On my Tomcat server (currently running version 6.x), I have set up a firewall rule to drop all IPv6 traffic. It seems that this is causing some issue on startup, because the startup delay is noticeable (takes around 3 minutes) when the IPv6 firewall rule is on. If the IPv6 rule is not on, the server usually starts in a few seconds. By looking more closely at the problem, my understanding is that the delay is caused by the server trying to access the database realm. It is using JDBC to connect to the database. The driver is likely trying to communicate first using IPv6 and when a timeout occurs (because all IPv6 packets are dropped by the firewall), the driver switches back to IPv4 and then the startup is able to complete. To me, this seems to be a JDBC driver issue, but I am wondering if there is configuration within Tomcat to force the driver not to use IPv6.
Martin
