A switch has unique MAC for each of its ports?

johnifanx98

I thought only a switch's uplink port or AUI admin has MAC. What is the use for assigning MAC to each of its ports?

When a switch forwards a frame, the decision is made based on the MAC of the host connected, not by the port's MAC address. Then what is the necessity to assign an unique MAC for each of its ports?

Or, such MAC addresses serve only for certain scenario, like STP protocol?

sizeon

you can assign a mac to a port for security reason.

YFZblu

--snip--

johnifanx98

YFZblu wrote: »

No, a switch does not have a unique MAC address for each of its ports. It might help if you told us where you're seeing/reading this and its context.

Switch>show int FastEthernet 0/1
Hardware is Lance, address is 0010.111e.1601 (bia 0010.111e.1601)

Switch>show int FastEthernet 0/2
Hardware is Lance, address is 0010.111e.1602 (bia 0010.111e.1602)

Switch>show int FastEthernet 0/3
Hardware is Lance, address is 0010.111e.1603 (bia 0010.111e.1603)

.....

YFZblu

I apologize, I misunderstood your original question - The port MAC address is used for things like CDP, STP, etc. My understanding is the port MAC address is used for traffic originated by the switch.

sizeon

you can manually type a mac address and make the port reject any other mac address.

her.yang

The only reason I could think of is for STP elections and to uniquely identify CDP neighbors.

vishaw1986

Hey john ,

In CISCO Switches we have unique MAC Address for ever port and there usage are :

STP , When we want to do Telent , Ping , SNMP to the switch or CDP