ccna certification routing and switching

ccna certification routing and switching.1 Horizontal splitting (SplitHorizon): Horizontal splitting ensures that the router remembers the source of each routing message and does not retransmit it on the interface where it was received. This is the most basic measure to ensure that no routing loops are created.2Toxicity Reverse( Poison Reverse): routes learned from an interface are sent back to that interface but have been poisoned, i.e., the hop count is set to 16 hops, which eliminates the effect of useless routing information in the other party's routing table.3 DefiningaMaximumCount: The RIP metric is based on the number of hops ( Hop). the number of hops in the path is added by one for each router it passes through. In this way, the more hops, the longer the path, and the RIP algorithm gives preference to paths with fewer hops. The maximum number of hops supported by RIP is 15, and a network with a hop count of 16 is considered unreachable.4 TriggeredUpdate: When a routing table change occurs, the update information is sent to all adjacent routers immediately, instead of waiting for a 30-second update cycle. This ensures that changes to the network topology are propagated across the network as quickly as possible, reducing the likelihood of routing loops.5 HolddownTimer: After a route is unreachable, the route is in a suppressed state for a period of time, i.e., no more route updates are received about the same destination address for a certain period of time, unless a better path is available. Because a router learns that a route is invalid from one network segment and then immediately learns that this route is valid on another segment, this valid information is often incorrect; suppression timing avoids this problem, and when a link changes frequently, suppression timing reduces route flip-flopping and increases the stability of the network.6.2.2 RIPvl and RIPv2 ComparisonRIPvl is a classful routing protocol and RIPv2 is a classless routing protocol, and the differences between RIPvl and RIPv2 are shown in Table 6-3.Table 6-3 Differences between RIPvl and RIPv2RIPvl RIPv2Does not carry subnet information during routing updates Carries subnet information during routing updates