IPv6 addresses can be represented in many different ways. They can be in the fully expanded IPv6 address format, or compressed in various different shortened forms. Since the shortened notation of an address can be done in different ways, it is important to follow the recommended rules when shortening an address so that they are represented in a consistent way.
A shortened IPv6 address may look something like:
2002:7f00:1::2
Shortening an expanded IPv6 address to its compressed form is an easy process which can be done with simple online tools. By using the IPv6 address shortener tool on this page, you can quickly and easily convert a fully uncompressed address into a shortened compressed one. Simply enter an expanded or improperly shortened address and press the shorten button.
The compressed notation is typically used for convenience and less visual clutter but can introduce some inconsistencies if the compression rules are not applied correctly. Shortened addresses can be compared in a consistent way which can be useful for comparing or de-duplicating addresses.
When dealing with IP addresses, having to type out the full format address can be quite time consuming and error prone whereas being able to use a shortened format can be more convenient and less likely to introduce errors. For example, the recommendation to use lowercase letters instead of uppercase can help reduce errors as often times numbers such as 8 and letters like B could be mixed up as they look similar.
If the shortening rules are not followed correctly, this can lead to the same technically valid IPv6 address being displayed in many different formats which can be confusing and lead to errors.
Some examples of incorrectly shortened addresses are below. You will notice the different leading zeros, capitalisation of letters, and the location of the ::.
2001:0db8:0000:0000:0001:0000:0000:0001 can be represented as:
There are several rules that need to be applied when shortening an IPv6 address. It is important to follow these rules in a consistent way to avoid potential confusion.
A fully expanded IPv6 address is represented by eight groups of four hexadecimal digits. Each group is separated by a colon (:)
Consider the fully expanded address: 2001:0DB8:0000:0000:0000:FF00:0042:8329
Remove any leading zeros - All leading zeros within each group of 4 hexadecimal digits should be removed.
For example, 0DB8 becomes DB8, 0000 becomes 0, and 0042 becomes 42.
The address is now: 2001:DB8:0:0:0:FF00:42:8329
Replace consecutive groups of zeros with double colons (::) - This can only be applied once if there are multiple consecutive groups, and should be applied to the largest grouping or the leftmost if there are multiple groupings of the same size. This should not be applied if there is only a single group of zeros.
The address is now: 2001:DB8::FF00:42:8329
Use lowercase for any alpha characters - This is to make case-sensitive searching or filtering possible, as well as improve clarity since some letters like B can sometimes be mistaken for numbers like 8.
The address is now: 2001:db8::ff00:42:8329
Any valid IPv6 address can be shortened, this includes fully uncompressed addresses or improperly compressed addresses.
Some examples: 0000:0000:0000:0000:0000:0000:0000:0000, 0000:0000:0000:0000:0000:0000:0000:0001, 2002:7F0:01::0001
