Changing TOS value

[Bikrant Neupane]

Hi,
	I am using freebsd 4.9 as a bandwidth manager. I would like to set IP TOS 
field to some desired value or is it possible to completely ignore the  TOS 
value? 
 I have observed that using different value of TOS affects fairness in b/w 
allocation in a pipe. So for that specific reason I would like to change the 
TOS of all IP pkts before it gets into the pipe. 
	I think this is very common problem however I didn't find any useful 
information in google either.

thanks,
Bikrant