MQC

MQC
Modular QoS CLI (MQC) is a method of classifying traffic, marking the
traffic, and setting policies for that traffic that can be used on most devices
with most kinds of policies. It’s most important contribution is the separation
of traffic classification from policy implementation. Here are general steps
for implementing MQC:
Step 1. Create the necessary access control lists, if classifying traffic by
ACL, or configure network-based application recognition
(NBAR).
Step 2. Create class maps that specify matching such items as ACLs,
protocol, DSCP, or IP Precedence values.
Step 3. Create a policy map that links to each class map and defines the
policy for each.
Step 4. Apply the policy map to the appropriate interfaces.
When access control lists (ACL) are used to classify traffic, the way a router
or switch reacts to specific access control entries (ACE) is different in a QoS
context than with security-based ACLs. In a QoS access list:
¦ If the traffic matches a permit statement, the designated QoS action is
taken.
¦ If the traffic matches a deny statement, the rest of the ACEs in that
ACL are skipped and the switch goes to the next ACL.
¦ If there are multiple ACLs in a policy applied to an interface, the
switch stops reading them as soon as a permit statement match is
found for the traffic.
¦ If the traffic does not match any ACL entry, the switch just gives besteffort
delivery to the traffic.