there are 3 different companies share one 2811 router and there is 5.0 Mbps in WAN connection. We'd like to provision bandwidth between these three companies. I know with the QoS, we can define bandwith based on ACL. is there any document that describe this solution?
yep.. you can have an independent input service policy.
match the ACL based on destination address and apply it in the input direction
access-list 111 permit ip any host publicip1
match ip address 111
police cir kbps
interface serial x/y
service-policy input inboundqos
The input and output policies are independent of each other so you can do both simultaneously