| 摘要 |
A facility is provided for operating an asynchronous packet transmit bus such that isochronous information packets may be transmitted from a source to a destination with a fixed, constant delay. The fixed, constant delay is achieved by employing a bandwidth management bus and assigning to port modules which contend for access to the transmit bus respective levels of priority, in which t he highest level of priority is associated with isochronous information and in whic h lower levels of priority are associated with other types of information, such as asynchronous information. In addition, each port module which transmits isochronous information is assigned at least one time slot of each frame of time slots. In this way, a port module that needs to transmit isochronous information is gra nted access to the transmit bus during its assigned time slot if the module asserts s uch highest level of priority in response to its address being transmitted over the bandwidth management bus. If the module fails to assert such priority, then the time slot is marked for open contention, thereby allowing the other port modules to contend for access to the transmit bus during that time slot.
|
