Technical data

Failover Behavior When Using Firewalls and Load Directors
Administration Guide 13-15
Failover Behavior When Using Firewalls
and Load Directors
In most configurations, the Netscape Enterprise Server Plug-In sends a request to the
primary instance of a cluster. When that instance is unavailable, the request fails over
to the secondary instance. However, in some configurations that use combinations of
firewalls and load-directors, any one of the servers (firewall or load-directors) can
accept the request and return a successful connection while the primary instance of
WebLogic Server is unavailable. After attempting to direct the request to the primary
instance of WebLogic Server (which is unavailable), the request is returned to the
plug-in as “connection reset”.
Requests running through combinations of firewalls (with or without load-directors)
are handled by WebLogic Server. In other words, responses of
connection reset
fail over to a secondary instance of WebLogic Server. Because responses of
connection reset fail over in these configurations, servlets must be idempotent.
Otherwise duplicate processing of transactions may result.