52-6
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 52 Configuring QoS
Understanding How QoS Works
Figure 52-4
PFC3 Classification, Marking, and Policing
Yes
Yes
7
Set internal
DSCP
to mutated
value
Egress
DSCP
mutation?
Yes
No
No
No
Yes
From ingress
LAN port or VLAN
From ingress
WAN port
IP
Packet?
ACL(s)
on ingress
interface?
1
Trust
received
DSCP?
1
Trust
received IP
precedence?
No
No
Yes
Yes
5
Set internal
DSCP
to marked
down value
Use default
ingress ACL
Yes
No
No
Match
ACE in ACL?
Yes
Yes
Yes
Yes
77890
PFC3 classification, marking, and policing
Use received
DSCP
2
Set internal
DSCP
from received
IP precedence
3
Set internal
DSCP
from received
or port CoS
Use DSCP
from ACE
1
Traffic is from
an untrusted
port
1
Trust
received or
port CoS?
2
Specified by AC
E
keyword or by
port keyword and
dscp
AC
E
keyword
3
From IP precedence-to-DSCP map
5
From CoS-to-DSCP map
4
For traffic forwarded by PFC3, only the ingress or egress
policing rule is applied, whichever is more severe.
7
F
6
Specified by ACE keyword
From DSCP-to-CoS map
8
From egress DSCP mutation map
1
rom DSCP markdown map
4
Policing
rule in
ACE?
Markdown?
Out of
profile?
Drop
packet
Yes
No
No
No
No
ACL(s)
on egress
interface?
6
Trust
internal
DSCP?
No
5
Set internal
DSCP
to marked
down value
Use default
egress ACL
To egress
interface
No
No
Match
ACE in ACL?
Yes
Yes
Yes
Yes
Use DSCP
from ACE
Use internal
DSCP
Traffic is
untrusted
8
Derive CoS
from internal
DSCP
4
Policing
rule in
ACE?
Markdown?
Out of
profile?
Drop
packet