Questions about Ciscos hierarchical network model

niel4575

Hey all

I've been reading a bit about ciscos network model, and the core layer confuses me a bit.

I've read that you could design the core layer with layer 2 switches - but i thought that the core layer was responsible for routing between the VLANs in your network, which is of course a layer 3 function.

Also i don't understand if routing to the internet occurs at the core layer, or if it actually not is a part of the hierarchical network model?

So i hope someone can explain these things

james43026

While you could have switches in the core layer, they are most likely going to be layer 3 switches, and at least one router. The core layer is responsible for moving traffic in between the devices in the distribution layer, and for providing access to the internet / a leased line like a dark fiber connection, T1, frame relay, MPLS VPN, or any of the other options out there. In a large corporation, that has multiple geographic locations, the core is responsible for connecting each geographic location to one another. That is a simplified version of how it works, in reality you could have a core layer at every geographic location as well, and the each geographic location would be connected to each other through the public internet, a leased line, or maybe a VPN over the public internet. It's truly a flexible system, and is just meant to be a model of how traffic should flow.