Text FSM

Text FSM

• Python module/library to get structured data out of raw data got from a network device( Routers and Switches )
• TextFSM is a template based state machine built by Google to simplify dealing with Regular Expressions and getting data from traditional network devices

Consider a sample input:

VLAN Type  Vlan-mode

---- ----- ----------

1    enet  CE    

2    enet  CE    

3    enet  CE    

4    enet  CE    

5    enet  CE  

Sample FSM Template that will define the data we want to extract:

Value VLAN_ID (\d+)

Value TYPE (\w+)

Value MODE (\w+)

First variables are defined. Next to each variable name is the regular expression that represents it.

The FSM code to parse the required information looks like :

Start

  ^${VLAN_ID}\s+${TYPE}\s+${MODE}\s+ -> Record

Makes your life easy while working with pattern matching : http://www.regexr.com/

Further Reading – Official Documentation https://code.google.com/archive/p/textfsm/wikis/TextFSMHowto.wiki