How to use TextFSM to streamline Text Parsing for Network Automation

Achieving a clear visibility into the functioning of systems is of utmost importance in simplifying the management of any IT Operations environment. It is imperative to capture and analyze performance metrics in a timely manner. Sounds pretty obvious, doesn’t it ? It absolutely does!! However, it’s the follow up question of how such a capture & subsequent analysis is done, that leaves most of the IT folks in a quagmire. This is where TextFSM can help! It enables data parsing from Network Devices. With TextFSM, you can automate various scenarios especially related to Network Automation, in a production environment based on the parsed data.

If you are lucky then your operations environment may already boast of a suitable and reliable system monitoring application, one that aids you in addressing the aforementioned challenge. However, should this be not the case, you have two choices : either collaborate with your customer and procure the latest shiny tool in the market, or outline your requirements and ascertain how much of the process can be methodically automated into distinct modules. By doing so, you not only gain knowledge and expertise for yourself, but also save a substantial amount of $$$ for your customer.

Since I am a Network/Unified Communications guy, my focus in this series will primarily revolve around Cisco CUBE Routers. The automation concepts and techniques discussed can easily be adapted to other network devices such as switches and APs, thereby enabling you to effectively capture, monitor and visualize performance metrics across your entire network.

I will start this series by covering an important tool called TextFSM that is extremely useful while working with unstructured or semi-structured data especially in the context of network automation. It is imperative that the underlying data is in a clearly formatted state before we can even begin the actual automation of use cases. In fact, the art of visualization comes even later. The table of contents is given below. You can click on the links to jump to the relevant section.

1. TextFSM
2. TextFSM Templates
3. TextFSM Template Repository
4. Sample Exercise
5. TextFSM Template
6. Output

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