RFC 1924 (rfc1924) - Page 2 of 6
A Compact Representation of IPv6 Addresses
Alternative Format: Original Text Document
RFC 1924 A Compact Representation of IPv6 Addresses 1 April 1996 groups of 4 hex digits are likely to be longer than a single non-zero digit (just as MAC addresses typically have digits spread throughout their length). This document specifies a new encoding, which can always represent any IPv6 address in 20 octets. While longer than the shortest possible representation of an IPv6 address, this is barely longer than half the longest representation, and will typically be shorter than the representation of most IPv6 addresses. 3. Current formats [AddrSpec] specifies that the preferred text representation of IPv6 addresses is in one of three conventional forms. The preferred form is x:x:x:x:x:x:x:x, where the 'x's are the hexadecimal values of the eight 16-bit pieces of the address. Examples: FEDC:BA98:7654:3210:FEDC:BA98:7654:3210 (39 characters) 1080:0:0:0:8:800:200C:417A (25 characters) The second, or zero suppressed, form allows "::" to indicate multiple groups of suppressed zeroes, hence: 1080:0:0:0:8:800:200C:417A may be represented as 1080::8:800:200C:417A a saving of just 5 characters from this typical address form, and still leaving 21 characters. In other cases the saving is more dramatic, in the extreme case, the address: 0:0:0:0:0:0:0:0 that is, the unspecified address, can be written as :: This is just 2 characters, which is a considerable saving. However such cases will rarely be encountered. Elz Informational
