[c-nsp] Migration from single L2 to multiple VLAN/subnet scenario...

[Mark Tohill]

Hi,
 
This was a thread which I posted in September 2006.
 
We would have a number of hosted and colo customers sitting on a wire
with internal systems and pretty much everything else. One flat L2
network.
 
In the very near future, we hope to split hosts into two legacy VLAN's.
Once we get to that stage we hope to start 'pairing-off' and
re-addressing customers/internal hosts.
 
Is their anyway to minimise impact on customers who are hosting WWW
service, for example. DNS tied to old addressing. Once we re-address and
place in a new vlan, customer black-holed for a few days, at best.
 
Can we route old IP's to new VLAN and implement secondary adddressing as
a temporary measure until DNS updates kick in?
 
To complicate things, we also hope to implement FWSM in our 6500's. If
secondary addressing on VLAN's is an option (is it?), does this have
implications for FWSM implementation? I think I read on CCO about
seconadry addressing and PIX/FWSM limitations.
 
I know this is going against all that is 'VLAN' and '6500' but I'm just
trying to come up with practical workarounds for where we are trying to
get to.
 
Thanks,
Mark