Photos: Inside Cisco's European datacentre

Sun once dominated Cisco's data centres. If Cisco was "the" networking company then Sun has always considered itself "the" networked computer company, creating a marriage that has flourished for years.

Sun is still the system of choice at Cisco; look in any of their data centres and you will see a sight that would make Sun chief executive Scott McNealy very happy.

But in today’s heterogeneous IT world, there will always be other players. For Cisco, the emergent technology has been Linux which is now the second-most-used operating system at Cisco, often running on IBM hardware.

Barriers are also being broken down by the rise of virtualisation, which is separating the OS from the hardware and freeing IT managers from the strictures they imposed. Given freedom of choice like that, will Cisco stay loyal to Sun?