Saturday, January 12, 2019

IPv6 address format

Unlike IPv4, which uses a decimal point format for every byte interval from 0 to 255, IPv6 uses eight groups of four hexadecimal digits separated by columns. For example, this is a valid IPv6 address:

2340: 0023: AABA: 0A01: 0055: 5054: 9ABC: ABB0

If you do not know how to convert hexadecimal numbers to binary values, here is a table to help you with the conversion:



IPv6 address abbreviation


The above IPv6 address looks scary, right? Well, there are two conventions that can help you shorten the code to write for an IP address:

1. A leading zero can be omitted

For example, the above address (2340: 0023: AABA: 001: 0055: 5054: 9ABC: ABB0) can be abbreviated to 2340: 23: AABA: A01: 55: 5054: 9ABC: ABB0 :.

2. Consecutive fields with zeros can be represented as two colons (: :).

For example, 2340: 0000: 0000: 0455: 0000: AAAB: 1121 may be written as 2340 :: 0455: 0000: AAAB: 1121

NOTE

You can shorten an address only for such an event. The reason is obvious - if you more than doubled the colon, you would not know how many nulls were left out in each part.


Here are some examples to help you understand the concept of IPv6 address truncation:


Long version: 1454: 0045: 0000: 0000: 4140: 0141: 0055: ABBB
Abstract: 1454: 45 :: 4140: 141: 55: ABBB

Long version: 0000: 0000: 0001: AAAA: BBBC: A222: BBBA: 0001
Abstract: :: 1: AAAA: BBBC: A222: BBBA: 1

1 comment:

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