Interpreting speed test resutls

[Uncle Michael]

We've been converted from TWC to Charter - now Spectrum - for cable internet. The fastest speed Time Warner advertised was about 25 Mbps. The slowest Spectrum advertises is "up to 60" Mbps. I was supposed to be getting 15 Mbps with my old TWC connection, and all my testing was consistent with that (unless there was a connection problem or other short term glitch).

I just signed up for the Spectrum plan and now my results are dramatically different depending on which test I run.

• M-Labs continues to report approximately 15 Mbps, though the speeds are higher initially and fall gradually as the test proceeds. M-Labs also links to historical data that indicate 15 Mbps or less is the typical speed available in this area. DSL is under 10, fiber is only slightly higher than cable. They claim they test 'real world' thoughput from servers that are dispersed around the country.
• Ookla always reports the fasted results, at or above the advertised speed of 60 Mbps. This test appears to link to just one server. Although I can choose from a list, the connection for a test is only to the selected server.
• DSLReports agrees with Ookla initially, but the speed typically drops dramatically near the end of the test, and the final reported speed is often below 10 Mbps. They also introduce the concept of "bufferbloat" which I'd not encountered before.

Clearly, all three sites use different protocols. Besides that, what's the take away?

[zwolfpack]

I'm also on Spectrum, former TWC. Getting comparable numbers between Speedtest.net (Ookla) and dslreports.net.
Interesting, I searched long and hard for what I'm "supposed" to be getting without luck. This page screams "Fastest Internet speeds available starting at 100Mbps", but couldn't find anything else. Recall that TWC pushed a bunch of levels, i.e. "starter", "standard", "turbo", "ultra", etc. etc.
The "Spectrum Internet" section of the bill just says I'm paying for "Spectrum Internet"... gee thanks...

On dslreports, I'm getting failing grades for "bufferbloat".

[Uncle Michael]

Spectrum isn't offering anything in our area near the speed you are getting. The biggest improvement I am seeing is in upload speeds. TWC capped it a 2 Mbps, now I'm seeing about 6 Mbps routinely.

What bothers me is the drop in performance the DSLReports identifies (red circle in the screenshot below). It shows download speeds of 60-70 Mbps, but then an abrupt drop back to about 15 Mbps; implying that the fast speeds are not sustainable, and (I wonder) may only be there to juice speed test results.

[Pete]

Personally use toast dot net for my real numbers and today they are piss poor.

Speedtest dot beta shows:



DSL reports without buffer bloat testing:



DSL reports with buffer bloat testing:



I do see some errors when doing the DSL reports checking.

6.49s Warning: 11 from 16 streams failed to start. See error:11
17.99s stream0 mbits=0 ms=6314 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
17.99s stream1 30.96 megabit Chicago, IL, USA
17.99s stream2 21.96 megabit Chicago, IL, USA
17.99s stream3 14.83 megabit Chicago, IL, USA
17.99s stream4 9.68 megabit Chicago, IL, USA
17.99s stream5 0.09 megabit Chicago, IL, USA
17.99s stream6 0.01 megabit Chicago, IL, USA
17.99s stream7 mbits=0 ms=8053 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
17.99s stream8 mbits=0 ms=7981 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
17.99s stream9 mbits=0 ms=7972 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
17.99s stream10 mbits=0 ms=7967 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
17.99s stream11 mbits=0 ms=7697 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
17.99s stream12 mbits=0 ms=7692 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
17.99s stream13 mbits=0 ms=7688 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
17.99s stream14 mbits=0 ms=7684 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
17.99s stream15 mbits=0 ms=7521 pingt=32 hxxp://t18.dslreports.com:80 [p=0 pcnt=0 s=pre]
26.38s End of download testing. Starting upload in 2 seconds

Toast shows:

[ATTACH]61179[/ATTACH]

[Pete]

@Michael,

Are you using an a la carte modem or an all in one combo ISP provided box?

Current Modem is a Motorola SB-6141. Different these days as it has Gb in and a Gb out network port.

A couple of years ago Comcast redid my old cable (~200 feet) to a newer much thicker cable.

You can do diagnostics of your modem going to web page:

192.168.100.1

Post your signal upstream and downstream bonding channel values.

Downstream (Rx) Receive Power Level:

This is the amount of signal received by the modem from the transmitter in the cable company head-end.

For all modems DOCSIS 3.0 / 3.1:

-7 dBmV to +7 dBmV "Recommended"
-8 dBmV to -10 dBmV / +8 dBmV to +10 dBmV - "Acceptable"
-11 dBmV to -15 dBmV / +11 dBmV to +15 dBmV - "Maximum"
Lower than -15 dBmV & Higher than +15 dBmV - "Out Of Spec."

SNR (signal to noise ratio) levels:

This is how clear the signal is at either the modem receiver (downstream SNR) or the receiver in the cable company head-end (upstream SNR).

DOCSIS specifications list minimum CNR (carrier to noise ratio) levels not SNR levels. The SNR levels listed here are based on commonly recommended MER levels for digital cable signals. Not all QAM demodulator chipsets accurately calculate SNR levels that approximate actual MER levels, so these levels may vary depending on which chipset and/or firmware is used in the equipment.

*There is no upper SNR limit.

For all modems DOCSIS 3.0 / 3.1:

256 QAM: 30 dB minimum. 33 dB or higher recommended.
64 QAM: 24 dB minimum. 27 dB or higher recommended.
16 QAM: 18 dB minimum. 21 dB or higher recommended.
QPSK: 12 dB minimum. 15 dB or higher recommended.

Upstream (Tx) Transmit Power (a.k.a. Return Signal) level:
This is the amount of signal transmitted by the modem to reach the receiver in the cable company head-end.

*Recommended Upstream signal levels are +35 dBmV to +47 dBmV (DOCSIS 3.1)
*Recommended Upstream signal levels are +35 dBmV to +49 dBmV (DOCSIS 3.0)

50 dBmV maximum for A-TDMA (DOCSIS 3.1)
52 dBmV maximum for A-TDMA & TDMA (DOCSIS 3.0)
53 dBmV maximum for S-CDMA DOCSIS 2.0 (All Modulations)
54 dBmV maximum for 32 QAM and 64 QAM. (A-TDMA DOCSIS 2.0)
55 dBmV maximum for 8 QAM and 16 QAM. (DOCSIS 1.0, 1.1)
58 dBmV maximum for QPSK. (DOCSIS 1.0, 1.1)

Important notes concerning signal levels:

1. Signal levels not within the specifications listed above can cause slow speeds, connection problems, and connection loss due to packet errors, packet loss, and/or constant packet re-transmission.

2. It's recommended to have the modem's signal levels at least 3dB away from the maximum/minimum levels listed above due to normal temperature related signal variation. If the modem's signal levels are at the maximum or minimum limits, they may be out of spec. if the temperature changes significantly. Signal levels that vary more then 3 dB in a 24-hour period usually indicate a problem that should be looked into.

3. Excess splits, bad connectors, and/or poor quality cabling will certainly effect cable signal levels and will cause problems.