mac flap

[kamleshkatariya1994]

n 3 13:04:27.746: %SW_MATM-4-MACFLAP_NOTIF: Host f6f6.0006.5a72 in vlan 11 is flapping between port Gi1/0/27 and port Gi1/0/25
Jun 3 13:04:28.343: %SW_MATM-4-MACFLAP_NOTIF: Host 9898.0008.2b90 in vlan 11 is flapping between port Gi1/0/27 and p

How do I solve this? Please help me.

[MHM Cisco World]

!!

MHM

[kamleshkatariya1994]

this is my network ring topology and all switches connected on camera and PC 

i have not found this issue 

all switches mac flapping error 

[kamleshkatariya1994]

STP working, but there are two switches different vlan, two port alternate and blocking port  

[kamleshkatariya1994]

SWITCH-1

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/25 Root FWD 4 128.25 P2p
Gi1/0/26 Altn BLK 4 128.26 P2p

VLAN0011
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address 2c1a.052d.b206
Cost 12
Port 25 (GigabitEthernet1/0/25)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32779 (priority 32768 sys-id-ext 11)
Address b08b.d067.dd80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/11 Desg FWD 19 128.11 P2p
Gi1/0/12 Desg FWD 19 128.12 P2p
Gi1/0/13 Desg FWD 19 128.13 P2p
Gi1/0/15 Desg FWD 19 128.15 P2p
Gi1/0/17 Desg FWD 19 128.17 P2p
Gi1/0/18 Desg FWD 19 128.18 P2p
Gi1/0/19 Desg FWD 19 128.19 P2p
Gi1/0/20 Desg FWD 19 128.20 P2p
Gi1/0/25 Root FWD 4 128.25 P2p
Gi1/0/26 Desg LIS 4 128.26 P2p

SWITCH-2

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/20 Desg FWD 100 128.20 P2p
Gi1/0/25 Root FWD 4 128.25 P2p
Gi1/0/27 Desg FWD 4 128.27 P2p

VLAN0011
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address 0087.64b6.c5f7
Cost 98
Port 27 (GigabitEthernet1/0/27)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32779 (priority 32768 sys-id-ext 11)
Address 00cc.fc54.b580
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/1 Desg FWD 19 128.1 P2p
Gi1/0/2 Desg FWD 19 128.2 P2p
Gi1/0/3 Desg FWD 19 128.3 P2p
Gi1/0/4 Desg FWD 19 128.4 P2p
Gi1/0/25 Altn BLK 4 128.25 P2p
Gi1/0/27 Root FWD 4 128.27 P2p

[MHM Cisco World]

!!

MHM

[kamleshkatariya1994]

SW1 and SW2 id different locations 

[Giuseppe Larosa]

Hello @kamleshkatariya1994 ,

the location of the switches does not matter if you link them with L2 links you build a single L2 domain.

From what we have seen the two switches do not agree on the Root Bridge ID in Vlan 11 they report different root bridge MAC addresses.

This probably means that your topology is too big and that STP BPPUs from one end of the network cannot reach the other end so the switches do not converge on a single root bridge election for Vlan 11.

The MAC flapping is just a result of this scenario.

Suggestion: during a maintenance time interval break the ring shutting one link between two switches and then check what happens.

Hope to help

Giuseppe

[kamleshkatariya1994]

hello 

Ring shutting down, then network is properly working fine  

[MHM Cisco World]

!!!

Goodluck 

MHM

[paul driver · Accepted solution]

Hello
Based on your OP  you are running pvst+ and either switch 1 or 2 is not the stp root switch for the estate
I would envisage server-room l3 switch is the most likely candidate to be the root switch , if not at present it possibly should be.

To make a switch running pvst+ a root switch for all vlans in a single stp estate you would use the following command:
conf t
spanning-tree vlan 1-4094 priority 0

[kamleshkatariya1994]

hello 

issue is STP ROOT ( Root SW, my L3 switch then working) 

issue has been resolved 

thanks 

[kamleshkatariya1994]

hello 

it worked fine for 2 days, today the same issue came back 

( we have block the port temporary)

Spanning tree enabled protocol ieee
Root ID Priority 1
Address 0078.8822.cc00
Cost 24
Port 25 (GigabitEthernet1/0/25)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address b08b.d067.dd80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/25 Root FWD 4 128.25 P2p

VLAN0011
Spanning tree enabled protocol ieee
Root ID Priority 11
Address 0078.8822.cc00
Cost 24
Port 25 (GigabitEthernet1/0/25)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32779 (priority 32768 sys-id-ext 11)
Address b08b.d067.dd80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/11 Desg FWD 19 128.11 P2p
Gi1/0/12 Desg FWD 19 128.12 P2p
Gi1/0/13 Desg FWD 19 128.13 P2p
Gi1/0/15 Desg FWD 19 128.15 P2p
Gi1/0/17 Desg FWD 19 128.17 P2p
Gi1/0/18 Desg FWD 19 128.18 P2p
Gi1/0/19 Desg FWD 19 128.19 P2p
Gi1/0/20 Desg FWD 19 128.20 P2p
Gi1/0/25 Root FWD 4 128.25 P2p

[paul driver]

Hello
Whatever switch your are showing has the same root port towards the stp root switch.
You can see this by the route ID priority value from your cfg output.

The stp root switch from this switch is connected via gig1/0/25 

VLAN001
Spanning tree enabled protocol ieee
Root ID Priority 1
Address 0078.8822.cc00
Gi1/0/25 Root FWD 4 128.25 P2p

VLAN0011
Spanning tree enabled protocol ieee
Root ID Priority 11
Address 0078.8822.cc00
Gi1/0/25 Root FWD 4 128.25 P2p

[kamleshkatariya1994]

Hello 

after Ring is ON, 

Spanning tree enabled protocol ieee
Root ID Priority 1
Address 0078.8822.cc00
Cost 24
Port 25 (GigabitEthernet1/0/25)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address b08b.d067.dd80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/25 Root FWD 4 128.25 P2p
Gi1/0/26 Altn BLK 4 128.26 P2p

VLAN0011
Spanning tree enabled protocol ieee
Root ID Priority 11
Address 0078.8822.cc00
Cost 24
Port 25 (GigabitEthernet1/0/25)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32779 (priority 32768 sys-id-ext 11)
Address b08b.d067.dd80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/11 Desg FWD 19 128.11 P2p
Gi1/0/12 Desg FWD 19 128.12 P2p
Gi1/0/13 Desg FWD 19 128.13 P2p
Gi1/0/15 Desg FWD 19 128.15 P2p
Gi1/0/17 Desg FWD 19 128.17 P2p
Gi1/0/18 Desg FWD 19 128.18 P2p
Gi1/0/19 Desg FWD 19 128.19 P2p
Gi1/0/20 Desg FWD 19 128.20 P2p
Gi1/0/25 Root FWD 4 128.25 P2p
Gi1/0/26 Altn BLK 4 128.26 P2p

Spanning tree enabled protocol ieee
Root ID Priority 1
Address 0078.8822.cc00
Cost 24
Port 25 (GigabitEthernet1/0/25)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address b08b.d067.dd80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/25 Root FWD 4 128.25 P2p
Gi1/0/26 Altn BLK 4 128.26 P2p

VLAN0011
Spanning tree enabled protocol ieee
Root ID Priority 1
Address 0078.8822.cc00
Cost 24
Port 26 (GigabitEthernet1/0/26)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32779 (priority 32768 sys-id-ext 11)
Address b08b.d067.dd80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15 sec

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/11 Desg FWD 19 128.11 P2p
Gi1/0/12 Desg FWD 19 128.12 P2p
Gi1/0/13 Desg FWD 19 128.13 P2p
Gi1/0/15 Desg FWD 19 128.15 P2p
Gi1/0/17 Desg FWD 19 128.17 P2p
Gi1/0/18 Desg FWD 19 128.18 P2p
Gi1/0/19 Desg FWD 19 128.19 P2p
Gi1/0/20 Desg FWD 19 128.20 P2p
Gi1/0/25 Desg FWD 4 128.25 P2p
Gi1/0/26 Root LIS 4 128.26 P2p