free_mascot (11/5/2013)

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The actual number of user connections allowed also depends on the version of SQL Server that you are using, and also the limits of your application or applications and hardware. SQL Server allows a maximum of 32,767 user connections. Because user connections is a dynamic (self-configuring) option, SQL Server adjusts the maximum number of user connections automatically as needed, up to the maximum value allowable. For example, if only 10 users are logged in, 10 user connection objects are allocated. In most cases, you do not have to change the value for this option. The default is 0, which means that unlimited user connections are allowed.

Ref: http://technet.microsoft.com/en-us/library/ms187030.aspx%5B/quote%5D

On one of our prod server after we reach around 32k connections. The server is not allowing new connections. While we connect thru ssms its throwing error a severe error occurred while connecting to the server. Jobs are failing and some jobs are missing their schedule. No info in the event viewer. After thorough investigation we came to the conclusion that it's not allowing newconnections after reaching tht threshold value.