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Difficulty: MediumIPv6 Addressing and Deployment

A network technician is performing an audit on core router configuration files and identifies an uncompressed Unique Local IPv6 Address (ULA) recorded in full hexadecimal format as `fd12:0000:0000:a1b2:0000:0000:0000:0099`. To ensure compliance with enterprise documentation guidelines, the technician must format this address according to standard RFC 5952 rules. What is the correctly compressed RFC 5952 representation of this IPv6 address?

Answer: fd12:0:0:a1b2::99

Answer

fd12:0:0:a1b2::99
Under RFC 5952 rules, leading zeros in every 16-bit hexadecimal field are suppressed, reducing `0000` to `0` and `0099` to `99`. When multiple zero runs exist, the double colon `::` must replace the single longest contiguous run of zero fields. In `fd12:0000:0000:a1b2:0000:0000:0000:0099`, the first zero run spans 2 fields (`0:0`) and the second zero run spans 3 fields (`0:0:0`). Compressing the longer 3-field sequence yields `fd12:0:0:a1b2::99`.

Step-by-Step Solution

1
Suppress leading zeros in each 16-bit hexadecimal field.
fd12:0:0:a1b2:0:0:0:99
RFC 5952 Section 4.1 mandates that leading zeros in a 16-bit field must be removed (e.g., '0000' becomes '0' and '0099' becomes '99').
2
Identify all contiguous sequences of all-zero 16-bit fields.
Sequence 1 has 2 zero fields ('0:0'); Sequence 2 has 3 zero fields ('0:0:0').
To apply double-colon ('::') compression properly, the lengths of all consecutive zero runs must be evaluated.
3
Apply double-colon ('::') compression strictly to the longest sequence of zero fields.
fd12:0:0:a1b2::99
RFC 5952 Section 4.2.2 requires that '::' must replace the single longest run of consecutive zero fields. Sequence 2 (3 fields) is longer than Sequence 1 (2 fields).

Key Concept

RFC 5952 IPv6 Address Text Representation and Zero Compression Rules
Estimated Time:1m 0s
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Topics

IPv6 Addressing and Deployment

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