Re: [RFC PATCH net-next 0/4] tcp: carry a BPF-chosen identifier in TSval low bits

[Stanislav Fomichev]

On 10/19, Jakub Sitnicki wrote:
> Hey Stan,
> 
> On Thu, Oct 15, 2026 at 02:45 PM -07, Stanislav Fomichev wrote:
> > On 10/13, Willem Ferguson wrote:
> 
> [...]
> 
> >> Questions for reviewers:
> >> 
> >>  1. Is encoding an identifier in the low bits of TSval acceptable in
> >>     principle, given the trade-offs above?
> >>  2. If so, what feedback do you have on the implementation?
> >
> > Don't see any feedback yet, so from the top of my head: looks like you
> > control two sides of the communication, so why not a custom (bpf) tcp option?
> > Would you need that on every packet and it makes it expensive?
> >
> > Or any other field you can abuse maybe? IPv6 Flow label?
> 
> Nah, we don't control the client unfortunately.
> 
> Client here is any device that connects to our edge PoP.

I see, so you rely on the fact that it gets mirrored back.. Btw, looks like
there is already some similar tsoffset/ts_off infra? Have you considered
plugging into that?