Windows 7 - What Constitutes a Connection Under the 20 Connection Limit?

Question

Background
Currently testing some enterprise software the company I work for designs, and our current scope of support allows for installations on Windows 7. We have multiple services running on the 'server' and we're communicating with clients on various IP ports,
as well as running a webpage through IIS. At the very minimum we have two connections from a client system at any time over two different ports, this can grow depending on what's being run as part of the client.
Environment
The environment consists of the following:
Windows 7 'Server' running a local instance of SQL Express, also hosting ASP.NET webpage.
Windows 7/Vista/XP Clients connecting over IP to 2-4 different ports
Question
There's a host of threads and documentation on the 20 connection limit within Windows 7, but really no clear answer as to what constitutes a 'connection'. Some Microsoft documentation says TCP connections, some say SMB connections, and a half dozen form
posts claim one or the other. I did a quick test last night with a client simulation tool which pushed two connections to the server for each client, and connected 25 clients (total of 50 connections) and was not refused subsequent connections.
What exactly removes an available connection from the pool of 20?
Unlimited connections from a single IP address? (each computer removes an available connection from the limit)
Per TCP connection? (each connection to a port removes an available connection from the limit)
Per Windows User? (each connection from a Windows user removes an available connection from the limit)
Or is the 20 connection limit strictly applied to SMB?
I also see the following in the EULA for Windows 7 Professional:
Device Connections. You may allow up to 20 other devices to access software installed on the licensed computer to use only File Services, Print Services, Internet Information Services and Internet Connection Sharing and Telephony Services.
Does this indicate the 20 connection limit only applies to IIS, ICS, File/Print Sharing?
Greatly appreciate the time taken to answer this.
Cheers,
James. 

Answer 1

Hi James,
The 20 connection limit applies to File and Printer sharing.
Limit the Number of Users of a Shared Folder
http://technet.microsoft.com/en-us/library/cc753521.aspx#BKMK_interface
Windows 7 incoming connection limit 
http://social.technet.microsoft.com/Forums/en/w7itpronetworking/thread/854f3e27-10e5-4629-bb77-007cc5e42b41
Regarding TCP, IIS connection limit, it is hard to confirm. Since Vista SP2 the limitation have been removed from TCPIP.SYS, and has been configured through a registry key. Windows7
should follow that same behavior. You can also consult in IIS forum.
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\]
Value: TcpNumConnections
Type: DWORD
More information
http://blogs.msdn.com/b/david.wang/archive/2006/04/12/howto-maximize-the-number-of-concurrent-connections-to-iis6.aspx
Best Regards,
Niki
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