Not sure if it was this year or last, but I remember Aaron talking about
QoS improvements to smooth out the jerkyness. I don't remember if that
was going into 14.2 or something later.
On 11/25/2016 12:58 PM, Ken Hohhof wrote:
What I’m really trying to determine is how Cambium handles the rate
limited traffic, not the high priority traffic.
The CDN and Windows Update traffic issues just keep getting worse. We
currently don’t use the radios for rate limiting, we do traffic
policing (RED) in the tower router, either Cisco or Mikrotik.
Trying to figure out if there’s anything we can do short of
Procera/Sandvine/Saisei. Our network topology doesn’t have a nice NOC
with a controlled environment with all bandwidth flowing through it.
I was thinking if we also implemented QoS at the AP, if it smoothed
out the bursts and put some back pressure on the CDNs in the form of
increased roundtrip latency, it might help.
Mainly interested since they added max burst rate. I think as we have
deployed more 450 sectors, it has bitten us in the ass, because a 3M
or 6M customer can burst at 50M for a few seconds. Plus the router
traffic policing propagates bursts while discarding some packets, and
the CDNs and video streams seem to look at that as an invitation to
just push more traffic and retry whatever doesn’t get ACK’d.
I have a suspicion that we are also seeing Netflix Ultra HD (~1080p)
streams now, whereas the highest we used to get was their HD (720p).
I saw something that Netflix Ultra HD only worked with a Koby Lake CPU
and Edge browser, but so many people are using Smart TVs now, I think
streaming on a PC has become irrelevant. So in addition to the
Windows 10 Update problem, I’m seeing a lot of 6M customers max’d out
with what appears to be a single video stream, while in the past we
would see the stream at more like 5M. I think now it just switches on
the fly between HD and Ultra HD, to use all available bandwidth. And
then the Windows 10 Update traffic which sends 180% of the rate limit,
plus people get frustrated and turn off the PC, so it never finishes
the download.
*From:*Af [mailto:[email protected]] *On Behalf Of *Mark Radabaugh
*Sent:* Friday, November 25, 2016 12:30 PM
*To:* [email protected]
*Subject:* Re: [AFMUG] Cambium 450 QoS details?
Ken,
Not entirely an answer to your question, but hopefully useful. The
backstory - I was getting pretty annoyed that our VoIP techs kept
claiming that Canopy QOS didn’t work even though I have proven with
packet captures a number of times that it does work, so we set up a
test lab to see how High Priority and standard traffic rate limits
interact. End result was that I was only partially correct and it
took a little more tweaking to the configuration than I thought. The
Canopy manual is correct - but you have to read the fine print and
it’s not all in one place if I recall correctly.
Anyway - this i what works for our VoIP customers using QOS with a
standard and voice vlan:
For All Dual-VLAN (Internet + VoIP) Juniper SRX Deployments:
On the SM....
0. Set "Sustained [Uplink|Downlink] Data Rate" (Kbit/s) based on
the customer's service plan (i.e. 6 down / 1.5 up)
1. Set "[Uplink|Downlink] Burst Allocation" (Kbit) to a value
equal to "Sustained [Uplink|Downlink] Data Rate"
2. Set "Max Burst [Uplink|Downlink] Data Rate" (Kbit/s) to a value
twice that of the "Sustained [Uplink|Downlink] Data Rate"
3. Enable "Hi Priority Channel"
4. Set "Hi Priority [Uplink|Downlink] CIR" to a suitable value.
i.e. [(100 * #phones) + 100] (aka 500 Kbit/s for 4 phones)
5. Set "Priority Precedence" "802.p then DiffServ" (either one
actually works, but this is belt & suspenders in case the SRX
config isn't fully implemented).
6. On the SRX, configure both WAN VLAN interfaces (i.e. internet
and phone) with firewall rules to mark traffic as high priority
(phone) or low priority (internet) [interfaces -> IFNAME ->
UNITNUM -> family inet -> filter]
7. On the SRX, enable rewriting (dscp and 802.1p) on both of the
WAN interfaces [class-of-service -> interfaces]
This config is valid and tested with 80 Mb/s of simulated upload
traffic, 500 Kb/s of simulated VoIP traffic, on an SM with only a
1.5 Mb/s upload cap. No lattency/jitter/packetloss on the
simulated VoIP traffic. Only 15-30 ms latency on the internet
upload (not bad, considering the SM is forced to discard 95% of
the traffic it's getting over the wire).
We didn’t analyze the traffic to see how the drops were handled on the
SM->AP side.
Mark
On Nov 25, 2016, at 12:56 PM, Ken Hohhof <[email protected]
<mailto:[email protected]>> wrote:
I also posted this question on the Cambium Community forum, but
maybe this is well known and someone here can answer for me, or
point me to the info.
How exactly does Cambium 450 QoS work? Does it buffer traffic and
shape it to the configured rate, or does it do traffic policing?
And if it buffers, what is the buffer size? Is it just a global
buffer pool whatever memory is available, or a fixed buffer per
SM/LUID? If it does policing (and even shapers have to discard
traffic if the buffer overflows), does it discard whole packets
(PFIFO instead of BFIFO)?
