I have Catalyst 3550 with the following config (disregard policy names since I am experimenting):
mls qos aggregate-policer pol_1Mbps 512000 8000 exceed-action drop
mls qos
policy-map 1Mbps
class 1Mbps
police aggregate pol_1Mbps
interface FastEthernet0/15
switchport access vlan 10
no ip address
load-interval 30
service-policy input 1Mbps
When I "show int fa0/15", I am consistently seeing an input rate of 750-760kbps even though my policer is configure for 512k. I understand that policing happens after input statistics are taken on an interface but I would expect that TCP would throttle the sessions because policing is causing dropped packets. No matter what rate I set on my policer, I am always seeing 200-500kbps more traffic on the Fast Ethernet.
The "sh mls qos int fa0/15 st" is incrementing dropped bytes so I know the policer is working. My question is, why would my Fast Ethernet input rate so different from my policer rate? I could understand if my input rate was around 510-520 but to be 50% higher than my policer rate seems a bit much.
