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A “local link address” is almost always an IPv6 link-local address: an address that devices use to communicate with other devices on the same network link. This article uses that standard term and defines it on that basis. If you saw the phrase in an IPv4-only tool or in a product’s own menu, check that product’s documentation, because this definition covers the IPv6 meaning only.
The short definition
An IPv6 link-local address is a unicast address intended for communication on the local link. Every link-local unicast address falls within the prefix FE80::/10. The address is defined as part of the IPv6 addressing architecture in RFC 4291, the IETF standard that sets out how IPv6 addresses work. Because link-local traffic stays on its own link, the address is useful for talking to neighbours on that segment and is not a globally reachable Internet address.
What “local” means in practice
“Local” refers to the link, not to the whole building, home or organisation. A link is a single network segment, such as one Ethernet LAN, one Wi-Fi network or one point-to-point connection. A site with several subnets or links has several separate link scopes, and a link-local address on one link does not by itself reach devices on another.
A useful way to picture it is as an address that works only inside one network segment. The same network can contain many such segments, and each interface on each segment can have its own link-local address.
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What link-local addresses are used for
Cisco’s configuration guide for its 1000 Series Connected Grid Routers, titled “Configuring IPv6,” names two functions that rely on link-local addresses. Its command and configuration details apply to that router family and software documentation, but the functions themselves are part of the IPv6 standard.
- Neighbor Discovery: helps nodes find neighbours and routers on the same link.
- Stateless address autoconfiguration: lets a device build its own IPv6 addresses from information advertised on the link, without a DHCP server.
Forwarding: where the address stops
The forwarding boundary is the main practical rule. Cisco’s guide states: “IPv6 routers cannot forward packets that have link-local source or destination addresses to other links.” A router will therefore not carry a link-local packet from one segment to another, which is what keeps the address confined to its link.
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Link-local versus unique local addresses
Unique local addresses (ULAs) are often confused with link-local addresses. Cisco describes ULAs as intended for local communications but routable within a limited area, such as a site, and potentially between a limited set of sites. The table compares the two on the points the cited sources address.
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstall| Attribute | Link-local address | Unique local address (ULA) |
|---|---|---|
| Reach | Same link only | Local communications within a limited area, such as a site, and potentially between a limited set of sites |
| Forwarding by routers | Not forwarded to other links | Routable within its limited area, per Cisco’s description |
| Purpose | Automatic local functions such as Neighbor Discovery and autoconfiguration | Local communication across a site or a limited set of sites |
| Whether ping or traceroute can reach infrastructure interfaces across the network | Discussed only in the router-to-router example (RFC 7404) below | Not stated in the sources cited for this article |
Not the same as IPv4 loopback
An IPv4 loopback address, 127.0.0.1, identifies the local host itself. A link-local address is for reaching other devices on the same link. The cited sources establish the link-local behaviour but do not discuss loopback; this distinction is general networking background.
Where the phrase turns up in troubleshooting
The wording sometimes appears in router and DHCPv6 questions. One networking forum post asks, “No local link address on wan for DHCPv6 client?” It concerns a WAN interface acting as a DHCPv6 client. That is one user’s informal phrasing rather than a standard term, so when searching for documentation or fixes, use “IPv6 link-local address” and the interface’s own status output.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Router-to-router links: a link-local-only design
RFC 7404, an informational IETF document published in November 2014, considers using only link-local addresses on IPv6 infrastructure links between routers. It makes no recommendation for or against the approach; whether it suits a network depends on that network’s operational needs. This is an advanced application, not part of the basic definition.
Potential advantages
- Smaller routing tables.
- Simpler address management.
- Reduced reachability of infrastructure interfaces beyond the link.
Operational caveats
- Some traditional techniques do not work in the same way. Pinging an interface or identifying interface information in traceroute, for example, behaves differently.
Anyone considering this design should test those troubleshooting habits against the network before relying on them.
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