This One Has Me Stumped

Win XP SP3, NIS 2011 ver .250

 

NIS 2011 generates a default outbound SSDP rule - UDP port 1900 for svchost.exe. I have tracked this and it connects to IP 239.255.255.250 as expected.

 

When this rule is allowed and I connect to the Internet using IE8, all my allocated local ports are above 5000.

 

If I block this rule which is a more secure configuration since I don't need uPnP, all my local ports allocated by IE8 start at 1024 and above as expected.

 

Is NIS 2011 the cause of the above "allowed" case? If so - why?