supernetting

Supernetting, also called Classless Inter-Domain Routing (CIDR), is a way to aggregate multiple Internet addresses of the same class. The original Internet Protocol (IP) defines IP addresses in four major classes of address structure, Classes A through D. Each class allocates one portion of the 32-bit Internet address format to a network address and the remaining portion to the specific host machines within the network. Using supernetting, the network address 192.168.2.0/24 and an adjacent address 192.168.3.0/24 can be merged into 192.168.2.0/23. The "23" at the end of the address says that the first 23 bits are the network part of the address, leaving the remaining nine bits for specific host addresses. Supernetting is most often used to combine Class C network addresses and is the basis for most routing protocols currently used on the Internet.

Supernetting was created as a way to solve the problem of routing tables growing beyond the ability of current software and people to manage and to provide a solution to the exhaustion of Class B network address space. Supernetting allows one routing table entry to represent an aggregation of networks much like one area code represents an aggregation of telephone numbers in an area.

The Border Gateway Protocol (BGP), the prevailing exterior (interdomain) gateway protocol and the Open Shortest Path First (OSPF) router protocol both support supernetting, but the older exterior or interdomain protocols, the Exterior Gateway Protocol (EGP) and the Routing Information Protocol (RIP) do not support it.

Read more about supernetting: - Red.net provides "An Introduction to Supernetting." - The original supernetting specification is described in IETF RFC 1338. - The later supernetting specification (CIDR) is described in RFC 1519.

Do you have something to add to this definition? Let us know. Send your comments to techterms@whatis.com

Digg This!     StumbleUpon     Del.icio.us

RELATED CONTENT Virtual machines present dynamic environment issues for network pros Find out why virtual machines (VMs) can present dynamic environment issues for network pros and how to manage the challenges of VMs. Network architecture and capacity planning for server virtualization Learn about the network architecture and capacity planning issues that must be considered when you implement server virtualization. Limit network energy consumption with computer cooling technologies Learn how various computer cooling technologies can limit network energy consumption to save money and reduce your impact on the environment.

RELATED GLOSSARY TERMS Terms from Whatis.com − the technology online dictionary Broadband over Power Line  (SearchNetworking.com) Broadband over Power Line (BPL) is a technology that allows Internet data to be transmitted over utility power lines. bus network  (SearchNetworking.com)