IPMP can be based on: 1) Detecting the Interface Link State as being up/down 2) Detecting other hosts on the network using ICMP or multicast.
For option 1, IPMP would require a single IP address for both NICs that are used as a single logical port/interface.
For option 2, IPMP would require 3 IP addresses: one for each of the two physical interfaces and a Local Host IP address which floats between the two interfaces depending upon which interface is active. This third IP is shared by the two physical interfaces. If there is a cluster created, IPMP would require a fourth IP address that is shared by each server.
This option sends ICMP pings to the default gateway. If default gateway is not pingable, this option can be configured to use multicast to see if other hosts are available on the network. Number of hosts on the network that must reply back is adjustable.