Friday, January 14, 2011

Global IP Addresses

Have you ever wondered who controls the allocation of IP space? Globally routable IP addresses are assigned and distributed by Regional Internet Registrars (RIRs) to ISPs. The ISP then allocates smaller IP blocks to their clients as required.

Virtually all Internet users obtain their IP addresses from an ISP The 4 billion available IP addresses are administered by the Internet Assigned Numbers Authority (IANA, IANA has divided this space into large subnets, usually /8 subnets with 16 million addresses each. These subnets are delegated to one of the five regional Internet registries (RIRs), which are given authority over large geographic areas.

The five RIRs are:

• African Network Information Centre (AfriNIC,
• Asia Pacific Network Information Centre (APNIC,
• American Registry for Internet Numbers (ARIN,
• Regional Latin-American and Caribbean IP Address Registry (LACNIC,
• Réseaux IP Européens (RIPE NCC,

Your ISP will assign globally routable IP address space to you from the pool allocated to it by your RIR. The registry system assures that IP addresses are not reused in any part of the network anywhere in the world. Once IP address assignments have been agreed upon, it is possible to pass packets between networks and participate in the global Internet. The process
of moving packets between networks is called routing.


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