i am buying about 150 used lan switches . how can i check that all ports of all switches are working ie all switches are in working condition .and as number of switches is high please tell a method which is fast.all are unmanaged switches

Buy a network signal tester and plug it into each port.
http://www.google.co.uk/products?hl=en&rlz=1W1GGIE_en&q=cat5+tester&um=1&ie=UTF-8&ei=tSQhS8qvHIqs4QbWwtnjCQ&sa=X&oi=product_result_group&ct=title&resnum=1&ved=0CB8QrQQwAA

Or to test full port functionality configure a ping -t and just swap a rj45 into each one until you get ping replies.(snap off the plastic tab on the RJ45 connector to make it easier to test each one)

I agree with the network cable tester, I bought an inexpensive one on ebay for about $5us.

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.