QoS - Bc and Be bucket sizes
When implementing QoS policing and shaping, network devices use the concept of "token buckets" determine how to rate limit or to discard arriving packets. The sizes of these buckets will affect the throughput and the algorithm used to achieve either policing or shaping.
The sizes of the buckets are typically determined by the operating system itself, based on the CIR, burst rates and other parameters used in setting up these QoS mechanisms. Typically, these values are not set directly or manually, but depending on the platform, you may be able to set them.
Links
https://forum.networklessons.com/t/qos-traffic-policing-explained/995/97?u=lagapidis
https://networklessons.com/quality-of-service/qos-traffic-policing-explained
https://networklessons.com/quality-of-service/qos-traffic-shaping-explained