During rate limiting configuration, the committed information rate (CIR) and committed burst size (CBS) need to be set. The CIR is the guaranteed average transmission rate, and the CBS is the average volume of burst traffic that can pass through an interface. To set the rate limit to 4 Mbit/s, set the CIR to 4096 kbit/s (4 x 1024 kbit/s). You are advised to set the CBS to be 100 to 200 times the CIR. If the CBS is not configured, the default value is used. The default CBS is 125 times the CIR.