Eric, I think Erlang is a telecom traffic unit which works on circuit switching. One circuit used for 1 hour makes 1 erlang traffic. Circuit switching needs a dedicated channel (although it may use mutiplexing). Packet switching shares a circuit or channel. So here, a circuit is not dedicated to anyone. Moreover, packets can travel through alternate routes. Kb/s is a measure of data flow for packet switching. So erlang does not apply here in that sense.