On Apr 7, 2011, at 1:18 AM, Vikas Sharma wrote:

Hi,

How to get link-local address from BIA. I have seen some information on Internet but it is not working for all.

Pretty simple: Split the BIA into two 24 bit chunks: cc000b / fc0000 Then insert fffe in the middle: cc000b fffe fc0000 Now invert the 0x02 bit of the first octet: ce000b fffe fc0000 Prefix with fe80:: fe80::ce00:0bff:fefc:0000 Which if you shorten it becomes: fe80::ce00:bff:fefc:0

============= The BIA in this case is cc00.0bfc.0000. The rules for the modified EUI-64 addressing are:

•FFFE will be put in between the vendor-id (3 most significant bytes) and the extension-id (3 least significant bytes), which will lead to cc00.0bFF.FEfc.0000 •Thereafter the seventh bit, known as universal/local bit, gets inverted. So first change the cc00 from hex to binary, which leads to 110011 0 000000000 and then invert the seventh bit (here a 0): 110011 1 000000000. Moved back to hex this will give CE00 •At last, change all points ‘.’ to colons ‘:’ and delete all leading zeros, then you got your link-local IPv6 address: FE80::CE00:BFF:FEFC:0 ============

So if your BIA is 0008.209a.081b (bia 0008.209a.081b), how link-local be calculated. This is the link-local on router => IPv6 is enabled, link-local address is FE80::208:20FF:FE9A:81B

Also on XR below is the link local address

Loopback6 is Up, ipv6 protocol is Up, Vrfid is default (0x60000000) IPv6 is enabled, link-local address is fe80::884c:2dff:fe84:8d75

I can not see any interface with BIA ending with 75 ...

Have you looked for the BIA on the loopback interface? While it's not a hardware interface, per se, the device is obviously assigning a BIA of 8a:4c:2d:84:8d:75 to the loopback6 interface.

Can someone explain me this?

I think I just did. ;-) Owen