Switch flapping error on port to Moxa - Host 0090.e800.0081

[adeebtaqui]

Greeetings to all,

I am continuously getting log on my 3560 switch of  %SW_MATM-4-MACFLAP_NOTIF: Host 0090.e800.0081 in vlan 12 is flapping between port Gi0/9 and port Gi0/8.

I have connected cisco 3560 to two moxa switches on these ports 0/8 and 0/9 with Moxa switches connected as end of turbo chain as shown in pic with lan cloud being cisco 3560.

Please advise about how remove this flapping message and will it errdisable the ports later?

My port configuration is as below -

interface GigabitEthernet0/8
description interface to MOXA-SW01
switchport trunk encapsulation dot1q
switchport trunk native vlan 12
switchport mode trunk
switchport nonegotiate
logging event trunk-status
logging event bundle-status
logging event status
load-interval 30
udld port aggressive
spanning-tree portfast
spanning-tree guard loop
end

//  

interface GigabitEthernet0/8
description interface to MOXA-SW02
switchport trunk encapsulation dot1q
switchport trunk native vlan 12
switchport mode trunk
switchport nonegotiate
logging event trunk-status
logging event bundle-status
logging event status
load-interval 30
udld port aggressive
spanning-tree portfast
spanning-tree guard loop
end

[balaji.bandi]

Looks like you have missed gi 0/9 config.

Either end device to moving between the switch, in some cases it's normal. as long as its not affecting services.

if this is effecting service - we need more information.

is your end turbo chain connected to bot the moxa ?  (any HLD diagram)

[adeebtaqui]

Pls see the attached pic and advise

How to stop the flap? will it cause shutdown of ports?

[adeebtaqui]

interface GigabitEthernet0/9
description interface to MOXA-SW02
switchport trunk encapsulation dot1q
switchport trunk native vlan 12
switchport mode trunk
switchport nonegotiate
logging event trunk-status
logging event bundle-status
logging event status
load-interval 30
udld port aggressive
spanning-tree portfast
spanning-tree guard loop
end

[Georg Pauwen]

Hello,

if configured correctly, all traffic should go through the Head port. It looks like MSTP is the only common spanning tree protocol both switches understand, so in order to get rid of the flapping, you would have to configure MSTP on both the Cisco and the Moxas, and then make port 9 on the Cisco the port with a lower priority (to make it the preferred port)

interface GigabitEthernet 0/0

spanning-tree vlan 12 port-priority 0

[adeebtaqui]

Moxa switches are configured with redundancy protocol of turbo chain to connect all moxa switches in ring and end at cisco switch as in pic with head moxa switch path at cisco 0/8 port being active or forwarding path and moxa tail at cisco 0/9 being blocked from moxa tail side as backup path.

So now why is there flap between ports on vlan12x

how to remove it and will it cause ports shutdown

pls advise

[adeebtaqui]

Kindly advise about how to remove the flap message and will it cause ports shutdown?

[Georg Pauwen]

Hello,

post the output of 'show spanning-tree vlan 12'...

Interface 09 should be in BLK (blocking) mode, and port 8 in FWD (forwarding) mode, is that the case ?

[adeebtaqui]

Both are in designated or forwarding state eventhough moxa side port corresponding to cisco 0/9 is in blocking as per moxa turbo chain protocol .

I shall share config in morning.

One more point is that as per moxa turbo chain protocal moxa tail port would change from blocking to forwarding whenever there is a cut in moxa ring of switches - ie there will be a sure time in future when both head and tail moxa switches connected to cisco would be forwarding.

So what is to be done in such scenario

[Georg Pauwen]

Hello,

port 9 on the 3650 needs to be in blocking state as well. Does that state change when you configure port 8 (the forwarding port) with:

spanning-tree vlan 12 port-priority 0

[balaji.bandi]

i would be intrested to see the config along with show spanning tree information to give you right direction.

[adeebtaqui · Accepted solution]

Config for ports on Cisco 3560:

!
interface GigabitEthernet0/8
description interface to ADWIP1-MOXA-SW01
switchport trunk encapsulation dot1q
switchport trunk native vlan X(moxa)
switchport mode trunk
switchport nonegotiate
logging event trunk-status
logging event bundle-status
logging event status
load-interval 30
udld port aggressive
spanning-tree portfast
spanning-tree guard loop
!
interface GigabitEthernet0/9
description interface to ADWIP1-MOXA-SW02
switchport trunk encapsulation dot1q
switchport trunk native vlan X(moxa)
switchport mode trunk
switchport nonegotiate
logging event trunk-status
logging event bundle-status
logging event status
load-interval 30
udld port aggressive
spanning-tree portfast
spanning-tree guard loop
!

!
interface VlanX(moxa)
ip address 192.168.x.250 255.255.255.0
!

SPANNING CONFIG

===============

VLAN00X(moxa)
Spanning tree enabled protocol ieee
Root ID Priority 32780
Address 5087.89ec.fb80
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32780 (priority 32768 sys-id-ext 12)
Address 5087.89ec.fb80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/8 Desg FWD 19 128.8 P2p
Gi0/9 Desg FWD 19 128.9 P2p

REPLY FROM MOXA TECHNICAL:

=========================

It is not port flapping. The MAC address 00:90:E8:00:00:81 is the special virtual MAC used as a source MAC by Moxa for some control protocols, such as LLDP, RSTP, Turbo Ring/Chain. It can't be changed. The workaround is to disable LLDP on the Moxa switches or disable the logging of flapping messages on the Cisco.

Should you have additional questions, please feel free to contact me.

Best regards,

MOXA
Sr. Technical Support Engineer

////////////

@balaji.bandi @Georg Pauwen  Pls adivse. 

Is there any command that can be given on cisco int 0/8,9 to stop showing flap messages?

[balaji.bandi]

if you like to disable LLDP for that interface as per the vendor suggestion, here is command syntax. it should work for you.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_55_se/configuration/guide/3560_scg/swlldp.html#52613

[Georg Pauwen]

Hello,

if you just want to stop the message from showing up in the logs, you can use the logging discriminator below:

logging discriminator MACFLAP severity drops 4 facility drops MATM mnemonics drops MACFLAP_NOTIF

!

logging buffered discriminator MACFLAP 100000
logging console discriminator MACFLAP
logging monitor discriminator MACFLAP
logging host 192.168.12.200 discriminator MACFLAP --> if you send the logs to a remote syslog server