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I do not understand about interface identifier in Link-Local IPv6 in Windows

    Question

  • I learnt about the link local address in https://technet.microsoft.com/en-us/library/dd392266(v=ws.10).aspx

    As per it, the last 64 bits of link local is derived from the mac address of the system..

    in my computer  the mac address is 00-15-5D-01-64-03 and the link local is fe80::5c1e:1af1:c5af:456d%3
    in this the link local is not derived from mac address..
    So i could not understand… how it is???
    Friday, September 15, 2017 10:28 AM

All replies

  • Hi ali1360,

    >>As per it, the last 64 bits of link local is derived from the mac address of the system..

    Sorry for the delayed response.

    Based on my research, it is the default behavior for Windows XP and Server 2003. For newer system, they would autoconfigure IPv6 using a random identifier (not the MAC address / EUI-64).

    You could change this default behavior to use M-EUI-64 process with the following commands:

    netsh interface ipv6 set privacy state = disabled store = active
    netsh interface ipv6 set privacy state = disabled store = persistent
    netsh interface ipv6 set global randomizeidentifiers = disabled store = active
    netsh interface ipv6 set global randomizeidentifiers = disabled store = persistent

    IP before the commands:
    Link-local IPv6 Address . . . . . : fe80::7df1:a39d:8930:45ca%12(Preferred)
    IP after the commands:
    Link-local IPv6 Address . . . . . : fe80::21d:d8ff:febb:e5e2%8(Preferred)
    Physical Address. . . . . . . . . : 00-1D-D8-BB-E5-E2
    So the second IP clearly uses the MAC address, while the first one doesn't.

    In addition, if the information provided was helpful, please "mark it as answer" to help other community members find the helpful reply quickly.

    Best Regards,

    Candy


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    Wednesday, September 27, 2017 7:23 AM