Comment Labs are not the whole answer (Score 1) 164
Labs, yeah, good times! The biggest problem is keeping the labs both operational and relevant. I just finished cleaning out my company's network lab as the switchgear was not L3-capable, out of production and out of our network, and none of the interfaces were faster than 100Mbps. None of it could be updated to a relevant OS level. It is mentioned earlier that if you are a large enough network, you designate a branch to serve as a guinea pig for planned changes. Also, if you have a branch close down, make sure you reclaim the equipment if it is new enough and use that for your 'lab' until the next refresh. Sadly, using older equipment only works if you never plan to use leading (bleeding?) edge features. However, my colleagues and I have found that using older equipment sometimes masks new and unknown interactions between the new services and older, perceived-stable, protocols.
Plan ahead meticulously - using paper and pen is not a sin as it is often faster than trying to model your system in software. Also, leverage your vendors heavily. They have the latest gear, and hopefully you will have service contracts, and they can assist you in planning out major changes.
Praying when a change goes in is good, too.