Network Infrastructure IP address re-addressing

Hi everyone,

Would anyone kindly share their experience or related information
(web, doc, etc) on this topic? e.g.

1. Initial planning for time usage, human resources usage and
requirement specification.
2. Rough estimation or forecast of the impact to current equipment
(hardware and software configuration.
3. Action plan, etc

Greatly appreciate for any bit of information about this topic. Thanks
alot!

Cheers~

 

:Would anyone kindly share their experience or related information
web, doc, etc) on this topic? e.g.

:1. Initial planning for time usage, human resources usage and
:requirement specification.
:2. Rough estimation or forecast of the impact to current equipment
hardware and software configuration.

There is an important issue that you are going to have to decide
up front before you can make any realistic time estimates:

Will the renumbering be done "all at one go", or
will the renumbering be phased in with full support required for
a mix of old and new IP spaces?

In my experience, the "all at one go" approach is a lot easier to
plan (especially if you already have multiple subnets), and a lot
faster to "get over with" -- but if you do decide on "all at one go"
then you MUST have a plan on how to revert to the previous configuration
if things go really wonky. The things that can go wonky are legion,
and when you are in the middle of the situation, the problems
will NOT make sense: doing a conversion en-masse is great when it works,
but when it doesn't you will be very taxed to track down the problems.
And since people will be wanting to get on their systems ASAP, you
will probably be racing the clock to get everything done -- one of those
instances when you work until 3 in the morning and only quit for the day
because your mind has completely unravelled.

The other approach, with a transitional configuration, can get to
be -very- messy during the transition. The beginning state is clear
and the end state is clear, but the mix of the two can be darn near
impossible to predict until you are right there, yanked cable in
hand, and suddenly realize that there -isn't- anywhere to plug it into
because you (e.g.) ended up needing N -times- M connections during
the transition instead of max(N, M) or N + M. No matter how many times
you draw it out on paper, you will miss something that is only
needed right during the transition. Having a switch/router with
"virtual router facility" can help a lot in such instances...

I usually end up leaving major network changes until Christmass
break (while the building is officially 'shut down') or until a 4-day
weekend at least. Unless, that is, it's a major firewall change,
in which case I try to get it done in the space of one night...
unsuccessfully. Some day I'll learn...