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DOCSIS 3.1 Channel Maximum Speed

jbarnes2112
Tutor

DOCSIS 3.1 Channel Maximum Speed

Sorry if similar questions have been answered elsewhere. I have checked here, and many outside sources but the answer is unclear. I am hoping someone on this forum might know. I have a CM1000v2 modem with 16 bonded QAM256 channels. What is my maximum download speed? Info I have found suggests the maximum speed per channel is around 42.88 mbps, which should imply a maximum around 686 mbps. Note this number seems to match my actual download speed (usually a bit under this). However, this speed is much slower than my promised ISP (Mediacom) speed of 1 gig. I would just like to confirm that I have no chance of reaching 1 gig with 16 bonded QAM256 channels. Please see attached for any additional information that may be needed to answer. Thanks in advance for the help.

Message 1 of 11
FURRYe38
Guru

Re: DOCSIS 3.1 Channel Maximum Speed

Who is your ISP? 

Most 1Gb services need or require all 32 channels and docsis 3.1 to be used to be able to achieve 1Gb on the down. Anything less then that would probably not see 1Gb. Something to talk to your ISP about. 

The CM modem is well capable of 1Gb services on the down side when 32 channels are being used. 

My Setup ISP SparkLight | Internet Cable 1000↓/50↑ CAX80 Modem Mode |  Wifi Router RBK853 (Router Mode) | and R9000 (Router Mode) | Switches NG GS105/8, GS308v3, GS110MX and XS505M | Additional NG HW: C7800/CAX80/CM1100/CM1200/CM2000, Orbi: CBK40, CBK752, RBK50, RBK853, RBK752, RBK953, SXK30 | NightHawk: MK63, MR6150, R7000, R7800, R7960P, R8000, R8500, R9000, RAXE500, RAX50, XR450, XR1000, EX7500/EX7700

Message 2 of 11
jbarnes2112
Tutor

Re: DOCSIS 3.1 Channel Maximum Speed

The ISP in this case is Mediacom. They insist that I am able to get 1gig with this configuration, but I do not. So I am looking for confirmation that it is not possible. And also to confirm if my info on channels and speed is correct.
Message 3 of 11
FURRYe38
Guru

Re: DOCSIS 3.1 Channel Maximum Speed

What are speed are you seeing with a wired PC connected to the back of the modem using Ooklas installable speed test app?

 

Possible the ISP is combining or compressing speeds into half the channels. Something you might want to check with the Cable Labs and the DOCSIS 3.1 specs. 

My Setup ISP SparkLight | Internet Cable 1000↓/50↑ CAX80 Modem Mode |  Wifi Router RBK853 (Router Mode) | and R9000 (Router Mode) | Switches NG GS105/8, GS308v3, GS110MX and XS505M | Additional NG HW: C7800/CAX80/CM1100/CM1200/CM2000, Orbi: CBK40, CBK752, RBK50, RBK853, RBK752, RBK953, SXK30 | NightHawk: MK63, MR6150, R7000, R7800, R7960P, R8000, R8500, R9000, RAXE500, RAX50, XR450, XR1000, EX7500/EX7700

Message 4 of 11
jbarnes2112
Tutor

Re: DOCSIS 3.1 Channel Maximum Speed

With a wired connection straight to a computer with a 1 gig Ethernet port I normally get around 630mbit, ignoring the occasional low times. I get the same on my WiFi. And note I easily get over 1 gig on WiFi, and full gig downloads from my NAS on WiFi.

Mentioned the possibility of compression. Is there any way to test for that? I mean without additional equipment.
Message 5 of 11
jbarnes2112
Tutor

Re: DOCSIS 3.1 Channel Maximum Speed

As a bump, and to clarify my last msg...

With a wired 1 gig Ethernet connection straight from the modem to a computer I normally get around 630mbit on download. This speed is pretty consistent, even when tested on the other side of my router/WiFi on multiple devices.

Given it's in the range of the max speed I calculated above, I suspect I'm getting ripped off by my ISP. Would just like to know if my calculation is correct.
Message 6 of 11
FURRYe38
Guru

Re: DOCSIS 3.1 Channel Maximum Speed

If your not seeing near 900Mpbs speeds on the wire at the modem, then you need to check with the ISP. If you have a 1Gb ethernet adatper and it's working well, CAT6 LAN cable and wired PC is working well and using Ooklas installable speed test app, you should need 900Mpbs or just a bit over. 

 

My Setup ISP SparkLight | Internet Cable 1000↓/50↑ CAX80 Modem Mode |  Wifi Router RBK853 (Router Mode) | and R9000 (Router Mode) | Switches NG GS105/8, GS308v3, GS110MX and XS505M | Additional NG HW: C7800/CAX80/CM1100/CM1200/CM2000, Orbi: CBK40, CBK752, RBK50, RBK853, RBK752, RBK953, SXK30 | NightHawk: MK63, MR6150, R7000, R7800, R7960P, R8000, R8500, R9000, RAXE500, RAX50, XR450, XR1000, EX7500/EX7700

Message 7 of 11
jbarnes2112
Tutor

Re: DOCSIS 3.1 Channel Maximum Speed

Ok so 16 bonded QAM256 channels have a maximum speed of 900 mbps not 680 mbps? How is that calculated?
Message 8 of 11
FURRYe38
Guru

Re: DOCSIS 3.1 Channel Maximum Speed

I presume channels vs QAM is in the formula. No idea though. For most ISPs, they use 32 channels for 1Gb speeds or higher. I guess some ISP are trying to squeeze more thru less channels? 

 

What Brand and model modem do you have? 

 

Post a screen capture of the Cable Connections status page. 

 

My Setup ISP SparkLight | Internet Cable 1000↓/50↑ CAX80 Modem Mode |  Wifi Router RBK853 (Router Mode) | and R9000 (Router Mode) | Switches NG GS105/8, GS308v3, GS110MX and XS505M | Additional NG HW: C7800/CAX80/CM1100/CM1200/CM2000, Orbi: CBK40, CBK752, RBK50, RBK853, RBK752, RBK953, SXK30 | NightHawk: MK63, MR6150, R7000, R7800, R7960P, R8000, R8500, R9000, RAXE500, RAX50, XR450, XR1000, EX7500/EX7700

Message 9 of 11
jbarnes2112
Tutor

Re: DOCSIS 3.1 Channel Maximum Speed

Screenshot_20220514-200358.png

Message 10 of 11
FURRYe38
Guru

Re: DOCSIS 3.1 Channel Maximum Speed

Well your power is ok, but you have way too many correct and un-correctables being listed. Those should all be zero's. 

Something you need to have the ISP review. 

Also check cable lines, connections and fittings. Ensure coax jacks are screwed in well and tight. Center copper wire is good. 

 

My Setup ISP SparkLight | Internet Cable 1000↓/50↑ CAX80 Modem Mode |  Wifi Router RBK853 (Router Mode) | and R9000 (Router Mode) | Switches NG GS105/8, GS308v3, GS110MX and XS505M | Additional NG HW: C7800/CAX80/CM1100/CM1200/CM2000, Orbi: CBK40, CBK752, RBK50, RBK853, RBK752, RBK953, SXK30 | NightHawk: MK63, MR6150, R7000, R7800, R7960P, R8000, R8500, R9000, RAXE500, RAX50, XR450, XR1000, EX7500/EX7700

Message 11 of 11
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