LLQ was developed by Cisco to bring strict priority queuing (PQ) to class-based
weighted fair queuing (CBWFQ).
Traditionally, FIFO (First in First out) was used for scheduling and RED (Random early detection) was used for packet dropping and to control the overall traffic flow.WFQ (
Weighted Fair Queuing) scheduler was used to prioritize different flows to provide service guaranty.
Our proposed class-based
weighted fair queuing algorithm shows performance improvements in comparison with the other traditional approach.
LLQ scheduling is an enhancement of Class Based
Weighted Fair Queuing CBWFQ in which one or more strict priority queues are integrated to solve latency issues in multimedia applications that makes it ideal for jitter and delay sensitive applications.
Few of them are as following: Class Based Queue (CBQ), Faire Queue (FQ), Weight Faire Queue (WFQ), Generalized Processor Sharing (GPS), Worst-case Fair
Weighted Fair Queuing (WF2Q), Deficit Round Robin (DRR), Deficit Transmission Time (DTT), Low Latency and Efficient Packet Scheduling (LLEPS), Credit Based SCFQ (CBSCFQ), Controlled Access Phase Scheduling (CAPS), Queue size Prediction-Computation of Additional Transmission (QP-CAT), Temporally-Weight Fair Queue (TWFQ), Contention-Aware Temporally fair Scheduling (CATS), and Decentralized-CATS (DCATS).
Weighted Fair Queuing was first presented in Demers et al.
According to the company, the SMC8024L2 model comes in a 1u high chassis and is designed to handle high-bandwidth applications at speeds reaching up to 48Gb/s with a non-blocking single chip switching architecture providing Gigabit Ethernet switching.In addition, the SMC8024L2 features ACLs and 802.1x for secure network access, IP filtering, Quality of Service (QoS) with four levels of priority and
weighted fair queuing. The unit is equipped with four combo ports that accept optional SX, LX or ZX SFP transceivers to provide the option for fiber connectivity, the company claims.
Prioritization uses well-known mechanisms, such as
weighted fair queuing, priority queuing and custom queuing, to control the relative priorities of applications.
Minimal delay in voice signals is achieved by managing traffic using a combination of prioritization schemes:
Weighted Fair Queuing (WFQ), Bounded Delay, and Weighted Random Early Detection/Drop (WRED).
The ability to classify packets into a variety of queues based on implicit or implied priorities, coupled with algorithms such as
Weighted Fair Queuing (WFQ) and Random Early Discard (RED), is a necessity for maintaining real-time service.
It is also possible to generalize SRR to handle channels with different rated bandwidths by assigning larger quantum values to the higher-bandwidth lines--this corresponds to
weighted fair queuing.