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Before go into “9800 custom QoS” post, it may be useful to understand Cisco NBAR – Network Based Application Recognition.As name implies it is the way Cisco can detect based on application layer characteristics.Since it is layer 7 detection even encrypted traffic, you should be able to understand application. Here is a great Ciscolive presentation that you can get deeper understanding about How NBAR is working.

CLEUR-2016-BRKAPP-2030 (AVC in Enterprise WAN)Download

Image below (taken from that presentation) shown the “Traffic Class” and “Business Relevance” NBAR attributes that can be used to group all those NBAR detected applications into groups that you can easily manage. When you develop a custom QoS policy in a Cisco device (including 9800 WLC), these two attributes can use to simplify your classification rules (ie class-maps)

NBAR use same 12 class model defined in RFC 4594. Note that “Best Effort” traffic is using “class-default” class-map which you do not require to explicitly defined. Also note that by default all applications marked with “Business Irrelevant” attribute goes into “Scavenger” class. Therefore you will see 10 traffic classes for the rest of the traffic. You can verify it as shown below.

C9800-2#sh ip nbar attribute traffic-class ?
  broadcast-video          Broadcast TV, live events, video surveillance
  bulk-data                Non-interactive data applications
  multimedia-conferencing  Desktop software multimedia collaboration applications
  multimedia-streaming     Video-on-Demand (VoD) streaming video
  network-control          Network control plane traffic
  ops-admin-mgmt           Network operations, administration, and management traffic
  real-time-interactive    High-definition interactive video applications
  signaling                Signaling traffic that supports IP voice and video telephony
  transactional-data       Interactive data applications
  voip-telephony           VoIP telephony (bearer-only) traffic
  |                        Output modifiers
  <cr>                     <cr>

C9800-2#sh ip nbar attribute traffic-class 
      Name :  traffic-class
      Help :  SRND class
      Type :  group
    Groups :  broadcast-video
           :  bulk-data
           :  multimedia-conferencing
           :  multimedia-streaming
           :  network-control
           :  ops-admin-mgmt
           :  real-time-interactive
           :  signaling
           :  transactional-data
           :  voip-telephony
      Need :  Mandatory
   Default :  bulk-data

If you want to look at what applications categorized into “VoIP-Telephony” class, you can use that “traffic-class” name at the end of above CLI command. (see below)

C9800-2#show ip nbar attribute traffic-class voip-telephony 
  aol-messenger-audio    DEPRECATED, traffic will not match
  cisco-collab-audio     Cisco Collaboration Voice by various Cisco unified communication clients.
  cisco-jabber-audio     Cisco Jabber Client; Audio Calls and Voice Mail
  cisco-media-audio      Cisco IP Phones and PC-based Unified Communicators
  cisco-phone-audio      Cisco IP Phones and PC-based Unified Communicators; Audio Calls
  cisco-smart-probe      Cisco smart probe
  cisco-spark-audio      Cisco Spark / Webex Teams Audio - unified communications client audio
  citrix-audio           Citrix Audio Traffic
  facebook-audio         Facebook Audio
  fring-voip             DEPRECATED, traffic will not match
  google-services-audio  Google Services Audio
  gtalk-voip             Protocol integrated into hangouts-audio
  hangouts-audio         Google Hangouts audio
  jabber-audio           Communications protocol for message-oriented middleware based on XML
  ms-lync-audio          Skype provides cost effective and collaborative tools for businesses
  rtp-audio              Real Time Protocol Audio
  telepresence-audio     Telepresentce Voice by various Cisco unified communication clients.
  yahoo-voip-messenger   Free P2P calls
  yahoo-voip-over-sip    Yahoo VoIP over SIP

Now, as a customer you may not want to classify those VoIP application traffic as EF. To make your life easy, Cisco came up with “Business-Relevance” attribute where you can easily classify any of those 10 traffic classes’ application into 3 business relevant categories

  1. Business-Relevant
  2. Business-Irrelevant
  3. Default
C9800-2#show ip nbar attribute traffic-class voip-telephony business-relevance ?
  business-irrelevant  Undesirable business traffic
  business-relevant    Business critical applications
  default              Related business applications

Now, if you want to see which VoIP-Telephony application goes into “business-relevant” category you can use the below CLI command.

C9800-2#show ip nbar attribute traffic-class voip-telephony business-relevance business-relevant 
  cisco-collab-audio     Cisco Collaboration Voice by various Cisco unified communication clients.
  cisco-jabber-audio     Cisco Jabber Client; Audio Calls and Voice Mail
  cisco-media-audio      Cisco IP Phones and PC-based Unified Communicators
  cisco-phone-audio      Cisco IP Phones and PC-based Unified Communicators; Audio Calls
  cisco-smart-probe      Cisco smart probe
  cisco-spark-audio      Cisco Spark / Webex Teams Audio - unified communications client audio
  citrix-audio           Citrix Audio Traffic
  jabber-audio           Communications protocol for message-oriented middleware based on XML
  ms-lync-audio          Skype provides cost effective and collaborative tools for businesses
  rtp-audio              Real Time Protocol Audio
  telepresence-audio     Telepresentce Voice by various Cisco unified communication clients.

Here is the list of “VoIP-Telephony” applications falls into “Business-Irrelevant” category

C9800-2#show ip nbar attribute traffic-class voip-telephony business-relevance business-irrelevant 
  aol-messenger-audio    DEPRECATED, traffic will not match
  facebook-audio         Facebook Audio
  fring-voip             DEPRECATED, traffic will not match
  gtalk-voip             Protocol integrated into hangouts-audio
  hangouts-audio         Google Hangouts audio
  yahoo-voip-messenger   Free P2P calls
  yahoo-voip-over-sip    Yahoo VoIP over SIP

Here is the “Default” VoIP-Telephony applications

C9800-2#show ip nbar attribute traffic-class voip-telephony business-relevance default 
  google-services-audio  Google Services Audio

How can you change these default classification ? If that does not fit for your business requirements, you can easily modify in your 9800 configuration under Configurations > Services > Application Visibility > Define Policy section.

Let’s classify Google Hangout audio as “Business-Relevant” “VoIP-Telephony” application category. Below shows “google-services-audio” classify as “Business-Relevant”.

If you go to “Business Irrelevant” category and “consumer-messaging” sub-category, then you can change “gtalk-voip” & “hangout-audio” into “Business-Relevant” application.

If you want to find out equivalent CLI configrations, you can find it out using “show archive config difference” command as shown below. (you have to issue this command prior to save your config via GUI)

C9800-2#sh archive config differences nvram:startup-config system:running-config
!Contextual Config Diffs:
+ip nbar attribute-map webui-relavant
 +attribute business-relevance business-relevant
+ip nbar attribute-set google-services-audio webui-relavant
+ip nbar attribute-set gtalk-voip webui-relavant
+ip nbar attribute-set hangouts-audio webui-relavant

I would encourage you to go through those 12 different traffic classes and which applications Cisco by default classify into “business-relevant”, “default” & “business-irrelevant” category.

In the next post let’s look at how we can use “Business Relevance” & “Traffic Class” attribute to define a custom QoS policy in 9800. In that way, you can re-classify your business relevant application traffic on SSID level with proper DSCP that closely match RFC8325. (Above diagram shows downstream direction, however classification policy on SSID level is more important in upstream direction)

RELATED POSTS
1. QoS for WLAN Professionals
2. RFC8325 – QoS Mappings
3. AireOS QoS Recommendations
4. 9800 QoS Overview
5. 9800 QoS Webinar
6. 9800 Custom QoS