Traffic shaping

AR=Access Rate = Serialization Rate (Ethernet 10Mbps)

It will take 1.2 ms to transmit a 1500Bytes PDU on Ethernet. [1500 * 8 bytes * 1000 ms / 10M]

CIR=Committed Information Rate
Bc=Committed Burst Size
Be=Excessive Burst Size
Tc=Time Interval

Bc/Tc=CIR/SEC

if
CIR=8bps
Tc=125ms

then
Bc=1bit

|125ms_|_|_|_|_|_|_|
<-   1000ms        ->

Reduce Bc for smaller Tc to improve VoIP traffic performance (which will wait shorter per time interval)

Be/Tc=(AR-CIR)/SEC

Be allow customer to bank "credit" from early time intervals and send it later on within a second, the overall traffic will not exceed the CIR.

Understanding Single-Rate and Dual-Rate Traffic Policing