The technology that underpins our infrastructures changes at a dizzying rate. What was bleeding edge a year ago is old hat today. This churn leads to an endless cycle of learning just enough about new tech to jam it into production, then moving onto the next thing. This frantic pace leaves little time for training, but when deadlines are looming and work is piling up, who has the time to learn?
Even if you had endless time and resources for classroom training, it only takes you so far. Apart from generally being an extravagant waste of time, classes often teach to a certification test -- or deal heavily in one-size-fits-all generalizations. Few students walk away completely competent in the subject matter.
So instead of sitting in classes for a few weeks a year, spend that time building a lab and conducting your own tests. With the widespread availability of easy-to-use server virtualization and simulators of every kind, there's really no excuse not to. Just the process of setting up and making it work will teach you a ton. Better yet, once you're done building out your lab, you'll have a test bed that's ready to accept just about any other new item that pops out of the woodwork.
The sacrificial system
The first piece of equipment you'll need is a decent server or high-end workstation. It doesn't have to be terribly special -- a recently retired multiprocessor server beefed up with memory and disk from its brethren should do nicely. If your goal is to emulate an entire multisite enterprise network -- don't laugh, that's a completely reasonable goal -- you'll obviously need some heavier iron to get the job done. After you've cobbled together some decent hardware, toss in a reputable free hypervisor such as VMware vSphere ESXi or Citrix XenServer and you're ready to go.
If you don't want to focus on a specific SAN platform and would rather emulate a simple iSCSI SAN that can connect with other parts of your lab, Openfiler is a great option. Openfiler is a Web-driven, open source network storage platform that can act as both a NAS and an iSCSI SAN. It's a great way to offer shared storage resources to a virtualized lab.
Your virtual network
Depending upon the hypervisor you're using, you can do a lot with the virtual networking framework you have already -- whether to build multiple virtual networks with some emulated routers in between or to test a software firewall. If you're looking for an easy-to-use, multipurpose router/firewall that can run in a virtual machine, I highly recommend the free Vyatta Core, which is available as a virtual appliance.
For really heavy work, you need look no further than GNS3, an open source graphical network simulator that leverages Dynamips and QEMU to run real Cisco and Juniper software images. You can emulate a very complex wide area network, run real traffic, capture and analyze the traffic, and save the configurations for use on real equipment later on. To read up on one InfoWorld blogger's experiences doing just that, see Paul Venezia's post, "Emulating Cisco networks for fun and profit," in the InfoWorld Test Center Lab Notes blog.
Provisioning virtual servers
Rolling our workstations
As with servers, since you're running a virtualized environment, you can create almost any mix of workstations. You can speed up the process a bit by using freely available physical-to-virtual migration tools to make a virtual copy of a real desktop image from your network, applications and all. You also put yourself in a good spot to learn about newer VDI packages from VMware and Citrix, among others.
As you can see, with some time invested, you can quite literally build your entire enterprise network in a box and play with it. Beyond being a learning tool, a self-contained lab can also serve as a test bed for re-creating and troubleshooting real problems you find in your infrastructure. If you dread setting foot in a classroom, consider spending that time on your own building a resource that will keep giving.
NB: Some of the techniques I've described here are not strictly legal. For example, using GNS3 and Dynamips to run Cisco IOS images is against Cisco's license agreement. However, Cisco has essentially ignored this use of its software, because it offers valuable traning opportunities that are in everyone's interest (Dynamips is commonly used to emulate Cisco routers by CCNA/CCDP/CCIE candidates). That said, exercise your own judgment.