[c-nsp] Handling redundancy between buildings.

[Kevin Seich]

We have 2 buildings on our Campus right next to each other.  They are
connected by 10 Gb fiber pulls.  Each building has it's own generator and
UPS.  Each building has it's own ISP.  We have an ASA 5520 failover pair,
one in each building.  We have 2 - 3750x stacked in each building as a
core.  We are currently a flat network, a /16.  We are in the
design/brainstorming phase of segmenting this into vlans.  We'd like to
take the burden off the ASA for routing and do all inter vlan routing on
the 3750s.  From what we can see, you cannot treat the 3750s as a failover
pair, like the ASAs.  What are our options in segmenting this?

1  We can do all routing on the ASAs.  This would achieve the same
redundancy we have now, but put the burden on the ASA for routing all vlans.

2  Put the routing on the 3750 stack.  This would essentially break our 2
buildings into separate networks, separate , non-overlapping vlans in each
building.  reconfigure services to talk across the buildings and vlans.

3  put in routers behind the ASAs that handle all the vlan routing.  These
function in a failover pair.  this keeps the redundancy we are looking for
but we are not utilizing the layer 3 capability that we paid for on the
3750s.

Are there other options?  What have you guys/girls done?

Looking for any other input you have just to spark the design creativity.

Thank you !
Kevin