| dc.description.abstract | The increasing availability of wireless technology, both at home and in the workplace, offers many advantages in terms of mobility and freedom of connectivity. However, switching from a wired to a wireless transmission medium also presents unique research challenges, especially in the field of Quality of Service (QoS). There are many difficulties associated with meeting user expectations in a wireless environment, due to the unreliable nature of wireless communications. This study focuses on QoS provision in an infrastructure-mode 802.1 1 wireless LAN (WLAN), simulated in the OPNET Modeler network simulation package. The topology consists of 802.1 1b access networks that send data to each other via a wired core network. The core is designed to include some of the unreliable characteristics of a wireless network. Multi-Protocol Label Switching (MPLS) is deployed in the network backbone as a means to
manage the allocation of available resources. We then study the effect MPLS has on the QoS of voice, video, and File Transfer Protocol (FTP) application traffic, as well as on the performance of the wireless access networks. Two experiments are performed, the first with limited core bandwidth, and the second to investigate the effect of a link failure on the level of QoS. For each experiment, the MPLS scenario is compared to two identical networks, one without any QoS present, and the other with Differentiated Services (DiffServ) scheduling.
The results from Experiment 1 show that MPLS traffic engineering is able to effectively
manage available resources to provide for all application types. The baseline scenario is
unable to guarantee acceptable QoS, while DiffServ favours real-time applications at the cost of FTP traffic. In Experiment 2, the use of backup MPLS Label Switched Paths (LSPs)
ensures that application QoS remains relatively unaffected despite the link failure, while notable QoS degradation occurs in the other scenarios. In addition, the use of MPLS in the network core achieves the highest WLAN throughput in both experiments. Our approach offers potential benefits for office or campus networks, both for ensuring
adequate QoS for application traffic, and to increase the reliability of the network backbone. Our research on MPLS traffic engineering should also be applicable in a wireless-only environment. | |
