One aspect relates to a communication protocol for communicating between one or more entities, such as devices, hosts or any other system capable of communicating over a network. Another aspect relates to a system architecture that permits more than one slave system (e.g., a slave device) to be connected to a master system (e.g., a master device) in a communication system implementing a master/slave protocol. In one aspect, a pass-through device is provided that facilitates communication and authentication to one or more downstream slave devices. Yet another aspect relates to a star-based configuration of slave devices coupled to the master, and protocols for communicating and authenticating slave devices. Another aspect relates to a protocol that allows communication between entities without a priori knowledge of the communication protocol. In such a protocol, for example, information describing a data structure of the communication protocol is transferred between communicating entities. Further, an authentication protocol is provided for providing bidirectional authentication between communicating entities. In one specific example, the entities include a master device and a slave device coupled by a serial link. In another specific example, the communication protocol may be used for performing unbalanced transmission between communicating entities.