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New Member

Strange MAC address

Hi All,


We are getting mac move notification for a mac address - 0000.0000.0000. Pls find below the log.


%MAC_MOVE-SP-4-NOTIF: Host 0000.0000.0000 in vlan 80 is flapping between port Gi2/11 and port Gi1/46


When i checked it, it is learning via both dynamic and static. PFB the log taken from our core switch. and suggest how to rid of this. This MAC address is showing as static in both of our core switches.


sh mac address-table address 0000.0000.0000

Legend: * - primary entry

age - seconds since last seen

n/a - not available


vlan mac address type learn age ports

------+----------------+--------+-----+----------+--------------------------

Active Supervisor:

* --- 0000.0000.0000 static No - Router

* 107 0000.0000.0000 dynamic Yes 10 Gi2/3

5 REPLIES
Silver

Strange MAC address

What kind of device and software version is it? Are you running port-security? You shouldn't be seeing devices with that MAC. Maybe there is a device with a faulty NIC or some kind of virtual server in the network?

Have you tried following what is connected to Gi1/46?

Daniel Dib
CCIE #37149

Please rate helpful posts.

Daniel Dib CCIE #37149 Please rate helpful posts.
New Member

Strange MAC address

Its WS-C6509-E. One of our core switch. we have port security only in access swtiches.

s72033_rp-ADVIPSERVICESK9_WAN-M), Version 12.2(33)SXI9.


A distribution switch is connected to gi1/46

Silver

Strange MAC address

Do you have any wireless AP connected to any of these interfaces?

These all zero MAC addresses are typically generated by end stations such as the following:

  A traffic generator, such as Spirent SmartBits

  Certain types of servers, such as load-balancing IBM WebSphere servers

  A misconfigured router, server or end station, such as a device that transmits all-zeros broadcasts

  A faulty NIC

The workaround is to identify the end station that generates frames with an all-zero source MAC address.

The workaround that I can think of is to configure the command below and see if message disappear:

mac-address-table static 0000.0000.0000 vlan 80 drop.

Thanks

Ankur

"Please rate the post, if found useful"

New Member

Strange MAC address

Hi Ankur,

We have APs but not directly connected to core switch. It is connected to access switch only. Will it create any problem in wifi if we deny this mac?

Silver

Strange MAC address

Hi,

If you block this mac, i don't think there should be any prob, because this mac does not belong to any working device.

Normally this mac is sent by rogue devices or devices with faulty NICs. So blocking this mac won't create any problems.

Thanks

Ankur

"Please rate this post if found useful"

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