The level of Quality of Service (QoS) guarantees in vehicular ad hoc networks (VANETs) is much more tasking and challenging as result of rapid topology changing and high mobility of mobile hosts. Thus, making multi-hop communication and as well as contention for channel access more difficult. QoS in VANETs is measured in terms of throughput, connection duration and packet loss. In this paper, UDP and TCP protocols are used as traffic to satisfy bandwidth requirement while optimizing network throughput for providing QoS using clustering approach. The results obtained through NCTUns simulator are used for analysis of throughput for both UDP and TCP traffics. © 2014 Springer-Verlag Berlin Heidelberg.