police cir and police rate commands
BennyLava
Member Posts: 60 ■■□□□□□□□□
The QoS Exam Certification Guide doesn't mention the 'police rate' command at all and I've been trying to figure out if there is any difference between this and the 'police cir' command (besides the fact that 'police rate' allows you to configure the rate as bps or packets per second, and 'police cir' only allows bps). I found this on Cisco's site which sounds like 'police rate' is meant to be used for control plane policing:
http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_n1.html#wp1013265
and this on Internetwork Expert's forums which says the same thing (read the last post by Petr Lapukhov):
http://ieoc.com/forums/t/2944.aspx
However I've found that both 'police rate' and 'police cir' are able to be configured in a policy and applied on an interface. Wouldn't the result of using either of the following 2 commands and applying the policy to an interface be the same?
Is there any reason not to use 'police rate' on an interface, or is this just two different ways of doing the same thing?
http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_n1.html#wp1013265
and this on Internetwork Expert's forums which says the same thing (read the last post by Petr Lapukhov):
http://ieoc.com/forums/t/2944.aspx
However I've found that both 'police rate' and 'police cir' are able to be configured in a policy and applied on an interface. Wouldn't the result of using either of the following 2 commands and applying the policy to an interface be the same?
police cir 64000 bc 8000 conform-action transmit exceed-action drop police rate 64000 burst 8000 conform-action transmit exceed-action drop
Is there any reason not to use 'police rate' on an interface, or is this just two different ways of doing the same thing?
Comments
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armsved
Registered Users Posts: 1 ■□□□□□□□□□
Does anyone have an answer to this?
What is the purpose of policy rate? If it's only control plane, shouldn't that mean it'll only police traffic destined to the router? -
d4nz1g
Member Posts: 464
hi armsved.
Police rate is usually used at CoPP policies, and it uses packets per second rate. a CoPP policy is attached to the control plane, not to an interface.
Ex: policy-map policy
class class
police rate 1500 pps
control-plane
service-policy input policy
Police cir is used to define the CIR for a given link (the commited information rate), which is usually defined by bps (you don't contract any service measuring in pps, right?). Usually used along with pir (peak information rate). Read about color aware policing.
Ex: policy-map policy
class class
police cir 1000 pir 3000
Honestly, I wouldnt know how to answer if you can exchange the usage, because most implementations use it this way.
However, you are free to test it on a lab.
Edit: sauce - End-to-End QoS Network Design: Quality of Service for Rich-Media & Cloud Networks, Second Edition, Video Enhanced Edition - Chap 4