Yes, spanning tree is turned on.
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MAC flapping on Cisco 3750G switch
I have a Cisco 3750G switch connected to (among other things) 2 Cisco Aironet 1200 wirless AP's.
One AP is connected to port Gi1/0/31.
The switch is connected to our main building via a laser link (FSO) connected via port Gi1/0/1.
When monitoring the switch I am getting these error messages appear at varying time intervals:
%SW_MATM-4-MACFLAP_NOTIF: Host 0012.f0xx.xxxx in vlan 1 is flapping between port Gi1/0/1 and port Gi1/0/31
or
%SW_MATM-4-MACFLAP_NOTIF: Host 0015.00xx.xxxx in vlan 1 is flapping between port Gi1/0/31 and port Gi1/0/1
I have many other 3750G's and Aironet 1200's on this site, but this is the only on I get this problem with.
This is the running config for Gi1/0/31:
interface GigabitEthernet1/0/31
description WIFI 2ND FLR
end
This is the running config for Gi1/0/1:
interface GigabitEthernet1/0/1
description FSO-LINK
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1-20
switchport mode trunk
switchport nonegotiate
speed 100
duplex full
ip dhcp snooping trust
end
This is the running config for the port connected to Gi1/0/1 on our core switch:
interface GigabitEthernet1/0/8
description FSO-LINK
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 1-20
switchport mode trunk
switchport nonegotiate
speed 100
duplex full
no mdix auto
ip dhcp snooping trust
The FSO link is transparent to the network. The error is consistently coming from the same 2 MAC addresses.
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Answers
Quite simple and quite a pain ... you simply have two users roaming from one AP to another connected on another switch.
I am getting the same issues on my network.
Unless the frequency of the flap is very high it should not affect in any way network performance.
If you really want to nullify the roaming flapping your only solution is to disallow the mac address on the less used AP (Services/Filters).
Regards,
you can also change the settings on the wireless network cards to stop them switching AP's so easly. as soon as the signel drops they will atempt to serch for a stronger signel. If they find one they will swap to it.
By changing the cut of points you can prevent them from cutting over.
however as Gothvf said it should casue to much of a problem for the core network this.. However rember that for the end station PC's this might not be the case, as each time they switch AP's there will be a small intruption in there network. Depending how they use there network will determin if it causes a problem.
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by: DevilWAHPosted on 2008-03-12 at 10:08:12ID: 21108241
have you got spanning tree turned on ?