In reply to manasa-n:
What you are showing and what you are saying does not be the same.
Additionally it is not a good coding practice to use the same names for the type and the object.
This is legal but it makes the reading complicated.
I’d like to see the piece of code where you are passing the virtual interface to the config_db.
The error message is pointing you to base_test, but we do not see the code for this.
Please refine your code and post the relevant pieces of code here.