IPv6 Addresses

The IPv6 logo adopted by The Internet Society.
The IPv6 logo adopted by The Internet Society.

Over the last few years, providers of Internet services have been actively working on rolling out support for the next generation of IP addressing, named IPv6. The IPv6 address space is many orders of magnitude larger than the older v4 space. IPv6 addresses use eight groups of hexadecimal numbers joined by colons to express a unique address. Because IPv6 addresses are so long, a shortened notation is allowed in which consecutive groups of zero values can be summarized with a double colon. For example, fd7e:e657:486d:9bcf:0000:0000:0000:0001 can be more simply written as fd7e:e657:486d:9bcf::1. The IPv4 addressing scheme allows a mind-blowing 340,282,366,920,938,463,463,374,607,431,768,211,456 possible unique addresses. IPv6 also implements new methods designed to make it easier v6 addresses and data packets to find their way around nearby devices and the Internet at large.

IPv6 uses a subnetting scheme that is similar to the v4 scheme on the surface. Certain subnet sizes have been designated as being the default for a given entity type (i.e., “residential”, “business”, “ISP”), but as with v4, subnet sizes can be tailored to a particular need as long as technical requirements are conformed to. A table of typical IPv6 subnet sizes:

IPv6 CIDR Subnet Number of IPs
/128 1
/127 2
/126 4
/125 8
/124 16
/123 32
/122 64
/121 128
/120 256
/119 512
/118 1,024
/117 2,048
/116 4,096
/115 8,192
/114 16,384
/113 32,768
/112 65,536
/111 131,072
/110 262,144
/109 524,288
/108 1,048,576
/107 2,097,152
/106 4,194,304
/105 8,388,608
/104 16,777,216
/103 33,554,432
/102 67,108,864
/101 134,217,728
/100 268,435,456
/99 536,870,912
/98 1,073,741,824
/97 2,147,483,648
/96 4,294,967,296
/95 8,589,934,592
/94 17,179,869,184
/93 34,359,738,368
/92 68,719,476,736
/91 137,438,953,472
/90 274,877,906,944
/89 549,755,813,888
/88 1,099,511,627,776
/87 2,199,023,255,552
/86 4,398,046,511,104
/85 8,796,093,022,208
/84 17,592,186,044,416
/83 35,184,372,088,832
/82 70,368,744,177,664
/81 140,737,488,355,328
/80 281,474,976,710,656
/79 562,949,953,421,312
/78 1,125,899,906,842,624
/77 2,251,799,813,685,248
/76 4,503,599,627,370,496
/75 9,007,199,254,740,992
/74 18,014,398,509,481,985
/73 36,028,797,018,963,968
/72 72,057,594,037,927,936
/71 144,115,188,075,855,872
/70 288,230,376,151,711,744
/69 576,460,752,303,423,488
/68 1,152,921,504,606,846,976
/67 2,305,843,009,213,693,952
/66 4,611,686,018,427,387,904
/65 9,223,372,036,854,775,808
Residential – /64 18,446,744,073,709,551,616
/63 36,893,488,147,419,103,232
/62 73,786,976,294,838,206,464
/61 147,573,952,589,676,412,928
/60 295,147,905,179,352,825,856
/59 590,295,810,358,705,651,712
/58 1,180,591,620,717,411,303,424
/57 2,361,183,241,434,822,606,848
/56 4,722,366,482,869,645,213,696
/55 9,444,732,965,739,290,427,392
/54 18,889,465,931,478,580,854,784
/53 37,778,931,862,957,161,709,568
/52 75,557,863,725,914,323,419,136
/51 151,115,727,451,828,646,838,272
/50 302,231,454,903,657,293,676,544
/49 604,462,909,807,314,587,353,088
Business – /48 1,208,925,819,614,629,174,706,176

If you are wondering why a “residence” would need 18,446,744,073,709,551,616 IP addresses, you are not alone… but in any event you can see that the v6 addressing scheme is well-suited for the IP address needs of the world (and perhaps beyond) well into the future.

Adoption of v6 has been slow, but with the rapid depletion of v4 addresses mentioned earlier, v6 will become increasingly important in the near future. Make IPv6 a part of your colocation strategy now to avoid headaches later.

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