Re: [81attendees] sucky Delta hotel network (and bufferbloat)

[Jim Gettys <[e-mail]>]

On 08/03/2011 12:43 PM, Dave CROCKER wrote:
> On 8/1/2011 3:01 PM, Ole Jacobsen wrote:
>>
>> "Expectations" are indeed important.
>>
>> Equally important is "common sense and common courtesy" which implies
>> a number of do's and don'ts on the hotel network. I am not going to
>> attempt to create that list here, but I can well imagine some things
>> that I should NOT be doing while on the hotel network, in
>> consideration of my fellow IETFers. (Large downloads, live video...)
>
> Ole,
>
> At various times, such examples have been cited, effectively placing
> the responsibility for poor hotel network performance onto IETF guests
> at the hotel.
>
> Is this merely a matter of being thorough in listing theoretical
> possibilities?  Or do we have any hard data to support the theory that
> IETF guests are, in fact, abusing the hotel networks?
>
> Is it equally plausible that problem hotels merely do not have
> adequate resources for reasonable use by an Internet-centric block of
> guests?
>
> What should the site qualifying teams do to assess a hotel's network
> capabilities?  I know what some of that is already being done but it's
> worth making sure that this issue is sufficiently covered by the site
> qualifying teams.
>
> d/
>
Hotel networks tend to be under provisioned in the first place; that
just makes network problems (such as bufferbloat, which only is an issue
when saturation occurs) worse.  In my wanderings over the last year,
I've had very bad experiences at most other hotels at peak hours, even
those not occupied by computer geeks, but by typical "users".  I think
there is a lot of video streaming  that has changed the workload
considerably.  The retirement of Windows XP is increasing the fraction
of connections that will saturate any link even with a single TCP
connection; so an increasing fraction of many other activies such as
backup or large file copy will induce saturation.

We may be polite to each other, but try explaining this to the unwashed
masses, who want to watch tonight's episode of "House" or other show as
they do at home.  People aren't just reading email any more.

We can test for whether the hotel's network and back haul network has
problems using existing tools (e.g. netalyzr, the mlabs tools, or even
iperf/netperf + ping) in advance.  I suspect that most of the major
hotels the IETF uses are less likely than most to use broadband
connections for their backhaul as commonly found in smaller
hotels/motels recently connected to the Internet. Resolving problems in
advance may be more of a problem. On a couple occasions, I've tried to
track down clue full people to talk to them, but as an individual patron
of the hotel, had no traction in doing so, and the hotel networks seemed
to be remotely managed by others. And once checked out, I had no
incentive to continue trying.

Wireless at a conference hotel is probably completely infeasible in the
short term: the first wireless networks I've seen working well under
load are those set up at NANOG and IETF, where both commercial grade
AP's and really clue full configuration have managed to succeed.  That's
not even been carefully written down anywhere, though the principles of
it is covered very quickly in Anton Kapela's lightning talk at NANOG 38. 

As soon as your wireless bandwidth is below that of the backhaul, your
problems with bufferbloat will be in your host OS and the hotel's
wireless gear; while we have some test bits for controlling buffering
for Linux (the debloat-testing tree), I have no clue as to when you
might see anything Mac or Windows; in the short term, you really want
the bottleneck some place other than your wireless hop.  Which hop is
the bottleneck link easily varies depending on the ratio of the hotel's
back haul is available to you and how much wireless bandwidth you can get.

In the short term, I'd focus on seeing if the wired hotel network is
provisioned properly under load, it's ISP runs with suitable AQM. At
least then, if you plug into the wired ethernet, it should behave
properly and degrade reasonably under load rather than falling off a cliff.
                                                    - Jim