zero suppression vs compression in addresses
jay at west.net
Sat May 16 02:24:22 CEST 2009
Alan Batie wrote:
> I think I may have misinterpreted how zero compression and suppression
> work: when I say 2607:f678:1::0/60, I expect the "::" to mean "all 0's
> from the preceding digit to the next", but from what I'm seeing
> configuring things, (leading) zero *suppression* seems to be happening
> at the same time within word (32 bit) boundaries, which colons always
> delineate, making that really 2607:f678:0001::0/60. Thus what I really
> wanted to say was 2607:f678:1000::0/60.
1. IPv6 addresses are 128 bits, written as eight quads of hex digits.
Each quad is delimited by a colon.
2. Within each quad, leading zeros may be dropped, but (for this step)
if a quad is all zeros leave a single zero.
3. After doing this, if one or more successive quads is zero, that group
of zeros can be replaced with a double colon, BUT only one double colon
can appear per address.
(You can reverse steps 2 and 3 if you choose)
So, if you have:
Which can EITHER be expressed as
Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service - http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV
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