I have several switches (some on same floor and another on other floors) all connected to core layer 3 switches through trunk links.

One of the vlan id / name is repeated along the switches. May I use the same network subnet for that repeated vlan id / name?

I would think so, because I can only have one default gateway per vlan once I implement inter-vlan on those layer 3 switches.

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Remember that layer-3 switches are still layer-2 switches. The layer-3 interfaces are SVIs (virtual interfaces, internal to the layer-3 switch), and you connect your layer-2 access switches to the layer-3 distribution switch via a layer-2 trunk, and all the layer-2 access switches could have the same VLAN(s).

A VLAN can be assigned to multiple layer-2 interfaces (including trunk interfaces) on the layer-3 switch. The layer-3 routing happens between the SVIs inside the layer-3 switch. The layer-3 address assigned to an SVI for a VLAN is the gateway address of the hosts on that VLAN.

  • Ok thanks, so I will need to use the same network subnet for the repeated vlan id / name since I can only assign one svi per vlan to be the default gateway for each of those vlans on the layer 3 switch. May 22, 2019 at 13:58

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