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Difficulty: MediumIPv6 Addressing and Deployment

A network engineer is configuring an interface using Stateless Address Autoconfiguration (SLAAC) with modified EUI-64 to derive the host portion of the IPv6 address. The network card has a MAC address of 00:1A:2B:3C:4D:5E, and the designated link-local prefix is fe80::/64. Which of the following represents the correctly formatted IPv6 link-local address for this host?

  1. fe80::21a:2bff:fe3c:4d5eAnswer
  2. B
    fe80::1a:2bff:fe3c:4d5e
  3. C
    fe80::21a::2bff:fe3c:4d5e
  4. D
    fe80::21a:2bff:ff3c:4d5e

Answer

fe80::21a:2bff:fe3c:4d5e
The address fe80::21a:2bff:fe3c:4d5e correctly follows EUI-64 address generation by inserting FFFE into the center of the MAC address, flipping the 7th bit of the first byte from 0 to 1 (changing 00 to 02), and dropping the leading zero in 021a per RFC 5952 compression rules.

Step-by-Step Solution

1
Split the MAC address into two 24-bit halves and insert FFFE in the middle.
00:1A:2B:FF:FE:3C:4D:5E
EUI-64 generation requires expanding a 48-bit MAC address into a 64-bit interface identifier by inserting 0xFFFE into the center.
2
Invert the 7th bit (the Universal/Local bit) of the first byte.
First byte 00 (0000 0000 in binary) becomes 02 (0000 0010 in binary). The 64-bit identifier becomes 021A:2BFF:FE3C:4D5E.
IEEE EUI-64 standards mandate toggling the 7th bit to indicate a unique locally administered or globally unique address.
3
Combine the fe80::/64 link-local prefix with the derived 64-bit interface identifier and apply RFC 5952 zero compression rules.
fe80::21a:2bff:fe3c:4d5e
Leading zeros within hex fields must be suppressed (021a becomes 21a).

Key Concept

Modified EUI-64 Interface Identifier Derivation
Estimated Time:1m 30s
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Topics

IPv6 Addressing and Deployment

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