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Terminology of Public versus Private pool definitions compared with internet routable versus non-internet-routable IP pool addresses


The terms Public versus Private IP pools, while simple to understand, may be confusing if one attempts to apply those terms to the internet routability of the addresses in such pools being defined as such (public versus private, etc.).

A Public IP pool is a pool that can dole out IP addresses to any subscriber (whether or not the IP pool or group that the pool is in has been specified in the configuration or from AAA)

A Private IP pool may only be used by subscribers which have been assigned a specified pool or group that that pool is in (if it is in a group).

These definitions have no relation to whether or not the address range of the pool being defined is internet routable or not. For example, a private or public pool could be defined to house either routable or non-routable internet addresses. The range of addresses defined (and therefore whether those addresses are internet routable or not) has nothing to do with the terms public or private with respect to the pool definition. Confusion may arise over use of the terms public and private pools as one might mistakenly infer address type as routable or not routable from those terms. But there is absolutely no correlation between the terms public/private and routability.

Note: For the purposes of the above discussion, from RFC 1918, the Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private internets (non internet routability).  The words "private" and "public" are used throughout the spec and are widely adopted for discussing this topic, hence the purpose of this short techtip to avoid any confusion that may arise.

     10.0.0.0        -   10.255.255.255  (10/8 prefix)

     172.16.0.0      -   172.31.255.255  (172.16/12 prefix)

     192.168.0.0     -   192.168.255.255 (192.168/16 prefix)

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‎01-09-2013 09:18 AM
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