What is class based weighted fair queuing?
CBWFQ is a scheduling mechanism used to provide a minimum bandwidth guarantee to traffic classes during times of network congestion at an interface. Each of the CBWFQ queues is assigned a weight, and the packets are served from the queues based upon the weight of the queue.
How does weighted fair Queueing work?
Weighted fair queueing (WFQ) is a method of automatically smoothing out the flow of data in packet-switched communication networks by sorting packets to minimize the average latency and prevent exaggerated discrepancies between the transmission efficiency afforded to narrowband versus broadband signals.
Which problem does a fair Queueing scheduling address?
2 Fair Queuing. The main problem with FIFO queuing is that it does not discriminate between different traffic sources, or, in the language introduced in the previous section, it does not separate packets according to the flow to which they belong.
What is the default dropping scheme for Cbwfq?
CBWFQ supports multiple class maps to classify traffic, with tail drop being the default dropping scheme. Weighted random early detection (WRED) can be used with CBWFQ to prevent class congestion.
What is Llq in networking?
Low-latency queuing (LLQ) is a feature developed by Cisco to bring strict priority queuing (PQ) to class-based weighted fair queuing (CBWFQ). LLQ allows delay-sensitive data (such as voice) to be given preferential treatment over other traffic by letting the data to be dequeued and sent first.
How is weighted fair Queueing similar to Round Robin How is it different?
At first glance, it may seem that WRR is very similar to WFQ. The difference between the two is that WFQ services bits at each scheduling turn, whereas WRR handles packets in each scheduling turn. The number of packets to be serviced in each scheduling turn is decided by the weight of the queue.
Which algorithm is based on queuing?
DropTail is one of the simplest algorithms mostly used in the internet routers. It is based on first in first out (FIFO) queue [17] policy. The entire incoming packets are stored in a buffer or queue of limited size. And router serves the packets stored in queue in the same order as they were placed.
Why was fair queuing algorithm proposed?
The algorithm is designed to achieve fairness when a limited resource is shared, for example to prevent flows with large packets or processes that generate small jobs from consuming more throughput or CPU time than other flows or processes. Fair queuing is implemented in some advanced network switches and routers.
How does flow based WFQ WFQ differ from class-based WFQ Cbwfq )?
The difference between WFQ and CBWFQ is that CBWFQ differentiates traffic by class (e.g., voice, data, or video) while WFQ differentiates traffic by flow (e.g., source and destination). WFQ offers fair queuing that divides the available bandwidth across active flows based on weights.
What is Cbwfq in QOS?
Class-based weighted fair queueing (CBWFQ) extends the standard WFQ functionality to provide support for user-defined traffic classes. For CBWFQ, you define traffic classes based on match criteria including protocols, access control lists (ACLs), and input interfaces.
How do I configure WFQ?
Configuration procedure
- Enter system view. system-view.
- Enter interface view. interface interface-type interface-number.
- Enable byte-count or packet-count WFQ queuing. qos wfq { byte-count | weight }
- Assign a queue to a WFQ group, and configure scheduling parameters for the queue.
- (Optional.)
What is class based weighted fair queuing (WFQ)?
Class Based Weighted Fair queuing is an advanced form of WFQ that supports user defined traffic classes i.e. one can define traffic classes based on match criteria like protocols, access control lists (ACLs), and input interfaces. A flow satisfying the match criteria for a class contributes the traffic for that particular defined class.
What protocols are supported for weighted fair queueing?
The following protocols are supported: No default behavior. This command was first introduced. For class-based weighted fair queueing (CBWFQ), you define traffic classes based on match criteria including protocols, ACLs, input interfaces, QoS labels, and EXP field values.
What is CBWFQ traffic class?
For class-based weighted fair queueing (CBWFQ), you define traffic classes based on match criteria including protocols, ACLs, input interfaces, QoS labels, and EXP field values. Packets satisfying the match criteria for a class constitute the traffic for that class.
How does CBWFQ fair queueing work?
For CBWFQ, which extends the standard WFQ fair queueing, the weight specified for the class becomes the weight of each packet that meets the match criteria of the class. Packets that arrive at the output interface are classified according to the match criteria filters you define, then each one is assigned the appropriate weight.