When ISPs start expanding their network to reach unserved subscribers, homes, or businesses, they may quickly run into a roadblock they hadn’t budgeted for: a lack of IPv4 addresses. IPv4 exhaustion has been a topic of discussion in the industry for over two decades, and it is a technical issue that larger service providers have already addressed with a combination of IPv6, CGNAT, dual-stack, and IPv4-IPv6 transition strategies.
However, for many smaller ISPs with limited budgets, resources, or prior opportunity for significant subscriber growth, the influx of significant funding may be the first opportunity they have had to reassess their core network requirements, including the capacity of their existing IPv4 address pools and a plan to eventually transition to IPv6.
A proper five-year business analysis of the benefits and drawbacks of the IPv4/IPv6 transition is a daunting task with several significant but highly unpredictable variables. While the number of additional subscribers/homes passed each year is fairly predictable, the volume and type of traffic generated is not. Furthermore, while additional IPv6 addresses are mostly “free” via Regional Internet Registries (RIRs), the cost and availability of IPv4 address blocks are determined by hot market supply/demand via third-party brokers. In the last year, the cost of an IPv4 address has risen to $60. A reasonable business cost estimation must account for several highly unpredictable variables:
These are some of the key factors that must be addressed for any credible analysis.
A10 recently released a quick assessment tool that enables network analysts and their management to structure some of the uncertainties associated with IPv4 cost analysis. The IPv4 Address Cost Estimator is an interactive online tool that estimates subscribers that can be supported based on two different traffic profiles and provides three potential IPv4 cost scenarios. The model’s inputs and assumptions are based on actual industry data. Using this tool, the network analyst will be able to quickly assess a variety of IPv4 cost scenarios and gain a better understanding of how they should proceed. A sales consultation can also provide a more personalized, in-depth assessment.
The Regional Internet Registries’ (RIRs’) “free” IPv4 addresses have now been fully allocated. Almost every block is now assigned to an entity. In November 2019, RIPE (the Regional Internet Registry for Europe, the Middle East, and parts of Central Asia) assigned its final 22-block assignment. As a result, IPv4 addresses are in short supply and have skyrocketed in price on the open market.
The open market “price” of an IPv4 address in a 256 address block (/24) in North America in 2021 increased from $25 in January to $60 in late November. In the first four months of 2022, the price ranged between $50 and $55. What should an ISP expect to pay to acquire more IPv4 addresses in order to sustain growth in the coming years? Will the current rate of price growth continue for the next five years, or has it “topped out” and will only increase marginally?
The A10 IPv4 Address Cost Estimator tool provides three plausible cost scenarios for estimating future IPv4 acquisition costs. It then computes the total cost of acquiring these IPv4 addresses over the next five years, based on the subscriber growth and price scenario selected.
It is assumed in these three scenarios that the service provider can expect to be paid the average cost rather than the highest peak price.
The A10 IPv4 Address Cost Estimator tool does not provide an additional worst-case scenario. That is, a service provider attempting to obtain additional IPv4 addresses quickly is forced to pay the “peak” price at the time. If this is the case, the price could start at more than $60 in 2022 and rise by 25% per year to $183 in 2026.
Technically, IP addresses cannot be bought or sold. According to the American Registry of Internet Numbers (ARIN), IPs are not purchased or sold but rather exchanged between two organizations. Organizations in possession of RIR-allocated IP addresses essentially transfer the rights to use and register those addresses to other organizations. IP addresses can be transferred for a one-time fee or leased for a specified period (e.g., monthly). IP addresses are transferred in blocks, usually through a broker and a bidding process. In addition to the costs for the IP blocks themselves, which vary by size of the block and other supply/demand factors, there are RIR transfer fees that vary by RIR.
CGNAT enables oversubscription of IPv4 addresses. Multiple subscribers can share the same public IPv4 address. As there is a practical limit to how many private IP addresses can be supported by a single public IP address, defining that limit is an open question with many variables.
The amount of oversubscription, or the number of IPv4 addresses required to support the subscriber base, is driven by:
The A10 IPv4 Address Cost Estimator tool supports two types of traffic: wireline and mobile. These profiles are based on best practices from live service provider networks that have used A10 Thunder CGN to deploy CGNAT. Because of the greater number of applications that sync and update on a mobile phone, mobile networks typically have lower oversubscription levels than wireline networks.
Service providers that have not yet deployed CGNAT often find that their existing allocation of IPv4 addresses are more than enough to meet five-year subscriber growth forecasts. The A10 IPv4 Address Cost Estimator tool also calculates the total number of excess IPv4 addresses using CGNAT and how many total subscribers could be supported.
With CGNAT, operators can avoid the cost of acquiring additional IPv4 addresses and still sustain growth. In addition, if the operator determines that there are unused blocks, these can be sold or transferred through an IPv4 broker or the RIR.
The alternative to IPv4 exhaustion and acquiring additional IPv4 addresses is, of course, to use the newer IPv6 standard. However, many organizations simply cannot justify the short-term cost and disruption of an IPv6 data center and network change-out. IPv6 adoption is both costly and time consuming. Every connected device must be inventoried and replaced or reconfigured. There is a chance that a required device or application will fail and cause service disruption, which will take time to troubleshoot and repair.
Many times, customer equipment is older and not compatible with IPv6, and the replacement cost too high. Balanced against the daily operational demands they face, as well as the need to move forward on strategic initiatives like 5G, cloud, virtualization, edge cloud, and others, administrators may need to delay IPv6 conversion in the short term.
Global IPv6 adoption will not happen overnight. To provide a complete IPv6 service, each link in the chain, from the end user to the carrier to the content provider, must be running IPv6. In reality, not all three links in the IPv6 chain will switch to IPv6 at the same time. IPv6 will almost certainly never be completely adopted. As a result, for the foreseeable future, most organizations, including communications service providers of all technologies and sizes, will need to support both IPv4 and IPv6 for some amount of traffic and subscribers.
Service providers must anticipate the challenges posed by IPv4 exhaustion, IPv6 adoption, and IPv6 migration, as well as the impact on the cost of adding new subscribers. Service providers must use caution when implementing CGNAT, addressing the immediate issue of IPv4 exhaustion while planning for an eventual transition to IPv6.
The most advanced carrier-grade networking solution, A10 Networks Thunder® CGN, provides high-performance CGNAT with protocol conversion, allowing communications service providers and enterprises to extend IPv4 investment while transitioning to IPv6 standards.
