Policing and CIR,PIR,BC,BE

Dear Amr,

The link brings a good understanding of Policing:

http://wiki.nil.com/QoS_Policing_in_Cisco_IOS

Petr's Policing vs Shaping article on INE Blog:

http://blog.internetworkexpert.com/2008/07/03/at-a-glance-the-difference-between-shaping-and-policing/

I do believe in some sort or the other the values do correspond to each
other (I mean shaping & policing values).
The way it is explained is the token bucket; tokens are always added to the
bucket in case of policing at the rate of the cir, when a packet comes, if
enough tokens in the bucket exist to send the packet it is sent; otherwise
it is discarded.

Then the concept of PIR is introduced, it comes with some ISPs which will
allow you to go above the CIR; filling the regular token bucket with the
rate of CIR and an additional excess token bucket with the PIR rate. So now
if a packet comes we will check if enough tokens (CIR+PIR) are available to
send the packet otherwise it will be dropped. When both CIR & PIR are
specified this is a dual token bucket where three actions can take place
(Conform/Exceed/Violate).

Police & Police cir as far as i believe do the same function. However police
rate is used for control-plane policing(traffic destined to the control
plane).

Check this link for the difference between Police commands:

http://www.cisco.com/en/US/docs/ios/12_3t/qos/command/reference/qos_o1gt.html#wp1090915

Best Regards,

-- 
KJ
Blogs and organic groups at http://www.ccie.net