[ppml] Big numbers

Michel Py michel at arneill-py.sacramento.ca.us
Wed Apr 9 16:46:04 EDT 2003


>> Marshall Eubanks wrote:
>> I thought that the rightmost 64 bits were supposed to be used
>> to store the MAC address and related info, so a /64 is like a
>> IPv4 /32 ?

> Leo Bicknell wrote:
> Much of the IPv6 documentation talks this way.  On my
> employer's test network we are using a /64 broken into /126's
> for point to point links with no issues.

One day you will have a surprise. Marshall is not entirely right as the
equivalent of a /32 is indeed a /128 _but yes_ the equivalent of a /30
is indeed a /64, please read:

There are plans that use the lower 64 bits for different purposes (such
as CGAs, going slowly because of IPR issues). CGAs (Crypto Generated
Addresses) embed a crypto key in the IID and will likely need the full
64 bits. The way you SNAFU your own network is your own business but
don't whine when you have to renumber because you violated IETF
standards. The mask bound to an interface should be a /128 (a loopback,
for example) or a /64 (almost any other kind of interface).


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