I often get asked questions along the lines of “How bad is IPv4 address exhaustion, honestly?”. I take the responsibility of answering questions like these seriously; I think it’s important that a broad cross section of people understand the issue.
First, I explain there are three options to obtain IPv4 addresses, via:
- Your local friendly Regional Internet Registry (RIR), who can possibly allocate a block of addresses to you, if you qualify under that RIR’s rules (policies).
- Your friendly upstream ISP, who can possibly assign a temporary address of block of addresses, if they have them available.
- The open market, which is available in some parts of the world.
I then provide the following explanation as to what IPv4 shortage means for each of these options.
There are five RIRs whose role is to allocate IP addresses to those who need them.
All of the RIRs have entered a stage of ‘IPv4 exhaustion’, which means that their supply of IPv4 addresses is now limited.
That said, each one has a remaining ‘rationed’ address pool, which can be allocated in small quantities and under special conditions in each case. The availability and conditions are specific to each RIR, but in most cases, a new member of an RIR can receive a small block, and only one block, of public IPv4 address space.
The main impact of ‘IPv4 exhaustion‘ is that a network operator can no longer receive large IPv4 blocks from a RIR that are sufficient to address any significant Internet infrastructure. Therefore, they need to rely on one of the other mechanisms for obtaining public address space.
As a customer of an ISP, you may receive one or more addresses that are assigned to you automatically on connection, or semi-permanently, while you remain a customer of that ISP. Because ISPs themselves have a shortage of available addresses, it is generally harder to obtain an assignment of public IPv4 in this manner. It depends on the ISP and their own policies and pricing (and obviously on the amount of addresses that they have available within their own allocated pools).
Since the advent of IPv4 exhaustion in each of the RIR regions, most have adopted rules (policies) allowing IPv4 address blocks to be transferred between consenting parties, under specific conditions. In some cases, and under specific conditions, transfers may be obtained from another RIR region (for instance a transfer may occur between the ARIN region and the APNIC region).
The primary condition for a transfer is that the parties (source and recipient) both consent to the transfer, however, the RIR(s) involved take no part in the transaction, which may be on commercial terms. There are ‘brokers’ operating in the IPv4 market who can locate sellers and/or buyers, and provide advice on pricing and availability of IPv4 transfers.
It’s time for IPv6
The ultimate solution to IPv4 exhaustion is, of course, the complete transition of the Internet to IPv6, however, this will take time and until then there will be (by definition) networks and sites that only support IPv4. This requires other networks and sites, even if they support IPv6, to maintain IPv4 connectivity, which in turn requires some number of IPv4 addresses. For that reason, IPv4 exhaustion certainly is an issue to be understood and dealt with, especially by those who are building new networks and services.
The views expressed by the authors of this blog are their own and do not necessarily reflect the views of APNIC. Please note a Code of Conduct applies to this blog.