1. An external processor for a network access system having a programmable access device, comprising: a message processor configured to parse a message for determining a type of communication service; a service controller configured to receive the message if the type of communication service corresponds to the service controller, wherein the service controller determines a policy based on the message and generates a control signal according to the policy; and a programmable access device (PAD) controller configured to receive the control signal for configuring a PAD to enforce the policy with respect to a network connection between a first network and a second network.