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MAC Address Flapping between Switch & Router

Hi All

I am getting following messages within every minute on Switches (IPTSW01 & IPTSW02)

%SW_MATM-4-MACFLAP_NOTIF: Host 0023.ebcb.59c0 in vlan 133 is flapping between port Po1 and port Gi0/4

Please refer attached topology

Topology.jpg


 

Here :

1) Gi0/4(Desig-FWD) of Switch (IPTSW01) is connected to Gi0/0 (BLK) of Router (IPTRT02)

i) interface GigabitEthernet0/0 (This is the interface of IPTRT02 connected with Gi0/4 of Switch IPTsw01)
  dampening
  no ip address
  carrier-delay msec 0
  duplex Full
  speed 1000
  media-type rj45
  bridge-group 1


ii) interface GigabitEthernet0/4 (This is the interface of IPTSW01 connected with Gi0/0 of Router IPTRT02)
     Switchport access vlan 133
     switchport mode access
     storm-contorl broadcast level 1.00
     spanning-tree portfast


2) Gi0/4(Desig-FWD) of Switch (IPTSW02) is connected to Gi0/1 (FWD) of Router (IPTRT02)

Here:

i) interface GigabitEthernet0/1 (This is the interface of IPTRT02 connected with Gi0/4 of Switch IPTsw02)
    dampening
    no ip address
    carrier-delay msec 0
    duplex Full
    speed 1000
    media-type rj45
    bridge-group 1

ii) interface GigabitEthernet0/4 (This is the interface of IPTSW02 connected with Gi0/1 of Router IPTRT02)
     Switchport access vlan 133
     switchport mode access
     storm-contorl broadcast level 1.00
     spanning-tree portfast

iii) Interface Gi0/0 & Gi0/1 of IPRT01 are in  BVI1

interface BVI1  (BVI is configured on IPTRT01)
ip address 1.1.1.1
dampening
ntp broadcast client
ntp broadcast
h323-gateway voip interface
h323-gateway voip bind srcaddr 1.1.1.1

iv) Interface Gi0/0 & Gi0/1 of IPRT02 are in BVI1


interface BVI1  (BVI is configured on IPTRT02)
ip address 2.2.2.2
dampening
ntp broadcast client
ntp broadcast
h323-gateway voip interface
h323-gateway voip bind srcaddr 2.2.2.2


3) Mac-address 0023.ebcb.59c0  is the address of interface Gi0/0 of IPTRT02 and same address for BVI1 on IPTRT02

Following are the MAC addresses of Router (IPTRT02) Interfaces


GigabitEthernet0/0 is up, line protocol is up
Hardware is BCM1125 Internal MAC, address is 0023.ebcb.59c0 (bia 0023.ebcb.59c0)

GigabitEthernet0/1 is up, line protocol is up
Hardware is BCM1125 Internal MAC, address is 0023.ebcb.59c1 (bia 0023.ebcb.59c1)


BVI1 is up, line protocol is up
Hardware is BVI, address is 0023.ebcb.59c0 (bia 0023.ebcb.59c0)

4) Po1 is the port channel on IPT SW01 (Gi0/23 and Gi0/24) and Core switch (VSS)

5) Po1 is the port channel on IPT SW02 (Gi0/23 and Gi0/24) and Core switch (VSS)

Note:
-----

i) From show mac address- table address 0023.ebcb.59c0 command on IPTSW01 i notices that IPTSw01 is sometime learning MAC Address (0023.ebcb.59c0) from Gi0/4 and sometime from P01. The learning of MAC Adress (0023.ebcb.59c0) b/w the two ports is very frequent (multiple times in one minutes).

ii) IPTSW02 is also sometime learning MAC Address (0023.ebcb.59c0) from Gi0/4 and sometime from P01. But on this switch learning of MAC Address b/w the ports is not very frequent.

iii) I noticed that on IPTsw02 two MAC Addresses (0023.ebcb.59c0, 0023.ebcb.59c1) are learned on interface Gi0/4


IPTSW02# show mac address- table dynamic interface gi0/4


vlan Mac Address Type   Ports
---- ----------- ----   -----
133 0023.ebcb.59c0 Dynamic    Gi0/4
133 0023.ebcb.59c1 Dynamic    Gi0/4

Appreciate your help & support.

2 REPLIES
New Member

MAC Address Flapping between Switch & Router

Hi Team

Appreciate if someone can provide feedback or share the experience

New Member

MAC Address Flapping between Switch & Router

Can you show the output of "sh spanning-tree vlan 133" on each switch including your core VSS switch? Seems like you have a layer 2 STP loop.

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