Cost of Running an IPv4 Network Will Increase

Operating an IPv4 network will become increasingly costly and make IPv6 more attractive

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IPv6 will make things easier because /64 will be the default prefix length for just about every type of link. There will be the occasional other prefix lengths for individual networks, but /64s will the dominant subnet size. There have been extensive discussion of /112, /126, /127, /128 (loopbacks and host routes). The use of /127 prefix lengths were originally considered a bad idea but now we are realizing there may be advantages to using them.

Operating a Dual Protocol Network

As we transition to IPv6, running a dual protocol network will be the dominant transition strategy. You will dual stack where you can and tunnel where you must. However, for many years you will need to maintain both an IPv4 and an IPv6 environment. This will add to the administrative burden of operating a network, systems, applications, and security systems. Everything that has an IPv4 address today will likely have both an IPv4 and an IPv6 address for many years. That means there will be twice as many things to configure. You will need to maintain twice the information in DNS and DHCP/DHCPv6. You will need to maintain twice the configuration information in routers, switches and servers. You will have to maintain two different firewall policies and maintain IPS signatures for each protocol. You will need to convert your IPv4-only applications to address-family independent applications and maintain that dual-stack code for many years. Having a router that holds both the IPv4 and IPv6 routing tables will add CPU and memory overhead for many years. All this will add to the cost of running a dual-protocol network. Therefore, the faster we can move to an IPv6-only environment the sooner we can realize the benefits of IPv6 and the cost savings. However, that day is a long way away.


As the costs of running an IPv4 network increase, organizations will start to see IPv6 as a more attractive solution. However, for the foreseeable future, most organizations will run both IPv6 and IPv4 and the decommissioning of IPv4 networks is a long way off. The real question is if we can even make it to IPv6 while the cost of operating IPv4 networks continue to rise. The effort we will have to put into operating networks with IPv4 will distract us from putting effort into making progress toward IPv6.


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Copyright © 2011 IDG Communications, Inc.

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