Kytos is a modular SDN controller, composed by the Kytos Core and by applications called Networks Applications (or napp), which means it has several parts that working together will compose a Kytos Controller.
The Kytos Core is responsible for the main core operations of the controller like keeping track of the connected switches, enabling, disabling and executing napps, and providing a web-ui interface server for example. It is switch protocol agnostic, which means it is not bound to any specific switch protocol like OpenFlow, and therefore can operate with switches of different protocols.
A web interface is being developed to manage the controller. This web interface aims to be intuitive and very easy to use.
The napps can be divided into two categories, kytos napps and user napps.
The kytos napps are those needed for the controller to deal with main operations with a switch using a certain protocol. ex: - of_core napp is responsible for providing interaction with OpenFlow switches, and deals with things like OF connection handling, OF version negotiation, OF message packing/unpacking (using python-openflow**), switch attributes and capabilities determination, among other things. - of_l2ls napp (Layer 2 Learning Switch) is responsible for learning flows and installing them on the OF switches. - of_topology napp aims to build and display the topology of the network (switches, hosts and the connections between them).
The core applications provides the kytos core with information about the switch and emits events that can be used by other core/user napps.
Several core applications were developed. Kytos's developer team is constantly developing new core application to improve Kytos's features.
The applications stack are general applications, created by Kytos’s users. These applications can be installed, loaded and unloaded on the fly by the user. Also, these applications make use of the OpenFlow library and information provided by the core application.
All applications developed by users can be uploaded to the Napp Server, which is a public repository of Network Applications. Once the application is uploaded to this repository, any user can install, load and run the application.
** The Python-OpenFlow library is an implementation of the OpenFlow protocol in Python. This library is used to pack/unpack and create/parse OpenFlow messages and is widely used by our OpenFlow core/user napps.