Debug for MAC address flaps?

Are there any good debug or show commands that will work for the NM-16ESW in dynamips for getting information about MAC address table changes? Ideally I'm looking for a debug that gives information every time theres a change to the MAC address table, if such a debug exists.

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Comments

redwarrior

We've had a problem with interface flapping with teamed NIC's on servers. That usually just shows up in the logs regardless of what we have set or not set for debugs.

BennyLava

redwarrior wrote: »

We've had a problem with interface flapping with teamed NIC's on servers. That usually just shows up in the logs regardless of what we have set or not set for debugs.

Yeah I've seen log messages like that before on switches. I'm not getting any log messages on the router though, even though "show mac-address-table" shows that a MAC address is constantly switching back and forth between different interfaces.

cisco_trooper

Yeah, I have seen this on switches before. Depending on how you are connected to the device you may need to tinker with the logging configuration in order to see the MAC flap messages come up as they occur.

logging monitor or logging console usually is all you need.

BennyLava

cisco_trooper wrote: »

Yeah, I have seen this on switches before. Depending on how you are connected to the device you may need to tinker with the logging configuration in order to see the MAC flap messages come up as they occur.

logging monitor or logging console usually is all you need.

I have logging enabled and there are log messages generated for other events, but not for MAC address flaps.

PStefanov

You can use the mac-address table notification feature and then debug snmp traps, but that's not supported on Dynamips, you need a real switch to do that.

cisco_trooper

Post your output from "show logging"

BennyLava

cisco_trooper wrote: »

Post your output from "show logging"

R1#show logging
Syslog logging: enabled (12 messages dropped, 1 messages rate-limited,
                0 flushes, 0 overruns, xml disabled, filtering disabled)
    Console logging: level debugging, 777 messages logged, xml disabled,
                     filtering disabled
    Monitor logging: level debugging, 0 messages logged, xml disabled,
                     filtering disabled
    Buffer logging: disabled, xml disabled,
                    filtering disabled
    Logging Exception size (4096 bytes)
    Count and timestamp logging messages: disabled

No active filter modules.

    Trap logging: level informational, 91 message lines logged

cisco_trooper

That looks like you should be getting some log messages when the MAC flaps. The only thing I can think of is that the NM module in dynamips isn't catching MAC flapping...