Date: Tue, 12 Feb 2002 16:15:40 -0800
From: "Michel Py" <[EMAIL PROTECTED]>
Message-ID:
<[EMAIL PROTECTED]>
| A dial-up connection gets a /48.....
Always?
Really?
Sure, if you're dialing into an ISP, with a whole bunch of /48's to
issue (as static assignments, or dynamically while a call is active)
that works just fine.
But I dial into my university (and I have a routed net in my house, as do many
on this list I guess).
The university is not an ISP, they're just an organisation. The university
has a /48. From where does it get this extra /48 to issue to me when I
dial in? The university has no interest in becoming an ISP, or getting
a bigger block of numbers, one /48 is easily big enough for us (64K subnets
is lots, we are managing quite well with a single /16 ("class B") that
we've had since forever, with something like 1K subnets allocated (though
very few current dial in users actually get more than /32 - just a few of us).
That is, there's plenty of space in that /48 to allocate /64's to all of the
dial in users that we have (even statically), as well as all the normal
connectivity.
But with a /64 allocated to me, and your theory of subnetting, how do I
manage to number my house? And no, do not tell me to use a switch and
a flat network, that isn't possible, and even if it were, I wouldn't do it.
Things of course aren't even that simple .. my house is also a dial in
provider, I can dial into it while I'm travelling, and then use its dial
out link to the university for my connectivity. Even if you suggest that
every university (and other company) should get a /40 (well, not big
enough, 256 /48's is not nearly enough, say /36 or /37 might do) instead
of the /48's we had planned for normal organisations (and now go recalculate
whether the H ratio says we really have enough address bits) and is able to
assign a /48 to my house, when it dials in, how does my house assign me
the /48 you claim that all dialup users should get, when I dial it???
Of course, it doesn't matter what prefix you say that every dial in user
must get, as soon as one dial in user dials into another dial in user,
the prefix size is never enough - if we start demanding fixed allocation
sizes. ("Dial in" here includes any kind of temporary connectivity, in
fact, that it is dialed really makes no difference at all, my house could
just as well have a fixed link to the university, when I lived close enough
for it to be cheap enough, I did have).
All we need here is flexibility - when I'm travelling (these days anyway)
all I need is one /128 when I dial in - sometime in the future I might
prefer to get something more than that (I can't see a /112 ever not being
enough, there's just so much I can carry, no matter how small it gets,
but this really doesn't matter).
All of the fixed allocation designs assume some model of how connectivity
must be achieved, that make no sense even now, and will make even less in
the future.
kre
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