Intermittent ping lost - Duplicate IP address

Intermittent ping lost

When we ping 10.21.22.22 from 10.21.22.1, it gave intermittent ping lose due to duplicate IP address issue.

We observed the gateway IP address [ 10.21.22.1] was configured in two switches.

 

How to troubleshoot:

1.       Enable mac address-table notification mac-move on Core layer 3 switch [ SVI] .

2.       Check the logs.

3.       Dec 20 22:32:40.862 MST: %IP-4-DUPADDR: Duplicate address 10.21.22.1 on Vlan243, sourced by 0018.196e.a9c1

4.       Find out the device and change the IP address.

 

Please consider the environment before printing this e-mail Disclaimer: This  communication  is  for the exclusive use of the intended recipient(s) and  shall  not attach any liability on the originator or ITC Infotech India Ltd./its  Holding company/ its Subsidiaries/ its Group Companies. If you are the addressee, the contents of this e-mail are intended for your use only and it shall  not be forwarded to any third party, without first obtaining written authorization from the originator or ITC Infotech India Ltd./ its Holding company/its  Subsidiaries/ its Group Companies. It may contain information which is confidential and legally privileged and the same shall not be used or dealt with  by any  third  party  in  any manner whatsoever without the specific consent  of  ITC  Infotech India Ltd./ its Holding company/ its Subsidiaries/ its Group Companies.

MAC address Duplicate ip address

 

Duplicate IP address

 

mac address-table notification mac-move

Please consider the environment before printing this e-mail Disclaimer: This  communication  is  for the exclusive use of the intended recipient(s) and  shall  not attach any liability on the originator or ITC Infotech India Ltd./its  Holding company/ its Subsidiaries/ its Group Companies. If you are the addressee, the contents of this e-mail are intended for your use only and it shall  not be forwarded to any third party, without first obtaining written authorization from the originator or ITC Infotech India Ltd./ its Holding company/its  Subsidiaries/ its Group Companies. It may contain information which is confidential and legally privileged and the same shall not be used or dealt with  by any  third  party  in  any manner whatsoever without the specific consent  of  ITC  Infotech India Ltd./ its Holding company/ its Subsidiaries/ its Group Companies.

Spanning-tree Topology changes

This commands shows the  recent spanning-tree topology  changes occurred  per Vlans.

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CAL-Core-Sw01#sh spanning-tree detail | i is executing |topology changes|form

VLAN0001 is executing the rstp compatible Spanning Tree protocol

  Number of topology changes 20159 last change occurred 02:14:44 ago

VLAN0030 is executing the rstp compatible Spanning Tree protocol

  Number of topology changes 6 last change occurred 1y21w ago

The below commands shows the port on the Vlan is designated or not.

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KNV-CORE-SW01#sh spanning-tree detail | i is executing |topology changes|Gi

VLAN0016 is executing the rstp compatible Spanning Tree protocol

  Number of topology changes 0 last change occurred 8w2d ago

Port 2 (GigabitEthernet1/0/2) of VLAN0016 is designated forwarding

Port 3 (GigabitEthernet1/0/3) of VLAN0016 is designated forwarding

Port 4 (GigabitEthernet1/0/4) of VLAN0016 is designated forwarding

Port 6 (GigabitEthernet1/0/6) of VLAN0016 is designated forwarding

Port 7 (GigabitEthernet1/0/7) of VLAN0016 is designated forwarding

Port 10 (GigabitEthernet1/0/10) of VLAN0016 is designated forwarding

We can change the last description to see the various changes. Ex. |topology changes|Gi or from  etc..

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