At the moment, network switching and routing with open source products + commodity servers can't scale like Cisco and Juniper...if you want to have a fairly standard network (OSPF, BGP, etc).

Google, for example, is able to use commodity hardware because what they are routing works with a non-traditional setup...specifically a Clos network. That works for them only because their app is designed in a way that it can served up like that. It would not work for the typical kinds of traffic that you see at a normal company.

At a certain scale, barring unusual exceptions, you really do have to go with someone like Juniper/Cisco, as the ASIC based acceleration and other features aren't there in the commodity world.

There's certainly some things in progress that may change all of that, like Intel's DPDK, QuickAssist, etc.

Facebook builds their own networking hardware (which runs open source software):

https://code.facebook.com/posts/843620439027582/facebook-ope...