I'd like to get some input regarding network infrastructure design, and L2/L3 boundary recommendations.
Let's assume the customer has a collapsed core w/ X IDFs. The current deployment is Layer 2 everywhere, w/ all routing coming back to the core stack/chassis. (They're not currently IP voice/video, but we'd like to design a solution that will support this, and efficient inter-data/v/v routing for collaboration purposes.) Each IDF/building will have Y endpoints.
At which point do you recommend a Layer 3 (L3) boundary at each IDF vs. an all L2 solution? Specifically, we could position a single L3 switch at each IDF (like a Cisco 3560), with 2960 L2 switches within the building, to 1) control b/m-cast traffic, and 2) to facilitate inter-VLAN routing (between data/voice/vid VLANs) for more efficient collaboration traffic. Without a L3 switch at each IDF, all this b/m-cast and routing traffic would go back to the core.
I'm hoping/looking for design recommendations - case studies/best practices, whatever. Customer-facing, I need to present real numbers for a L3 IDF switch vs. pure L2 for whatever number of ports. (Again, keep in mind that we need to design the solution to comfortable support IP voice/video in the future.)
Thanks, and reference docs/links are always appreciated.