blocking MAC address on any port

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Oct 14th, 2007
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I got an inquiry in blocking MAC address. I know that MAC can be blocked per port thru port-security (sticky/dynami). What i want to ask is if it is possible to block a MAC somewhere the distribution layer or core layer so that whenever the laptop connects on any of the edge or access switches the port will be blocked or access is denied.


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guruprasadr Sun, 10/14/2007 - 22:25
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I don't thinkso this will be possible. Normally the Laptops or workstations are connected at the Edge level where the MAC Address Table is maintained.

The MAC Address Table is not propagated to the Distribution Layer / Core Layer of the Network where as the IP Connectivity is only propagated over the Routing table.

In theory, blocking at the Source or Originating side is the best way to do so. By this the Port-Security can be used to block the access.


Best Regards,

Guru Prasad R

ankbhasi Sun, 10/14/2007 - 22:44
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Hi Friend,

Port security will not help and suffic your requirement.

I can think of 2 possible solutions that is dot1x which is identity based networking or VMPS where you have pre approved mac address listed in a text file with vlan number they should be assigned dynamically and is any machine gets into the network whose mac address is not from the pre configured list can be assigned to a non routable vlan or an isolated vlan which does not have any connectivity into your network just like a guest and then you can have control on that vlan.

But I agree 802.1x will give you more security and control in your network.

You can have a look at these links for 802.1x as well as VMPS

For 8021.1x




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