Re: [RRG] Six/One Router Design Clarifications

[Christian Vogt <christian.vogt@nomadiclab.com>]

Brian,

sorry for responding with delay.

I do agree with the disadvantages of translation that you are naming.
But let me re-emphasize that my arguing in favor of translation is on
the basis of this being a deployment tool, not a permanent mechanism.

I believe we agree that, of the three issues with NATs,...

(1) non-unique addresses make it hard to contact hosts behind a NAT

(2) state inside the network prevents re-routing of traffic

(3) non-end-to-end addresses require NAT traversal by applications

...the backwards compatibility mode of Six/One Router avoids the first
two because it is stateless and uses only globally unique addresses.

What remains is issue (3).  I believe we agree that no future routing
architecture should have this issue on a permanent basis.  Where we
disagree is whether the issue is acceptable for backwards compatibility
and deployment.

Lixia has named it:  Whether we deem issue (3) acceptable or not, the
issue will be present in IPv6 anyway because hosts will have to
traverse IPv4/IPv6 NAT-PTs.  The functionality that applications
*require* because of NAT-PTs is exactly the functionality that Six/One
Router's backwards compatibility mode will re-use.

Furthermore, the time period during which NAT-PTs will be needed will
likely outlast the time period during which Six/One Router's backwards
compatibility mode will be used, due to the yet-small deployment of
IPv6 compared to that of IPv4.  (This is a personal opinion, though.)

Brian, I fully understand and agree with the concerns you have with
translation.  Where our opinions differ is the extent to which
translation is acceptable as a deployment aid.

- Christian



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