Elasticity is one of the prerequisite of any SDN application if it has to scale out horizontally. Scaling the entire SDN application does not make sense when the scale requirement is only for few of the services. However, if the SDN application is written in monolithic architecture in that the entire code has to recompile just for few scale requirement. Monolithic Architecture becomes head of line blocking in case the application has to scale out.

As per Wikipedia, “A software system is called “MONOLITHIC” if it has a monolithic architecture, in which functionally distinguishable aspects (for example data input and output, data processing, error handling, and the user interface) are all interwoven, rather than containing architecturally separate components.”

Monolithic application always build as single unit which means in case of change of any small code; requires the recompilation of the entire code. Below are the challenges if the applications are deployed with Monolithic Architecture:-
1. Scaling is one of the biggest challenge of Monolithic Applications
2. Slow speed and processing
3. Monolithic applications are implemented as single development stack