Cisco WS-SUP32-GE-3B Software Configuration Guide - Page 552

Understanding How PFC QoS Works Chapter 38 Configuring PFC QoS Aggregate Policers PFC QoS applies the bandwidth limits specified in an aggregate policer cumulatively to all flows in matched traffic. For example, if you configure an aggregate policer to allow 1 Mbps for all TFTP traffic flows on VLAN 1 and VLAN 3, it limits the TFTP traffic for all flows combined on VLAN 1 and VLAN 3 to 1 Mbps. • You define per-interface aggregate policers in a policy map class with the police command. If you attach a per-interface aggregate policer to multiple ingress ports, it polices the matched traffic on each ingress port separately. • You create named aggregate policers with the mls qos aggregate-policer command. If you attach a named aggregate policer to multiple ingress ports, it polices the matched traffic from all the ingress ports to which it is attached. Microflow Policers PFC QoS applies the bandwidth limit specified in a microflow policer separately to each flow in matched traffic. For example, if you configure a microflow policer to limit the TFTP traffic to 1 Mbps on VLAN 1 and VLAN 3, then 1 Mbps is allowed for each flow in VLAN 1 and 1 Mbps for each flow in VLAN 3. In other words, if there are three flows in VLAN 1 and four flows in VLAN 3, the microflow policer allows each of these flows 1 Mbps. You can configure PFC QoS to apply the bandwidth limits in a microflow policer as follows: • You can create microflow policers with up to 63 different rate and burst parameter combinations. • You create microflow policers in a policy map class with the police flow command. • You can configure a microflow policer to use only source addresses, which applies the microflow policer to all traffic from a source address regardless of the destination addresses. • You can configure a microflow policer to use only destination addresses, which applies the microflow policer to all traffic to a destination address regardless of the source addresses. • For MAC-Layer microflow policing, PFC QoS considers MAC-Layer traffic with the same protocol and the same source and destination MAC-Layer addresses to be part of the same flow, including traffic with different EtherTypes. With a PFC3B, you can configure MAC ACLs to filter IPX traffic. • By default, microflow policers only affect traffic routed by the PISA. To enable microflow policing of other traffic, including traffic in bridge groups, enter the mls qos bridged command. • You cannot apply microflow policing to ARP traffic. • You cannot apply microflow policing to IPv6 multicast traffic. You can include both an aggregate policer and a microflow policer in each policy map class to police a flow based on both its own bandwidth utilization and on its bandwidth utilization combined with that of other flows. Note If traffic is both aggregate and microflow policed, then the aggregate and microflow policers must both be in the same policy-map class and each must use the same conform-action and exceed-action keyword option: drop, set-dscp-transmit, set-prec-transmit, or transmit. For example, you could create a microflow policer with a bandwidth limit suitable for individuals in a group, and you could create a named aggregate policer with bandwidth limits suitable for the group as a whole. You could include both policers in policy map classes that match the group's traffic. The combination would affect individual flows separately and the group aggregately. 38-18 Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY OL-11439-03