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Zorluk: ZorIPv6 Addressing and Prefixes

A network administrator is configuring IPv6 auto-configuration using SLAAC and EUI-64 process on Cisco router interfaces. Match each 48-bit MAC address on the left to its corresponding EUI-64 derived IPv6 Link-Local address on the right.

  • 0012.3456.789Afe80::212:34ff:fe56:789a
  • 0212.3456.789Afe80::12:34ff:fe56:789a
  • 1012.3456.789Afe80::1212:34ff:fe56:789a
  • 1212.3456.789Afe80::1012:34ff:fe56:789a

Cevap

MAC 0012.3456.789A matches fe80::212:34ff:fe56:789a; MAC 0212.3456.789A matches fe80::12:34ff:fe56:789a; MAC 1012.3456.789A matches fe80::1212:34ff:fe56:789a; MAC 1212.3456.789A matches fe80::1012:34ff:fe56:789a.
Each MAC address is correctly converted to EUI-64 format by inserting FFFE into the middle of the 48-bit address and inverting the 7th bit (the Universal/Local bit) of the first byte. The resulting 64-bit interface ID is appended to the Link-Local prefix fe80::/64, with leading zeros in any 16-bit block omitted per standard IPv6 address formatting rules.

Adım Adım Çözüm

1
Split each MAC address into its OUI (first 24 bits) and NIC-specific extension (last 24 bits), and insert FFFE in hex between them.
For MAC 0012.3456.789A, the split sequence becomes 00-12-34-FF-FE-56-78-9A.
EUI-64 expansion requires inserting the 16-bit reserved value FFFE into the center of a 48-bit MAC address.
2
Invert the 7th bit (Universal/Local bit) of the first byte in binary representation.
Byte 0x00 (00000000200000000_2) becomes 0x02 (00000010200000010_2); 0x02 becomes 0x00; 0x10 (00010000200010000_2) becomes 0x12 (00010010200010010_2); 0x12 becomes 0x10.
IEEE EUI-64 specification requires flipping the 7th bit of the first octet to represent global/local scope.
3
Combine the inverted 64-bit interface ID with the fe80::/10 link-local prefix (defaulting to /64 subnet prefix fe80::/64) and apply standard RFC 4291 zero compression rules.
The 64-bit interface ID 0012:34ff:fe56:789a compresses leading zeros to 12:34ff:fe56:789a, resulting in fe80::12:34ff:fe56:789a.
Standard IPv6 address formatting suppresses leading zeros in each 16-bit hex field.

Anahtar Kavram

EUI-64 Interface Identifier Generation and SLAAC Link-Local Addressing
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Konular

IPv6 Addressing and Prefixes

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