Layer 2 switch vs Layer 3 switch

Hello,

I would just like to confirm. If I want to setup VLANS using a Layer

2 switch, I would also require a router to be added to the setup and with a Layer 3 switch, I'll need no router.

Thanks for any help in advance.

R.

Reply to
ramcneilly
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I think the confusion is caused by the terminology.

VLANs operate at layer 2. VLANs are virtually separated layer 2 nets.You can use VLANs just like any two or more physically separate layer two networks, with or without a router to tie them all together.

In principle, there's no need for routers UNLESS you want to tie together separate layer 2 nets. So the same applies to VLANs. No need for a router UNLESS you want hosts on separate VLANs to be able to communicate with each other.

A "layer 3 switch" *IS* a router. So by definition, if hosts in different VLANs must be able to communicate with each other, you will need a router, or a layer 3 switch, or call this layer 3 box whatever else some marketer dreams up next.

A router may be "VLAN aware," meaning that the Ethernet interfaces of the router are capable of decoding the 802.1Q extensions of the Ethernet header. It's perfectly okay to call such a box a "router."

And some routers provide some interface ports which are bridged together, meaning that the hosts connected to this subset of its interfaces belong to the same IP subnet. So a box like this is actually a combination of Ethernet switch (layer 2 switch) and IP router (layer 3 switch).

Bert

Reply to
Albert Manfredi

Thanks Bert for clearing that up.

Reply to
ramcneilly

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