I haven’t been following this thread closely, but has anyone
identified the traffic?
*From:* Ken Hohhof <mailto:[email protected]>
*Sent:* Monday, April 27, 2015 8:46 AM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] 450SM sustain bucket throttle not working..
If we could get Procera to create a signature for this type of
behavior, then we could create a rule to restrict this traffic
to some percentage less than 50% of the subscriber’s speed
tier. This would perhaps have several desirable results:
- if the CDN algorithm aims to oversubscribe the customer’s pipe
by 2X, then making the pipe look 0.5X as small should counteract
that
- I would actually set it lower than 50%, the objective to have
the customer say “XYZ service sucks” and complain to them or
stop using them, rather than “my Internet sucks”
- if we can pool our information about who is doing this (not
just the CDN but the content provider paying them), we could
complain directly to them, and if necessary take the position
that blocking or throttling their traffic would be reasonable
network management and allowable under net neutrality rules,
since they are in effect attacking our network with a flood of
traffic beyond what the customer has subscribed to
Another approach would be to rate limit this traffic with a
queue that has a very large buffer, introducing latency rather
than packet loss, hoping that their algorithm recognizes late
ACKs as a sign of congestion and will back off the sending
rate. But when I asked Simon about buffer size in Procera, my
understanding was that it’s more of a traffic policing box than
a shaping box.
*From:* Wireless Admin <mailto:[email protected]>
*Sent:* Monday, April 27, 2015 9:08 AM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] 450SM sustain bucket throttle not working..
Ken,
Your assessment of the problem is exactly correct. I was going
to compare it tor DoS as you did here. I don’t see an easy fix
for this.
Steve
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*From:*Af [mailto:[email protected]] *On Behalf Of *Ken Hohhof
*Sent:* Monday, April 27, 2015 10:00 AM
*To:* [email protected] <mailto:[email protected]>
*Subject:* Re: [AFMUG] 450SM sustain bucket throttle not working..
I don’t think you’re understanding the situation that we are
speculating is happening.
He is using Cambium QoS. However, he is seeing twice that
amount of traffic destined to the customer, the SM is throwing
half of it away (as it should), and as a result the customer’s
service sucks.
The problem is that the sender is not observing traditional
congestion control, it is not backing off the sending rate when
it sees high packet loss.
That’s why I say it is similar to a DoS attack, someone sending
far more traffic than the subscriber can receive.
*From:*David Milholen <mailto:[email protected]>
*Sent:*Monday, April 27, 2015 7:05 AM
*To:*[email protected] <mailto:[email protected]>
*Subject:*Re: [AFMUG] 450SM sustain bucket throttle not working..
This is why we like setting the QOS at the subscriber. If I
remember the cambium burst allocation ignores tcp and udp and
work strictly on a token bit system.
We do not receive these complaints. The only time I hear them is
if we get overloaded at the backhaul link.
On 4/26/2015 8:58 PM, Ken Hohhof wrote:
I think George forgot the sarcasm emoticon.
Also note that the problem here is the edge provider is sending
more than the customer’s plan rate, ignoring TCP congestion
control. Not only does this consume Internet bandwidth over
and above what the customer has subscribed to, it makes
anything else the customer is trying to do on the Internet
unusable because normal TCP is unusable with 50% packet loss.
It is not surprising the customer calls saying his Internet is
slow.
There’s a saying that comes to mind, involving a 5 pound bag.
*From:*Faisal Imtiaz <mailto:[email protected]>
*Sent:*Sunday, April 26, 2015 8:37 PM
*To:*[email protected] <mailto:[email protected]>
*Subject:*Re: [AFMUG] 450SM sustain bucket throttle not working..
I see that the net neutrality is going to be the next boogieman
under the bed for WISP's from now on...
Please, please, please, correct your understanding on
Net-Neutrality...
It allows for one to traffic shape any and all kinds of
traffic, as long as :-
a) You declare your practice on your website.
b) You DON"T DO IT specific to A SPECIFIC Network.. i.e. all
VOIP, or all Video, or ALL Streaming..
(applying a throttle on video to netflix while allowing
Hulu would be considered a violation, but applying throttle to
all types of video content is NOT !)
:)
Faisal Imtiaz
Snappy Internet & Telecom
7266 SW 48 Street
Miami, FL 33155
Tel: 305 663 5518 <tel:305%20663%205518> x 232
Help-desk: (305)663-5518 <tel:%28305%29663-5518> Option 2 or
Email: [email protected]
<mailto:[email protected]>
------------------------------------------------------------------------
*From: *"George Skorup (Cyber Broadcasting)"
mailto:[email protected]
*To: *[email protected] <mailto:[email protected]>
*Sent: *Sunday, April 26, 2015 7:12:13 PM
*Subject: *Re: [AFMUG] 450SM sustain bucket throttle not
working..
So you'd be purposely slowing down or blocking legitimate
traffic from an edge provider to the customer? Oh no, net
neutrality violation!
So when everyone starts with the 4k streaming and we're
selling the customer 20Mbps, then we have to take on 40Mbps
because of this!?
On 4/26/2015 5:58 PM, Ken Hohhof wrote:
I could justify declaring such traffic an attack and
blocking the source as malicious.
*From:*George Skorup (Cyber Broadcasting)
<mailto:[email protected]>
*Sent:*Sunday, April 26, 2015 4:30 PM
*To:*[email protected] <mailto:[email protected]>
*Subject:*Re: [AFMUG] 450SM sustain bucket throttle not
working..
Yep, I see this all the time and Ken is exactly right.
The Canopy QoS works exactly as designed, the AP is
definitely not delivering more than the sustained rate,
but is instead discarding the extra 50%. I've tested
this situation thoroughly. Stick a MT simple queue in
at the upstream router and the 2X rate traffic stops
hitting the AP's ethernet interface, but it's still
coming in at double the sustained rate farther
upstream. There's no way around it except throwing
bandwidth at it.
This is CDN traffic. And when the customer thinks they
can install one of those "internet download managers"
to speed up their connection. The only thing it does is
screw with TCP acks or window sizes or something which
just puts more traffic on your transit just to be
discarded at the congestion point (SM, queue, Procera,
whatever). Gotta love it.
You'd think with 70% of the internets being streaming
video they'd think hmm.. maybe we can cut down on the
peering congestion by NOT doing this crap. But no.
On 4/26/2015 11:01 AM, Ken Hohhof wrote:
Sorry to answer a question with a question, but are
you measuring at the SM, or at some upstream router?
The reason I ask, is I have seen some CDN traffic
that does not seem to follow traditional TCP
congestion control. It will send at twice the rate
limit, causing 50% packet loss to its own traffic
and everything else to that same subscriber.
Evidently some TCP geniuses have decided to use
latency rather than packet loss as the indicator of
congestion, and that the objective is goodput not
throughput. Works for last mile technologies like
T1 and DSL with big buffers at the head end of the
fixed speed serial connection, not so good with the
type of rate limit queues we tend to use unless we
can provision the queues with big buffers.
Probably not your problem, but I thought I’d bring
it up just in case.
*From:*Kurt Fankhauser <mailto:[email protected]>
*Sent:*Sunday, April 26, 2015 10:50 AM
*To:*[email protected] <mailto:[email protected]>
*Subject:*[AFMUG] 450SM sustain bucket throttle not
working..
I have a 450 SM that is rate limited in the SM to
1500kbps download on the sustain side. I noticed
last night that this customer was pulling a steady
almost 3mbps download for several hours on end. How
is this possible? Is there a problem with 13.2
firmware? Its a 3.65ghz SM.
see attached.
Kurt Fankhauser
Wavelinc Communications
P.O. Box126
Bucyrus, OH 44820
http://www.wavelinc.com <http://www.wavelinc.com/>
tel. 419-562-6405 <tel:419-562-6405>
fax. 419-617-0110 <tel:419-617-0110>
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