On Thu, Mar 19, 2015 at 3:58 PM, Livingood, Jason <Jason_Livingood@cable.comcast.com> wrote:

On 3/19/15, 1:11 PM, "Dave Taht" <dave.taht@gmail.com> wrote:

>On Thu, Mar 19, 2015 at 6:53 AM, <dpreed@reed.com> wrote:
>> How many years has it been since Comcast said they were going to fix
>>bufferbloat in their network within a year?

I¹m not sure anyone ever said it¹d take a year. If someone did (even if it
was me) then it was in the days when the problem appeared less complicated
than it is and I apologize for that. Let¹s face it - the problem is
complex and the software that has to be fixed is everywhere. As I said
about IPv6: if it were easy, it¹d be done by now. ;-)

I think this was the hope that the buffer size control feature in Docsis could at least be used to cut bufferbloat down to the "traditional" 100ms level, as I remember the sequence of events. But reality intervened: buggy implementations by too many vendors, is what I remember hearing from Rich Woundy.

>>It's almost as if the cable companies don't want OTT video or
>>simultaneous FTP and interactive gaming to work. Of course not. They'd
>>never do that.

Sorry, but that seems a bit unfair. It flies in the face of what we have
done and are doing. We¹ve underwritten some of Dave¹s work, we got
CableLabs to underwrite AQM work, and I personally pushed like heck to get
AQM built into the default D3.1 spec (had CTO-level awareness & support,
and was due to Greg White¹s work at CableLabs). We are starting to field
test D3.1 gear now, by the way. We made some bad bets too, such as trying
to underwrite an OpenWRT-related program with ISC, but not every tactic
will always be a winner.

As for existing D3.0 gear, it¹s not for lack of trying. Has any DOCSIS
network of any scale in the world solved it? If so, I have something to
use to learn from and apply here at Comcast - and I¹d **love** an
introduction to someone who has so I can get this info.

But usually there are rational explanations for why something is still not
done. One of them is that the at-scale operational issues are more
complicated that some people realize. And there is always a case of
prioritization - meaning things like running out of IPv4 addresses and not
having service trump more subtle things like buffer bloat (and the effort
to get vendors to support v6 has been tremendous).

>I do understand there are strong forces against us, especially in the USA.

I¹m not sure there are any forces against this issue. It¹s more a question
of awareness - it is not apparent it is more urgent than other work in
everyone¹s backlog. For example, the number of ISP customers even aware of
buffer bloat is probably 0.001%; if customers aren¹t asking for it, the
product managers have a tough time arguing to prioritize buffer bloat work
over new feature X or Y.

I agree with Jason on this one. We have to take bufferbloat mainstream to generate "market pull". I've been reluctant in the past before we had solutions in hand: very early in this quest, Dave Clark noted:

"Yelling fire without having the exits marked" could be counter productive. I think we have the exits marked now. Time to yell "Fire".

Even when you get to engineers in the organizations who build the equipment, it's hard. First you have to explain that "more is not better", and "some packet loss is good for you".

Day to day market pressures for other features mean that:

1) many/most of the engineers

don't see that as what they need to do in the next quarter/year.

2) their management don't see that working on it should take any of their time. It won't help them sell the next set of gear.

***So we have to generate demand from the market.***

Now, I can see a couple ways to do this:

1) help expose the problem, preferably in a dead simple way that everyone sees. If we can get Ookla to add a simple test to their test system, this would be a good start. If not, other test sites are needed. Nice as Netalyzer is, it a) tops out around 20Mbps, and b) buries the buffering results among 50 other numbers.

2) Markets such as gaming are large, and very latency sensitive. Even better, lots of geeks hang out there. So investing in educating that submarket may help pull things through the system overall.

3) Competitive pressures can be very helpful: but this requires at least one significant player in each product category to "get it". So these are currently slow falling dominoes.

One suggestion I have made to increase awareness is that there be a nice,
web-based, consumer-friendly latency under load / bloat test that you
could get people to run as they do speed tests today. (If someone thinks
they can actually deliver this, I will try to fund it - ping me off-list.)
I also think a better job can be done explaining buffer bloat - it¹s hard
to make an Œelevator pitch¹ about it.

Yeah, the elevator pitch is hard, since a number of things around bufferbloat are counter intuitive. I know, I've tried, and not really succeeded. The best kinds of metaphors have been traffic related ("building parking lots at all the bottlenecks"), and explanations like "packet loss is how the Internet enforces speed limits" http://www.circleid.com/posts/20150228_packet_loss_how_the_internet_enforces_speed_limits/.

It reminds me a bit of IPv6 several years ago. Rather than saying in
essence Œyou operators are dummies¹ for not already fixing this, maybe
assume the engineers all Œget it¹ and what to do it.

Many/most practicing engineers are still unaware of it, or if they have heard the word bufferbloat, still don't "get it" that they see bufferbloat's effects all the time.

Because we really do
get it and want to do something about it. Then ask those operators what
they need to convince their leadership and their suppliers and product
managers and whomever else that it needs to be resourced more effectively
(see above for example).

We¹re at least part of the way there in DOCSIS networks. It is in D3.1 by
default, and we¹re starting trials now. And probably within 18-24 months
we won¹t buy any DOCSIS CPE that is not 3.1.

The question for me is how and when to address it in DOCSIS 3.0.

We should talk at IETF.

- Jason

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