I have been doing some research on different modems and I am getting quite confused about some of the speed numbers in the product specifications. Below are some examples from Motorola modems.
If you take a look at the Motorola MB8611 specifications, it lists the following specifications:
Downstream
• Data Rate:
Up to 6,000 Mbps*
• Bonded Channels:
Up to 32 SCQAM (DOCSIS 3.0) or
2 OFDM (DOCSIS 3.1)
• Frequency Range:
108 to 1002 MHz
• Operating Level Range:
-15 to +15 dBmV
Upstream
• Data Rate:
Up to 800 Mbps*
• Bonded Channels:
Up to 8 SCQAM (DOCSIS 3.0) or
2 OFDMA (DOCSIS 3.1)
• Frequency Range:
5 to 42 MHz or 5 to 85 MHz switchable
• Operating Level Range:
+65 dBmV (64 QAM, single channel)
+57 dBmV (64QAM, 4-8 channels)
+65 dBmV (16 QAM, single channel)
+65 dBmV (OFDMA)
The MB8611 has a single 2.5Gb port. So where I am confused is the 6000 Mbps listed in the specs. Wouldn’t a 2.5Gb port be a hardware limit? I am interested in the actual hardware limitations of these modems. So, let’s say that all the ISPs can offer plans up to 10Gb. Can this modem support up to 6000Mbps or will the max be 2.5Gb?
My other theory is that 2.5Gb is the max speed that can actually get to the devices on the network and 6000Mbps is the max speed it can handle coming down the line from the WAN side. If that’s the case, would sending 10Gb down the line from the WAN side mean this modem would essentially fail to work? Also, I’d like to ignore anything past the modem on the LAN side, like cabling (cat 5e, vs 6), just looking to understand the modem hardware itself.
Another example is Motorola’s MB8600 modem. In its specs, it lists the up and down data rate as 3.8Gb. This makes sense to me because the modem has one 1GB port and 3 masked 1Gb ports that can be bonded or used in link aggregation. So in this case, it makes sense to me but in the case of MB8611, it has a single 2.5Gb port but lists 6000Mbps as the data rate so not sure where the 6000 is coming from.
This isn’t just for Motorola, I see these kind of numbers displayed on a lot of brands. Basically, my overall goal is to document the limits of different modems. I assume there are probably two limitations to modems: 1) being the speed that a modem can handle from the WAN side and, 2) The speed that can actually be passed onto the LAN side. I would like some help in understanding and being able to correctly interpret the varying speed numbers listed in these modem’s specification sheets.
Another question I have is about upload limitations. I noticed that a lot of modems do not list the actual upload speeds. In those cases, can upload speeds be calculated by taking the speed limits of the DOCSIS version and multiplying it by the number of upstream channels? For example, this Netgear CM600 does not list the upload speed but says it has 8 upstream channels. Since this router supports DOCSIS 3.0, is it safe to assume that this route can support 1600 Mbps upload (200 (DOCSIS 3.0 upload limit) * 8 channels)? That seems wrong, too high.
As you can see, I am having a hard time trying to correctly understand the up and down limitations of these modems given spec information.
