Zero Latency Queuing System Based on Deficit Round Robin
Byoung-Chul Kim, In Suk Chun · 2007
As the Internet grows in size and bandwidth, a variety of real time applications such as voice over IP (VoIP) and video conferences require low latency, bandwidth guarantee and delay bounded service constraints. Because current Internet provides only offer best effort services, packet scheduling algorithms supporting quality of service (QoS) requirements play an important part in switches and routers. This paper discusses a new packet scheduling discipline called zero latency queuing scheduler (ZLQS), which has one special zero latency queue (ZLQ) for real time traffic flows. When a packet comes to the ZLQ, it is serviced at a time from en-queue to de-queue without queuing latencies. The ZLQS offers zero latency queuing for real time traffic flows, and in addition it supports not only committed rate (CR)1 but also peak rate (PR)2 or burst rate (BR) for the bandwidth reservation. The ZLQS is a frame-based scheduler like deficit round robin (DRR), and therefore has the good properties of simple implementation at high speeds routers or switches, per packet work complexity of O(l) and almost perfect fairness.