When I first started reading about IPv6, seeing what appeared to be incomplete addresses where x’s had been put in the address in place of the actual hex address made things a little confusing at times to keep up with. In building up my library of IPv6 reading materials, I came across RFC3849 (http://tools.ietf.org/html/rfc3849), I have read this RFC several times and each time I go over it, I pick up another tidbit or two. The reason behind “reserving” a range or prefix is that if a lesser experienced person is using a configuration example without changing any of the addresses using in the example, they wont cause a problem either on their network or cause one or more routes to flap elsewhere with their provider or on the internet.
The reserved prefix to use when writing documentation is 2001:0db8::/32. For those that are just getting started, the address that you would use might look something like this – 2001:0db8:baba:0000:0000:baba:1310:face. I still think in terms of IPv4 addresses, so learning the “shorthand” used with the longer IPv6 addresses will take some getting used to. Another post I am working on will be a collection of addresses I am building to be able to see on site whether an address is good or not. I have been looking for something like this as I have been reading up on IPv6 and havent quite found what I am looking for, so this will be something that I will contribute to other IPv6 newbies such as myself.