CCIE Data Center: The Cisco NX-OS XML API

By Anthony Sequeira on August 22nd, 2012

Nestled in the CCIE Data Center Written Exam Blueprint we find the following:

  • Describe XML for network management and monitoring

We did not have time during our live lecture sessions in the CCIE Data Center Written Bootcamp in order to cover this one, so let us do it here.

The XML capabilities on the Cisco Nexus device is an alternative which one can use to configure and monitor the device. This Nexus capability relies on the XML-based network configuration protocol called NETCONF. This allows management from an XML tool or application.

NETCONF is implemented with an XML schema that allows the formatting of device configuration elements within a Remote Procedure Call (RPC) message. Your entire set of CLI commands can be initiated on the device in this manner. There are four layers of NETCONF:

  • Secure Shell (SSH) transport protocol – this provides the secure, encrypted connection between the NX-OS device and the management station; this is implemented using a service called xmlagent that uses NETCONF over SSH version 2
  • RPC tag – the Remote Procedure Call tag introduces the configuration command to the NX-OS device
  • NETCONF operation tag – this indicates the type of configuration command
  • Content – this is the XML representation of the feature that is to be configured

Think this XML API in the NX-OS might be a passing fad? Do not count on it. Cisco is very excited about this initiative because it addresses some of the shortcomings that have been noted regarding Simple Network Management Protocol (SNMP), namely:

  • Many statistics and counters are not available in SNMP Management Information Bases (MIBs)
  • A lack of scalability with SNMP due to excessive CPU loading
  • Difficulties in reading MIB information
  • MIBs suffering from 32-bit counter rollover
  • Interface index changes

Since there are no MIBs that assist with Virtual Device Context management, XML management permits such management using XML schema files.

In order to verify that your Nexus device is properly equiped for the XML management, ensure that SSH version 2 is operational:

show ssh server

Next, verify the XML server status with:

show xml server status

For a simple test of the capabilities, issue the following command:

debug cli force xml-output

Then, issue a sample command such as:

show env temp

Notice the command output is presented in XML format at the CLI. You can use no debug cli force xml-output in order to reverse this test.

Anthony Sequeira CCIE, CCSI
Twitter: @compsolv
Facebook: http://www.facebook.com/compsolv

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    One Response to “CCIE Data Center: The Cisco NX-OS XML API”

    1. Krunal says:

      Very good post Anthony. One more thing to add here is most of the cli show commands (except of system internal commands) can be displayed in xml format.

      show module | xml

      OR

      terminal output xml
      show module

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