25 November, 2010

IPv6: The Impact on Users

Geoff Huston has written a brilliant article on "IPv6 and Transitional Myths".

On the topic of how IPv6 will impact the user community he writes:

"Myth:  It's just a change of a protocol code. Users won't see any difference in the transition."
If only that were true!

In an open market environment scarcity is invariably reflected in price. For as long as this transition lasts this industry is going to have to equip new networks and new services with IPv4 addresses, and the greater the scarcity pressure on IPv4 addresses the greater the scarcity price of IPv4 addresses. Such a price escalation of an essential good is never a desirable outcome, and while there are a number of possible measures that can be taken that would be intended to mitigate, to some extent or other, the scarcity pressure and the attendant price escalation, there is still a reasonable expectation of some level of price pressure on IPv4 addresses as a direct outcome of scarcity pressure.

In addition, an ISP many not be able to rely solely on customer-owned and operated NATs to locally mask out some of the incremental costs of IPv4 address scarcity. It is likely, and increasingly so the longer the transition takes, that the ISP will also have to operate NATs. The attendant capital and operational costs of such additional network functionality will, ultimately be a cost that is borne by the service provider's customer base during the transition.

But it's not just price that is impacted by this transition. The performance of the network may be impacted during the transition. Today a connection across the internet is typically made by using the DNS to translate a name to an equivalent IP address, then launching connection establishment packet (or the entire query in the case of UDP) to the address in question. But such an operation assumes a uniform single protocol. In a transition world you can no longer simply assume that everything is contactable via a single protocol, and it is necessary to extend the DNS query to two queries, one for IPv4 and one for IPv6. The client then needs to select which protocol to use if the DNS returns addresses in both protocols. And then there is the tricky issue of failover. If the initial packet fails to elicit a response within some parameter of retries and timeouts, then the client will attempt to connect using the other protocol with the same set of retries and timeouts. In a dual stack transitional world not only does failure take more time to recognise, but even partial failure make take time.

So users may see some changes in the Internet. They may be exposed to higher prices that reflect the higher costs of operating the service, and then may see some instances where the network simply starts to appear "sluggish" in response.

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