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Cisco 7609 User Manual

Cisco 7609
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32-18
Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
78-14064-04
Chapter 32 Configuring PFC QoS
Understanding How PFC QoS Works
For all egress traffic, PFC QoS uses a configurable mapping table to derive a CoS value from the internal
DSCP value associated with traffic (see the Mapping Internal DSCP Values to Egress CoS Values
section on page 32-67). PFC QoS sends the CoS value to the egress LAN ports for use in scheduling and
to be written into ISL and 802.1Q frames.
Policy Maps
Note You can globally disable marking and policing with the mls qos queueing-only command (see the
Enabling Queueing-Only Mode, page 32-34).
You can disable marking and policing on a per-interface basis with the no mls qos interface
command (see the Enabling or Disabling PFC Features on an Interface section on page 32-51.
The PFC supports filtering, marking, and policing using policy maps (see the Configuring a Policy
Map section on page 32-42). Each policy map can contain multiple policy-map classes. You can
configure a separate policy-map class for each type of received traffic.
Policy-map classes specify filtering with the following:
Cisco IOS access control lists (optional for IP, required for IPX and MAC-Layer filtering)
Class-map match commands for Layer 3 IP precedence and DSCP values
Policy-map classes specify actions with the following:
(Optional) Policy-map class trust commands. If specified, PFC QoS applies the policy-map class
trust state to matched traffic. Policy-map class trust states supersede ingress LAN port trust states.
Note If traffic matches a policy-map class that does not contain a trust command, the trust state
remains as set on the ingress LAN port.
(Optional) Aggregate and microflow policers, which can use bandwidth limits to either mark or drop
both conforming and nonconforming traffic. See the PFC Marking and Policing section on
page 32-16.
The PFC uses the trust state (set by the ingress LAN port configuration or by a trust policy-map class
command) to select the Layer 2 and Layer 3 PFC QoS labels that the egress port writes into the packets
and frames before it is transmitted:
Trust IP precedenceSets the internal DSCP value to a mapped value based on received IP
precedence (see the Mapping Received IP Precedence Values to Internal DSCP Values section on
page 32-67).
Trust DSCPSets the internal DSCP value to the received DSCP value.
Trust CoSSets the internal DSCP value to a mapped value based on received or port CoS. With trust
CoS, note the following:
Received CoS is overwritten with port CoS in traffic received through ports not configured to
trust CoS.
Received CoS is preserved only in traffic received through ports configured to trust CoS.
Port CoS is applied to all traffic received in untagged frames, regardless of the port trust state.
For information about mapping, see the Mapping Received CoS Values to Internal DSCP
Val ue s section on page 32-66.

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Cisco 7609 Specifications

General IconGeneral
Chassis Slots9
Switch Fabric Capacity720 Gbps
Power Supply OptionsAC or DC
Product TypeRouter
Form FactorRack-mountable
Supported Line CardsVarious Cisco 7600 Series line cards
Operating SystemCisco IOS
ManagementCLI, SNMP
Forwarding Performance400 Mpps
Maximum Power Consumption4000 Watts
RedundancyYes
Interfaces/PortsVarious, depending on line cards installed

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