Clasification of devices in opmanager

Dear support ,

I want to know how opmanager classifies devices,

i have like 1000 devices monitored in opmanager and all automatically calsified if its router or switch,

but now we are changing our network infrastrcture and we have problem of clasification of devices,

we have lots of Cisco switches (cisco WS-C2960-24LC-S (PowerPC405) processor (revision D0) with 65536K bytes of memory.)

but this all switches opmanager recognized as ROUTER not SWITCH its problem for us at it do not applied correct monitor which are define for switches and it applies monitors of Routers

i want urgent help in this case..

thanks in adv ,

Arpit.