[CodeWriter23]

Xfinity says your wireline speed will not be impeded by others who are using WiFi via the xfinitywifi shared service. Since DOCSIS 3.0 has no limit on the maximum number of channels (source http://en.wikipedia.org/wiki/DOCSIS#Bandwidth_tables ), I believe in order to make that claim, they have to allocate additional channels to the xfinitywifi traffic.

BUT OP will only double his bandwidth if he is purchasing a rate less than or equal to the actual realized throughput of his WiFi connection, somewhere from 50-90Mbps.

Additionally, all Cable modems have some kind of throttling because the speeds offered by ISPs (30x5, 100x8, etc.) are not evenly divisible by the per-channel rate of DOCSIS 2.0/3.0 (38Mbps Down, 27Mbps up).

And then there's this: http://www.dslreports.com/forum/r29743167-Signals-Report-16-...

[windexh8er]

Every modem has a finite number of channels it can bond. Up and down are different. Also the CMTS (the device the cable modem connects to) limits the number of bonds per source modem.

A piece of coax has a finite amount of bandwidth it can carry. As modulation schemes get better (QAM256) you can do more with less.

To say DOCCIS 3 is limitless is not taking into consideration the hardware and frequency constraints. The more frequency you allocate to Internet the less is available for other programming (TV).

[CodeWriter23]

Yes, and more than a couple of people have observed downstream 16 channel bonding on Comcast. That would be 4 times as many as you cited "Most commonly 4 channel bond on the downstream and 2 on the up", in your post that I failed to reply to.

[windexh8er]

I have Comcast 100Mb service and have 4 QAM256 bonded downstream right now. I've deployed and managed these networks (as a Comcast subsidiary in fact). 16 down doesn't mean anything other than fragmented frequency usage.

If you have a Motorola cable modem go to: 192.168.100.1 to get to the web UI of your Surfboard. Click on the "Signal" tab at the top. My guess is the majority of people will see 4 x bonded down. Probably 2-3 bonded up using a lesser QAM as well.

Not sure why all the hate - I'm a network engineer who's dealt with these networks and a lot of what's been posted here is incorrect.

[philiplu]

Surfboard 6141 here on Comcast, and the Signal page is showing 8 QAM256 channels downstream, 4 QPSK/64QAM up. Speedtest.net has been showing 125M down/12M up for the past few months, which was a silent bump up from the 75/10 I noticed before that (Seattle Eastside area).

I'm curious how much faith to put in the speedtest numbers. Does Comcast detect speedtest, or is that what I'd really get elsewhere as well?

[NKCSS]

If you google for 100mb.bin or 1000mb.bin you'll find a lot of networks/exchanges that offer files for speedtest purposes if you want to independantly verify.

Here's a list: http://www.glasvezel.nu/speedtest-servers-100mb-1000mb-bin

[Havoc]

>Xfinity says your wireline speed will not be impeded by others who are using WiFi

From my experience with low throughput 2-4mbps lines I'm deeply sceptical about claims like that. Throughput will generally be OK...but if you want stable latency...good luck. The second someone else is on the same line goes flakely unless its a high powered line (fibre etc)