What is the meaning of the Event Wait "Network - Network" on the Activity Page. Does it have anything to do with with Packets In/Out, or does it relate to the SQL*Net message to/from client ?
This is refering to the lower right box, with the event listed as "Network - Network". This happens to be from the Waits tab for troubleshooting some slowdowns in the production.
The specific wait events that make up the network category are:
SQL*Net break/reset to client
SQL*Net message to client
SQL*Net more data from client
SQL*Net more data to client
You should also use the 'Waiting Events' drilldown and set the category to 'Network - Network', this may give some more insight as to which sessions / SQL are contributing. You could also use the OS Performance drilldown in Spotlight on Oracle, or for even better detail, the Network drilldown in Spotlight on UNIX or Spotlight on Windows (depending on the operating system). If you are using the Professional edition of Spotlight on Oracle you could have also used the Impending Bottlenecks in Predictive Diagnostics to predict the slowdown issue before it became more severe.