ECN Capability in the Network Layer

[Feighery, Patrick D.]

I am currently trying to integrate an ECN capability into a third
party's transport layer protocol.  In the past I have used Dummynet to
test how transport protocols react under a variety of strange and
non-typical network characteristics.  Now I am trying to use a
combination of Dummynet and ECN.  Unfortunately after crawling the
network for a few days, I can't really figure out how to configure
FreeBSD to support ECN.  I have been testing with a FreeBSD 6.2
installation and have added the ALTQ into the kernel.  However I can't
figure out how to create an /etc/pf.conf config file for ECN.  Do I
need to install a different version of FreeBSD to get this
functionality.
 
Can anyone point me into the correct direction?
 
Best Regards
 
    Pat Feighery