IP addresses

[msc75]

Assuming that there are a finite number of IP addresses available, approximately when will we run out?

I know that large companies use gateways, so a company with 10,000 employees can actually get by with only a couple of public IP addresses.

But with the onset of cable modems and DSL, where nearly every house will have a static IP address, what are the plans for when we run out of numbers using the existing format?

[Gozu Tashoya]

I read an article on this a year or two ago. I think it said that we had, at the time of printing, about another 5 years or so. I believe the plan was to tack on another 3 number set to the current 4, though I really can't remember what recommendations were floating around.

[Arjuna34]

Existing IP numbers are a 32-bit address, which gives over 4 billion numbers. This is quite a few, but not enough for the day when everyone's toaster, electric shaver, and pencil sharpener have their own IP address.

The next generation standard, IPv6 (http://www.ipv6.org/), uses a 64-bit address, which should be gives over 1.8x1019 addresses, and should be plenty.

Arjuna34

[yabob]

The IPng proposal is intended to address future growth:

http://webopedia.internet.com/TERM/I/IPng.html.

The addressing scheme will become quite a bit more sophisticated, but the proposal is for a 128 bit basic address.

[Arjuna34]

In addition to the numerous typos in my previous post, I mistakenly stated that IPv6 uses a 64-bit address.

It actually uses a 128 bit address. That should really be plenty.

Arjuna34

[Gut]

Under IPv4 (http://webopedia.internet.com/TERM/I/IP_address.html) we have 232 or 4,294,967,296 IP addresses. IPv6 or IPng (http://www.technocrat.net/933749726/index_html) will give us 264 or 340,282,366,920,938,463,463,374,607,431,768,211,456 IP address. It will be a long time until we run out under IPv6.

[yabob]

rats. try http://webopedia.internet.com/TERM/I/IPng.html

The IPng 128 bit space has some smarts built into it for different types of addressing, but I agree - it should be plenty (at least it SEEMS that way).

[Bobort]

Just to give you an idea how big a 128-bit address space is, I once calculated that 128 bits is sufficient to give a unique IPv6 address to every atom in a smallish swimming pool.

There's a rumor that IPv6 was initially planned to have 64-bit addresses. Somebody thought that might not be enough, so they decided to "double" the address space by doubling the size of the adresses. Probably false, but amusing nonetheless.

[DMC]

In case you were wondering why we're already running out, even though we don't have over 4 billion devices connected to the net, it's due to the way the addresses are allocated.

Class A networks are a major factor. A class A network begins with the intial number between 000 and 127 (yes, 127 is actually for loopback), such as 019.xxx.xxx.xxx (Ford Motor Co., by the way). That means Ford has taken up over 16 million possible addresses (about 1/255th of the possible address space), even though they probably only use a small fraction of them. There are quite a few allocated, over 50 last time I checked. IBM even has two of them.