Hi Ole,
On 11/7/2025 11:19 AM, Ole Troan via lists.fd.io wrote:
Hi,
This behaviour is intended. As in, "working as designed".
But we can argue if it’s correct or particularly useful. It’s for an isolated
NAT64 instance, where all traffic you’d send to it is expected to be translated.
Let me argue that this behavior is not always the best. When you operate
a stateful NAT64 gateway, then same device can be a router for native
IPv6 traffic and a NAT64 gateway for the traffic to be translated to IPv4.
In its Section 5.3. RFC 8219 writes regarding the benchmarking of such
devices:
Considering that a transition technology could process both native
IPv6 traffic and translated/encapsulated traffic, the following
traffic setups are recommended:
i) IPvX only traffic (where the IPvX traffic is to be
translated/encapsulated by the DUT)
ii) 90% IPvX traffic and 10% IPvY native traffic
iii) 50% IPvX traffic and 50% IPvY native traffic
iv) 10% IPvX traffic and 90% IPvY native traffic
Source: https://datatracker.ietf.org/doc/html/rfc8219#section-5.3
I think that I already should have reported you that when Ahmed, my PhD
student, benchmarked FD.io VPP MAP-E implementation, he was not able to
use native IPv6 traffic, because FD.io VPP attempted to decapsulate all
IPv6 packets even if the did not contain an IPv4 packet and thus such
packets were dropped.
All the details can be found in his (open access) paper: A. Al-hamadani,
and G. Lencse, "Benchmarking the Mapping of Address and Port with
Encapsulation Border Relay Routers", /IEEE Access/, vol. 13. pp.
124628-124650, July 2025. DOI: https://doi.org/10.1109/ACCESS.2025.3587302
So I think it would be useful to enable FD.io VPP to distinguish the
packets to be translated/decapsulated from the native IPv6 packets that
only need to be routed.
What do you think?
Best regards,
Gábor
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