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New Member

a mac address for a Vlan

Could someone please tell me if a mac address is getting created as a result of creating a layer 2 Vlan?

Thanks..

4 REPLIES

Re: a mac address for a Vlan

Mac address of what? A switch port?

Every switch port has a mac address.

I dont understand your question.

New Member

Re: a mac address for a Vlan

No, a MAC address is not created as a result of creating a layer 2 VLAN. A MAC address is a uniquue hadware identifier (expressed in hex format) and is present when a device comes out of the box. Each switch port has a MAC associated with it. Each host also has a MAC associated with it.

New Member

Re: a mac address for a Vlan

MAC addresses can be mapped to VLANs when using STP with PVST+. PVST+ allows the switch to create an STP instance per VLAN and allows an STP topology PER Vlan, therefore, you'll have one root bridge per VLAN and a MAC address for each root bridge on these VLANs. Can someone correct me if I'm wrong?

Sorry if this isn't the answer you're looking for, I'm new at answering questions. =]

New Member

Re: a mac address for a Vlan

Just tested this on a Cisco 3750 on my desk.

I had VLAN 1 Shutdown.

I did a show mac-address-table and there was no MAC for Vlan 1.

I unshut the VLAN 1 interface (no IP configured on it) and now there IS a mac-address entry in my table.

Understand that this is different than just adding say VLAN 10 to your vlan database or something like that.

If all you did was add a VLAN (re, not a virtual interface) to your vlan config then it will NOT create a mac-address entry.

However, if you create an interface, it will.

So the answer to your question is, it depends on what you are trying to do.

Hope that helps!

James

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