Summarization, also called route aggregation, allows routing protocols to advertise many networks as one address. The purpose of this is to reduce the size of routing tables on routers to save memory, which also shortens the amount of time for IP to parse the routing table and find the path to a remote network.
Figure 5-12 shows how a summary address would be used in an internetwork.
Summarization is actually somewhat simple because all you really need to have down are the block sizes that we just used to learn subnetting and VLSM design. For example, if you wanted to summarize ...