I'd like to ask you some question about policing and shaping. I decided to test these two traffic conditioners, and wrote these two simple policy-maps:
shape average 256000
than I applied them one after another to fa0/2 interface in the outbound direction, while downloading a big file from the Internet:
service-policy output POLICE/SHAPE
and I've got to tell you I was surprised. With service-policy POLICE configured, the download speed was only 15,2KB, while with service-policy SHAPE configured it was 31,2KB.
Could somebody please explain these results?
Is that because the policer drops packets instead of just queuing them thus causing the sender slow its transmission rate?
Generally, end customers should use traffic shaping and service providers policing. Best performance with most applications will be achieved with shaping, but you need a router or more expensive switch to do it, and it can only be done on egress ports. Policing can be done easily on all SP edge devices ingress ports. If the customer shapes, the service provider's policing should never kick in.
At least this is my theory.
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