ccna security exam 9

ccna security exam 9.. It reduces the size of routing tables, thereby reducing the amount of memory and processing time required .. It reduces the size of routing updates, thereby reducing the bandwidth required .. It limits the reach of network problems such as routing rollovers.As seen in Figure 7.6, the size of routing updates is reduced from four routes to one, which reduces the processing that needs to be done by the routers receiving these messages. As a result, fewer bandwidths are required to advertise updates, and less memory and processing time is required by the receiving router to process the updates.Another advantage of routing aggregation is that it helps to limit the reach of certain network problems. For example, if devices on the announcement subnet 192.168.1.64/26 are sometimes available and sometimes unavailable, this will lead to a situation known as flipped routes. This obviously affects connected routers as well as other routers that are aware of the subnet: whenever the route switches between available and unavailable, the other routers must modify their routing tables accordingly. However, routers that know only the aggregated route are not affected by the subnet flip; they are affected only if all four subnets fail, causing the router performing the aggregation to no longer advertise the aggregated route.This is obviously an advantage, but route aggregation has a disadvantage. Route aggregation hides the complete construction of the network, which can lead routers to make incorrect assumptions. For example, when subnet 192.168.1.64/26 out fails, routers elsewhere in the network will still receive updates about the aggregated route (192.168.1.0/24). It appears to these routers that addresses 192.168.1.0 ~192.168.1.255 are reachable because the router performing the route summarization is still advertising the summarized route (which is obviously not the case). Therefore, the other routers still send traffic to 192.168.1.64/26, because they think that subnet is reachable.Be sure to know the definition of route summarization: the grouping of a series of connected network numbers in a routing table into fewer routingThe benefits of route summarization include The benefits of routing aggregation include: smaller routing tables and routing updates; limiting the impact of network problems7.2.2 Classless7.2.2 Classless Inter-Domain Routing