It must be assured that the missing networks do not exist outside of this route. It is followed by a slash and then the number of common bits. The summary route is found by setting the remaining bits to zero, as shown below.

Lastly, the number of common bits is counted. Secondly, the bits at which the common pattern of digits ends are located.

A router has the following networks in its routing table:įirstly, the addresses are converted to binary format and aligned in a list: The summary route is calculated as follows. The determination of the summary route on a router involves the recognition of the number of highest-order bits that match all addresses. Each router now only recognizes its own subnet and the other 49 summarized routes. Each route is summarized before being advertised to other districts. However, if a hierarchical addressing system is implemented with supernetting, then each district has a centralized site as an interconnection point. Without supernetting, the routing table on any given router might have to account for 150 routers in each of the 50 districts, or 7500 different networks. Other routing protocols with CIDR support include RIPv2, Open Shortest Path First, EIGRP, IS-IS and Border Gateway Protocol.Ī company that operates 150 accounting services in each of 50 districts has a router in each office connected with a Frame Relay link to its corporate headquarters. By default, EIGRP summarizes the routes within the routing table and forwards these summarized routes to its peers. Interior Gateway Routing Protocol, Exterior Gateway Protocol and version 1 of the Routing Information Protocol (RIPv1) assume classful addressing, and therefore cannot transmit the subnet mask information required for supernetting.Įnhanced Interior Gateway Routing Protocol (EIGRP) supports CIDR. Supernetting requires the use of routing protocols that support Classless Inter-Domain Routing (CIDR). Hence, it increases the speed of convergence resulting in a more stable environment. This can significantly reduce any unnecessary routing updates following a topology change. If a router only advertises a summary route to the next router, then it does not need to advertise any changes to specific subnets within the summarized range. This can improve the stability of the network by limiting the propagation of routing changes in the event of a network link failure. Supernetting in large, complex networks can isolate topology changes from other routers. Supernetting has helped address the increasing size of routing tables as the Internet has expanded. Supernetting is the process of aggregating routes to multiple smaller networks, thus saving storage space in the routing table, simplifying routing decisions and reducing route advertisements to neighboring gateways. Supernets are always larger than their component networks. In IP networking terminology, a supernet is a block of contiguous subnetworks addressed as a single subnet from the perspective of the larger network. Supernetting, however, can introduce interoperability issues and other risks. The benefits of supernetting are efficiencies gained in routers in terms of memory storage of route information and processing overhead when matching routes. This method facilitates regional route aggregation. Supernetting within the Internet serves as a strategy to avoid fragmentation of the IP address space by using a hierarchical allocation system that delegates control of segments of address space to regional Internet registries. The process of forming a supernet is called supernetting, prefix aggregation, route aggregation, or route summarization. The new routing prefix for the aggregate network represents the constituent networks in a single routing table entry. An example of route aggregation as a part of CIDRĪ supernetwork, or supernet, is an Internet Protocol (IP) network that is formed by aggregation of multiple networks (or subnets) into a larger network. For the broadband network in the province of Alberta, see Alberta SuperNet.

Ip route summary calculator