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A supernetwork, or supernet, is an Internet Protocol (IP) network that is formed from the combination of two or more networks (or subnets) with a common Classless Inter-Domain Routing (CIDR) prefix. The new routing prefix for the combined network aggregates the prefixes of the constituent networks. It must not contain other prefixes of networks that do not lie in the same routing path. The process of forming a supernet is often called supernetting, prefix aggregation, route aggregation, or route summarization. Supernetting within the Internet serves as a preventive strategy to avoid topological fragmentation of the IP address space by using a hierarchical allocation system that delegates control of segments of address space to regional network service providers.〔RFC 1338, ''Supernetting: an Address Assignment and Aggregation Strategy'', V. Fuller, T. Li, J. Yu, K. Varadhan (June 1992)〕 This method facilitates regional route aggregation. The benefits of supernetting are conservation of address space and efficiencies gained in routers in terms of memory storage of route information and processing overhead when matching routes. Supernetting, however, has risks.〔 ==Overview== In Internet networking terminology, a supernet is a block of contiguous subnetworks addressed as a single subnet in the larger network. Supernets always have a subnet mask that is smaller than the masks of the component networks. The size of routing tables has been rapidly increasing during the expansion of the Internet. Supernetting is the process of aggregating routes to multiple smaller networks, thus saving storage space in the routing table and simplifying routing decisions. Routing advertisements to neighboring gateways are reduced. Supernetting in large, complex networks can isolate topology changes from other routers. This can aid in improving the stability of the network by limiting the propagation of routing traffic after a network link fails. For example, if a router only advertises a summary route to the next router, then it does not advertise any changes to specific subnets within the summarized range. This can significantly reduce any unnecessary routing updates following a topology change. Hence, it increases the speed of convergence and allows for a more stable environment. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Supernetwork」の詳細全文を読む スポンサード リンク
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