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Webcast-Catalyst9k
New Member

VLAN by port or MAC address?

Hello,

I would need some explanation about the different types of VLANs.

In the papers I read about VLANs, I have the feeling that the most popular way to implement VLANs is by port. But in that case, what happens if a PC changes from one location to another one (staying on the same VLAN)? Isn't it then necessary to configure each concerned switch relevantly?

On the contrary, VLAN by MAC address seem to be more flexible, as the fact of changing the location is easier.

What is the most common implementation used? In which kind of situation?

Thank you in advance.

2 REPLIES
New Member

Re: VLAN by port or MAC address?

The most common implementation is by port. This allows you better control of broadcasts.

Example. A stack of 3548's with all ports assigned to a VLAN connected with a trunk to a 4006. A broadcast happens on that VLAN. The broadcast stays on that stack of switches.

Using MAC addresses, if you have users scattered all over the building when a broadcast happens it will have to go to every switch with a PC defined in that VLAN. This broadcast will have to travel to all trunked ports that have a PC on that VLAN on the other end.

As you can see you don't have as much broadcast control if you use MAC addresses.

New Member

Re: VLAN by port or MAC address?

I would expect that there is a case to be made for both implementation.

In general, I would expect that the VLAN per port implementation is the most used, due to ease of implementation. Especially combined with DHCP thisa is basicaly a "configure and forget" setup.

However, this implementation is only valid to reduce the broadcast/error domains. If you want to implement VLANs and separate networks for security or policy reasons, this might very well not be the preferred option. If people move around a lot, but keep their PC (MAC address) the implementation of a MAC-address-based scheme might help you in reducing the amount of reconfiguration necessary. However, bear in mind that initial configuration (the addition of the MAC address) is more that in hte previous configuration.

Regards,

Niek van Oostenbrugge

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