Re: UDP source ports for HTTP/3 and QUIC

[Poul-Henning Kamp <[e-mail]>]

--------
Willy Tarreau writes:

> Stefan made a good point about the problem that might result, with
> inbound load balancing between multiple listeners (typically what's
> achieved by L3 switches doing L3+L4 hash between multiple servers,
> and operating systems hashing the source+destination port to pick a
> different listening socket). Thus a suggestion might be to possibly
> save resources by using a small amount of sockets, with "small" left
> to the appreciation of the implementation.

We should run the question "few or many UDP ports?" past some some
friendly 100G and 400G device driver maintainers.

The NICs I have been working with for the ESO ELT project all
included UDP ports in the hash they used to decide which CPU core
to deliver packets/interrupts to and we had to spread across UDP
ports to or all the traffic would hit one single core.

I dont know if QUIC has registered with the NIC designers and device
drivers writers yet, but given the opacity of QUIC packets, it is
very hard to see what else than the UDP port they can feed into
their hash, so I expect the answer to be "many".

But it would best to ask, and find out how important they think it
will be, and what "many" means for them.

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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