Ideas behind Visual Class-Based-QoSMonitor (V-CBQM)

Visual Class-Based-QoS Monitor (V-CBQM)offers three main features for QoS management: QoS configuration exploration, QoS statistics monitoring, and QoS traffic report generation.

V-CBQM allows user to explore current QoS setting, monitor DiffServ-based quality of service statistics via graphical presentation of real time data as well as historical data,and, finally, generate traffic reports in PDF and MS Word format. V-CBQM is based on Cisco’s Class-Based QoS MIB (CBQosMIB) from QoS Policy Manager (QPM). Below is an excerpt of what the book “Cisco QoS Exam Certification Guide” says about QPM:

“QPM provides many of the features that you need when you get serious about deploying QoS across an enterprise. The following list summarizes some of the more important features:

  • Enables you to define a QoS policy based on business rules.
  • Automatically configures some or all network devices with QoS features, based on the QoS policy described to QPM. The features that QPM enables include marking, queuing, shaping, policing, and Link Fragmentation and Interleaving (LFI) tools.
  • Loads the correct configurations automatically.
  • Enables you to monitor the device configurations to make sure no one has made changes to them. If the configurations have been changed, you can use QPM to restore the original configuration. “

And here is an excerpt from the same book about QPM and CBQoSMIB:

“Cisco QPM (QoS Policy Manager) uses Telnet and the Simple Network Management Protocol (SNMP) to configure and monitor devices. Cisco IOS includes a couple of important proprietary SNMP Management Information Bases (MIBs) that provide a lot of good information about QoS performance in a router. When QPM displays performance data for MQC-based QoS tools in a router, the performance data comes mostly from these specialized QoS MIBs.

First, the Class-Based QoS MIB (CBQoSMIB) contains variables that describe the MQC configuration commands in a router. This MIB also includes statistical variables, which are essentially the same kinds of stats seen with the show policy-map interface command.

More interestingly, CBQoSMIB goes beyond those statistics, providing statistics for packets before a policy map has been processed, and afterward. In other words, you can see statistics about packets before the PHBs have been applied and after they are applied. QPM, of course, knows about this MIB, so it is ready to show graphs of packet statistics comparing the pre- and post-policy map. “

In summary, provided with the mechanism to explore CBQoSMIB, it’s possible to obtain current QoS setting of a device which supports CBQoSMIB (I still need to complete the research on what Cisco IOS supports CBQoSMIB. As far as I know, devices with Cisco IOS version 12.0 and up support CBQoSMIB.). If the MIB info is parsed and organized properly, one can also plot traffic statistics for any DiffServ or DSCP class.

Reference Web Pages:

1. Cisco SNMP Object Navigator

2. Intro to MQC, QPM, and AutoQoS

3. Commercial QoS Browser