All things related to multicast

[Wilson Dillaway <>]

     Here's a question regarding receiving multicast on a 
Windows XP Professional desktop.  We have multiple VBrick 
MPEG-2 encoding appliances, and we distribute VBrick's 
"StreamPlayer Plus" viewing software to desktops on request.
However, as the popularity of Windows XP (versus W2K, W98, 
etc.) has risen, we have encountered a number of people who
choose to run Microsoft's Internet Connection Firewall (ICF),
an imbedded component of Windows XP that allows desktops to 
do local packet filtering.  When ICF is enabled, StreamPlayer
no longer sees the SAP announcements (or the streams 
themselves).  While ICF does have some customization options 
as regarding blocking certain TCP or UDP ports, etc., it
does not seem to have any mechanism for selective treatment
of multicast.

     Some of our security folks are recommending that ICF be
turned on by default on all desktops, so we have the problem
of asking our users to choose between good desktop security 
(turn ICF on) or being able to watch multicast video (turn 
ICF off).  Does anyone have experience with this?  We'd like 
to find a middle ground whereby nasty unicast packets can be 
blocked without having to disable multicast reception.  
Although our experience is with VBrick, I would guess that 
any multicast viewing software (e.g. Cisco's IP/TV client) 
would suffer similarly when used with XP and ICF.

     Any thoughts?  How do the non-Microsoft desktop firewall
products behave in this respect?


         Wilson Dillaway
         Tufts University