Issues with instant messaging filtering can involve, for example, the connection between client and server or the application of the implemented filtering rules.
Keep-alive data packets are sent in regular intervals as part of the instant messaging traffic to indicate the communication partners are still connected and responsive. Intervals vary between 20 and 80 seconds, depending on the IM protocol and client software. These data packets are not processed by the filtering rules that are implemented on an appliance.
If you detect such data packets in a troubleshooting situation, you can use rule engine tracing to see which rules are still executed.
When a client sends a request for logon to the server, it is redirected to the appliance if you have configured the appropriate settings. However, a client can at the same time try to log on to another server that requires SSL-secured authentication. If this fails, the client can also drop the connection to the appliance.
Some clients also provide options for performing basic troubleshooting tests after a failure to log on to the server.