42-116
Cisco7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter42 Con figuring PFC QoS
Common QoS Scenarios
Class Map match-any class-default (id 0)
Match any
Class Map match-all CLASSIFY-PC-SAP (id 2)
Match access-group name CLASSIFY-PC-SAP
Class Map match-all CLASSIFY-VOICE-SIGNAL (id 4)
Match access-group name CLASSIFY-VOICE-SIGNAL
Class Map match-all CLASSIFY-VOICE (id 5)
Match access-group name CLASSIFY-VOICE
To monitor the byte statistics for each traffic class, enter this command:
Router# show mls qos ip gig 5/1
[In] Policy map is IPPHONE-PC [Out] Default.
QoS Summary [IP]: (* - shared aggregates, Mod - switch module)
Int Mod Dir Class-map DSCP Agg Trust Fl AgForward-By AgPoliced-By
Id Id
------------------------------------------------------------------------------------
Gi5/1 5 In CLASSIFY-V 46 1 No 0 0 0
Gi5/1 5 In CLASSIFY-V 24 2 No 0 0 0
Gi5/1 5 In CLASSIFY-O 0 3 No 0 0 0
Gi5/1 5 In CLASSIFY-P 25 4 No 0 0 0
Router#
Accepting the Traffic Priority Value on Interswitch Links
The previous section described how to configure the marking operation. This section describes how the
upstream devices will use the packet marking.
You must decide whether the incoming traffic priority should be honored or not. To implement the
decision, you configure the trust state of the port. When traffic arrives on a port that is set not to trust
incoming traffic priority settings, the priority setting of the incoming traffic is rewritten to the lowest
priority (zero). Traffic that arrives on an interface that is set to trust incoming traffic priority settings
retains its priority setting.
Examples of ports on which it might be valid to trust incoming priority settings are ports that are
connected to IP phones and other IP voice devices, video devices, or any device that you trust to send
frames with a valid predetermined priority. If you know that appropriate marking is completed when
traffic first enters the network, you may also want to set uplink interfaces to trust the incoming priority
settings.
Configure ports that are connected to workstations or any devices that do not send all traffic with a
predetermined valid priority as untrusted (the default).
In the previous example, you configured QoS to properly mark the voice, SAP, and other best effort
traffic at the access layer. This example configures QoS to honor those values as the traffic passes
through other network devices by configuring the interswitch links to trust the packet DSCP values.
The previous example had several different traffic classes entering a port and selectively applied
different QoS policies to the different traffic types. The configuration was done with the MQC QoS
policy syntax, which allows you to apply different marking or trust actions to the different traffic classes
arriving on a port.