Layer 2 vs. Layer 3 to TOR

Brandon Ewing nicotine at
Thu Nov 12 20:39:01 UTC 2009

On Thu, Nov 12, 2009 at 12:19:36PM -0800, Seth Mattinen wrote:
> I'd always wondered how you make a subnet available across racks with L3
> rack switching. It seems that you don't.
> ~Seth

It's possible, with prior planning.  You can have the uplinks be layer 2
trunks, with a layer 3 SVI in the trunk acting as your actual routed uplink.

Requires much planning in advance regarding what vlans are trunked where,
etc.  Allows one to do layer 3 termination at top of rack for single
servers, but offer vlans that span multiple layer 3 switches with HSRP at
distribution as an option for systems/services that require a common
broadcast domain.

Brandon Ewing                                        (nicotine at
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