The class TapAgent is a simple class derived from the base Agent class. As such, it is able to generate simulator packets containing arbitrarily-assigned values within the ns common header. The tap agent handles the setting of the common header packet size field and the type field. It uses the packet type PT_LIVE for packets injected into the simulator. Each tap agent can have at most one associated network object, although more than one tap agent may be instantiated on a single simulator node.