[c-nsp] SNMP question

[Gert Doering]

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".

> 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 :-))

gert


-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de