ccna pdf material

ccna pdf material.1. TrafficPolicingTraffic policing is a traffic management technique applied on the incoming or outgoing interface to restrict a certain amount of traffic entering the router. The typical application of traffic policing is to monitor the specifications of a traffic entering the network and limit it to a reasonable range, or to "penalize" the excess traffic, such as dropping packets, in order to protect the network resources and the interests of the operator. ServiceLevelAgreement (SLA) is signed between operators and subscribers, which contains CommittedInformationRate (CIR), PeakInformationRate (PIR), Committed Burst Size (CBS), and PeakInformationRate (PIR) for each service flow. The traffic parameters such as Committed Burst Size (CBS)^ Peak Burst Size (PBS) are used for traffic supervision. The traffic regulation uses CommittedAccessRate (CAR) to control the traffic, and based on the evaluation result, the predefined regulation actions are implemented, and the traffic regulation actions are described below.Pass: Packets whose measurement does not exceed the committed rate (CIR) are normally forwarded normally.Discard: Packets whose measurements exceed the peak rate (PIR) are normally discarded.Remark: Remark action is normally performed for traffic between CIR and PIR, when the packetInstead of dropping, best-effort forwarding is performed by Remark lowering the priority.To achieve traffic control, there must be a mechanism that allows for the metering of traffic passing through the device. The TokenBucket is one of the most commonly used traffic measurement methods to evaluate whether the traffic rate exceeds a specified value. A token bucket can be thought of as a container for tokens, with a predetermined capacity. The system places tokens into the bucket at a set rate, and when the bucket is full, the excess tokens are overflowed. The token is added to the token bucket periodically, the period is T, the number of tokens added in each cycle is and, the rate of addition is called CIR(CommittedInformationRate) = BC/TO The token bucket is divided into the following three ways of traffic regulation of packets.(1) Single bucket single rate two-color traffic regulationA token bucket, the capacity of which is CBS, is filled with tokens at the rate of CIRo When an 8-byte packet is passed, the packet is processed according to the current capacity of the bucket. When the packet is to be forwarded out, the corresponding number of tokens needs to be removed from the token bucket.424.Cisco Networking Lab CCNA Lab Guide (Release 2)