grout use-cases for host traffic

[Robin Jarry]

Christoph, May 23, 2026 at 21:29:
> Will there be documentation / guides on how to configure host traffic 
> termination?

End-user and developer documentation is certainly lacking at the moment
as Morten gracefully noted ;)

https://github.com/DPDK/grout/issues/3#issuecomment-4528553554

We have a lot on our plates these days, but I agree it would help to
have something easy to consume to help newcomers. I will see if I can
put something in place so that people can enrich it as they go.

> Yes we are looking at high bandwidth use cases (>10Gbps).

Then, do not use grout as direct termination (for now).

> Since frr (bgp)/grout is expected to decide where to route the traffic 
> (which grout interface), this can't be done using a separate non-grout 
> interface on the same system, correct? So we would use the TUN/TAP setup 
> I guess or am I missing something? :)

You can do it by spitting your physical NIC in multiple VFs and exposing
only one to the outside world. Hiding the others behind for local Linux
use. See
https://hosted-files.sched.co/dpdksummit2026/75/grout-dpdk-summit-2026.pdf
(slide 11) for more details.

Grout was designed to be good at *forwarding* traffic. Local TCP/UDP
termination was added for low bandwidth use-cases (BGP/OSPF/ISIS).

Being better than Linux at *terminating* traffic (especially TCP) is
hard. The challenge is matching the level of batching and tweaks that
were added in the Linux TCP stack (end-to-end TSO mainly).

What are you planning to use grout for? Could you describe your topology
and use-case?

Cheers,

-- 
Robin

> Processed at location stamped in code at top of carton.