Policy_map Bandwidth Issue

hi all,

I have always wondered, and been confused, and had different opinons:


When we define bandwidth underpolicy map for defined class with in policymap.

- Does it restrict bandwidth for the traffic defined in that class under that policy map?

- Can it burst over the defined Bandwidth in policy map for the defined traffic in class?

eg:

policy-map Bw_test
class FTP
bandwidth 256

once applied on interface can FTP traffic burst over 256?

Please state how does it behaves, as some say it an burst to port speed depends on availability , some say its like hard coded.