Monday, February 19, 2018

Routing at the core versus routing at the distribution layer

Quick background of my network: Four 6509s at the core. Roughly 700 distribution and access layer switches. Around 80 buildings at a campus for higher education. Multiple 10gig paths to the internet, north and south.

At the moment, this network is pretty much a flat Layer 2 network across the entire campus. We have some vlans that exist on every single switch, such as camera vlans, HVAC equipment, door controllers. Some other VLANs only live in certain buildings. All routing is done on a pair of VSS 6509s at the core. This is the routing between VLANs and from the various VLANs to the internet.

I have included rough, generic maps for visualizing the concepts.
At the moment, we have fiber runs from the core building to each other building in a star pattern. We are currently working on getting a fiber ring up to provide multiple fiber paths.

I am trying to convince my co-workers and boss to move routing to the distribution layer. At the moment, a packet storm on any of the VLANs that stretch end-to-end would cripple us. We have broadcast domains that include every switch on the campus. I would also like to route at the distribution layer in each building, so that we can take advantage of the multiple fiber paths in case we lose a link between the core and any single building.

My problem is that those two arguments aren't enough to sway the rest of my department. I need help. What other arguments can I use? What other benefits would we gain from pushing routing out to the individual buildings? Or am I flat wrong about this?

https://imgur.com/a/gICSy - Routed at Core

https://imgur.com/KU4q64P - Routed at Distribution layer

https://imgur.com/U2TVPre - Routed at Distribution layer w/ multiple paths

Thank you in advance for any help you all might be able to send my way.



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