Hello,
Link local address is used to communicate within that link only. It can't travel more than a single hop.
This is how the link local address is found out:
fe80::MAC(fffe) address. fffe is inserted in between mac address. Then invert the 7th bit of mac address. Lets check in details.
R1#sh int fa0/0 | i bia Hardware is AmdFE, address is cc03.0c98.0000 (bia cc03.0c98.0000)
cc03.0c98.0000 is the mac address.
So the link local address would be fe80:cc03.0cff:fe98.0000. Now I have to invert the 7th bit.
cc03.0c98.0000: converting first 2 nibbles to binary c=1100
1100 1100 03:0c98.0000 . Inverting the 7th bit
1100 1110 03:0c98.0000 .
Converting 1100 1110 03:0c98.0000 back to hex: ce03:0c98.0000
So the final link local address of that interface would be fe80::ce03:0cff.fe98.0000
EUI-64 also use the same logic to generate a 128bit unique global unicast IP address when we provide a /64 prefix. The remaining /64 is found out using the above mentioned logic.
Krishna
