notes: Cisco Modular QoS CLI (MQC)

 

- MQC is short for Modular Quality of Service CLI (Command Line Interface).
- MQC provides a framework for multiple QOS methods to be applied in the same direction on the same interface in contrast to legacy QOS mechanisms.

Mechanics of MQC
MQC separates the classification function of a QoS tool from the action (PHB) that the QoS tool wants to perform. To do so, there are three major commands with MQC, with several subordinate commands:
■ The class-map command defines the matching parameters for classifying packets into
service classes.
■ The PHB actions (marking, queuing, and so on) are configured under a policy-map
command.
■ The policy map is enabled on an interface by using a service-policy command.

Class-maps

- The purpose of class-maps are to classify traffic.
- Class-map names are Case-Sensitive.
- The match sub-commands are used to specify various criteria for classifying packets.
- If a packet matches the specified criteria, that packet is considered a member of the class.
- If a packet does not match the class criteria, it is evaluated against the next class.
- Packets that fail to match any of the class-maps are classified as members of the default traffic class.
- If more than one "match" criterion exists in the class-map, a evaluation instruction should be specified.
- The instruction could be one of the following: ('match-all' is the default)
   - match-any - The traffic being evaluated by the class-map must match one of the "match" statements.
   - match-all - The traffic being evaluated by the class-map must match ALL of the "match" statements.

Policy-maps

- Are used to configure the QOS features that should be associated with the traffic that has been classified with class-maps.
- Policy-map names are Case-Sensitive.
- Multiple class-map can be referenced, which will be evaluated sequentially top-down.

MQC Class-Default
- MQC always has a default class created named 'class-default'.
- Any traffic not matched by a higher class will belong to the class class-default.
- If no other class-maps were defined in a policy-map, ALL traffic will belong to the class class-default.

Steps to configure MQC policies:
1. Define traffic classifications using class-maps.
2. Create the policy-map, and apply the QOS features to the individual class-maps.
3. Apply the policy-map to a interface inbound or outbound.

- MQC Classification options
> Access-lists
> DSCP
> IP Precedence
> NBAR (see below)
> Packet Length
> FR-DE
> Interface
> QOS-group

- MQC Marking options
> Atm-clp
> Cos
> Discard-class
> Dscp
> Fr-de

- Matching VOIP traffic can be done in two ways:
> Matching UDP/RTP headers and RTP port numbers:

class-map VOIP
match ip rtp 16384 16383

> Using NBAR (Specifies matching for RTP voice payload type values 0-23)

class-map VOIP
match ip rtp audio

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COMMANDS
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- Shows the configured class-map/s

sh class-map [name]

- Shows the configured policy-map/s

sh run policy-map [name]

- Shows the policy-map info and counters associated with the interface

sh policy-map interface {int}

- Creates a class-map for classification, (default = match-all)

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

- Specifies the various match criteria

match {options}

- Creates a policy-map

policy-map {name}

- References previously created class-maps

class {name | class-default}

- Specifies a specific QOS feature for the class

{bandwidth | priority | shape | policy}

References nested policy-maps

service-policy {nested-policy}

- Applies a policy-map to an interface

interface s0/0
service-policy {input | output} {policy-name}