Re: Is 1111 1110 10 equal to 0xfe80 or 0x3fa?

Tom,
FE8::/10 == 0FE8::/10  up to here OK, but
If prefix-lengh is 10 bits, then it should be:   FE8::/10 == 0FE8::/10 ==
0FC0::/10 == FC0::/10

Right?

On Mon, Jun 10, 2019 at 5:04 PM Tom Herbert <tom@herbertland.com> wrote:

> On Mon, Jun 10, 2019 at 6:58 AM Mudric, Dusan (Dusan) <dmudric@avaya.com>
> wrote:
> >
> > > On Friday, June 7, 2019 at 3:48 PM Tom Herbert
> > > <tom@herbertland.com> wrote
> > > >
> > > > >
> > > > > Message: 3
> > > > > Date: Fri, 7 Jun 2019 10:53:28 -0700
> > > > > From: Fred Baker <fredbaker.ietf@gmail.com>
> > > > > To: Alexandre Petrescu <alexandre.petrescu@gmail.com>
> > > > > Cc: IPv6 <ipv6@ietf.org>
> > > > > Subject: Re: Is 1111 1110 10 equal to 0xfe80 or 0x3fa?
> > > > > Message-ID: <A722E202-7671-4111-BA92-8A67B3D3B924@gmail.com>
> > > > > Content-Type: text/plain; charset="us-ascii"
> > > > >
> > > > >
> > > > >
> > > > > If I have prefix fe80::/10, as described in RFC 4291, the next bit
> > > > > is bit 11. Doing the same subdivision of the prefix is fe80::/11
> and
> > > fea0::/11.
> > > > [Dusan] The hexadecimal definition for LL address is not
> syntactically
> > > correct. The binary 10 bit prefix 1111111010 cannot be presented as
> > > hexadecimal FE80::/10. It is rather a range FE80::/10 - FEBF::/10. In
> this
> > > notation, FE80::/10 = FEBF::/10,  because the first 10 bits are equal
> and other
> > > 6 should be ignored. 111 1111010 can be defined as FE80::/10 only if
> every
> > > time it is also mentioned that the trailing 6 bits are all zero.
> > >
> > > By that logic, we'd have to mention that the trailing 118 bits are
> zero.  E.g.
> > > FE80::/10 == FEBD:F676:BBBB:C654:FEBD:F676:BBBB:C654/10
> > > also. It's obviously convenient canonical notication to express all
> the trailing
> > > bits as zeroes for a prefix, but not required. For instance, ifconfig
> shows my
> > > host address as fe80::ac2f:ea58:94a:438/64 which in one string
> indicates both
> > > a fully qualified address and it's prefix bits.
> > [Dusan] In this example fe80::ac2f:ea58:94a:438/64 is LL address with
> 0xfe80 0x0000 0x0000 0x0000 prefix. Based on LL prefix definition, this LL
> address can have a value of feab::ac2f:ea58:94a:438/64 and still have the
> binary 10 bit prefix 1111111010
> >
> > May be LL address can be defined in hex notation as a range FE8::/10 -
> FEB::/10? This range always has the same well know LL identifier, the
> binary 10 bit prefix 1111111010.
>
> FE8::/10 - FEB::/10, only three digits in IPv6 notation? So wouldn't
> FE8::/10 == 0FE8::/10 == 0FE0::/10 == FE0::/10. I don't think that's
> right.
>
> Tom
>
> >
> > >
> > > Tom
> > >
>
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