ccna pdf github

ccna pdf github.2.4 Class-Based Weighted Fair Queuing (CBWFQ) Class-Based Weighted Fair Queuing (CBWFQ) extends the functionality of standard WFQ to support user-defined traffic classes, which can be defined based on protocols, access control lists, input interfaces, etc. A FIFO queue is reserved for each class, and traffic belonging to a class is directed to that class's queue. Administrators can assign bandwidth, weights, and maximum packet limits to each class, and the bandwidth assigned to a class is the guaranteed bandwidth for transmitting data from that class during congestion. Adding more packets to that class queue after the queue has reached its configured queue limit will result in tail drops or otherwise dropped packets (depending on how the class policy is configured). The differences between CBWFQ and WFQ are as follows.1 The user has no control over the categorization in WFQ, it is determined by the HASH algorithm itself, which is fine for normal traffic processing, but not forVoice traffic appears "too fair" (because voice traffic requires low latency).2 User-defined traffic classes in CBWFQ, while taking into account the fairness feature, do not take into account the application of voice.2.5 Low Latency Queueing (LLQ) Low Latency Queueing (LLQ) brings strict priority queuing to CBWFQ. Strict priority queuing allows delay-sensitive data such as voice to be sent before packets in other queues, thereby reducing delay and jitter in voice traffic. LLQ has all the benefits of CBWFQ, including custom traffic classes, bandwidth guarantees for each class of traffic, and the ability to apply the appropriate drop method to all classes of queues. For both LLQ and CBWFQ, any traffic that is not explicitlyTraffic that shows the classification is considered class-default traffic. you can change the queue for the class-default traffic class from FIFO to WFQo.420.Cisco Networking Lab CCNA Lab Guide (Release 2)2L3 QoS Implementation Techniques21.3.1 Classification and MarkingBefore a QoS policy can be applied to a packet, it must be classified. Classification and marking is the process of classifying packets into different categories based on certain characteristics in the IP packet (or frame) and marking (also called coloring) the packet for further processing by other devices. Classification and marking are usually done at the same time, with classification being for marking and marking being the result of classification. The way packets are classified depends on the QoS policy. Methods for classifying traffic at layers 2 and 3 include the use of interfaces and ACLs, etc. Traffic at layers 4 to 7 can be classified using Network Based ApplicationRecognition (NBAR). Tagging indicates that a value is added to the packet header and the device receiving the packet looks at this field to determine if it matches the defined policy. Tagging should be done as close to the source device as possible, which establishes trust boundaries. The way traffic is tagged is usually technology dependent, and Table 21.1 describes the tagging fields for various technologies.