[139400] in North American Network Operators' Group
link-local address calculation
daemon@ATHENA.MIT.EDU (Vikas Sharma)
Thu Apr 7 04:18:41 2011
Date: Thu, 7 Apr 2011 13:48:33 +0530
From: Vikas Sharma <vikassharmas@gmail.com>
To: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
Hi,
How to get link-local address from BIA. I have seen some information
on Internet but it is not working for all.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
The BIA in this case is cc00.0bfc.0000. The rules for the modified
EUI-64 addressing are:
=95FFFE 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
=95Thereafter 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
=95At last, change all points =91.=92 to colons =91:=92 and delete all lead=
ing
zeros, then you got your link-local IPv6 address:
FE80::CE00:BFF:FEFC:0
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
So if your BIA is 0008.209a.081b (bia 0008.209a.081b), how link-local
be calculated. This is the link-local on router =3D>
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 ...
Can someone explain me this?
Regards,
Vikas
