[Bloat] BBR implementations, knobs to turn?

[erik.taraldsen at telenor.com]

________________________________________
Fra: Toke Høiland-Jørgensen <toke at toke.dk>

> > I really appreciate that you are reaching out to the bufferbloat community
> > for this real-life 5G mobile testing.  Lets all help out Erik.
>
> Yes! FYI, I've been communicating off-list with Erik for quite some
> time, he's doing great work but fighting the usual up-hill battle to get
> others to recognise the issues; so +1, let's give him all the help we
> can :)

Thanks!  I'll need all the patting on the back which can be provided. :)


> > From your graphs, it does look like you are measuring latency
> > under-load, e.g. while the curl download/upload is running.  This is
> > great as this is the first rule of bufferbloat measuring :-)  (and Luca
> > hinted to this)

I've been using Flent since day one of the Fixed Wireless project.  In fact
it was an part of the CPE RFQ process that all participating vendors must 
deliver test results from Flent as a part of the technical response.  Not so much
that we should save ourselves the work of testing.  But to force the vendors
to see how their equipment handle latency. Trying to establish Flent as a 
standard part of their test suit.

Toke and Dave has been of great help both in helping me in interpreting
Flent results, and moral support as it can be an up hill battle to achieve 
awareness of the bufferbloat issues.


> > The Huawei policer/shaper sounds scary.  And 1000 packets deep queue
> > also sound like a recipe for bufferbloat.  I would of-cause like to
> > re-write the Huawei policer/shaper with the knowledge and techniques we
> > know from our bufferbloat work in the Linux Kernel.  (If only I knew
> > someone that coded on 5G solutions that could implement this on their
> > hardware solution, and provide a better product Cc. Carlo)

I have tried on several occasions to get the vendors to subscribe to this
mailing list.  And individuals here have been willing to do consulting
work for vendors in Telenors RFQ, but as far as I know they have not
been contacted.


> Your other points about bloated queues etc, are spot on. Ideally, we
> could get operators to fix their gear, but working around the issues
> like Erik is doing can work in the meantime. And it's great to see that
> it seems like Telenor is starting to roll this out; as far as I can tell
> that has taken quite a bit of advocacy from Erik's side to get there! :)

As you say Toke, I have had some success.  In particular with Huawei
on the base station side I believe we will have the largest impact.

The CPE side has met willingness to investigate these issues from early
on, but it seems that buffer handling is much harder on CPE chipsets 
than on base station chipsets.  In particular on 5G.  We have had some 
very good results on 4G, but they do not translate to 5G.


-Erik