1 . Use netsh interface ipv6 show interface on Host A to obtain the link-local address and the interface index for the Ethernet interface.
For example, the link-local address of Host A is FE80::210:5AFF:FEAA:20A2, and the interface index of the Ethernet interface is 4.
2 . Use netsh interface ipv6 show interface on Host B to obtain the link-local address and the interface index for the Ethernet interface.
For example, the link-local address of Host B is FE80::260:97FF:FE02:6EA5, and the interface index for the Ethernet interface is 3.
3 . From Host A, use Ping.exe to ping Host B.
For example, ping FE80::260:97FF:FE02:6EA5%4
Source
The interface index is also known as the zone index. The zone index differs by operating system. Windows example is given above. This is needed because the only routing information your hosts have is the FE80 address prefix.
For most unix like systems (Linux) use fe80::%eth0
For Mac OS X fe80::%en0