Re: [quicwg/base-drafts] When the sender is using standard Reno congestion control, ack every ~2 packets (#1428)

[janaiyengar <[e-mail]>]

The Reno spec is a simple CC for those senders who need something simple and reasonably effective to implement on the send side. I don't think we can afford to specify a receiver that assumes only Reno senders though. Given that senders (such as Google's servers, for instance) will use non-Reno CCs right off the ground, we would want receivers to do something better than simply ack every two packets right off the ground.

Any sender should be adaptive to this, but it's useful to have a knob by which we can control receiver behavior and reduce the number of ACK-only packets that are being sent on the wire. The point of acking every other packet is basically an attempt to reduce the number of ACK-only packets, and we ought to be able to make it more generalizable.

As I mentioned in my earlier comment, I think the sender can specify something like:
ack_ratio: number of retransmittable packets received after which an ack must be sent. 2 by default.

We can also additionally have an ack_delay param that the receiver tells the sender about, but I think that can be a separate issue (and there's already #981).

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/issues/1428#issuecomment-396419114