RE: Robustness to packet reordering

[Floris Bruynooghe <[e-mail]>]

On Thu 06 Feb 2025 at 09:34 +0000, Ingemar Johansson S wrote:

> OK, so that means that time based loss detection is not yet
> implemented in QUIC stacks, or ?
>
> The reason I ask is that we poll the interest in the support for out
> of order delivery of packets in 5G. The outline is that we ensure in
> order delivery for up to some given milliseconds, to handle possible
> HARQ retransmissions on the MAC layer. Beyond that we forward packets
> as they are processed by the radio stack.
>
> The rationale behind this is to avoid that packets for latency
> sensitive flows (streams) are delayed more than necessary if they
> share the same data radio bearer as other streams.
>
> We see that TCP Linux is robust to packet reordering (up to 1 RTT
> reordering depth) and fast retransmits are avoided (except in the
> initial phase when the reordering window grows). Thus I wonder if
> there are plans to make also QUIC stacks support time based RACK?

I think you're asking for this:
https://www.rfc-editor.org/rfc/rfc9002.html#name-time-threshold ?

Though I'm not sure what stack *actually* implement.

Cheers,
Floris