*sigh*
IANA controls the IP addressing scheme. There are 5 regional registrars under them. IANA allocates addresses in blocks of /8 (16.7 million) to the registrars as they request them. Registrars in turn on-sell these addresses to ISPs. ISPs use them for their customers, both residential and business - a static IP address is one that you get to keep permanently, while most residential connections get automatically assigned IP addresses and they can change over time. You need a globally routable IP address to allow bi-directional communication on the internet - that is for packet replies to actually reach your computer. You need static IP addresses to host thing like webservers or other types of servers on the internet.
IPv4 has 4.3 billion addresses in total, but a lot of these have been fenced off for specific purposes: 127/8 is loopback, 10.0.0.0/8, 172.16-31.0.0/16, 192.168.0.0/24 are private, 224.0.0.0/24 to 240.0.0.0/24 are multicast, 241-254.0.0.0 'reserved for future use'. The remaining IP addresses are available to be allocated to ISPs in /8 blocks.
What has actually just happened (your friend's professor is out of the loop) is that APNIC, one of the regional registrars,
has requested the last 2 available /8 blocks from IANA, which has triggered IANA's final allocation policy of distributing the remaining 5 /8's, 1 each to all of the regional registrars.
This means each registrar has at least one full /8 block (16.7 million addresses) that they can sell to ISPs as they see fit. APNIC estimates that it's current policy of allocations will continue for the next 3-6 months, and after that they'll have to change.
IANA has run out of addresses that it can allocate to the RIRs (unless some companies relinquish their address blocks back), but the RIR's themselves still have a lot of IP addresses they can give out to their supplicant ISPs. The ISPs in turn will each have their own stockpile of IP addresses that they can use. ISPs will probably also be able to reclaim some inefficiently used IP addresses if they need to - there hasn't been any point doing it up till now because they could always just ask for more from their regional registrar, but now that the RIR's are running out, ISPs will have to make sure they're using the addresses they have as efficiently as possible.
What does this all mean? Probably not much will change for the next year, as RIR's and ISPs will have IPs still left to allocate. But towards the end of the year, or next year, some ISPs may run out, at which point they may start charging more money to their customers for IP addresses, and in particular may start taking static IP addresses back from residential customers.
The solution, which has been standardised for over 10 years now, is IPv6, which has addresses that are 16 bytes long instead of 4 like IPv4, meaning there are 34,028,236,692,093,846,346,337,460,743,177,380,000,000 addresses available - considerably more than the 4,294,967,296 available in IPv4.
The problem with IPv6 is that it is not backwards compatible with IPv4 - all of your (networking) software and hardware will need to be upgraded or replaced so that it can handle IPv6. Vista and Windows 7 handle IPv6 out of the box, and Windows XP has supported it since service pack 2 I believe - Apple and Linux also support it. Even though IPv6 has been around for 10 years, it hasn't been seriously or widely used except for the last 2 or 3 years, so there are still many corner cases around where IPv6 tools or functionality simply doesn't work the way it should, because it's buggy and it hasn't been seriously thrashed.
Eventually once most ISPs have transitioned over to IPv6 (probably by about 2015-2016) this means when you get IP addresses from your ISP, instead of getting a nice IPv4 address like 145.13.7.3, you'll get something that looks like 2001:db8:85a3:8d3:1319:8a2e:370:7348
Note: I work as a software engineer at
Allied Telsis so I do this stuff all day. Last couple of weeks I've been fixing bugs in OSPF for IPv4 and IPv6.
Post has been edited 4 time(s), last time on Feb 2 2011, 7:31 am by Lanthanide.
None.