Evolving Technologies – Scripting


Network management tools often create more frustration for network engineers than problem they can solve. This is true for a number of reasons, including:

  • Many of them are difficult to install and maintain
  • They are often proprietary and support only a single vendor
  • They often lack scalability and reliability

As a result, many engineers give up and instead rely on the command-line interface (CLI) to manage individual switches. An increasing number of network engineers stretch the limitations of those tools by writing scripts in TCL, Perl, Python or other languages.

Of course these engineers are not writing sophisticated software, just scripts that allow them to scale certain tasks, such as reconfiguring multiple switches using a screen scraping of CLI commands.

Scripting is a critical component of many Software Defined Networking (SND) implementations – including that of Cisco Systems with the Application Centric Infrastructure (ACI).

We know that in this technology, Cisco likes to use REST as the Northbound API. Yet Cisco engineers prefer to use Python instead of sending plain vanilla REST calls. This is because Python allows the parsing of command line options and configurations. Of course it is possible to use Python with sample scripts to turn XML into REST calls, but this approach requires formatting the XML configuration files according to the ACI object model. This results in scripts that are shared requiring administrators to have knowledge of this ACI object model.

The Python SDK for ACI permits the creation of scripts with configuration files and command line options that anyone skilled in networking can use. The ACI SDK provides models that enable you to perform all the operations that the Cisco ACI fabric offers with several advantages:

  • Python can parse configuration files in whichever format you prefer
  • The SDK APIs can be identical over time, while the specific format of the XML object model can change
  • You can perform more sophisticated conditional operations, string manipulations, etc

7 thoughts on “Evolving Technologies – Scripting

  1. Hi Anthony, I’ve just bought your CCENT ICND 100-105 book and it looks great! I wondered if you would also be releasing a book for the ICND2? Many thanks and a Happy New Year. Daniel

  2. Dear Anthony,

    Thanks for such a speedy reply..

    I wondered if there was a place I could buy the book you mentioned? I want to get my hands on it as soon as I can 🙂

    I am really enjoying the ICND1 Book. Lots of useful info!

    Many thanks


    1. The CCNA is indeed still in development. This weekend I am actually doing the last proof read – so it must be out soon.

  3. Hi Anthony,

    When will the materials of section 7 of CCIE R&S be posted on CBT nuggets?

    Thanks and regards,
    Ashwin D V

    1. There are no plans to cover that section in the existing course at CBT Nuggets. I suppose we might cover that section in the next MAJOR revision of CCIE R&S.

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