I was thinking about David Maynor’s post on Cisco’s latest security updates. His feelings are quite clear on the danger of a homogenous network:
Again let me state for the record how I feel about this: do not buy a single vendor solution for something as important as the very basis for how your network operates. I know you may get volume discounts or sales reps might take you to nice lunches but eventually something like this will happen.
A homogenous network is a weak network. Yes, all products from every vendor have bugs and vulnerabilities. In a homogenous network, all of those bugs and vulnerabilities are arranged like a row of billiard balls. One good smack on one end will travel clear to the end of the row. In a heterogenous network, the bugs and vulnerabilities don’t line up so neatly. In fact, the heterogenous network looks more like a set off balls randomly dispersed on the table. A bump on one side is far less likely to make it all the way across – that is a form of defense in depth.