Dropped or Lost Pings following Switchover or Failover

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Summary

This Knowledgebase article provides information about the symptoms, causes, and resolutions of lost pings following a switchover or failover.


More Information

Dropped/Lost pings can occur when there are ARP table issues on servers and switches that connect the networked devices.

Symptoms

Following a switchover/failover, there have been issues where pings will be dropped between networked clients/servers and the Neverfail active server.  This issue can cause loss of communication between client/server machines and the Neverfail active server.

Causes

Lost pings following a switchover/failover are due to an incorrect MAC address being stored in the ARP cache of either the network switch or client/server machine.  This incorrect MAC address is the result of the network adapters within the Primary and Secondary server having unique MAC addresses, which are not updating the network infrastructure correctly during the switchover/failover process.

Note:  This issue is seen most often in network environments that use CISCO switching devices.

Resolutions

Switch Resolution

To resolve the issue at a switch-level, you should connect to the network switch and perform a clear ARP command on the relevant switch.  This command will force the switch to rebuild the ARP table and will therefore update the MAC address for the relevant Neverfail server.

Client/Server Resolution

To resolve the issue on client/server machines, perform the following steps:
  1. Locate the client/server machine that is experiencing the connection issues.
  2. Open a command prompt window on the relevant server.
  3. Enter the following command: ARP –D <IP Address of Neverfail Server Public Network>
  4. Example: ARP –D 192.168.1.1

  5. Check that the client/server machine can ping the Neverfail active server without any issues.

Applies To

All Versions


Related Information

None

KBID-1351

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