Re: Ideas for IPv6 BGP and tunnelling

[Ole Troan <otroan@employees.org>]

Adrian,

[...]

>> I don't recall why that never became an RFC.
>
> That is exactly what I am talking about.
>
> It uses "The IPv4-mapped IPv6 address is defined in [V6ADDR]" as the
> next hop. That means ::FFFF:x.x.x.x as an IPv4 address.
>
> What is not clear to me is what this the best practice and workable IPv6
> next hop to specify. Seems to me it could be:-
>
> ::x.x.x.x
> ::FFFF:x.x.x.x
> 2002:xxxx:xxxx::
>
> The latter seems to express that we want to use simple protocol 41 IPv6
> over IPv4 tunnelling. The first two seem to me to just indicate an IPv4
> address as the next hop without saying how the traffic is to be sent to
> it (e.g. GRE, protocol 41, whatever).
>
> Do we need an RFC on this?
>
> FYI, I'll make our routers understand any of the above as a next hop to
> send over protocol 41 when received, but need to know what I should used
> when generating this as a next hop to send.

I believe you have to pick either ::x.x.x.x if you want to use IPv4
compatible automatic tunnelling or 2002:x.x.x.x:: for 6to4. the first
mechanism has been deprecated for a number of years, so I'd recommend
6to4. but it is basically an operational choice.

using a 6to4 address also implies how traffic is sent.

cheers,
Ole