Computer Networks · M2 · read

Expand :: by counting visible groups

IPv6: addresses and packet format

Unit 4 · IPv6

Definition. IPv6 expansion restores exactly eight groups, each written with four hexadecimal digits.

Simple meaning. Visible groups count karo; 8 mein se minus; utne zero groups :: ki jagah.

Understand it step by step

  1. Count groups on the left of :: and on its right. The double colon itself is not an additional visible group.
  2. Missing zero groups = 8−visible groups. Insert them at the location of ::.
  3. Pad every group on the left with zeroes until it has four digits. Do not pad on the right.
  4. Count the final result: exactly eight groups must appear. A written group “0” already counts as one visible group.

Practice question. Explain how to expand an abbreviated IPv6 address containing ::. [3 practice marks]

Answer

Count all explicitly written groups. Insert 8 minus this count all-zero groups at ::, then left-pad every group to four hexadecimal digits. The result must contain exactly eight groups.

Yaad rakho: Already-written 0 ko bhi count karna.