Predicting the future is easy. It's trying to figure out what's going on now that's hard.
Fritz R.S. Dressler
This chapter is an attempt to do two things. First, to summarise the current thinking on unresolved issues, so you can make your best guess about how things are likely to turn out in the future. Our summary will present both sides of a case—where we feel they actually exist—and as such, is liable to lose us all the friends we have gained throughout the rest of the book! Second, we deal in some detail with various up-and-coming subject areas where IPv6 uses its features to good effect—for example, how large scale mobility and globally unique addressing can support third generation mobile services (also known as 3G). We do this so that people seeking to understand the traditional telco background or the traditional IETF/Internet components of the 3G puzzle can both benefit.
In this section we'll look at some of the unresolved issues around site-local addresses, anycast, DNS, and multihoming.
Site-local addresses have been an area of hot debate within the IETF IPv6 working groups. Many IPv6 deployments will be able to entirely ignore the site-local address debate, because global addresses adequately serve their needs. Nonetheless, we'll try to explain what the fuss is about.
Anycast is another technology like unicast, multicast and broadcast. The details of anycast in IPv6 have not yet been sorted out. It is not as emotive a subject as site-locals, ...