Saturday, December 1, 2012

Emergency Preparedness & IT Part 3: Documentation

Documentation is something that every IT professional should do, but it's something that none of us really do.  There's lots of reasons for this: lack of time, environment changes too fast, lack of desire.  Whatever the reason is, there's no reason good enough to not document your network.  And in emergencies, documentation is invaluable.
When everything on your network is busted, you need to know how to put it back together.  Look at your network like a big puzzle.  It's really hard to put a puzzle together without the picture of what it looks like when it's done.  The same applies for your network.  Without documentation saying how it all interconnects and is configured, you're basically playing from memory and/or starting over.  In an emergency situation, you don't have time to start over and your brain is being overwhelmed with lots of stuff.  Having a well documented network takes out the guesswork and ensures a faster recovery time.  (In addition to the obvious benefits of documentation like planning and designing around your existing infrastructure.)

A common mistake I've made (and I"m sure others as well) is having all your documentation in electronic form and no hard copies.  In an emergency situation, inevitably whatever server you have your documentation on will be down...because Murphy says so.  You should have the output of "show run" for all your routers and switches, IP address lists for all your equipment, wiring diagrams, block/functional diagrams, services each host provides...basically anything you need to rebuild your entire infrastructure...all printed out in a binder, as well as saved up on your file server and backed up on a flash drive.

A good tool for doing your diagrams, if you haven't used it already, is Microsoft Office Visio.  It's a product that's worth the money.  It does a great tool for helping you diagram out your network and network functions.  It's the de facto standard for doing network diagrams.

For more complicated setups that can't fit all your data into simple word documents, you may want to consider using a wiki for organizing your data.  Wiki's provide searchable pages, history tracking, and access control to keep all your data neat and tidy.  There are lots of wiki products out there.  If your organization uses Microsoft Office Sharepoint Server, that has a Wiki site type built into it.  If you have a *nix server, your options are almost endless.  One of my favorites is MoinMoin.  It's small, written in Python, and gets the job done.  Wikipedia as a nice listing of wiki software at to help you find one you're happy with.  But don't forget that even with a wiki, you should still print it all out.

In many large networks you've got lots of devices with static IP addresses: routers, switches, and servers are the most common ones.  There are lots of different ways you can track these.  The easiest way is with a spreadsheet in whatever program you'd like (like Microsoft Excel, Google Docs, LibreOffice Calc, etc).  This can become unwieldy depending on how many subnets and addresses you have.  A better solution for larger and more complex networks is to use a product specifically designed to do this, like SolarWinds IP Address Manager.  It's expensive ($1995), but it does a lot and helps keep your network addressing at bay.  A middle of the road solution is to write something yourself.  It's a lot easier then you'd think.  With a database backend like PostgreSQL that has a specific datatype to represent IP addressing, you can do all sorts of neat queries to find addresses in certain CIDR ranges.  Combined with some simple PHP pages, you can have yourself a simple IP management program in about a day, top.  Whatever you do...again...keep a hard copy!

When everything goes south, you don't want to be scrambling to figure out how to get your network back on it's feet.  If you've got good documentation that's easily accessible, it makes your job much easier.

In Part 4 (another smaller article in this series), I'll be talking about warranties & service contracts for your gear.  Stay tuned!

1 comment:

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