
> I've run some testing, and different Cisco platforms update the SNMP-viewable
> counters at different intervals.
>
> Cisco 3560s seem to do it in 1-second intervals, 6500 (Sup720, SXF) at
> 10-second intervals, 7200s (12.2S) at 20-second intervals.
>
> So the best you can get is "poll in 1-second intervals, and if the value
> you read back is changing, calculate the delta from the time of the 
> previous change".
>   
Thanks Gert, this is very helpful. I'm guessing then that there isn't 
any offical cisco documentation on this?
>> Presumably it's a function of the H/W platform and/or the OS but I've 
>> never been able to find any documentation on this. If anyone can shed 
>> any light on this - oh so fascinating subject - I would be most grateful."
>>     
>
> SNMP isn't fascincating.  "Frustrating" is a much better word.
>
> (OTOH, any sort of *counters* on Cisco boxes is fascinating indeed :-))
>   
Indeed.

Sam