As far as CoDel is concerned, we could have two stages of control : The current one, to mark/drop packet as specified by Kathleen & Van
Then, for marked (ecn) packets, pass a second codel stage, but dropping packets this time, to make sure we dont allow queue to become too large. On Sun, 2012-08-05 at 09:53 -0700, Andrew McGregor wrote: > Well, there's a lot of people at the IETF who really want to do other things > with ECN, but it seems like the simple version is far too aggressive. > > So, I think the desirable properties are something like: > 1) Allow ECN flows to achieve the same or slightly higher throughput to > maintain an incentive to deploy it. > 2) Still drop ECN flows eventually to avoid too much queue buildup. > 3) Account somehow for the fact that marking takes longer to control the > queue (but we don't know how much longer). > > Maybe mark ECN instead of dropping, but if we end up trying to mark/drop > twice in one round, drop the later packets? > > Oh, and ECN nonce deployment is negligible, to the extent that there are > proposals in the IETF to reuse the bits for other things, and there is no > pushback on that. > > Andrew > > On 4/08/2012, at 10:30 PM, Eric Dumazet <[email protected]> wrote: > > > On Sat, 2012-08-04 at 20:06 -0700, Andrew McGregor wrote: > >> Well, thanks Eric for trying it. > >> > >> Hmm. How was I that wrong? Because I was supporting that idea. > >> > >> Time to think. > > > > No problem Andrew ;) > > > > Its seems ECN is not well enough understood. > > > > ECN marking a packet has the same effect for the sender : reducing cwnd > > exactly like a packet drop. Only difference is avoiding the > > retransmit[s]. > > > > It cannot be used only to send a 'small' warning, while other competing > > non ECN flows have no signal. > > > > As far as packet schedulers are concerned, there should be no difference > > in ECN marking and dropping a packet. I believe linux packet schedulers > > are fine in this area. > > > > Now, there are fundamental issues with ECN itself, out of Codel scope, > > thats for sure. > > > > How widely has been RFC 3540 deployed, anybody knows ? > > > > > > > _______________________________________________ Codel mailing list [email protected] https://lists.bufferbloat.net/listinfo/codel
