[NNagain] [M-Lab-Discuss] The FCC 2024 Section 706 Report, GN Docket No. 22-270 is out!

Mon Feb 26 21:06:05 EST 2024

Yes, latency is complicated....  Back when I was involved in the early 
Internet (early 1980s), we knew that latency was an issue requiring much 
further research, but we figured that meanwhile problems could be 
avoided by keeping traffic loads well below capacity while the 
appropriate algorithms could be discovered by the engineers (I was 
one...).  Forty years later, it seems like it's still a research topic.

Years later in the 90s I was involved in operating an international 
corporate intranet.  We quickly learned that keeping the human users 
happy required looking at more than the routers and circuits between 
them.  With much of the "reliability mechanisms" of TCP et al now 
located in the users' computers rather than the network switches, 
evaluating users' experience with "the net" required measurements from 
the users' perspective.

To do that, we created a policy whereby every LAN attached to the 
long-haul backbone had to have a computer on that LAN to which we had 
remote access.   That enabled us to perform "ping" tests and also 
collect data about TCP behavior (duplicates, retransmissions, etc.) 
using SNMP, etherwatch, et al.   It was not unusual for the users' data 
to indicate that "the net", as they saw it, was misbehaving while the 
network data, as seen by the operators, indicated that all the routers 
and circuits were working just fine.

If the government regulators want to keep the users happy, IMHO they 
need to understand this.

Jack Haverty

On 2/26/24 16:25, rjmcmahon wrote:
> On top of all that, the latency responses tend to be non parametric 
> and may need full pdfs/cdfs along with non-parametric statistical 
> process controls. Attached is an example from many years ago which was 
> a firmware bug that sometimes delayed packet processing, creating a 
> second node in the pdf.
>
> Engineers and their algorithms can be this way it seems.
>
> Bob
>> I didn't study the whole report, but I didn't notice any metrics
>> associated with *variance* of latency or bandwidth.  It's common for
>> vendors to play games ("Lies, damn lies, and statistics!") to make
>> their metrics look good.   A metric of latency that says something
>> like "99% less than N milliseconds" doesn't necessarily translate into
>> an acceptable user performance.
>>
>> It's also important to look at the specific techniques used for taking
>> measurements.  For example, if a measurement is performed every
>> fifteen minutes, extrapolating the metric as representative of all the
>> time between measurements can also lead to a metric judgement which
>> doesn't reflect the reality of what the user actually experiences.
>>
>> In addition, there's a lot of mechanism between the ISPs' handling of
>> datagrams and the end-user.   The users' experience is affected by how
>> all of that mechanism interacts as underlying network behavior
>> changes.  When a TCP running in some host decides it needs to
>> retransmit, or an interactive audio/video session discards datagrams
>> because they arrive too late to be useful, the user sees unacceptable
>> performance even though the network operators may think everything is
>> running fine.   Measurements from the end-users' perspective might
>> indicate performance is quite different from what measurements at the
>> ISP level suggest.
>>
>> Gamers are especially sensitive to variance, but it will also apply to
>> interactive uses such as might occur in telemedicine or remote
>> operations.  A few years ago I helped a friend do some tests for a
>> gaming situation and we discovered that the average latency was
>> reasonably low, but occasionally, perhaps a few times per hour,
>> latency would increase to 10s of seconds.
>>
>> In a game, that often means the player loses.  In a remote surgery it
>> may mean horrendous outcomes.  As more functionality is performed "in
>> the cloud" such situations will become increasingly common.
>>
>> Jack Haverty
>>
>> On 2/26/24 12:02, rjmcmahon via Nnagain wrote:
>>
>>> Thanks for sharing this. I'm trying to find out what are the key
>>> metrics that will be used for this monitoring. I want to make sure
>>> iperf 2 can cover the technical, traffic related ones that make
>>> sense to a skilled network operator, including a WiFi BSS manager. I
>>> didn't read all 327 pages though, from what I did read, I didn't see
>>> anything obvious. I assume these types of KPIs may be in reference
>>> docs or something.
>>>
>>> Thanks in advance for any help on this.
>>> Bob
>>>
>>>> And...
>>>>
>>>> Our bufferbloat.net submittal was cited multiple times! Thank you
>>>> all
>>>> for participating in that process!
>>>>
>>>> https://docs.fcc.gov/public/attachments/DOC-400675A1.pdf
>>>>
>>>> It is a long read, and does still start off on the wrong feet
>>>> (IMHO),
>>>> in particular not understanding the difference between idle and
>>>> working latency.
>>>>
>>>> It is my hope that by widening awareness of more of the real
>>>> problems
>>>> with latency under load to policymakers and other submitters
>>>> downstream from this new FCC document, and more reading what we
>>>> had to
>>>> say, that we will begin to make serious progress towards finally
>>>> fixing bufferbloat in the USA.
>>>>
>>>> I do keep hoping that somewhere along the way in the future, the
>>>> costs
>>>> of IPv4 address exhaustion and the IPv6 transition, will also get
>>>> raised to the national level. [1]
>>>>
>>>> We are still collecting signatures for what the bufferbloat
>>>> project
>>>> members wrote, and have 1200 bucks in the kitty for further
>>>> articles
>>>> and/or publicity. Thoughts appreciated as to where we can go next
>>>> with
>>>> shifting the national debate about bandwidth in a better
>>>> direction!
>>>> Next up would be trying to get a meeting, and to do an ex-parte
>>>> filing, I think, and I wish we could do a live demonstration on
>>>> television about it as good as feynman did here:
>>>>
>>>> https://www.youtube.com/watch?v=raMmRKGkGD4
>>>>
>>>> Our original posting is here:
>>>>
>>>
>> https://docs.google.com/document/d/19ADByjakzQXCj9Re_pUvrb5Qe5OK-QmhlYRLMBY4vH4/edit 
>>
>>>>
>>>>
>>>> Larry's wonderful post is here:
>>>> https://circleid.com/posts/20231211-its-the-latency-fcc
>>>>
>>>> [1] How can we get more talking about IPv4 and IPv6, too? Will we
>>>> have
>>>> to wait another year?
>>>>
>>>>
>>>
>> https://hackaday.com/2024/02/14/floss-weekly-episode-769-10-more-internet/ 
>>
>>>>
>>>>
>>>> -- 
>>>> https://blog.cerowrt.org/post/2024_predictions/
>>>> Dave Täht CSO, LibreQos
>>> _______________________________________________
>>> Nnagain mailing list
>>> Nnagain at lists.bufferbloat.net
>>> https://lists.bufferbloat.net/listinfo/nnagain
>> _______________________________________________
>> Nnagain mailing list
>> Nnagain at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/nnagain

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