cisco memory theshold

Hi,

I want to set a threshold for mem5minFree on cisco routers.

The trick is that i want to set it to 30% based on the installed memory which i can see that zenoss knows about since it is in the overview section on the device.

So the question is how can i reference that value in the threshold?.

linux servers uses: (here.hw.totalMemory/1024 * 0.30) but isnt working for cisco.

where can i see the  parameters avilable for a device like : totalMemory which i can then reference in thesholds, etc.?

using zenoss 4.2.4