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New Member

mac in multiple vlan

hello

i have mac address in multiple vlan:

10 001a.30da.3c00 DYNAMIC Gi0/2

20 001a.30da.3c00 DYNAMIC Gi0/2

30 001a.30da.3c00 DYNAMIC Gi0/2

40 001a.30da.3c00 DYNAMIC Gi0/2

50 001a.30da.3c00 DYNAMIC Gi0/2

60 001a.30da.3c00 DYNAMIC Gi0/1

70 001a.30da.3c00 DYNAMIC Gi0/2

80 001a.30da.3c00 DYNAMIC Gi0/2

what is the reason of this proble and how to overcome?

10xs

14 REPLIES
New Member

Re: mac in multiple vlan

10xs edison

Hall of Fame Super Bronze

Re: mac in multiple vlan

The mac-address (001a.30da.3c00) could be from a switch and Gi0/2 could be a trunk port.

If so, that's an expected behavior.

Cisco Employee

Re: mac in multiple vlan

Hi,

The mac address belongs to Cisco, so it could be normal and no problem at all, as a switch uses the same MAC address in different VLANs in some environments.

This situation is then not something to overcome, as it likely is the normal behaviour.

Which device is connected to Gi0/2 and Gi0/1? Which protocols do you have enabled, like PVST etc.?

Regards, Martin

New Member

Re: mac in multiple vlan

hello1

ofcourse PVST We have Cisco gear in our Network.any idea

Hall of Fame Super Blue

Re: mac in multiple vlan

Hi Ali

If gi0/2 is a trunk port this could well be a switch at the other end that you are seeing.

Jon

New Member

Re: mac in multiple vlan

hello freinds!

yes it's a trunk port;but unusual this mac address generated high IPv6 Traffic wich we dont haver It

10xs

New Member

Re: mac in multiple vlan

more over i can't trace it:

Hall of Fame Super Bronze

Re: mac in multiple vlan

Devices connected on that switch may have IPv6 enabled by mistake.

If you go directly onto that switch, you can find the egress switchports on workstation generating that traffic.

New Member

Re: mac in multiple vlan

Hello

how can i find this:

you can find the egress switchports on workstation generating that traffic.

10xs

Hall of Fame Super Bronze

Re: mac in multiple vlan

By sniffing the IPv6 packets from a monitoring station and capturing the MAC Address.

Once you have the MAC Address of the workstation, on the switch command line interface, issue:

show mac-address | include xxxx.xxxx.xxxx

Replace xxxx.xxxx.xxxx with the mac-address from the workstation

New Member

Re: mac in multiple vlan

edison!

i have to know the wrong behavior if the IPv6 enabled by mistake on the workstation connected to switch.

Hall of Fame Super Bronze

Re: mac in multiple vlan

The only way to know is to proactively sniff packets in your network.

There are many tools in the market that perform this task, NetFlow comes to mind.

New Member

Re: mac in multiple vlan

U DIDN'T TELL ME WHAT IS THE PROBLEMS IF THEY ENABLED IPv6 bymistake.plz i have to know?

many 10xs

Hall of Fame Super Bronze

Re: mac in multiple vlan

I don't see any problems with enabling IPv6. You wanted to find out what workstations had IPv6 enabled and I explained how to do it.

Workstations can run IPv6 in your network without causing any problems in general. It's just an additional protocol in the wire.

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