Smart meters, sensors and other measuring devices in smart grid networks are expected to generate huge amounts of data continuously. Data generated from these devices must be delivered reliably to utility control centers within specified time for wide-area monitoring and control. Overall grid status would be determined by using this data in a timely manner. Hence reliable and efficient data aggregation is an important process in smart grid communication network. Several network designs have been proposed for data aggregation using various communication technologies. WiMAX and WLAN are the two promising technologies of wireless networks. The combined operation of WiMAX and WLAN can extend transmission range and significantly improve the efficiency of a hybrid network by improving link quality. Hybrid network allows flexible data aggregation to reduce signaling and protocol overheads. We implemented multilevel WLAN WiMAX communication environment for data aggregation in smart grid to support multiple traffic sources/ applications using Network Simulator3 and analyzed the performance of the network in terms of quality of service parameters specified for smart grid applications. Results indicate that proposed network architecture can satisfy the delay requirements of multiple smart grid traffic sources/ applications.