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Re: ISP customer assignments
- From: Cord MacLeod
- Date: Tue Oct 13 19:34:58 2009
On Oct 13, 2009, at 4:26 PM, Chris Adams wrote:
Once upon a time, Michael Dillon <wavetossed@googlemail.com> said:
How many addresses do you like on point-to-point circuits?
That will become one of those great interview questions, because
anyone who says
something like "a /127" or "a /64" will be someone that you probably
don't want to hire.
The right answer is to explain that there are some issues surrounding
the choice of
addressing on point-to-point circuits and there has even been an RFC
published discussing
these issues, RFC 3627 <http://www.ietf.org/rfc/rfc3627.txt>
Still learning here, so please go easy...
I read the above, and I see section 4 item 3 says:
The author feels that if /64 cannot be used, /112, reserving the
last
16 bits for node identifiers, has probably the least amount of
drawbacks (also see section 3).
I guess I'm missing something; what in section 3 is this referring to?
I can understand /64 or /126 (or maybe /124 if you were going to
delegate reverse DNS?), but why /112 and "16 bits for node
identifiers"
on a point-to-point link?
I'm actually completely unclear why people would use anything but a /
126 in 90% or more of cases. For all intensive purposes a /126
translates to a /30 in IPv4. Do people assign /24's to their point to
point links today with IPv4? What's the point of a /64 on a point to
point link? I'm not clear why people would intentionally be so
frivolous with their IP space simply for the sake of "because I can."
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