Re: Discussion of the Home/SOHO environment

[Remi Denis-Courmont <rdenis@simphalempin.com>]

On Fri, 04 Jan 2008 17:51:38 +1300, Brian E Carpenter

<brian.e.carpenter@gmail.com> wrote:

> On 2008-01-04 15:45, james woodyatt wrote:

> ...

>> + Customers with public IPv4 addresses get satisfactory 6to4 relay

> service.

> 

> That's presumably a requirement on the ISP. The requirement

> on the CPE is to act as a 6to4 router, i.e. implement RFC 3056.



I am very much mixed on this.

Yes, implementing a zero-configuration 6to4 relay on the CPE, if:

- it has a public IPv4 address, and

- it has native IPv6

will improve connectivity a lot... if 6to4 actually works.



I have seen several different networks where you get public IPv4

addresses, yet 6to4 does not work properly:

- because proto-41 is black-holed by the ISP, and/or

- because of stateful firewalling.



The second bullet is a minor issue for a 6to4 relay, but it is

a critical issue for a 6to4 gateway. Another argument against

zero-configuration 6to4 gateways is that you cannot check

whether the anycast relay actually works at the other end.



Unless we invent some kind of sanity checks for automatic

RFC3056, I'd rather CPEs avoid doing this by default...



With Teredo, these relaying issues mostly don't exist because

it has some kind of connectivity checks, but it comes at a

significant higher complexity from the CPE.



-- 

Rémi