One reader and multiple writers is exactly what I am trying to do. The idea with threads was to have one thread as the reader and another thread to control the writers using a shared memory space. What you suggested is essentially what I am doing now...

in pseudo code 

while (1)
   if accept (non blocking)
      initialize writer
      add Ptr to writer hash
   if %writer
      read_cell (atm cells)
      foreach connection %writer
         if lifetime of writer exceeded
            undef $writer{connection}
            next
         write cell

and then back through the loop.
[download]

The problem is that initializing a writer takes a non zero amount of time. During this period we can't read any cells off the interface and at OC3 and OC12 speeds (which is what we are dealing with) it can be a significant bit of data lost. So the ideal solution would be to off load the writer initialization and handling to another thread so that existing writers wouldn't have the data flow interrupted.

The goal is to have a server that can gracefully handle gigabit speeds and more than 5 writers at a time.

Also, as I stated, I do not think forking can work. I can only have one reader on an interface at a time. If there is some way to only fork a subroutine I'm all ears (eyes, whatever).