1

Is it possible to have Layer 3 switches at access level (meaning the PCs are connected to it) if multiple VLANs are spread out accross multiple switches? For example, VLAN 10 is present at SW1 and SW2.

My guess is that such thing would not be possible and that Layer 2 switches should be used instead, and one Layer 3 Switch can act as a default gateway for the VLANs.

Am I right?

Improve this question
0

1 Answer 1

Reset to default
2

A layer-3 switch is first a layer-2 switch. You can configure physical interfaces to be either routed or layer-2 interfaces. In most cases, they default to layer-2 interfaces. Most of the layer-3 routing happens on virtual interfaces, e.g. Cisco SVIs.

Improve this answer
6
  • For example, if SVI is configured at access level switch 1 for VLAN 10 and subnet 10.10.10../24, this means that I cannot have SVI for the same subnet but at switch 2?
    – Quirik
    Dec 10, 2021 at 17:28
  • That actually does not make sense. The interfaces to which the hosts connect can be layer-2 interfaces for that VLAN. With a layer-3 SVI for that VLAB you cannot have any physical interfaces a layer-3 interfaces for that network. Other devices can have interfaces in that network, but only one at layer-3 per device.
    – Ron Maupin ♦
    Dec 10, 2021 at 17:31
  • 1
    For example, you can have many routers per network, each with one interface in that network. A layer-3 switch has a routing module, and it works like a router, so you can have multiple layer-3 switches, each with one SVI per network.
    – Ron Maupin ♦
    Dec 10, 2021 at 17:37
  • 1
    @Quirik You can have only one SVI interface per VLAN per switch. Every switch can have its own SVI on that VLAN.
    – Ron Trunk
    Dec 10, 2021 at 18:12
  • @Ron Trunk I don't understand the second sentence. Could you, please, explain it? Do you mean that every switch can have a SVI with an IP address from that VLAN/subnet? For example, SW 1 SVI with 10.10.10.1, and SW2 SVI with 10.10.10.20? Does this mean that devices from this particular VLAN will have their default gateway at 10.10.10.1 at SW1, and at 10.10.10.20 at SW2?
    – Quirik
    Dec 11, 2021 at 14:26

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.