Application Server Failure and Recovery

When an application server, for example, Server1, fails, then the following occurs:

• The connections from the client fail.
• Other connections through TSA1 to Server2 and Server3 remain established.
• When a connection breaks due to an application server failure, and the peer tries to reestablish the connection on the same TSA, then the connection is delegated to another available application servers in the same TSA.
• IPFE-A1 routes new connection requests to the remaining application servers (Server2 and Server3). If all application servers in a target set fail, and IPFE-A1 receives a request for a new connection to TSA1, then it alternatively notifies the client that the request cannot be fulfilled using either a TCP RST packet (for TCP connections) or a configurable ICMP message.

When Server1 recovers:

• IPFE-A1 detects Server1's availability.
• IPFE-A1 routes new connection requests to Server1.
• Some imbalance across application servers in TSA1 exists after recovery. IPFE-A1 monitors for imbalances in traffic and distributes new connections to reduce the imbalance.