Solved: You can not extend a VLAN

aleksandarsofranic · ‎03-13-2015

i have a question, what if you have two l3 switches besides each other, with each switch configured with an SVI for lets say the same vlan. The two switches have an L3 link between each other. How will routing occur???

Lets say a host from that vlan want to communicate with another host from the same vlan on the other switch, he will contact his default gatway???, and then the L3 switch will route those packets to the same subnet on the other switch? This i dont understand???

Please helpp

Terry Cheema · ‎03-13-2015

You can not extend a VLAN beyond a layer 3 boundary. You will always have a layer 2 link between 2 switches in a campus. Traffic for same vlan will be broadcast to all ports in same VLAN till L3 boundary, where its dropped.

Iner-Vlan traffic will be routed through the SVI interfaces.

VLAN extension over layer 3 boundaries is done in complex scenarios - like providing HA/redundancy for mulch-tenanted data centers only.

I hope you get some clarity.

-Terry

View solution in original post

Terry Cheema · ‎03-13-2015

You can not extend a VLAN beyond a layer 3 boundary. You will always have a layer 2 link between 2 switches in a campus. Traffic for same vlan will be broadcast to all ports in same VLAN till L3 boundary, where its dropped.

Iner-Vlan traffic will be routed through the SVI interfaces.

VLAN extension over layer 3 boundaries is done in complex scenarios - like providing HA/redundancy for mulch-tenanted data centers only.

I hope you get some clarity.

-Terry

SVI and routing, please help