Ajax和多个会话

Can any one tel me whether ajax calls lead for multiple sessions. In my application I can see more than 5 sessions are created for each user. (By monitoring the firewall). main web page in the Application sends five ajax calls to the webserver once a 30 seconds to retrieve data. Is there is any connection between ajax calls and multiple sessions? Can anyone pls explain.

That's possible if it doesn't send the session cookie along in the request header. With Firebug you can verify this.

In decent Ajax frameworks like jQuery this is already taken into account.