Control transmission pace at IP layer to avoid packet drop

Abstract

Avoiding packet loss is critical for time sensitive network applications, such as multimedia streams for video/voice. Delaying and dropping low priority packets to ensure high priority and time sensitive data stream deliver during network congestion is a basic QoS (quality of service) mechanism over current network infrastructure. This mechanism works if time sensitive data stream is the minority of the network traffic and if the network is not very congested. The methodology of dropping low priority data does not scale when time sensitive data stream uses high percentage of network bandwidth. This is because bandwidth required by video/audio applications can vary in very wide range when real-time data becomes majority network traffic, that is, television (TV), telephone, visual telephone, videoconferencing, gaming, and other video/audio based applications are all deployed on Internet. Then, what is the proper percentage of bandwidth to reserve? and which packets should be dropped if available bandwidth is less than demanding? A major issue is that letting bottleneck routers drop packets is not a proper methodology to guarantee quality of service. If packets cannot be delivered due to exhausted network bandwidth, these packets should be tossed as earlier as possible to reduce bandwidth waste or should be delayed at transmission hosts for later transmission. Also, applications should have right to selectively toss data for enhancing service quality, rather than let routers randomly drop packets. Therefore, mechanisms to avoid packet drop need to be deployed in Internet infrastructure. This paper studies how well priority (class) based traffic shaping can help time sensitive data delivery, addresses technology of packet drop avoidance (PDA), and shows how packet drop avoidance mechanism improves real-time applications' performance by reducing bandwidth waste, packet delay and loss. This paper then addresses why PDA should be deployed in Internet protocol (IP) layer.