Automatic Reconnection

The Automatic Reconnection feature allows a client to reconnect to an existing session (after a short-term network failure has occurred) without having to resend the user's credentials to the server.

After a successful log on, the server sends the client an "auto-reconnect cookie" in the Save Session Info PDU. This cookie is bound to the current user's session and is stored by the client. In the case of a disconnection due to a network error, the client can try to automatically reconnect to the server. If it can connect, it sends a cryptographically modified version of the cookie to the server in the Client Info PDU (the Secure Settings Exchange phase of the connection sequence, as specified in section The server uses the modified cookie to confirm that the client requesting auto-reconnection is the last client that was connected to the session. If this check passes, then the client is automatically connected to the desired session upon completion of the connection sequence.

The auto-reconnect cookie associated with a given session is flushed and regenerated whenever a client connects to the session or the session is reset. This ensures that if a different client connects to the session, then any previous clients that were connected can no longer use the auto-reconnect mechanism to connect. Furthermore, the server invalidates and updates the cookie at hourly intervals, sending the new cookie to the client in the Save Session Info PDU.