Its important to determine the bandwidth and number of connections required.
If your doing 200 100mbps connections then you need to move 20gbps in and out. If your doing this with cake or preseem then your going to need at least two 40gbps network cards (this has to do with buss speed not port speed), 32gb ram and a 12core (not 6core 12 thread) x64 cpu. If your also wanting additional shaping or features then you will need to add more ram and cpu cores.
If you are adding any routing or encryption then you will of course need more CPU cores.