Ipv6 – the Realization of Ipv4 Address Exhaustion

IPv6 – The Realization of IPv4 Address Exhaustion

BY BUCK GRAHAM

APRIL / 2011

Any information in this white paper regarding plans for future product development is based on current expectations and is inherently uncertain. Statements about future product development should not be relied upon in making purchase decisions.

IPV6 – THE REALIZATION OF IPV4 ADDRESS EXHAUSTION

Understanding and Preparing for the IPv6 Transition

In 1995, the hot topic in the IP community was the coming of IPv6. Since then, it has been heralded so many times that it has nearly become passé. The main motivation for IPv6 adoption has always been to remediate the depletion of the IPv4 address space. Fortunately, it has taken 15 years for the IPv6 vision to catch-up to reality. Through a series of innovations, including network address translation and application layer gateways, time was granted to the Internet engineering community that allowed it to evolve the protocols and plan for the cutover. By the time you finish reading this whitepaper, you’ll have a brief appreciation for how difficult it would have been to hastily convert the global Internet to a wholly new protocol stack.

Though long in coming, on January 31, 2011, the Internet Assigned Numbers Authority (IANA) allocated the last large block of IP addresses. This event rippled across the world and created sensational headlines, but the reality is that most people don’t truly understand the immediate and long-term impact of this event.

Initial Reactions to IPv4 Depletion

Let’s assume that you are an IP service provider and even though you’ve known for 15 years that IPv4 address space was nearing depletion, you did nothing to prepare for it. You look at the headlines on February 3rd and you see that IANA’s IPv4 well has run dry. Your business can continue to operate unaffected even though the IPv4 address pool is exhausted. If you need new IP addresses, you can still ask your upstream service provider for another allocation of IPv4 addresses. It’s possible they still have some IPv4 address allocations remaining that they can give to you.

How is it that IANA is out of address space, but that you can get IPv4 addresses from your Internet provider? The answer is that Regional Internet Registries (RIRs) and wholesale ISPs still have IPv4 networks. In fact, the last IPv4 /8 (class A equivalent) networks were allocated to the five Regional Internet Registries, RIPE and ARIN included. Further, wholesale Internet providers have planned for public IP address depletion and have been allocated blocks of addresses based upon their optimistic business trends. As such, there are small caches of IPv4 addresses that remain available for use. Since there are no agencies or organizations that report how much address space they have cached, it is very difficult to say when the largest caches of IPv4 addresses will actually be depleted.

IPV6 – THE REALIZATION OF IPV4 ADDRESS EXHAUSTION

For discussion sake, let’s assume that your public IPv4 addresses have been completely allocated. You ask your upstream Internet provider for more IPv4 addresses and their IPv4 address space is also depleted. You’re now faced with the reality that no new IPv4 addresses can be obtained through the traditional IP address allocation channels. However, like every scarce resource, it’s likely that a market will emerge where IPv4 allocations are bought and sold. We have seen early indications of this with the recent news that the former Nortel Networks IP address blocks are “up for sale” as they continue to sell off assets.

Now, let’s assume that the going rate for an uncut block of portable IPv4 addresses is well outside of your organization’s budget. You can certainly tidy up you IP subnets and you can change some of your DHCP lease policies, but you will get limited mileage out of these address conservation methods. So what’s next? IPv6.

The Transition to IPv6 will be Gradual

When all the public IPv4 addresses are exhausted, you will need to request an allocation of IPv6 addresses that you can use for new subscribers asking for Internet service. However, before you can use new IPv6 addresses, you must make a few procedural decisions and set up additional support infrastructure. For example, it’s likely you will decide to use DHCPv6 for allocation of IPv6 addresses or subnets to your subscribers. You will need to set up the host configuration service and then you should select the supported customer or business premises equipment (DSL modem, residential gateway, etc.) that can be used with IPv6. If you’re lucky, the CPE that you are currently deploying already supports IPv6 or can be upgraded to enable native IPv6 support. You will need to verify that your access equipment will support IPv6 using the same subscriber management processes used for IPv4 subscribers so that the parallel IPv6 network will dovetail smoothly with your existing operational procedures.

Beyond the access network, the access aggregation routers will need to simultaneously support both IPv4 and IPv6 protocol stacks. Integrated within the router software, or deployed in conjunction with the router, will be a NAT64 gateway. This gateway allows IPv6 devices to communicate with the predominately IPv4 Internet by converting packets from IPv6 to IPv4 format. Without this gateway, a subscriber that has been allocated an IPv6 address cannot access a service on the IPv4 Internet even if the services are provided locally. Why? Because many IPv6 subscriber packets will need to traverse a NAT64 gateway to allow their packet traffic to reach “destinations” located on IPv4 networks or IPv4 addressable hardware. It’s unlikely this requirement will go away in this decade because there is a large IPv4 installed base that also requires migration and it will likely take several years to be completed.

IPV6 – THE REALIZATION OF IPV4 ADDRESS EXHAUSTION

Next, you should look at increasing the number of services that natively support IPv6 without requiring a NAT64 gateway. Discuss your options with your upstream service provider and if possible, enable IPv6 routing to the IPv6 Internet. Only a portion of IPv4 hosts have been dual- homed so that they can offer services on the IPv6 network, but many of the big names such as Google (http://www.google.com/intl/en/ipv6/), Facebook, and YouTube have already taken steps to support IPv6. More are being added daily. Local services such as web portals, search engines, and even voice and video need to be dual homed to both IPv4 and IPv6 networks as well. So while the NAT64 gateway is critical for providing a seamless Internet experience for IPv6 subscriber, every effort should be made to enhance native IPv6 services and reduce the amount of traffic crossing the NAT gateway as soon as possible.

Below is a graphic used by the Broadband Forum to explain the migration to IPv6. Note that we have already passed the “IPv4 address pool exhausted” milestone. The next BBF milestone is brought about by the need to support a native IPv6 endpoint such as a handset or a residential gateway.

At some point, marked by milestone labeled “IPv6 Internet,” the IPv6 hosts outnumber the IPv4 hosts and the IPv6 Internet becomes the default network. When this milestone is reached, the majority of hosts are IPv6 and able to communicate and access services without the use of the NAT64 gateway. In fact, the same gateway can now be considered a 4to6 gateway, which would enable legacy IPv4 only hosts to access services on the larger IPv6 Internet. It is conceivable that

IPV6 – THE REALIZATION OF IPV4 ADDRESS EXHAUSTION

the IPv4 Internet would actually be shutdown someday, but the BBF didn’t think it would happen anytime in their foreseeable future.

Develop an IPv6 Plan

As we have explored briefly in this document, the worst-case scenario of public IP address depletion can be survived even if you do nothing to address IPv4 addresses exhaustion until today. However, today would be a good time to begin planning for IPv6 support or look at ways to expand your IPv6 support. Here’s a short list of suggested actions that may help you prepare:

 Talk to your staff. Educate them. Help them to understand the problem at hand.

 Talk to your network component vendors, first mile to last mile. Understand what your limitations are and ask for vendor suggestions.

 Investigate alternatives to components for which there are no plans to support IPv6.

 Talk to your upstream ISP. Understand their plans for IPv6 and when they can give you a native IPv6 connection to their routers. Make sure that they take care of domain name services (DNS) for IPv6. Investigate their ability to host or provide the NAT64 gateway server.

 Begin internal discussions about transitioning to an all IPv6 network perhaps in the 2013 timeframe. Plan DNS and DHCPv6 services. Start the ball rolling to transition network management and back office systems to IPv6.

 Engage Calix Professional Services to accelerate your IPv6 expertise.

 Put together a test bed and get an IPv6 address allocation. Test your assumptions.

Calix and IPv6

Many of the services offered through a Calix access network are implemented using IPv4’s private address space and use layer 2 VLANs for traffic isolation. These are largely unaffected by the transition to IPv6 and are supported today. As you can see from the illustration below, only business and residential Internet access are expected to be offered using IPv6 in the near-term. Eventually, all services will move to IPv6, but because there is no urgency for business and residential consumers to migrate away from private IPv4 addressing / networks, services such as IPTV and softswitch-based voice can be converted to IPv6 in a slow and deliberate manner.

IPV6 – THE REALIZATION OF IPV4 ADDRESS EXHAUSTION

Calix IPv6 plans are aligned with the Broadband Forum’s vision of the Internet transition as illustrated in the diagram above. The Calix B-, C-, and E-Series platforms primarily use Layer 2 for network connectivity, while utilizing modern chipsets capable of supporting IPv4 and IPv6, facilitating a smooth service delivery migration to IPv6. Calix subscriber management will be available to provide the same high performance network and subscriber security / traceability for an IPv6 subscriber / endpoint as is currently available to an IPv4 subscriber / endpoint. In order to ensure an orderly IPv6 transition, subscriber management support is planned as a phased software upgrade. Central to this release is Lightweight DHCP Relay Agent (LDRA), the IPv6 equivalent to IPv4’s DHCP option 82 relay function.

In a similar manner, the network management plane will evolve and will eventually require IPv6; but due to the variety of 3rd party legacy network devices that may never be upgraded to IPv6, the management network will remain predominately IPv4. This simplifies network management, ensures stability, and maintains accessibility. Only after a great deal of testing with back office systems, including service activation and billing systems, should the network management plane be cut over to IPv6.

Calix offers Professional Services to help plan, test, and operationalize IPv6 in your network. Experienced engineers are available to rapidly work through your deployment issues and quickly ramp up your technical staff’s expertise.

IPV6 – THE REALIZATION OF IPV4 ADDRESS EXHAUSTION

Conclusion

While it is uncertain when the IPv4 address space will truly become irrelevant, Calix has been ahead of the IPv6 curve since our first day of business. The decisions to use IP over Ethernet and to augment the benefits of connectionless packet services – with powerful per-VLAN IP subscriber management functions at the subscriber edge of the access network – make seamless IPv4 / IPv6 support simple and straightforward.