AUTO LL4 Plugin

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The Auto LL4 Plugin is a mechanism that uses the NHDP Plugins dualstack capability to automatically generate linklocal IPv4 addresses from the 169.254.0.0/16 prefix.

The idea behind the plugins algorithm is to use the local interfaces IPv6 linklocal address as a seed for a random number generator to create your IPv4 address. Before setting the address, the algorithm verifies that the choice does not collide with any already known IPv4 address in the one- and two-hop neighborhood. It also makes sure that it doesn't select the initial random number based on the IPv6 address of the neighborhood.

Mobile Adhoc Networks can be mobile of course (as the name says), so two routers might select the same linklocal address while being far apart and later move into communication range with each other. The Plugin constantly monitors the interface addresses of the neighborhood for an address collision. If the collision happens, the node will randomly select a new address which doesn't collide with the current neighborhood and its initial random IP address selection.

The plugin also detects if the user sets an address on the interface. The plugin only generates an address of its own if there is NO IPv4 address on the interface and it removes its address as soon as the user sets one.

Configuration

The AUTO LL4 plugin adds two configuration sections named auto_ll4 and interface.

auto_ll4 section

The plugin defines the auto_ll4 configuration section with one setting.

Key Default Type Limits
startup 10 clock

startup defines the time the plugin will listen to incoming NHDP event before it sets a linklocal IPv4 address.

Interface section

The plugin adds one setting to the interface configuration section.

Key Default Type Limits
auto_ll4 true boolean

auto_ll4 activates the IPv4 autoconfiguration for this interface.