QUIC traffic throttled on AT&T residential

Thu Feb 20 16:34:46 UTC 2020

On Thu, Feb 20, 2020 at 10:19 AM Blake Hudson <blake at ispn.net> wrote:

>
>
> On 2/19/2020 3:21 PM, Daniel Sterling wrote:
> > On Wed, Feb 19, 2020 at 3:34 PM Blake Hudson <blake at ispn.net> wrote:
> >> Yeah, that was a nice surprise to find that my tethered LTE connection
> >> was out performing my wired cable modem service. Of course, I had
> >> already signed up for a year of service and there were early termination
> >> fees for cancelling... that and there are no other wireline providers
> >> available at my home (not even ATT).
> > So we're left with some questions:
> >
> > 1. It's clear I'm not the only one experiencing this issue. How
> > widespread is this problem, really? Has it gotten rather worse over
> > the past ~year?
> >
> > 2. Are customers of larger ISPs much more impacted than customers of
> > smaller ones that (assumedly) don't have to deprioritize UDP so much?
> > 2a. If users *are* impacted, as Blake notes, they may not be able to
> > switch ISPs to improve their lot.. will customers complain to their
> > ISP or to Google?
> >
> > 3. How much worse is the problem when using v4 UDP QUIC vs v6? If QUIC
> > only works on v6 (and if it in fact continues to actively BREAK
> > v4-only users), then is this v6's "killer app" that will drive
> > adoption?
> > 3a. Or will this issue hinder HTTP/3 deployment (or cause mass
> > blocking of UDP on clients)?
> >
> > 4. Will ISPs be willing to give UDP traffic higher priority to improve
> > user experience? Will that only happen once HTTP/3 is widely deployed?
> >
> > 5. We can only assume Google is aware of this issue; will Google work
> > to improve QUIC fallback to TCP, or will they work with ISPs to get
> > QUIC (esp v4 QUIC) prioritized, or will they do nothing, or will they
> > actively encourage QUIC to break v4 at the expensive of current user
> > experience?
> > 5a. Will another company that wants HTTP/3 to succeed take the mantle
> > and work with ISPs to improve the situation? I'm reminded of when
> > Microsoft worked with ISPs to ensure xbox UDP traffic would transit
> > properly
> >
> > -- Dan
> Dan, my experience with Cox is that their standard cable internet
> package (advertised as 150Mbps) rate limits UDP to ~10Mbps. This appears
> to be controlled via the cable modem config file which is enforced by
> both the cable modem and the CMTS. I do not know if this is per flow or
> per circuit or affects IP4 differently than IP6. I suspect that someone
> at Cox decided that the only applications using UDP were VoIP and DNS
> and that those applications never needed more than 1Mbps so anything
> else must be "bad" and should be stopped. Whether "bad" means harmful to
> network operation, harmful to support costs, or harmful to profits, I do
> not know.
>
> Your comments seem to differentiate IP4 vs IP6, but I don't believe that
> is relevant to the issue of an ISP throttling or breaking specific
> applications. If you have evidence that UDP on IP4 is treated
> differently than UDP on IP6 by your provider, without further
> information I would suspect that this is simply an unintentional over
> sight on their part.

This is your misunderstanding. The protections are to drop ipv4 udp because
that is where the ddos / iot trash is , not v6.... for now

>
>
> Perhaps the attention you've generated on this topic, along with the
> adoption of additional UDP based applications like QUIC, will encourage
> ISPs to treat UDP in a more neutral manner and not simply see UDP as
> something that is "bad".
>

Dropping udp is not from a “best practice” doc from a vendor, it is
deployed by network ops folks that are trying to sleep at night.

> --Blake
>
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