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MAC Address Issue - Switch

Eduardo Corzo

Hi everyone, now I'm asking for a issue in my network:

I got this laptop and plug it in a switch 3560 port, the output of show int gig0/10 tell me that the port is up, but when I perform the show mac add int gig0/10 I cannot see any mac address asociated to that port.


Any ideas of what's going on?


Thanks in advance!

10 Replies 10

First... in order to see the Laptop's MAC in the MAC table, be sure to generate traffic, so the switch can dinamically learn it.

Assuming you already did it, check if the port is a switched port or a routed port.

Remember that 3560 is a L3 switch, so if you used the "no switchport" command on that interface, then it is a routed port and shoul behave that way (not as a port which belongs to a switch).

Hope that helps.

Fahad Wasi


Hi eduardo,

pls try to reconnect the ethernet cable from the laptop to the switch port, and check.



usually the switches learns the MAC but i would suggest to ping any other ip or SVI interface and then issue the command .


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SVIs shouldn't be relevant, remember that by default they are shutdown and the switch still must function normally without any configuration.

However, it could be necessary to check that the port in question is assigned to an existing VLAN with the "show vlan brief" command.

yes you are right but my main intention to get some traffic passed through the switch .

oh, I see


let see when any feedback is received from we will know ..the result...!!!!!

Eduardo Corzo

Thanks my friends for the answers.

Well, as itskashif said, I performed ping command to SVI (of course, the port is a layer 2 interface) but I got no reponse from default gateway.

So I plug and unplug the cable severy times (and also deactivate and activate the network card) but nothing happend. I though it maybe was a problem with the card or SO so I reboot the laptop a couple of times until it finally works.

As I said, I have no idea of why this happen; maybe is just one of those weird windows bugs.

Thanks a lot again for you answers!


Best Regards



 pls check, if the ICMP protocol is not disabled on the switch.
 Is it possible that we can even block ICMP/Ping for specific VLAN?

Note that:

A: if disabling ICMP from the switch was possible it would only prevent the switch itself from receiving or sending ICMP packets, not from forwarding them.

B: It is possible to block ICMP packets on the ports of the switch (for most of them) or even the VLAN interfaces with ACLs, the same way as in a router. Which is funny considering that a switch is a L2 device, but it still can check for the fields in Layer 3 or Layer 4 headers.

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