From: Jason Madsen (madsen.jason@gmail.com)
Date: Sat Jan 03 2009 - 14:26:46 ARST
Hi Sajid,
To me MAC Flapping indicates that a switch is "seeing" a MAC address flap
between different ports. Typically with Layer 2 switches Spanning Tree runs
and determines a loop-free path through our topology. With a stable network
you should only see 1 MAC address coming from 1 port. The main reason I can
think of continually seeing it in different places is because a loop is
present in your network somewhere.
Some potential causes could be having redundant paths in your network and
having "spanning-tree disable", "bpdu-filter", or possibly "portfast"
without bpduguard on one or more of your trunk links preventing
Spanning-Tree from doing the necessary "blocks". It's difficult to say
exactly what's happening on your switch without seeing config's though. I'd
certainly take a look at your Fa0/7 and Po1 interface config's for
starters.
Jason
On Sat, Jan 3, 2009 at 2:31 AM, sajid mavani <sajidmavani@gmail.com> wrote:
> Hi Jason,
>
> Sorry for the late reply, I dont have a access to the switches as I was
> doing a remote session online. As far as my knowledge goes I dont think
> that bpdu-filter or spaning tree was disable.. I just had to do a layer 2
> etherchanel between all the 4 switches .. as i enabled lacp on it .. I
> started gettting that error message,
>
>
> Kindly let me know in such cases if you get this kind of error messages,
> what all trouuble shooting steps could be performed.
>
> Thanks everyone for your guidance and jason sorry once again for replying
> late,
>
> Have a ncie day.
>
> Regards
>
> Sajid
>
> On Fri, Jan 2, 2009 at 7:55 PM, Jason Madsen <madsen.jason@gmail.com>wrote:
>
>> you don't have bpdu-filter or spanning-tree disable on any of your trunk
>> links, do you?
>>
>>
>>
>>
>> On Fri, Jan 2, 2009 at 7:17 AM, Jason Madsen <madsen.jason@gmail.com>wrote:
>>
>>> maybe you've created a spanning tree loop. do you have physical access
>>> to the switch, or is a remote rack type situation?
>>>
>>>
>>> On Thu, Jan 1, 2009 at 10:12 PM, sajid mavani <sajidmavani@gmail.com>wrote:
>>>
>>>> Hello Everyone,
>>>>
>>>>
>>>> Please let me know what could I do to get this resolved..
>>>>
>>>>
>>>> When I created a etherchanel between SW1 & SW2 .. I got the following
>>>> error
>>>> message listed below.. Please let me know how would i get this resolved,
>>>> as
>>>> I have got this similar type of messages on many occasions.
>>>>
>>>>
>>>> {Configuration used
>>>>
>>>>
>>>> SW1 & SW2
>>>>
>>>>
>>>> conf t
>>>>
>>>>
>>>> int range fas 0/19 - 20
>>>>
>>>> switchport trunk encapsulation dot1q
>>>>
>>>> switchport mode trunk
>>>>
>>>> chanel-group 1 mode active ( lacp) }
>>>>
>>>>
>>>> Below is the error message i received.
>>>>
>>>> SW2#
>>>>
>>>> %SW_MATM-4-MACFLAP_NOTIF: Host *0030.8587.f331* in vlan 1 is flapping
>>>> between port Fa0/7 and port Po1
>>>>
>>>> %SW_MATM-4-MACFLAP_NOTIF: Host 0030.8587.f331 in vlan 1 is flapping
>>>> between
>>>> port Fa0/7 and port Po1
>>>>
>>>> *
>>>> *
>>>>
>>>> *####################################################################
>>>> *
>>>>
>>>> *Trouble shooting the problem *
>>>>
>>>> * *
>>>>
>>>>
>>>>
>>>> *1) Below oput shows this for verification *
>>>>
>>>>
>>>>
>>>> SW2#sh mac address-table vlan 1
>>>>
>>>> Mac Address Table
>>>>
>>>> -------------------------------------------
>>>>
>>>>
>>>>
>>>> Vlan Mac Address Type Ports
>>>>
>>>> ---- ----------- -------- -----
>>>>
>>>>
>>>>
>>>> 1 001a.2fd4.3d17 DYNAMIC Po3
>>>>
>>>> *1 0030.8587.f331 DYNAMIC Po1*
>>>>
>>>> * 1 0030.8587.f332 DYNAMIC Po1*
>>>>
>>>>
>>>>
>>>>
>>>> 2)
>>>>
>>>> * *
>>>>
>>>> *SW3#sh mac address-table address 0030.8587.f331 *
>>>>
>>>> * Mac Address Table*
>>>>
>>>> *-------------------------------------------*
>>>>
>>>> * *
>>>>
>>>> *Vlan Mac Address Type Ports*
>>>>
>>>> *---- ----------- -------- -----*
>>>>
>>>> 1 *0030 .8587.f331* DYNAMIC Po1
>>>>
>>>> Total Mac Addresses for this criterion: 1
>>>>
>>>>
>>>> 3)
>>>>
>>>>
>>>>
>>>> SW2#clear mac address-table dynamic interface port-channel 1 vlan 1
>>>>
>>>>
>>>> SW2 #clear mac address-table dynamic interface port-channel 1 vlan 1
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ............................................................................
>>>>
>>>>
>>>>
>>>> Still I am getting the same error message.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> I would be great full if anyone could let me know how to get this
>>>> resolved.
>>>>
>>>>
>>>>
>>>> Regards
>>>>
>>>>
>>>> Sajid
>>>>
>>>>
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