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Zorluk: ZorIPv6 Addressing and Deployment

A network engineer is configuring a static host entry on a datacenter firewall for a server deployed on the IPv6 subnet 2001:db8:cafe:10::/642001:\text{db8}:\text{cafe}:10::/64. The server interface uses the MAC address 00:50:56:A1:B2:C300:50:56:\text{A1}:\text{B2}:\text{C3} and generates its host portion automatically via the IEEE EUI-64 mechanism. Which of the following represents the fully compliant RFC 5952 IPv6 global unicast address for this server?

  1. 2001:db8:cafe:10:250:56ff:fea1:b2c3Cevap
  2. B
    2001:db8:cafe:10:50:56ff:fea1:b2c3
  3. C
    2001:db8:cafe:10::250:56ff:fea1:b2c3
  4. D
    2001:db8:cafe:10:0250:56ff:ffff:a1b2:c3

Cevap

The correct IPv6 address is 2001:db8:cafe:10:250:56ff:fea1:b2c3.
To construct an EUI-64 IPv6 interface identifier from a MAC address (00:50:56:A1:B2:C3), insert FF:FE into the middle (00:50:56:FF:FE:A1:B2:C3) and invert the 7th bit of the first byte (0x00 becomes 0x02). Grouping into 16-bit hextets yields 0250:56ff:fea1:b2c3. Appending this to the subnet prefix 2001:db8:cafe:10::/64 gives 2001:0db8:cafe:0010:0250:56ff:fea1:b2c3. Applying RFC 5952 rules suppresses leading zeros in each hextet (0db8 -> db8, 0010 -> 10, 0250 -> 250), producing 2001:db8:cafe:10:250:56ff:fea1:b2c3.

Adım Adım Çözüm

1
Split the MAC address into two 24-bit halves and insert the hex value FF:FE in the middle.
The MAC address 00:50:56:A1:B2:C3 becomes 00:50:56:FF:FE:A1:B2:C3.
EUI-64 requires expanding a 48-bit MAC address into a 64-bit interface identifier by inserting 16 specific bits (FF:FE).
2
Invert the 7th bit (Universal/Local bit) of the first byte.
The first byte 0x00 (binary 00000000) becomes 0x02 (binary 00000010). The expanded address becomes 0250:56ff:fea1:b2c3.
IEEE EUI-64 specifies that the Universal/Local bit must be inverted (0 for universally administered MAC addresses changed to 1 for local scope representation).
3
Combine the network prefix 2001:db8:cafe:10::/64 with the calculated 64-bit interface ID.
Uncompressed full address: 2001:0db8:cafe:0010:0250:56ff:fea1:b2c3.
The first 64 bits represent the network prefix and subnet, and the last 64 bits represent the host interface identifier.
4
Apply RFC 5952 address compression rules.
2001:db8:cafe:10:250:56ff:fea1:b2c3.
Leading zeros in each hextet must be suppressed (0db8 -> db8, 0010 -> 10, 0250 -> 250). The double colon (::) is not used when no hextet consists entirely of zeros.

Anahtar Kavram

EUI-64 Interface Identifier Generation and RFC 5952 Address Compression
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IPv6 Addressing and Deployment

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