CBS is configured in kilobytes through the CLI; MBS is configured in bytes or kilobytes. These configured values are converted to the corresponding number of buffers. The conversion factor is a non-user-configurable, fixed default value that is equal to the system-defined maximum frame size, ensuring that even the largest frames can be hosted in the allocated buffer pools. This type of WRED is called buffer-based WRED.
User-defined minThreshold and maxThreshold values, each defined as a percentage, are also converted to the number of buffers. The minT is converted to the system-minThreshold, and the maxT is converted to the system-maxThreshold.
The system-minT must be the absolute closest value to the minT that satisfies the formula below (2^x means 2 to the exponent x):
system-maxThreshold – system-minThreshold = 2^x
The 6-port Ethernet 10Gbps Adapter card and the 7705 SAR-X Ethernet ports use payload-based WRED (also called byte-based WRED); see Payload-based WRED. The above ‟system-minT” calculation does not apply to payload-based WRED. The 7705 SAR-X TDM ports use buffer-based WRED.