MAC address on ports

[zafar_118]

Hello,

How will switch handle a frame destined for MAC address that is being learned of two ports?          

[cadet alain]

Hi,

a  unicast MAC can't be on 2 ports in the same VLAN.

Regards

Alain

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[certifiedrawi37]

the switch will update the MAC address table when it recive a packet from MAC address. The old information will be invalid. So only one port will have the same MAC

[chandra_rc16]

A switch never have a single mac-address assigned to two of its ports.

Example:

Let say Switch1 has learned PC-1 Mac on its Fa0/1 (Defaulty switch won't flush PC-1's mac from it's CAM table for 300'sec). In between these 300 sec's if i unplug the PC-1 from Fa0/1 and connect it to Fa0/2, the switch will assume that PC-1 is moved to Fa0/2 add then it will add PC-1 mac on its Fa0/2 and then flush it from its Fa0/1 port.

Last learned address will be recoreded.

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Regards,

Chandu

[zafar_118]

Thanks everyone for your responses.

How about a multicast address? If a frame is destined to multlicast address (which is learned off more than one port depending if client has send igmp join message), will it then be forwarded to multiple ports?

[cadet alain]

Hi,

unknown multicast will always get flooded like broadcasts but multicast and broadcast are never source addresses so they are never learned but unicast are.

Regards

Alain

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[chandra_rc16]

Mostly multicast messages are sent by protocols (Eg: STP,VTP,DTP), those protocols will know which ports are participating in their operation. All the ports that are participating in that protocol funtion will get that frame.

Please rate helpful posts.

Regards,

Chandu