A network diagnostic device or component such as a network analyzer or a jammer that is placed in-line between two nodes in a network to perform a flow control operation transparently without the requirement of a separate link layer implementation. The network diagnostic device may include a diagnostic module configured to perform network analyzer operations, a memory a first flow control module a second flow control module. In some embodiments, when performing the flow control operation, various modules and/or components may cause the network diagnostic device to enter a first pass-through mode and to then enter into a first flow control handshaking mode from the first pass-through mode. The various modules and/or components may also cause the network diagnostic device to enter a second pass-through mode from the first flow control handshaking mode and to then enter into a second flow control handshaking mode from the first pass-through mode.