Imagine moving into a brand-new smart home. You step through the front door and — BAM! — the lights adjust to your mood, the thermostat knows your favorite temperature, and the fridge has already ordered your favorite snacks.
Welcome to the world of SLAAC: Stateless Address Autoconfiguration.
SLAAC is IPv6’s way of saying, “Relax, I’ve got this.”
In the old IPv4 world, getting an address meant begging a DHCP server for help, manually setting static addresses, or suffering from clunky setups.
IPv6 said, “Hold my beverage.”
What is SLAAC?
Stateless Address Autoconfiguration (SLAAC) is a method where an IPv6 device:
- Creates its own IP address.
- Learns important network information.
- Does it all without a server!
Like a responsible adult. 🤓
How SLAAC Works (Step-by-Step)
- Device joins the network (e.g., Wi-Fi at a coffee shop).
- Device generates a Link-Local Address (an address valid only on the local network).
- Device sends a Neighbor Solicitation to check if that address is already in use.
- Router Advertisement (RA) arrives — the router announces:
- “Here’s the network prefix (like 2001:db8:abcd:0012::/64)”
- “You should use SLAAC!”
- Device combines the network prefix + its own interface identifier to create a full IPv6 address.
- Device is ready to roll!
No hands needed. No IT tickets filed. No grumpy network admins.
Real-World Example
You connect your phone to a new public Wi-Fi network. Without you noticing, it:
- Creates a temporary link-local address.
- Checks to make sure it’s unique.
- Listens to the network’s router.
- Configures a full-blown global IPv6 address — all within seconds.
Before you even open Instagram.
SLAAC vs DHCPv6
| Feature | SLAAC | DHCPv6 |
|---|---|---|
| Server Required? | No | Yes |
| Address Control | Device chooses itself | Server assigns address |
| Additional Info | Needs RDNSS or DHCPv6 for DNS info | DHCPv6 can provide lots of options |
Fun Fact: Many networks today use both SLAAC and DHCPv6 for extra features!
Coming Up Next
Now that devices have addresses, how do they keep their addresses private? And why does your laptop sometimes have two IPv6 addresses?
Get ready to explore IPv6 Privacy Extensions and how your network identity can stay hidden!
Quick Quiz: Check Your Knowledge!
- What does SLAAC allow a device to do?
- a) Request an IP address manually
- b) Automatically configure its own IPv6 address
- c) Broadcast to the whole network
- What key message helps a device learn the network prefix?
- a) Neighbor Advertisement (NA)
- b) Router Advertisement (RA)
- c) Redirect Message
- True or False: SLAAC requires a DHCP server.
- Bonus: Name one advantage of using SLAAC instead of DHCPv6.
📚 Answer Key: Chapter 4 Quiz
1. Which IPv6 address type is used to send data to exactly one device?
✅ Answer: a) Unicast
2. Which address type routes your request to the nearest available device?
✅ Answer: c) Anycast
3. True or False: IPv6 still uses broadcast messages like IPv4.
✅ Answer: False
4. Bonus: Real-world multicast example?
✅ Sample Answer: Streaming a live video feed to multiple devices simultaneously.
