Quiz Entry - updated: 2026.07.14
What is an IPv6 Link-Local Address (LLA) and what is it used for?
An fe80::/10 address required on EVERY IPv6 interface; it lets devices talk on the same link only (never routed) and is used for next-hop/default gateway and Neighbor Discovery.
IPv6 Link-Local Address (LLA):
| Characteristic | Description |
|---|---|
| Range | fe80::/10 (fe80:: through febf::) |
| Scope | Local link only - NOT routed |
| Requirement | Every IPv6 interface MUST have an LLA |
Structure:
fe80:0000:0000:0000:xxxx:xxxx:xxxx:xxxx/10
|←── Fixed prefix ──→|←── Interface ID ──→|
10 bits 54 bits
Uses for Link-Local Addresses:
- Default gateway - Routers advertise LLA as gateway
- Neighbor Discovery - Finding other hosts on link
- Router-to-router communication - Routing protocol traffic
Important facts:
- Created automatically when IPv6 is enabled
- Packet with LLA source cannot leave the local network
- Routers will not forward packets with LLA destination
- Not globally unique - same LLA can exist on different links
Example: fe80::1 is commonly used for router interfaces
Go deeper:
Link-local address (Wikipedia) — the fe80::/10 range, why every interface needs one, and its non-routable scope.- RFC 4291 §2.5.6 — Link-Local IPv6 Unicast Addresses — the formal fe80::/10 definition.