The obvious benefit to this type of solution is the fact that a single IPv4 address can support thousands of customer subscribers, drastically increasing the usable life of IPv4. So what's the problem? If ISPs are ensuring their IPv6 subscribers will still have IPv4 connectivity for the foreseeable future through this dual-stack scheme using shared IPv4 addresses, why do you need to get your organization's content on the IPv6 Internet anytime soon?

To answer that question, we have to look more closely at this LSN technology and ask ourselves if it will introduce problems as clients try to connect to your systems. And, indeed, in many circumstances we see this is the case. These problems can be broken down into three categories:

1. Functional: there is no guarantee that ISPs LSN solutions will work with your application. And the fact that each ISP may deploy different LSN solutions from different vendors means that you have no reasonable way of testing every possible technology. The result could be your application not working properly with potentially large swaths of the world population.

2. Performance: LSN solutions, just like traditional NAT solutions, maintain a state table for flows that traverse the device. Every packet that flows through the device triggers a lookup in the state table. Do you see a problem here? In fact there are several.