legacy /8

You know, I've felt the same irritation before, but one thing I am wondering
and perhaps some folks around here have been around long enough to know -
what was the original thinking behind doing those /8s?

Read your network history. In the beginning all allocations were /8s, in fact
the slash notation hadn't been invented yet. Network numbers were 8 bits
and there was a 24 bit host id appended.

Then someone realised that the net was growing really fast, so they
invented class A, B and C addresses in which the network numbers
were 8, 16 or 24 bits respectively. You could tell which class by looking
at the first two bits of the address. In that time period only very big
organizations got class A allocations. Mid-sized ones got class B
and small ones got class C. In fact what happened was that some
smaller organizations got multiple non-aggregatable class C blocks
(and aggregation didn't exist anyway).

Later on some clever folks invented VLSM for the routers which allowed
network ops folks to invent CIDR. That was when people really got
interested in justifying the size of an allocation, and working based
on 3 months, or 6 months requirements. This is when ARIN was
created so that the community had some input into how things were
done. But nobody could really unroll the past, just clean up the bits
where people were changing things around anyway. For instance this
is how Stanford's /8 ended up being returned.

Lots of folks believed that VLSM and CIDR were only stopgap measures
so around the same time they invented IPv6. It was released into
network operations around 10 years ago which is why most of your
network equipment and servers already support it.

But that's all water under the bridge.

It's too late to do anything about IPv4. The ROI just isn't there any more,
and it doesn't escape the need to invest in IPv6. The network industry
has now reached consensus that IPv6 is the way forward, and you
have to catch the wave, or you will drown in the undertow.

--Michael Dillon

/8's were not given out to large companies. They were given out to
*everyone*! In the beginning there was the ARPANET and it was considered
a large network (it was certainly an expensive network!). The notion was
that there would only be a small number of "large" networks, so 8 bits
was enough to enumerate them. The original IP plan didn't have classes
of networks at all. It was 8 bits of network and 24 bits of

It was only after network numbers started to hit the early thirties that
folks realized that there needed to be more networks and the
"class-full" approach was invented.

So most of the existing class A holders just happened to be the very
early adopters (actually the original research and government
organizations that were connected to the network).


On the topic of IP4 exhaustion: 1/8, 2/8 and 5/8 have all been assigned in the last 3 months yet I don't see them being allocated out to customers (users) yet.

Is this perhaps a bit of hoarding in advance of the complete depletion of /8's?

Doubt it. 1/8 is still being evaluated to determine just how usable
portions of it are, thanks to silly people of the world that decided 1.1.1.x and the like were 1918 space.

As for the others, the RIR requests it when they are running low,
but certainly not exhausted, and as slow as people are to update their bogon filters, it sounds like general good practice not to assign out of
a new /8 until pre-existing resources are exhausted.

Was looking for the "allocated" file on the ARIN website, but can't remember
where it is. They used to have a file with one line per allocation that started
like this "arin|US|ipv4". Is that still public somewhere?

Can we put the tinfoil hats away and let this thread die now?


Good luck with that one :->

I've got a rather stupidly simple and straightforward plan, since we're all throwing ideas out.

Take back all the IP space from China and give them a single /20 and tell them to make do. They're already behind a great firewall, so they should have no problem using NAT with their citizens for easier restricting of freedoms, and for the actual services they need to run, they can assign a limited amount of static IP addresses for servers, and the rest NAT as well, and port forward for specific services.

If they want to be an intranet, I say, lets help them achieve that goal. They get to play in their own sandbox, and we get some IP space back to buy us more time.

Probably not the biggest flaw in this plan, but:

Total number of RFC-1918 addresses: 18+ million.
Population of China: More than 1.325 billion.

I'll leave the other political aspects to others, but, the math simply doesn't work.


Aha! Someone else who believes the internet should model a justice

Sigh... Guess you missed the last several go-arounds of

Running out of IPv4 will create some hardships. That cannot be avoided.

  we won't run out, we won't exaust, we are -NOT- killing the last tuna.
  what we are doing is roughly what was anticipated in RFC 2050, we will
  get more efficent utilization of all the space.

Even if we were to reclaim the supposed unused legacy /8s, we'd still
only extend the date of IPv4 runout by a few months.

  wrong analogy. there won't be "green field" space - but there will
  still be lots to go around... for legacy style use (e.g. the Internet
  as we know it today) -- want to do something different? then use IPv6.

The amount of effort required to reclaim those few IPv4 addresses would
vastly exceed the return on that effort. Far better for that effort to be
directed towards the addition of IPv6 capabilities to existing IPv4
deployments so as to minimize the impact of IPv4 exhaustion.

  here we disagree. Im all in favor of demonstrating 85% utilization
  of the IPv4 address pool before handing out new address space.


Cutler James R wrote:
>I also just got a fresh box of popcorn. I will sit by and wait

I honestly am not trying to be a troll. It's just everytime I glance
over the IANA IPv4 Address Space Registry I feel rather annoyed about
all those /8s that were assigned back in the day without apparently
realising we might run out.

  its well to remember that when they got that space, the minimum
  allocation was a /8. you couldn't get anything smaller because
  "classful" addressing wasn;t invented yet. Only (much) later could
  you get "B" or "C" space... and after classful died in v4, we had
  CIDR. IPv6 as effectively reindroduced classful addressing.



The expectation was that those /8s would be subnetted into vast arrays of "Class C" sized chunks and that subnets within a given /8 all had to be the same size (this used to be necessary to keep RIP happy and every machine participating in RIP routing had to have an /etc/netmasks (or equivalent) table that tracked "THE" subnet mask for each natural prefix).

  er, again, not true. the space was originally, net/host - the mantra was "bridge where
  you can, route when you must" - there were expected to be a few networks with millions
  of hosts within each broadcast domain. (anyone else remember the ARP storms of the

  routing came into its own later, along with classful addressing.



ipv4 spae is not 'running out.' the rirs are running out of a free
resource which they then rent to us. breaks my little black heart.

even if, and that's an if, ipv6 takes off, ipv4 is gonna be around for a
loooong while. when 95% of the world has end-to-end ipv6, do you think
amazon et alia are gonna blow 5% of their market by decomissioning ipv4?

we are gonna learn how to distribute and use ipv4 more efficiently.
it's not that hard, we know how to do it. internet engineers have
worked through and around a lot of problems, it's our job. making
connectivity continue work for folk who, for whatever reason, delay
migration from ipv4 is just part of our job. not to panic.

the hard part is figuring out how the rirs make money off ipv4 holders
redistributing it among themselves. if that becomes a non-goal, things
get a lot simpler.


IPv6 as effectively reindroduced classful addressing.

but it's not gonna be a problem this time, right? after all,
32^h^h128^h^h^h64 bits is more than we will ever need, right?


well... looking at a diet analogy, when .gt. 50% of your
  diet is HFCS and filler, its not real healthy. the way
  most folks are using IPv6, .gt. 50% of the bits are wasted
  as filler (got to love me some ::slight_smile:

  so it seems like a lot, yet folks have already predicted the
  demise of IPv6 in the next 20years. (Klensin I think it was)


Just like 640k or memory :slight_smile:

At current consumption rates, that'd buy us another year or so. Then what?


To quote:

"we get some IP space back to buy us more time"

Didn't say it was a solution, but we're all talking about buying more time for ipv6 transition. Its no worse then any other suggestion people have proposed. :slight_smile:

So, jump through hoops to kludge up IPv4 so it continues to provide
address space for new allocations through multiple levels of NAT (or
whatever), and buy a bit more time, or jump through the hoops required
to deploy IPv6 and eliminate the exhaustion problem? And also, if the
IPv4 space is horse-traded among RIRs and customers as you allude to
above, IPv6 will look even more attactive as the price and preciousness
of IPv4 addresses increases.

The idea isn't for IPv4 to be replaced (decommissioned). The idea is
for IPv6 to be added, then things will slowly transition. IPv4 will be
around for a long time indeed, but increasingly, new sites/services, and
old sites/services will be adding IPv6 as a way to connect to them.
Then at some point, IPv6 will become the "normal" way to connect, and
IPv4 will be a the "legacy" way, with fewer and fewer using it.

Also, reading your other post, if you don't understand the difference
between 2^32 and 2^128, please start here:

Anyway, I see it as pretty much moot, since many major players (Comcast,
Google, etc) are in the midst of major IPv6 deployments as we speak.
Eventually you will have to jump on the bandwagon too. :slight_smile:

- Jim

Just like last time.

Larry Sheldon wrote:

Sigh... Guess you missed the last several go-arounds of

Running out of IPv4 will create some hardships. That cannot be avoided.

we won't run out, we won't exaust, we are -NOT- killing the last tuna.
what we are doing is roughly what was anticipated in RFC 2050, we will
get more efficent utilization of all the space.

That statement becomes less truthy when more realistic definitions of 'we'
are used.

I'd suggest that attempts to stretch v4 addresses is going to fall over on
its side, for large segments of we. Address exchanges on the free market,
and RIR reclamation will certainly be sufficient for other large segments.

However, there will be a point in the next 3-5 years in which neither of
these methods will be able to keep up with the tide of technological

Even if we were to reclaim the supposed unused legacy /8s, we'd still
only extend the date of IPv4 runout by a few months.

wrong analogy. there won't be "green field" space - but there will
still be lots to go around... for legacy style use (e.g. the Internet
as we know it today) -- want to do something different? then use IPv6.

I already feel like a dinosaur sitting in front of my desktop, with a

The Internet as we know it today only has 2-3 years of v4 address supply
left. The more we stretch address usage, the more we create something that
does not resemble the Internet as we know it today.

The last time I discussed IP Address needs with a company the builds automobiles, they wanted forty million addresses for robots, sensors, and the like for manufacturing. A single /8, were it available, would only yield about 20% of that requirement.