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Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
OL-4266-08
Chapter 42 Configuring PFC QoS
Understanding How PFCQoS Works
Figure 42-4 PFC QoS Features and Component Overview
Component Overview
These sections provide more detail about the role of the following components in PFC QoS decisions
and processes:
• Ingress LAN Port PFC QoS Features, page 42-6
• PFC and DFC QoS Features, page 42-8
• PFC QoS Egress Port Features, page 42-12
Ingress LAN Port PFC QoS Features
These sections provide an overview of the ingress port QoS features:
• Flowchart of Ingress LAN Port PFC QoS Features, page 42-7
• Port Trust, page 42-8
• Ingress Congestion Avoidance, page 42-8
Port Trust
- CoS
- IP Prec
- DSCP
- MPLS Exp
DSCP
map
Final internal
DSCP is
mapped to CoS
Identify traffic
based on match
criteria:
- ACL (L2, IP)
- DSCP
- IP Prec
- MPLS Exp
- Class-map
Scheduler operates
on WRR, DWRR,
SP
Ingress Port
Egress PortPFC/DFC
Policy Result
SP
DSCP CoS
rewrite
C
l
a
s
s
i
f
i
c
a
t
i
o
n
CoS determies
queue selection
Scheduler queue
and threshold are
configurable
Q1
Q2
Q3
Q4
WRR
DWRR
Outgoing
CoS set on
trunk port
DSCP set
for IP
Action - policy map
Trust - DSCP, IP Prec
MPLS Exp
Mark - set internal
DSCP
Police - rate limit; mark; drop
Scheduling rules: WRR, PQ
Queueing based on CoS
Scheduler
Q1
Q2
ToS
CoS
Incoming
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