Compression of IPv6 address

IPv6 address is short form of IP address version 6. It is basically a 128 bit address. In IPv6 adress, hexadecimal notation is preferred. There are total 8 fields in IPv6 hexadecimal notation and each field consists of 16 bits.
Hence, total bits are 8 x 16 = 128

Rules for compression:
There are basically three rules for compression:

  • Rule-1: When only 0 (zero) is available in a field then it is removed from the IPv6 address notation.
    IPv6 = FE82:1234:0:1235:1416:1A12:1B12:1C1F
    After compression,
    IPv6 = FE82:1234::1235:1416:1A12:1B12:1C1F 
  • Rule-2: When continuous 0s (zeros) are available in IPv6 address notaion then all zeros are replaced by ::.
    IPv6 = FE82:0:0:0:0:1A12:1234:1A12
    After compression,
    IPv6 = FE82::1A12:1234:1A12 
  • Rule-3: When zeros are present in discontinuous places then at only one junction, 0s (zeros) are replaced by ::.
    IPv6 = 2001:1234:0:0:1A12:0:0:1A13
    After compression,
    IPv6 = 2001:1234::1A12:0:0:1A13
         = 2001:1234:0:0:1A12::1A13 

Unspecified Address: When in hexadecimal notation of IPv6 all fields are 0. It is denoted by ::.

:: = 0:0:0:0:0:0:0:0

Loop Back Address: When in hexadecimal notation of IPv6 all fields are 0 except the last field and last field value is 1. It is denoted by ::1.

::1 = 0:0:0:0:0:0:0:1

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