Classification, Marking, And Policing With A Layer 3 Switching Engine - Cisco WS-C6506 Software Manual

Chapter 52 Configuring QoS
Ethernet Ingress Port Classification Features with a Layer 3 Switching Engine
You can use the untrusted, trust-ipprec, trust-dscp, and trust-cos port keywords to classify the traffic
on a per-port basis for a Layer 3 switching engine to mark.
The trust-ipprec and trust-dscp keywords are supported only with a Layer 3 switching engine and are
not supported on the 1q4t ports except Gigabit Ethernet. On the 1q4t ports (except Gigabit Ethernet),
the trust-cos port keyword displays an error message, activates the receive-queue drop thresholds,
and—as indicated by the error message—does not apply the trust-cos trust state to the traffic. You must
configure the trust-cos ACL that matches the ingress traffic to apply the trust-cos trust state.
In addition to the per-port classification, you can create the ACEs that classify the traffic on a per-packet
basis (for the IP and IPX traffic, see the
Modifying the Named IPX ACLs" section on page
see the
configuration (see the
To mark the traffic in response to per-port classification, the traffic must match an ACE that contains the
dscp ACE keyword (see the
ACEs in the default ACLs contain the dscp ACE keyword.
and the marking rules that they invoke.
Table 52-1 Marking Based on Per-Port Classification
Port Keyword ACE Keyword Marking Rule
untrusted dscp
trust-ipprec dscp
trust-dscp dscp
trust-cos dscp
QoS uses the configurable mapping tables to set the internal and egress DSCP, which is a 6-bit value,
from the CoS and IP precedence, which are 3-bit values (for more information, see the
Values" section on page 52-16

Classification, Marking, and Policing with a Layer 3 Switching Engine

Note With a Layer 3 switching engine, the Catalyst 6500 series switches provide QoS only for the following
frame types: Ethernet_II, Ethernet_802.3, Ethernet_802.2, and Ethernet_SNAP.
OL-8978-04
"Creating or Modifying the Named MAC ACLs" section on page
"Marking Rules" section on page
"Marking Rules" section on page
Set the internal and egress DSCP as specified in the ACE.
For the IP traffic, set the internal and egress DSCP from the received Layer 3 IP precedence
value. For the other traffic, set the internal and egress DSCP from the received or port Layer 2
CoS value.
Note—With the trust-ipprec port keyword, QoS uses only the IP precedence bits. If the traffic
with a DSCP value enters the switch through a port that is configured with the trust-ipprec
port keyword, the three most significant bits of the DSCP value are interpreted as an IP
precedence value; QoS ignores the rest of the DSCP value.
For the IP traffic, set the internal and egress DSCP from the received Layer 3 DSCP value. For
other traffic, set the internal and egress DSCP from the received or port Layer 2 CoS value.
Set the internal and egress DSCP from the received or port Layer 2 CoS value.
and the
"Named IP ACLs" section on page 52-46
52-51) or on a per-frame basis (for the other traffic,
52-23).
"Configuring the DSCP Value Maps" section on page
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
Understanding How QoS Works
and the
52-53), regardless of the port
52-23). In their default configuration, the
Table 52-1 lists the per-port classifications
"Creating or
"Internal DSCP
52-73).
52-15