On Tue, 4 Aug 2015, Bob Briscoe wrote:
*Combining ECT(0) and CE with a globally assigned DSCP solely during initial deployment of L4S seems the least worst choice.
Having the same bits in the header mean different things in combination with DSCP seems like a really hard to get deployed Internet-wide.
ECN is just now gaining traction and seems like it might actually see real deployment. Repurposing those bits just now would most likely just cause confusion.
I started using ECN when it first appeared in the Linux kernel around 2001 or whenever it was. I had to immediately turn it off because some firewalls dropped those packets. Now almost 15 years later after this sitting in the operating systems for at least 10 years, we're now getting to a point where we're ready to start turning it on widely because things do not break when it's turned on.
So whatever you come up with now that requires host stack changes, expect 5-10 years at least until it can be deployed. This means you have to be really sure this is what you actually want before you start to push for deployment. Also, deployment impacts should be taken a lot into account when deciding what to do.
So how sure are you that L4S as it currently stands is the way to go? If you think you're going to invent something new in 2-3 years, then please wait until then. Experimentation is all fine and dandy, but until we can actually get DSCP codepoints working on Internet-wide scale, this approach isn't feasable for that use-case (which for me is close to "the only" use-case).
My proposal has been before that we should try to get 7 DSCP codepoints deployed by using 000xxx, and nudge providers to incrementally just not bleach them and treat them as BE in their core networks, so we can use them on the edge to influence AQM there.
So, if we're going to invent new meaning of ECN bits in combination with DSCP, then that needs to be coupled with work of getting some DSCP working Internet-wide in a fashion that someone actually believes will work out, as in actually getting significant Internet-wide deployment.
-- Mikael Abrahamsson email: swm...@swm.pp.se _______________________________________________ aqm mailing list aqm@ietf.org https://www.ietf.org/mailman/listinfo/aqm
