OK First things first - didn't choose the hardware or setup, I've just walked into the place :)

To clarify the observations, SNMP stops working, other services are OK.
Watching the CPU on the switch, CPU isn't very high (about 35%) and SNMP server is using about 10%.

It kicks into high gear and stops responding during the dot1dStpPortEntry dot1dBasePortEntry polling once it hits a few  VLANs that exist in the vlan table but not used. Our active VLANs pass without any issues. Once it hits this wall, no further queries get responses.

Polling these same values on the unused VLANs from other switches in the same VTP causes no issues (various models and versions)


On Mon, Mar 4, 2013 at 12:26 PM, Adam Armstrong <adama@memetic.org> wrote:

It's probably related to either ARP or FDB tables.

You can run discovery by hand as Tom suggests and then disable the module
causing the issues.

Next time you might think twice of buying shitty 3750s. (and using the
pointless "stacking" crap, which basically has resulted in your 300 ports
having a single, massively underpowered control plane cpu) :)

adam.

On Mon, 4 Mar 2013 10:02:04 -0500, Patrick Zaloum <pzaloum@gmail.com>
wrote:
> Hello
> I are testing Observium in a new environment after previous success
stories
> elsewhere.
> We have noted that when we run device discovery on a stack of 5 Cat3750
> (12.2-50-SE1) the "device" becomes unresponsive to any other queries /
> pings / ssh for approximately 5-6 minutes (during the discovery cycle).
>
> Once the discovery is complete, the poller, pings, and other operations
> return to normal. Note that traffic flow does not appear to be affected
> across the switch.
>
> Total ports on the stack are 278 (no argument that it is a large number
of
> ports to poll from a single device).
>
> Regular polling of the device does not appear to have any consequences,
it
> is specific to the discovery module.
>
> Does anyone have any insight into this?
>
> Thanks
> Patrick
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