I have two datacentres, where each has the following setup. The servers connects to two 450x switches which connects to two 650x switches. This is a two-tier design since the 6506 forms the core layer of the network. I have clustered servers in the two DCs that needs a L2 LAN extension over CWDMs. Many design guides shows that i have to extend the L2 over the core since i don't have a dedicated access layer and distribution Layer. However i don't want to do this since it will lead to STP issues at the core. What would happen if instead of implementing a collapsed core, i implement a collapsed distribution layer such that the 450x switches forms the access & distribution which would connect to the 650x over L3 links. With this i would have the L2 VLAN extension over the four 450x switches in the two datacentres. I know the ultimate solution is to invest in a 3 tier design but i need this to work and to work perfectly.Kindly shed some light into this design.
In addition i have redundant L3 connections between the two datacentres connected over the 650x core switches, With this, how do you deal with the datacentre subnet that will be learnt and advertised from two different sources?
