tcpdump

I am generating artificial Web traffic.
The parameters such as RTD, # of inlines and Viewing time has been collected
by pasring tcpdump data by perl script.
I am having hard time let script identify one page in tcpdump.
If someone has idea about how to do or if there are more powerful tools 
than tcpdump, please tell those.

Secondly, I have found that some server close HTTP connection after sending 
all data, and some servers do not disconnect conennection until new request 
comes typically Apache server.
Why is that?
Your answer would be really appreciated.


CHK
URL: http://www.ee.gatech.edu/users/hkchoi