Problem: Client requests fail when using IPv6 MAC forwarding with HP-UX back-end servers

After setting up Load Balancer for IPv6 on the HP-UX operating system, client requests to the cluster address fail. This error is a result of the interaction between the neighbor discovery function for the operating system and the Load Balancer.

When a back-end server is added to the configuration, Load Balancer tries to ping the new server for the MAC address. The HP-UX server might choose a configured cluster address as the source address of the ping request, instead of using the nonforwarding address (NFA) of the machine. In this case, a new entry is created for the cluster address in the routing table of the back-end HP-UX server in addition to the local loopback entry. The new entry has a higher routing priority than the local loopback. Thus, the client requests that reach the back-end server are then redirected back to the Load Balancer server, which does not respond.

To work around this problem, after Load Balancer is set up completely, configure the loopback alias on the back-end server as a final step. If the cluster address is aliased on the loopback when the Load Balancer configuration is loaded, remove the cluster loopback alias on the back-end server completely and then re-alias it. To bring down the loopback alias, use the ifconfig lo0:1 inet6 command from the terminal window. Re-alias the loopback alias.



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Last updated: February 21, 2013 02:45 PM EST
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