Home > Articles > Cisco QoS Exam Certification Guide: MQC, QPM, and AutoQoS

Cisco QoS Exam Certification Guide: MQC, QPM, and AutoQoS

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: Dec 23, 2004.

Chapter Description

This chapter focuses on Modular QoS CLI, QoS Policy Manager, and AutoQoS with an eye toward passing the Cisco QoS Exam.

Foundation Summary

The "Foundation Summary" is a collection of tables and figures that provide a convenient review of many key concepts in this chapter. For those of you already comfortable with the topics in this chapter, this summary can help you recall a few details. For those of you who just read this chapter, this review should help solidify some key facts. For any of you doing your final preparation before the exam, these tables and figures are a convenient way to review the day before the exam.

Figure 3-7 shows the general flow of MQC commands.

Figure 7Figure 3-7 MQC Commands and Their Correlation

Table 3-10 lists the match command options available for the IOS revision covered by the current QOS exam, 12.2(15)T.

Table 3-10 match Configuration Command Reference for MQC Tools



match [ip] precedence precedence-value [precedence-value precedence-value precedence-value]

Matches precedence in IPv4 packets when the ip parameter is included; matches IPv4 and IPv6 packets when the ip parameter is missing.

match access-group {access-group | name access- group-name}

Matches an ACL by number or name.

match any

Matches all packets.

match class-map class-map-name

Matches based on another class map.

match cos cos-value [cos-value cos-value cos-value]

Matches a CoS value.

match destination-address mac address

Matches a destination MAC address.



match fr-dlci dlci-number

Matches a particular Frame Relay DLCI.

match input-interface interface-name

Matches an input interface.

match ip dscp ip-dscp-value [ip-dscp-value ip-dscp- value ip-dscp-value ip-dscp-value ip-dscp-value ip- dscp-value ip-dscp-value]

Matches DSCP in IPv4 packets when the ip parameter is included; matches IPv4 and IPv6 packets when the ip parameter is missing.

match ip rtp starting-port-number port-range

Matches the RTP's UDP port-number range, even values only.

match mpls experimental number

Matches an MPLS Experimental value.

match mpls experimental topmost value

When multiple labels are in use, this command matches the MPLS EXP field in the topmost label.

match not match-criteria

Reverses the matching logic; in other words, things matched by the matching criteria do not match the class map.

match packet length {max maximum-length-value [min minimum-length-value] | min minimum-length-value [max maximum-length-value]}

Matches packets based on the minimum length, maximum length, or both.

match protocol citrix app application-name-string

Matches NBAR Citrix applications.

match protocol http [url url-string | host hostname- string | mime MIME-type]

Matches a host name and URL string.

match protocol protocol-name

Matches NBAR protocol types.

match protocol rtp [audio | video | payload-type payload-string]

Matches RTP audio or video payload, based on the payload type. Also allows explicitly specified payload types.

match qos-group qos-group-value

Matches a QoS group.

match source-address mac address-destination

Matches a source MAC address.

Table 3-11 lists the various MQC subcommands available in Cisco IOS Software for defining actions to be taken.

Table 3-11 Action (PHB) Subcommands Inside a Policy Map




CB Marking action, with options to mark several fields inside headers


Reserves bandwidth for the class for CBWFQ


Reserves bandwidth, and provides LLQ with CBWFQ


Shapes traffic in the class with a defined bandwidth and burst sizes


Polices traffic in the class with a defined bandwidth and burst sizes


Performs TCP and RTP header compression on packets in the class

Because routers and switches do different tasks, QoS differs slightly between them, but to get an idea about what AutoQoS does, consider that AutoQoS on routers works to classify packets into three service classes:

  • Voice payload

  • Voice signaling

  • All other traffic

Table 3-12 lists the commands related to AutoQoS VoIP, followed by an example configuration.

Table 3-12 Command Reference for AutoQoS VoIP (for Routers)



auto qos voip [trust] [fr-atm]

Configuration command that enables AutoQoS VoIP on an interface (PPP or HDLC) or VC (FR and ATM)

no auto qos

Disables AutoQoS VoIP on an interface (PPP or HDLC) or VC (FR and ATM)

show auto qos [interface interface-type]

Displays what AutoQoS actually created

show policy-map interface interface-name [input | output]

Displays actual configuration of MQC-based parts of the configuration, including any later changes made by an engineer

Table 3-13 shows the PHBs that can be configured by AutoQoS VoIP on a router and some comments about its choices.

Table 3-13 PHBs Generated by AutoQoS VoIP Configuration (for Routers)



Class and Mark

If the trust parameter is omitted, AutoQoS VoIP configures CB Marking, using NBAR, to classify traffic into voice payload (marked DSCP EF), voice signaling (marked DSCP AF31), and all else (marked DSCP BE).


Voice payload is placed into an LLQ. Voice signaling is in another queue with a low-bandwidth CBWFQ queue. All other traffic defaults into the class-default queue, which by default gets 25 percent of link bandwidth.


If the link has a bandwidth of 768 kbps or less, cRTP is enabled.


If the link has a bandwidth of 768 kbps or less, AutoQoS enables LFI. For interfaces originally configured for HDLC or PPP, AutoQoS reconfigures MLP with LFI on those interfaces. For Frame Relay, AutoQoS configures FR Fragmentation, unless the fr-atm option is configured on the auto qos command. In that case, AutoQoS configures MLP over Frame Relay LFI. In each case, the fragment size is tuned for a 10-ms fragment.


On Frame Relay interfaces, FRTS is configured, tuned for a Shaping interval of 10 ms.

Cisco IOS switches use the same interface subcommand as routers, but with a couple of different options. The full syntax is as follows:

auto qos voip {cisco-phone | trust}

Figure 3-8 shows the locations where the cisco-phone and trust options should be used, along with some notes about how the cisco-phone option works.

Figure 8Figure 3-8 Two Settings, Three Actions, for Classification and Marking

The list of PHBs created by AutoQoS VoIP differs from routers and is summarized in Table 3-14.

Table 3-14 PHBs Generated by AutoQoS VoIP Configuration (for 2950 EI Switches)



Class and Mark

Classifies based on CoS on trusted ports, or on cisco-phone ports on which an actual phone is attached. Assumes CoS 0 on ports with cisco-phone configured when no phone is detected with CDP 2.0. Re-marks DSCP of packets based on CoS (CoS 5 – DSCP EF, CoS 3 – DSCP AF31, CoS 0 – DSCP BE).


Creates an LLQ for voice payload (CoS 5), and assigns 20 percent of remaining bandwidth to voice signaling (CoS 3), and 80 percent to all other (CoS 0) traffic.

Table 3-15 lists the four competing options for AutoQoS settings on each port when configuring AutoQoS on Cat-OS. The QoS course includes a wonderful table comparing these three options, included here as Table 3-16, summarizing the comparison points between the three options.

Table 3-15 Comparing Options for set port Command with AutoQoS



trust cos

Accept the CoS of incoming frames.

trust dscp

Accept the DSCP of incoming packets.

voip ciscoipphone

Use CDPv2 to discover the absence or presence of an IP Phone. If one is there, trust CoS, and extend the trust boundary to the IP Phone, causing the PC's frames to be marked CoS 0. If no phone is there, treat all incoming frames as CoS 0.

voip ciscosoftphone

Trust DSCP, but police DSCP EF at 320 kbps and DSCP AF31 at 32 kbps.

Table 3-16 Comparisons of CLI, MQC, and AutoQoS





Ease of Use




Ability to Fine Tune


Very Good

Very Good

Time to Implement








9. For Further Reading | Next Section Previous Section

Cisco Press Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Cisco Press and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Cisco Press products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@ciscopress.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by Cisco Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.ciscopress.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020