GravCPA: Controller Placement Algorithm Based on Traffic Gravitation in SDN

Table 3

Symbols of Algorithm 2.

Symbol	Description
	Factor for STEP penalty
	Iteration accuracy for STEP
	Factor for distance tolerance
EH	Function that calculates the minimum covering circle’s center ofusing Elzinga–Hearn [24]
STEP	Step length of controller movement
	Resultant force of intra-/extra-domain nodes
	Set of subdomain abstract nodes except