%SW_MATM-4-MACFLAP_NOTIF: Host xxxx in vlan 170 is flapping between port Te2/1/6 and port Po112

[MusaKenan]

Hi all,

I have a issue with my Cisco switches. On each switch I got the failure. Diffenrent VLANs and different MACs are affected:

%SW_MATM-4-MACFLAP_NOTIF: Host 0000.0000.0000 in vlan 20 is flapping between port Te2/1/1 and port Po22
%SW_MATM-4-MACFLAP_NOTIF: Host 0000.0000.0000 in vlan 160 is flapping between port Te2/1/1 and port Po22
%SW_MATM-4-MACFLAP_NOTIF: Host 0000.0000.0000 in vlan 160 is flapping between port Te2/1/1 and port Po22
%SW_MATM-4-MACFLAP_NOTIF: Host 0000.0000.0000 in vlan 140 is flapping between port Te2/1/1 and port Po22
 %SW_MATM-4-MACFLAP_NOTIF: Host 0000.0000.0000 in vlan 140 is flapping between port Te2/1/1 and port Po22
%SW_MATM-4-MACFLAP_NOTIF: Host 0000.0000.0000 in vlan 162 is flapping between port Te2/1/1 and port Po22
%SW_MATM-4-MACFLAP_NOTIF: Host 787e.61a7.ecc6 in vlan 145 is flapping between port Te2/1/1 and port Po22

Does anybody know what is it about.

Thanks!
Br

Musa

[Furose M]

what is the paltform and software version running on it?

you could be affected by the following bug

https://tools.cisco.com/bugsearch/bug/CSCth28616/?reffering_site=dumpcr

[MusaKenan]

The following Cisco devices are in use.

      1 56    WS-C3850-48P       03.06.00E         cat3k_caa-universalk9 INSTALL
*    2 56    WS-C3850-48P       03.06.00E         cat3k_caa-universalk9 INSTALL

[Furose M]

interesting.. can u check if the port which is supposed to be in blocked state is indeed in blocking state? do you see a mac move messages on that port too?

[lcotter]

Looks like a loop event, do a "sh cdp nei" to help troubleshoot, are you seeing  neighbours out of te2/1/1 ?

[MusaKenan]

Hi,

the interesting thing is in my opinion, this is happening between the port-channel and the port to the core switch (C4500X).

interface TenGigabitEthernet2/1/1
 switchport trunk allowed vlan 10,20,30,40,50,60,80,90,100
 switchport mode trunk
 switchport nonegotiate
 ip arp inspection trust
 storm-control broadcast level 30.00
 storm-control multicast level 20.00
 storm-control action trap
 channel-group 21 mode active
 ip dhcp snooping trust
end

interface Port-channel22
 description PO22-CoreVSS-Tex/1/9
 switchport trunk allowed vlan 10,20,30,40,50,60,80,90,100
 switchport mode trunk
 switchport nonegotiate
 ip arp inspection trust
 storm-control broadcast level 30.00
 storm-control multicast level 20.00
 storm-control action trap
 ip dhcp snooping trust
end

any ideas?

Thank you!

[lcotter]

 do a " sh etherchannel X port-channel" where x is the Po

Also output "sh cdp nei" for the downstream switch

[MusaKenan]

The output:

AccessSwitch#sh etherchannel port-channel
                Channel-group listing:
                ----------------------

Group: 22
----------
                Port-channels in the group:
                ---------------------------

Port-channel: Po22    (Primary Aggregator)

------------

Age of the Port-channel   = 449d:01h:42m:47s
Logical slot/port   = 12/22          Number of ports = 2
HotStandBy port = null
Port state          = Port-channel Ag-Inuse
Protocol            =   LACP
Port security       = Disabled

Ports in the Port-channel:

Index   Load   Port     EC state        No of bits
------+------+------+------------------+-----------
  0     00     Te1/1/1  Active             0
  0     00     Te2/1/1  Active             0

Time since last port bundled:    179d:22h:32m:42s    Te2/1/1
Time since last port Un-bundled: 180d:15h:10m:08s    Te1/1/1

AccessSwitch## sh cdp neighbors

Core-Switch         Ten 2/1/1         135             R S I  WS-C4500X Ten 1/1/7

[lcotter]

So I can see only one nei from your access switch, should this not be 2?

Also, what's the deal with Po22?

[MusaKenan]

Sorry this is also Po21. I made a mistake. Po22 is on a diffenrent switch.