Apache + Tomcat = no cookies and no session ids

We deployed our Tomcat-based system on an Apache+Tomcat site and
session management disappeared completely. Every Tomcat access to the
session resulted in the creation of a new session. Url rewriting did
not solve the problem.

This is apparently a known situtuation. Searching around I found
references to this situation going back to 2001. However, I was unable
to find what needs to change to enable session management in an
Apache+Tomcat environment.

Since the application works normally on Tomcat only, it seems pretty
certain that Apache needs to be configured to handle Tomcat session
management either by cookies or url rewriting or both.

Can someone describe what is going on and what needs to be done?

Thanks,
-=beeky