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Zorluk: OrtaIPv6 Addressing and Prefixes

A network interface with a MAC address of 7069.5A11.22337069.5\text{A}11.2233 is configured on a subnet with the assigned IPv6 prefix 2001:db8:1000:abc::/642001:\text{db8}:1000:\text{abc}::/64. The interface automatically generates its IPv6 addresses using IEEE EUI-64 format. Which two statements regarding the resulting IPv6 configuration on this interface are correct?

  1. The calculated EUI-64 interface identifier for the host is 7269:5aff:fe11:2233.Cevap
  2. The complete global unicast address formed by the interface is 2001:db8:1000:abc:7269:5aff:fe11:2233.Cevap
  3. C
    The interface identifier is constructed as 7069:5aff:fe11:2233 because the first byte of the MAC address remains unmodified during EUI-64 generation.
  4. D
    The /64 prefix allows 264−22^{64} - 2 usable host addresses because IPv6 reserves the first address for network identification and the last address for broadcast.

Cevap

The two correct statements are that the calculated EUI-64 interface identifier is 7269:5aff:fe11:2233 and the complete global unicast address formed by the interface is 2001:db8:1000:abc:7269:5aff:fe11:2233.
The EUI-64 process inserts 0xFFFE between the OUI and vendor portion of the MAC address and flips the 7th bit of the first byte (from 0x70 to 0x72), resulting in the interface ID 7269:5aff:fe11:2233. Appending this to prefix 2001:db8:1000:abc::/64 generates the global unicast address 2001:db8:1000:abc:7269:5aff:fe11:2233.

Adım Adım Çözüm

1
Insert FFFE into the 48-bit MAC address
Splitting MAC 70:69:5A:11:22:33 into 70:69:5A and 11:22:33 and inserting FFFE produces 70:69:5A:FF:FE:11:22:33.
EUI-64 formatting expands 48-bit MAC addresses to 64 bits by inserting 16 bits (0xFFFE) in the middle.
2
Invert the Universal/Local (7th) bit of the first octet
First octet 0x70 in binary is 0111 0000. Inverting the 7th bit yields 0111 0010, which is 0x72 in hex. The interface ID becomes 7269:5aff:fe11:2233.
IEEE EUI-64 standards invert the 7th bit to reflect local scope management in IPv6 host addresses.
3
Combine prefix and EUI-64 interface ID
2001:db8:1000:abc::/64 + 7269:5aff:fe11:2233 = 2001:db8:1000:abc:7269:5aff:fe11:2233.
The subnet prefix forms the upper 64 bits and the EUI-64 ID forms the lower 64 bits of the global unicast address.

Anahtar Kavram

EUI-64 Interface Identifier Generation and IPv6 Addressing
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Konular

IPv6 Addressing and Prefixes

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