Monday, March 8, 2010

Avahi-autoipd

It is an Zeroconf implementation of Avahi which facilitates configuration of a network element automatically on the local network in the absence of DHCP server. It uses a special address range 169.254.0.0/16 and prefix fe80::/16 for IPV4 and IPV6 link-local addressing respectively. When the autoipd daemon starts, it generates an IP address randomly using the MAC address information and announces its new IP using ARP probe to find address conflict. If the given address is being used by another network element, it generates a new IP and does ARP probe till it successfully claims the address. It stores this IP address in a file for persistence across network restart (file location on linux machine will be "/var/lib/avahi-autoipd/<mac_address>"). To configure this address to be routable on the local link, autoipd adds routing rule for this IP address in the routing table.

Source: RFC3927, Avahi