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VLANs router support vs. switch support

K

KingGheedora

Diamond Member
While looking at routers and switches I noticed that routers can let you create VLANs, and also that some switches have support for VLANs. Is it necessary to have a switch that supports VLANs in order to use VLANs created on a router?

What exactly do the more complicated switches that have built-in VLAN support do in terms of VLANs?
 
VLANs are a feature of switches. They basically divide a signle physical switch into multiple logical switches at layer 2. If your switch is only a layer 2 switch, then you will need a router in order for devices on one VLAN to talk to the another (router-on-a-stick configuration). If your switch is a layer 3 switch, then you can do inter-VLAN routing on the switch itself.
 
KingGheedora said:
While looking at routers and switches I noticed that routers can let you create VLANs, and also that some switches have support for VLANs. Is it necessary to have a switch that supports VLANs in order to use VLANs created on a router?

What exactly do the more complicated switches that have built-in VLAN support do in terms of VLANs?
Click to expand...

Yes the switches need vlan support if you actually want to use it for anything. Some unmanaged switches will barf on vlan tagged packets some may not it varies. The more expensive switches can share vlan config information allowing you to centralize the vlan configuration rather than configuring multiple switches at a time. Some also support vlan based loop detection, and vlan barrier checking (IE someone in vlan 220 loops a cable in to vlan 420, the switch can block the ports. Normally is a function of spanning tree however.)
More expensive switches also support more. Cheap ones may only support 4-16 while good ones support 4096 etc.
 
theevilsharpie said:
Yeah, you can't have automation taking away all those billable hours, now can you? :awe:
Click to expand...

Well there's that. And when I've been called in to a site that wiped out all their vlans on every single switch...automatically.

A client isn't supposed to be able to update a server, but it will and does. Best practice is still to set to transparent mode.
 
spidey07 said:
Well there's that. And when I've been called in to a site that wiped out all their vlans on every single switch...automatically.

A client isn't supposed to be able to update a server, but it will and does. Best practice is still to set to transparent mode.
Click to expand...

Or you can just use GVRP like the rest of the networking world :awe:
 
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