bandwidth remaining percent: policing or shaping?

Unanswered Question
Sep 23rd, 2009
User Badges:

Using "bandwidth remaining percent" makes it policing or shaping? It seems policing as you only have limited bandwidth available which includes what is allocated to a class plus what is left as unused by any upper class (except that with priority command).


Thanks,

Nadeem

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
Laurent Aubert Wed, 09/23/2009 - 10:46
User Badges:
  • Cisco Employee,

Hi,


Bandwidth command is closer to shaping as packets are buffered and not dropped.


Bandwidth remaining represents the bw minus the one used by the priority class.


HTH


Laurent.

Peter Paluch Wed, 09/23/2009 - 10:47
User Badges:
  • Cisco Employee,

Hello,


The command "bandwidth remaining percent" provides neither policing nor shaping. It only provides a minimum bandwidth guarantee in the case of interface congestion. The amount of guaranteed bandwidth is expressed in percents of the remaining bandwidth, that is, the reservable bandwidth (determined from the interface "bandwidth" and "max-reserved-bandwidth" commands) minus the bandwidth allocated for all classes with the "priority" command in the same policy-map. If, however, the interface is not congested or the congestion is not so severe, the class configured with "bandwidth remaining percent" may receive more bandwidth than is actually allocated.


Best regards,

Peter


Joseph W. Doherty Wed, 09/23/2009 - 12:05
User Badges:
  • Super Bronze, 10000 points or more

"Using "bandwidth remaining percent" makes it policing or shaping?"


Neither, it's just a different method for defining the bandwidth allocation for a CBWFQ class.


e.g.

Asuming 75% bandwidth reservation, believe both the following policies will provide same bandwidth for "someclass".


policy-map A

class LLQ

priority percent 25

class someclass

bandwidth percent 50


policy-map B

class LLQ

priority percent 25

class someclass

bandwidth remaining percent 100


The advantage of the latter policy-map configuration, it's more likely to be considered "good" if interface reserved bandwidth or LLQ class bandwidth settings modified.

Actions

This Discussion