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

Alexandre Petrescu <alexandre.petrescu@gmail.com> Thu, 06 June 2019 17:18 UTC

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To: IPv6 <ipv6@ietf.org>
From: Alexandre Petrescu <alexandre.petrescu@gmail.com>
Subject: Is 1111 1110 10 equal to 0xfe80 or 0x3fa?
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Date: Thu, 06 Jun 2019 19:18:00 +0200
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Hi 6MANners,

In private discussion we disagree about this point:

I maintain that 1111 1110 10 equals 0x3fa, because that's what my 
Windows Calculator says: I type 1111 1110 10 and it converts to 0x3fa.

On another hand, I am rhetorically asked how can 1111 1110 10 be 0x3fa?

(the 1111 1110 10 are the 10 leading bits of the IPv6 link local 
addresses, which is familiarly known to start with an fe80).

On my side, this is a difficulty to understand this 0xfe80, especially 
since 1111 1110 10 is so printed in Figure in RFC4291.

Alex

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