ipv6 address autoconfig
Instructs the interface to dynamically discover its IPv6 address variables using Stateless Address Autoconfiguration (SLAAC). Instead of polling a central DHCP server, the interface listens for ICMPv6 Router Advertisements, extracts the network prefix, and dynamically builds its own interface ID using EUI-64 or randomized tracking.
CLI Deployment Scenarios
Scenario 1: Enabling SLAAC on a Branch Ingress Inbound
Setting an upstream interface to learn its address dynamically from an ISP router backplane.
CCNA Exam Gotchas
EUI-64 MAC Manipulation
When using SLAAC via the autoconfig command, the router will frequently employ the **EUI-64** metric to build the last 64 bits of the address based on its physical burned-in MAC address. The exam heavily tests this conversion process:
The router splits the 48-bit MAC address in half, inserts **`FFFE`** directly in the middle, and then flips the **7th bit** of the first byte (the Universal/Local bit) to invert the state. Keep this mathematical process clean for multiple-choice tracking!