| 摘要 |
A method and apparatus for rate-based cell traffic arbitration in a switch are provided, wherein arbitration is provided between eight traffic sources in the form of eight cell bus service modules on the same cell bus. A cell bus controller (CBC) is programmed with an 8-bit Relative Service Delay (RSD) value for each of the eight service modules. The value for each RSD is calculated based on the bandwidths allotted for each service module. This RSD value determines the portion of the total bandwidth of the switch platform reserved for the respective service module. Furthermore, each service module uses an 8-bit Service Delay Accumulator (SDA) register. The SDA register of each service module is configured using an SDA value, wherein the SDA register keeps track of when each of the service modules should receive service. The SDA value is calculated at each cell bus frame time for each of the service modules based on the RSD value for each of the service modules, a request for service, and the minimum SDA value among the service modules during a cell bus frame time. If the bandwidth is under-subscribed, the remaining bandwidth is shared among all eight service modules according to the RSD value of each service module. If the bandwidth is over-subscribed, each service module will have the assigned bandwidth portion decreased according to the RSD values.
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