LGRR: A new packet scheduling algorithm for differentiated services packet-switched networks

Since Quality of Service (QoS) support is a mandatory requirement in the next-generation networking, each router in a packet-switched network must provide a better service to higher-priority packets under any situation such as congestion. We propose in this paper the loan-grant based Round Robin (LGRR) packet scheduler for use in each output port of a router in a DiffServ network. LGRR is a frame-based scheduler to pass traffic streams according to their class types and to their immediate upstream source routers. It uses a loan-grant scheme so that a higher priority traffic stream can be processed quickly by requesting a bandwidth loan from the scheduler. To control the amount of transmitted bits from each stream and to prevent malicious abuse, the bandwidth loan must be paid back from the quantum values acquired in future. LGRR gives a fair opportunity to different traffic streams to access to the network bandwidth. It performs better than MDRR+, MDRR++, and OCGRR in handling traffic under both normal and bursty traffic, but it also gives a better loss and delay performance to the higher-priority traffic when traffic load is very high.