The challenging characteristics of Smart Grid such as the vast size of covered area and tight requirements of reliability (higher than 0.98) and delay (in terms of second and millisecond) impede the procedure of communication network designing. This paper investigates the problem of network designing subject to the reliability constraint. The main contribution is dividing the problem into two sub-problem, Primary Topology Design Sub-problem (PTDS) and Reliability Assurance Sub-problem (RAS). In PTDS a primary network of routers is devised to cover all network nodes using linear programming and RAS makes the primary topology reliable by adding more routers through a repetitive procedure. The main idea of RAS is balancing degrees of nodes in the network graph. Results show that the provided approach devises a fairly optimal network in an acceptable time.