OpenFlow is the protocol that allows SDN controllers to communicate along with the forwarding plane of network devices. OpenFlow is the most generally used protocol, especially in the data center network used for the SDN southbound interface of SDN, which separates the data plane from the control plane, which describes the interaction of single or more control servers with OpenFlow compliant switches.

An OpenFlow lets a server inform the network switches where to transmit packets. An OpenFlow controller installs flow table entries in switches to forward traffic in accordance which following their entries. Controllers can often bring forth a similar interface to applications called the northbound interface to exhibit the programmability of the network.

The Application layer Routing protocols are Open Shortest Path First (OSPF) and Border Gateway Protocol (BGP). Some protocols used for the southbound interface of SDN are,

 •  Path Computation Element (PCE)
 •  Interface to the Routing System (I2RS)
 •  Application Layer Traffic Optimization (ALTO)
 •  Open virtual switch Database (OVSDB)
 •  FORwarding & Control Element Separation (ForCES)
 •  Network Configuration Protocol (NETCONF)
 •  OpenFlow Configuration (OF-CONFIG)
 •  Representational State Transfer Configuration Protocol (RESTCONF)
 •  OpFlex

SDN has also covered a large variety of Algorithms. It is the base for the SDN controller since it extracts the widest available bandwidth from source to destination for a single path. The various algorithm includes,

 •  Multi constrained Algorithm
 •  Rule caching Algorithm
 •  Dynamic-time out Algorithm
 •  Shortest path emulation Algorithm
 •  Dijkstra’s Shortest Path Algorithm
 •  Wavelength assignment Algorithm
 •  Genetic-based Load Balancing Algorithm
 •  Dynamic Algorithm for loop detection
 •  Heuristics-based algorithms for energy optimization
 •  Malware detection Algorithm in mobile devices
 •  Dynamic Algorithm for loop detection and
 •  Existing Routing Algorithm

The routing algorithm is a procedure that places down the route to transfer data packets from source to destination. It helps in directing internet traffic efficiently along with a large variety of numerous routes to reach its destination. Here, an Existing Routing Algorithm that broadly classified into three main categories, such as

 •  Routing Algorithm with static link cost (RA-SLC)
 •  Routing Algorithm with dynamic link cost (RA-DLC)
 •  Routing Algorithm with dynamic link cost and minimum interference (RA-DLCMI )