Calculating available ephemeral ports

Hi,

I seem to be running short of ephemeral ports for tcp connections on IPv4. This has lead me to try get a solid understand of just how many ephemeral (eph) ports I have available for IPv4 tcp connections.

I start with the output from netsh int ipv4 show dynamicport tcp which outputs I have 16384 ports in my tcp Dynamic Port Range. I know I can increase this number but this is just a calculation exercise.

Now assume my server has multiple NICs and of course multiple IPs as well as loopback - 127.0.01.

I kind of doubt that I have only 16384 eph ports available across the entire host regardless of the number of local IPs.

Perhaps I have 16384 eph ports available per local IP. That makes more sense. But I know in terms of making a unique tcp connection I need a eph port for each outgoing connection to a foreign host's individual listener.  

My port exhaustion seems to be on loopback so let me put my question like this:

using this format : LocalHost:ephPort -->  RemoteHost:Listener

for example, do I have

a) 127.0.0.1:EphPort[16384 possibilities] --> 127.0.0.1:443 and

127.0.0.1:EphPort[16384 possibilities] --> 127.0.0.1:444 and so on

or 

b) 127.0.0.1:EphPort[16384 possibilities] -->127.0.0.1:[regardless of listener]

or

c) Host: EphPort[16384 possibilities] --> RemoteHost

Another thing that has lead to my question above is the word global in event #4231 I am getting.

"A request to allocate an ephemeral port number from the global TCP port space has failed due to all such ports being in use."

Perhaps I should have just asked for the definition of the global TCP port space.

Thanks,

-Wes