Consolidated Platform Configuration Guide, Cisco Ios Release 15.2(4)E (Catalyst 2960-X Switches - Cisco Catalyst 2960 series Configuration Manual

IP Traffic Classification
Trust the IP precedence value
Trust the CoS value
IP standard or an extended ACL
Override configured CoS
After classification, the packet is sent to the policing and marking stages.

Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)

Description
Trust the IP precedence value in the incoming packet (configure the port
to trust IP precedence), and generate a DSCP value for the packet by using
the configurable IP-precedence-to-DSCP map. The IP Version 4
specification defines the 3 most-significant bits of the 1-byte ToS field as
the IP precedence. IP precedence values range from 0 for low priority to
7 for high priority.
You can also classify IP traffic based on IPv6 precedence.
Trust the CoS value (if present) in the incoming packet, and generate a
DSCP value for the packet by using the CoS-to-DSCP map. If the CoS
value is not present, use the default port CoS value.
Perform the classification based on a configured IP standard or an extended
ACL, which examines various fields in the IP header. If no ACL is
configured, the packet is assigned 0 as the DSCP and CoS values, which
means best-effort traffic. Otherwise, the policy-map action specifies a
DSCP or CoS value to assign to the incoming frame.
Override the configured CoS of incoming packets, and apply the default
port CoS value to them. For IPv6 packets, the DSCP value is rewritten by
using the CoS-to-DSCP map and by using the default CoS of the port. You
can do this for both IPv4 and IPv6 traffic.
Information About QoS
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