Multiple IE7 tabs and network connections

When IE7 has multiple sites open, multiple tabs, how many network connections are open? Does each page have it's own network connection, meaning socket - ip address & port#, or does IE7 share one socket, switching between the sites with one socket? I ask this because since we have switched to IE7 the number of open tabs has increased a lot while there are a lot more unable to connect issues occurring. Since our network is slow to begin with, the users click to open IE7 more, opening more tabs.