[arin-ppml] Why are ISPs allowed?

[Randy Bush]

> NAT breaks lots of things.  In addition to the obvious (p2p, services)
> it breaks native IPSec and ipip tunnels (6to4 and static IPv6 tunnels).
> There are many applications like FTP that break in various ways
> depending on how good/bad the hacks in the NAT box are.  There will be
> applications that NAT vendors have never heard of.  Google "nat breaks"
> for some other examples.

i just had a depressing private email exchange with your small and 
partially-clued isp.  they felt that v4/v4/v4/v4 nat was the way to go 
because it was easier for them and easier for the customer.  all i could 
say was that 'easier' might not be considering the customer support costs.

the v6 end user experience today is not great.  vendor support is 
mediocre, both for dual stack and for transition tools (siit/nat-pt). 
and the global infrastructure is often tunneled and tromboned. neither 
of these will be really fixed until there is financial pressure behind 
them.  the market, not the mailing lists, rules.

randy