What is class-based weighted fair queuing?

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.

How does WFQ implement tail dropping?

WFQ uses a slightly modified tail-drop policy for choosing when to drop packets. The decision is based on several factors, one being the SN of the packet. WFQ places an absolute limit on the number of packets enqueued among all queues; this value is called the hold-queue limit.

What does the FIFO queuing stands for?

first-in, first-out
A FIFO queue is a queue that operates on a first-in, first-out (FIFO) principle. This means that the request (like a customer in a store or a print job sent to a printer) is processed in the order in which it arrives.

Which algorithm is based on queuing?

The Stochastic Fairness Queuing (SFQ) algorithm is a simpler and less accurate implementation of the FQ algorithms and requires less calculations. SFQ ensures that each flow has the opportunity to transmit an equal amount of data and takes into account data packet sizes [338]. Class-Based Queuing (CBQ).

What is IP precedence in QoS?

The IP precedence is a 3-bit field in TOS that threats high priority packets as more important than other packets. In contrast, DSCP is 6 bits of the Differentiated Services Field (DS Field) in the IP header for packet classification purposes.

How do I configure WFQ?

Configuration procedure

1. Enter system view. system-view.
2. Enter interface view. interface interface-type interface-number.
3. Enable byte-count or packet-count WFQ queuing. qos wfq { byte-count | weight }
4. Assign a queue to a WFQ group, and configure scheduling parameters for the queue.
5. (Optional.)

What are the different types of queuing discipline?

Examples of the common queuing disciplines are first-in- first-out (FIFO) queuing, priority queuing (PQ), and weighted-fair queuing (WFQ). The idea of FIFO queuing is that the first packet that arrives at a router is the first packet to be transmitted.

What is weighted fair queueing?

Weighted fair queueing (WFQ) creates a queue for every class for which a class map is defined. Packets satisfying the match criteria for a class accumulate in the queue reserved for the class until they are sent, which occurs when the queue is serviced by the fair queueing process.

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 WFQ (fair queueing) in Cisco IOS?

WFQ allocates an equal share of the bandwidth to each flow. Flow-based WFQ is also called fair queueing because all flows are equally weighted. The Cisco IOS software provides two forms of flow-based WFQ:

How does CBWFQ use weights assigned to the queued packets?

After the weight for a packet is assigned, the packet is enqueued in the appropriate class queue. CBWFQ uses the weights assigned to the queued packets to ensure that the class queue is serviced fairly. Configuring a class policy—thus, configuring CBWFQ—entails these three processes: