From: Scott Morris (swm@emanon.com)
Date: Thu Dec 22 2005 - 22:25:18 GMT-3
You'll just have multiple global unicast addresses. OR, the concept of
aggregation won't be quite as spectacular as the original designers
envisioned. It's still a little early in deployment to see what's gonna go.
Networking karma. :)
_____
From: CCIEin2006 [mailto:ciscocciein2006@gmail.com]
Sent: Thursday, December 22, 2005 2:49 PM
To: swm@emanon.com
Cc: lab
Subject: Re: IPv6 Address Allocation Excessive?
Speaking of multihoming, how does that affect the address aggregation? Does
it force each provider to punch a hole in their address block?
On 12/20/05, Scott Morris <swm@emanon.com> wrote:
Actually, it's more reminiscent of IPX. You know, the 32 bit network ID
plus your MAC address. And since the network ID was announced by servers,
your workstations could be less intelligent and you have magical networking.
IPv6 isn't all that much different. New colors, same basic flavor. :)
Anyway, the /64 was used in order to make things more magical with the
automatic addressing. Why 64 bits instead of 48? Great question, haven't
got a clue. My theory on the insertion of the FFFE is that someone figured
that with everyone throwing away old devices and (in theory) MAC addresses
only being used once, we'dd run out of them too. FFFE is a starting point.
IMHO, it would seem to make sense to have different codes for different
media types, and it's likely spelled out someplace, I just haven't been
bored enough to research that part!
Every company/enterprise/customer is supposed to get a /48 which gives you
64K of subnets to use which should suffice for damned near everyone. There
are always exceptions, and there's nothing saying that you CANNOT have
subnets different than a /64 (like a /128 for loopbacks or /127 on P2P links
or whatever your heart (or lab) desires), but if every company aggregates to
a /48 the thought was that route summarization throughout the global table
would be easier.
Now this was done before multihoming was big. IPv6 was designed 10-12 years
ago. A few things have changed since then as we make stuff work! (grin)
But otherwise yes, there should be plenty of addresses to go around for a
long long time! Although currently they've only released a small portion of
"all" the addresses (2000-3FFF range) for unicast global address space.
Even as registries are handing out /48's, that's still bigger than the full
32-bit space we have now. So that means we can have somewhere in the
neighborhood of 281,474,976,710,656 (281 trillion'ish) individual
companies/enterprise customer networks. We'll have plenty so that your
wireless toothbrush can still catch a virus without any need for NAT!
Yay.
Scott
PS. When the United Federation of Planets becomes a reality, someone,
someplace wanted to be sure we still had address space available! ;)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
CCIEin2006
Sent: Tuesday, December 20, 2005 3:46 PM
To: lab
Subject: IPv6 Address Allocation Excessive?
According to the Cisco Press book "Implementing Cisco IPv6 Networks", RIR's
allocate /32 prefixes to ISP's. ISP's allocate /48 prefixes to each customer
site. Each customer site uses /64 prefixes for each subnet.
Isn't that a little excessive?
Why does every subnet need a /64?!? Isn't that 1.8 quintillion addresses per
subnet?!? What a waste!
On the other hand If the average ISP has a /32 and he is allocating /48 that
means he only has 2^16 or 65536 prefixes to allocate. Doesn't seem that much
at all.
I know IPv6 is supposed to provide plenty of addresses, but aren't these
large allocations reminiscent of the 1980's when IPv4 registries were
handing out Class A and Class B subnets to every Tom, Dick and Harry that
asked for one?
What I'm saying is that even though the IPv6 address space can accommodate
3.4*10^38 addresses, if the registries keep handing out such large chunks of
address most of the addresses will be wasted.
I'm just concerned that in the future there won't be any addresses left to
assign to my wireless electric toothbrush!
Any thoughts?
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