Frame Relay DE bit

- Input interface

- Source MAC address

- Destination MAC address

- Any packet

Classification using MQC is accomplished by specifying a traffic match criteria within a configured class map for each different service class. In order for QoS mechanisms to use the class map, the map must be referenced through the use of a policy map, which is subsequently applied to an inbound or outbound interface as a service policy.

In older Cisco IOS software releases, the router classified a packet against every individual QoS feature. This resulted in additional processing overhead, inaccurate packet counters, and double accounting issues. Common classification is a feature that was introduced in Cisco IOS Release 12.2, and is enabled by default whenever classification is invoked within a policy map. With common classification, a packet is classified only once per service policy and matches a single class in the policy. Because matching terminates at the first matching class, it is important to ensure that the classes are configured in the right sequence within a policy. After a packet is classified against a particular class, that packet is subjected to all the QoS features configured within that class.

MQC classification with class maps is extremely flexible and can classify packets by using these classification tools:

■ Access list: Access lists for any protocol can be used within the class map configuration mode. The MQC can be used for other protocols, not only IP.

■ IP precedence: IP packets can be classified directly by specifying IP precedence values.

■ DSCP: IP packets can be classified directly by specifying IP DSCP values. DiffServ-enabled networks can have up to 64 classes if DSCP is used to mark packets.

■ MPLS experimental bits: Packets can be matched based on the value in the experimental bits of the MPLS header of labeled packets.

■ QoS group: A QoS group parameter can be used to classify packets in situations where up to 100 classes are needed or the QoS group parameter is used as an intermediate marker; for example, MPLS-to-QoS-group translation on input and QoS-group-to-DSCP translation on output. QoS group markings are local to a single router.

■ Protocol: Classification is possible by identifying Layer 3 or Layer 4 protocols. Advanced classification is also available by using the Network-Based Application Recognition (NBAR) tool where dynamic protocols are identified by inspecting higher-layer information.

■ Class map hierarchy: Another class map can be used to implement template-based configurations.

■ Frame Relay DE bit: Packets can be matched based on the value of the underlying Frame Relay DE bit.

■ CoS: Packets can be matched based on the information contained in the three CoS bits (when using IEEE 802.1Q encapsulation) or priority bits (when using the Inter-Switch Link [ISL] encapsulation).

■ Input interface: Packets can be classified based on the interface from which they enter the Cisco IOS device.

■ MAC address: Packets can be matched based on their source or destination MAC addresses.

■ User Datagram Protocol (UDP) port range: Real-Time Transport Protocol (RTP) packets can be matched based on a range of UDP port numbers.

■ All packets: MQC can also be used to implement a QoS mechanism for all traffic in which case classification will put all packets into one class.

This topic describes the Cisco IOS commands used to configure classification of packets with MQC.

You can use the class-map global configuration command to create a class map and enter the class map configuration mode. A class map is identified by a case-sensitive name; therefore, all subsequent references to the class map must use exactly the same name.

You can use the match command to specify the classification criteria when in class map configuration mode. You can use multiple match commands within a class map. At least one match command should be used within the class map configuration mode. The default is match none.

You can also nest class maps in MQC configurations by using the match class-map command within the class map configuration. By nesting class maps, the creation of generic classification templates and more sophisticated classifications are possible.

class-map [match-any | match-all] class-map-name

Syntax Description

Parameter

Descri ption

[match-any | matchall]

(Optional) Determines how packets are evaluated when multiple match criteria exist. Packets must either meet all of the match criteria (match-all) or one of the match criteria (match-any) to be considered a member of the class. The default is "match-all."

class-map-name

Name of the class for the class map. The name can be a maximum of 40 alphanumeric characters. The class name is used for both the class map and to configure policy for the class in the policy map.

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