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Quality of Service or QoS give network administrators a set of tools to help them maximize network bandwidth and responsiveness.

Theory

Contents 1 Theory 2 Commands 3 Default Settings 4 Verification 5 Troubleshooting, Tips, and Tricks 6 Online Resources 6.1 Cisco Resources 6.2 Other Sources

Cisco created the Modular QoS CLI or MQC to standardize how QoS features are configured in IOS. Tools using MQC all start with the phrase "class-based".

MQC commands have three major commands, each with associated subordinate commands -

• Under the class-map command, you define what values you are looking to match in packets.
• Under the policy-map command, you configure what actions you want to apply to your defined classes.
• Finally, wit the service-policy command, you define what interface(s) you want your policy maps to apply to.

Class-maps - the class-map command can be followed by the keywords match-all or match any; and then name (case sensitive) of the class-map.

• The class-map command is followed by one or more match commands which specify out what will make for a match on a packet. There are MANY options for the match command to match on.
• The match-all keyword means that ALL match subcommands must match for the given class map. The match-any command means that only ONE of the following match subcommands must be matched.
• The match protocol command uses NBAR to perform the match
• Class-maps can be nested into one another! The command to call this would be match class name.
• Packets that do not match a defined class are considered to match a class called class-default

Commands

• Nothing listed yet

Default Settings

• Nothing listed yet

Verification

• Nothing listed yet

Troubleshooting, Tips, and Tricks

• CCIE Pursuit has a nice tip in using the same name for all of your related MQC QoS elements.

• Simulating interface counters by using a QoS policy-map from Cisco IOS hints and tricks.

• Some random QoS tips and a tip on renaming class and policy maps from Routing Bits.

Online Resources

Cisco Resources

• Cisco's 12.4 QoS Configuration Guide.

• Cisco Learning Module presentation on an introduction to modular QoS CLI (must be registered to view).

• Nice presentation from Cisco giving a QoS overview.

• Thanks to 6200 Networks for pointing out this QoS learning module hosted by the Cisco Learning Network.

Other Sources

• A Networker Blog has a big page of QoS notes as well as a page on Catalyst QoS.

• CCIE Pursuit has a funny post about the difference between a couple of options with the show policy map command.

• CCIE Paradise has some QoS stuff: QoS Notes and more QoS notes.

• Community String has a nice little post on why is QoS needed?.

• Jeremy Stretch contributes a comparison of shaping vs. policing to the CT3 Wiki. He also goes in-depth examining bandwidth reservation in QoS and gives us a QoS cheatsheet.

• Internetwork Expert's Petr has some insights into Class-Based Weighted Fair Queuing.

• A solution that entailed applying a service-policy to a SVI interface from routing bits.

• CCIE Candidate Carl shares a nice diagram of the 3560 queuing process.

• MUST-SEE mind-map detailing the various QoS IOS solutions from Arden Packeer.

• Router Ric has an article examining hardware queues.

• Another article on time-based QoS policies.

• Keith of CCIE Candidate has some general notes a variety of QoS topics.

• More general QoS MQC notes from Mar of CCIE Pilot. Mar also has a quick little QoS challenge.

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