[c-nsp] IPV6 in general was Re: Large networks

[TJ]

Good evening!


>I read through RFC2373 and it doesn't detail how it works either - it just
>specifies what you can and cannot do.  The main point is that anycast only
>works on routers, not hosts.  I can tell you that the router shows that DAD
>is *not* enabled on either interface.  But, this is interesting.  When I
>ping the ::1 address from one of the PF boxes, the neighbor entry changes
>from "state" to "reach" which seems to indicate that the "reach" router is
>being seen as geographically closer.

2373 is two revisions old, try http://tools.ietf.org/html/rfc4291 ...
amongst other changes, relaxes the whole (quite silly) "router only"
language.  

In principle, yes - anycast is one-to-one-of-many, with the "nearest"
answering.  When they are not on the same link then "nearest" is defined by
the underlying routing topology (with equidistant falling into equal-cost
multi-path, where approp.).  When on the same link, "nearest" usually means
"answers first".

Amongst other things, anycast is used for the DNS root servers that we all
hopefully agree are rather important.  
And for littler things like 6to4 relays.
Or any other time we want some cheap and easy fault-tolerance/redundancy or
better performance + easier configuration by distributing the point of
service.


/TJ