Efficient QoS scheme for voice traffic in converged LAN

Abstract

Data service and voice communications are being converged into the same IP networks. For the success of such converged networks, three major QoS parameters of voice service-delay, jitter, and loss- must be first considered for good quality because the characteristic of voice traffic is different from that of data traffic. Jitter and loss are generated in networks but general schemes for solving jitter and loss problems do not exist in network level but in end user applications. Generally jitter problem is solved by adjusting playback time of received voice packets at the destination application. And loss(not burst loss) can be compensated at the destination application for sound lost in network. However delay is a different problem from jitter and loss because delay cannot be solved at application level. Hence delay is the problem which must be solved in network level. This thesis focuses on the delay problem and presents efficient mechanisms for supporting voice service in converged networks. In this thesis, a policy for guaranteeing or supporting voice service in converged LAN is introduced by using WFQ. How to set the weight of voice traffic is related to how many voice users are served with the minimum delay in routers. This policy offers the mapping between the weight of voice traffic and the number of voice users. With this policy, a converged LAN can guarantee or support voice service users by configuring the weight of voice traffic in WFQ. Hence, users in converged LAN are free from delay problem. This thesis next presents two mechanisms-active rerouting and selective dropping mechanisms- to cope with temporary overload condition. In this overload condition, voice traffic can temporarily exceed its boundary determined by the policy. This problem can be solved by adopting active rerouting and selective dropping. Active rerouting can be implemented with active network technology. Active routers can reroute voice packets according to the network conditions...