[Lightning-dev] Forwarding hints in channel update messages

[Rusty Russell]

Joost Jager <joost.jager at gmail.com> writes:
> Hello all,
>
> I'd like to bring up an idea that builds on top of "non-strict" forwarding.
> I commented about this on conner's non-strict forwarding lightning-rfc pr,
> but it is probably better to discuss it on its own in this list.

The decision was made to allow additional channel_update in the error
reply:

        DECISION: document that scid is not binding, allow extra
        channel_updates in errors for “upselling”.

AFAICT this is a deeply weird case.  If another channel had capacity you
would have just used it.  If another channel doesn't, sending a
channel_update doesn't help.  And if there's a channel available at a
higher feerate or longer timeout, it raises the question of why you're
doing that rather than just taking the offer in front of you; that value
clearly used to be acceptable, and now you risk them routing around you.

Cheers,
Rusty.