My employer has your standard 3 layer architecture, however they want both core and distribution routing and switching.

This is so that some networks are routed, and some use only layer 2 between multiple distributions and core.

I was always against letter layer 2 cross a layer 3 devices, but has this standard changed as every device does routing and switching?

I'm also being asked to make the same subnet with same vlan number in two different distributions, routed at the core, tagged across. This essentially turns the core router into a distribution switch. I feel this is against best practices, but am being told to ignore that. Is this something that has become standard elsewhere?

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1 Answer 1


There really are no "standards," just manufacturer recommendations and general practices.

But every network is different, so "general practices" may not apply in your particular case.

Also, while having layer 2 crossing the core router may not be an ideal design, it may be the only practical way to accomplish the business needs.

Bottom line: Your architecture instincts are generally correct. But sometimes you have to make exceptions to get the job done. Sometimes you can't buy new equipment, or you can't renumber subnets, etc.

If you provide more specific information about your topology, we might be able to suggest alternative designs.

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