Place the bits for six prefix lengths
02A prefix is the leading fixed part of an address. Its bit length determines where the four IPv4 octets go, including the reserved u octet.
IPv4 occupies 96–127. The prefix itself includes bits 64–71, which MUST still be zero. Only this layout permits the dotted-decimal tail for the embedded IPv4 address.
Source for this drawing: RFC 6052 · Read RFC section 2.2 ↗
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Use one of six permitted prefix lengths.
- Use one of six permitted prefix lengths.
- Lengths are /32, /40, /48, /56, /64 or /96. IPv4 bits are most-significant first. Bits 64–71 MUST be zero, including inside a /96 Network-Specific Prefix.
- For lengths below /96, u separates any IPv4 parts at bits 64–71. Remaining suffix bits SHOULD be zero; /96 has no suffix. The Well-Known Prefix is always /96.
The bit strip is proportional: one cell is one octet (eight bits), numbered from zero. Prefix, IPv4 octets, u and suffix have literal labels as well as colors. All six address results reproduce Table 1 documentation examples. /96 dotted-decimal notation is permitted; shorter formats must not pretend the IPv4 bits are always the last 32 bits.
Read the RFC section ↗