Overview[1]#

Private-Use Networks is a network that uses private IP Address space, following the standards set by RFC 1918 for Internet Protocol Version 4 (IPv4), and RFC 4193 for Internet Protocol Version 6 (IPv6). These addresses are commonly used for home, office, and enterprise Local Area Networks (LANs).

Private-Use Networks address spaces were originally defined in an effort to delay IPv4 address exhaustion, but they are also a feature of IPv6 where exhaustion is not an issue.

The Internet Engineering Task Force (IETF) has directed the Internet Assigned Numbers Authority (IANA) to reserve the following IPv4 address ranges for private networks, as published in RFC 1918:[1]

RFC 1918 name	IP Address range	number of addresses	largest CIDR block (subnet mask)	host id size	mask bits	classful description
24-bit block	10.0.0.0 – 10.255.255.255	16,777,216	10.0.0.0/8 (255.0.0.0)	24 bits	8 bits	single class A network
20-bit block	172.16.0.0 – 172.31.255.255	1,048,576	172.16.0.0/12 (255.240.0.0)	20 bits	12 bits	16 contiguous class B networks
16-bit block	192.168.0.0 – 192.168.255.255	65,536	192.168.0.0/16 (255.255.0.0)	16 bits	16 bits	256 contiguous class C networks
N-A	100.64.0.1-100.127.255.255	100.64.0.0/10	100.64.0.0/10 (255.192.0.0)	14 bits	10 bits	Carrier-grade NAT

Carrier-grade Network Address Translation#

Carrier-grade NAT (CGN) is defined in RFC 6598 allocated 100.64.0.0/10 This address block should not be used either on Private-Use Networks or on the public Internet

it is intended only for use within the internal operations of carrier networks.

Private IPv6 addresses#

Private IPv6 addresses is described in RFC 4193

Private-Use Networks Summary Table#

More Information#

There might be more information for this subject on one of the following:

• Carrier-grade NAT
• Network Address Translation
• Network Security
• RFC 1918
• Unique Local IPv6 Unicast Addresses

---

• [#1] - Private_network - based on information obtained 2017-04-23-