docsis 3.0 cable modem + gateway

It all started with I noticing the intermittent degradation of video quality when watching Netflix. There are so many variables and sorting out where the problem is/are can be taxing even with someone who's career has been in the technology field.

Without getting into a lot of specifics I finally fault-diagnosed the problem to my 802.11n Netgear router/gateway. By now I vowed never to buy another one of the usual suspect brands - Netgear, D-Link, Belkin etc. In my experience they all disappoint and with very poor post-sale support in the firmware update department. To add insult to injury I paid a lot of money for the Netgear when 802.11n router/gateways first released. In time I would find out the bit rate when set to 802.11n is worst than my previous 802.11g counterpart. I felt screwed.

my Netgear 802.11n router/gateway that never live up to the performance of the "N" spec

In the recent days I have conducted a lot of tests. I was able to determine my poor Mbps was not due to my cable modem, but only with the wifi connection using the Netgear 802.11n gateway. If I connect my computer to it using an Ethernet cable I get 1/3 higher performance. Likewise if I connect the computer directly to the DOCSIS 2.0 modem I get the same 1/3 higher performance. When set to 802.11n mode the router/gateway actually performs worst than setting to 802.11g mode. Freaking unbelievable!

my trusty Motorola Surfboard DOCSIS 2.0 modem - it work perfectly fine after 8 years of service and it is by no mean the bottleneck

I have been buying my own cable modem ever since cable modems first started for sales to consumers. A lot of cable companies sneak in their own modem to the unsuspecting customers, and tag on a monthly lease fee of as high as $8. I often encounter people that has no idea this recurring fee in their monthly statement. Better yet, with Comcast now deploying their Xfinity wifi hotspots across many cities. How do they do this? From what I learnt, this service, at least in a large part, relies on the wifi modem+AP on those lease modems. In addition to serving the broadband subscriber who pay for the lease modem+AP, the equipment also serves as an Xfinity wifi hotspot to strangers. In this clever scheme Comcast gets the best of both worlds.

xfinity wifi hotspot (the second one in the list) signal visible around my house

I don't believe paying through the nose for very high speed broadband service. I only want to pay for what I need. My most important service is Netflix video and movie streaming. With advance CODEC Netflix uses, one can get very good quality video without paying through the nose for top tier ISP. Yes, I believe broadband ISP should be kept as dumb pipe, a dumb data pipe that is. I don't get discounts triple play customers enjoy. I only subscribe to broadband basic internet - as Comcast likes to call it.

after doing a bit of research I found this DOCSIS 3.0 modem and router/gateway combo; in the past I tend to stay away from combo products; but with reliable brands of Motorola and Arris I have little reservation, especially the gateway supports 802.11n - I knew it is a future-proof purchase

arrived from Amazon via snail free shipping

the shaded column shows the feature of this SBG6580 modem/gateway/router combo

here is the front panel of my old crappy Netgear 802.11n router/gateway - what a waste of money

here is the front panel of the new modem/router/gateway

the back side of the old DOCSIS 2.0 cable modem

the back side of the crappy Netgear 802.11n router/gateway

the back side of the new DOCSIS 3.0 modem/router/gateway with 802.11n that actually delivers; note that this single device replaces two pieces of my old equipment

Last time I registered and set up my own cable modem was many years ago. At the time the only way to do that was to call Comcast because each modem has an unique MAC ID. Fast forward to 2014 it is much easier if you are tech savoy. No more wasting your precious time with the phone tree, and talking to clueless CSR. With your own newly purchased modem this is what you do.

1) Have a personal computer ready. Have one that has Ethernet LAN would make life a lot easier. Connect the PC to the modem with an Ethernet cable.

2) Connect the cable modem to the coax cable from Comcast. For most people this is likely the cable wall jack in your house near where you want to install the cable modem.

3) Power up the cable modem and give it some time to make contact with the ISP headend.

4) Open a browser and you should see this once the modem locked and communicates with the headend.

5) Enter your Comcast credential.

After you enter a valid credential it may take a long time for Comcast to register your cable modem after it reads the MAC address of the modem. My understanding that it take a while for the information to propagate thought the ISP's system.

according to Comcast this may take as long as 15 minutes

 you should see this screen next

 if all is well you should see this screen - just click continue

when you see this screen acknowledge you are registered and activated, you are good to go with your new modem

Once I have internet connection with my new modem/gateway, I compare the new DOCSIS 3.0 modem to my old trusty DOCSIS 2.0 modem. I am showing this for the reader's benefit. On DOCSIS 2.0 modem there is one channel of upstream, and one channel of downstream. Both are 6 MHz channels on the cable TV spectrum.


 old DOCSIS 2.0 modem - one downstream and one upstream channel

With DOCSIS 3.0 modem, what are different is a technology advance called channel bonding. Instead of one upstream and one down stream channel, multiple channels are used to carry the data (analogous to multi-lane highway). Depends on your price tier with your ISP, your upstream and downstream mega-bit per second varies. In my case the DOCSIS 3.0 is not gaining me any better performance because Comcast throttles my speed to nominal bit rate that even a DOCSIS 2.0 modem suffices. I bought this modem/gateway because my Netgear 802.11n router/gateway is a piece of shit - not delivering what it claims to do.

new DOCSIS 3.0 modem - 6 downstream and 4 upstream channels

 With this new DOCSIS 3.0 modem/gateway with 802.11n, my wireless connection is now giving me 1/3 higher speed as well as better coverage through out my house. Instead of paying $114.97  I paid $71.50 with a open box unit, which is essentially brand new. Why I say it is essentially brand new? Well, there is a lot of returns on Amazon on this modem/gateway because a lot of people buying it has very little idea how to set it up properly. The gateways out of the box is defaulted to very low bit rate (I think 802.11g instead of 802.1n) for backwards compatibility reasons. I infer a lot of people return it seeing the performance is no better than their existing 801.11g or older gateway.

When upgrading the wifi to 802,11n there are a lot of knobs to be tweeted. It can be challenging for the less tech savvy. In my case I have to worry about some of my older devices. I have 9 devices at home that connect to wifi. Some does not operate with newer wifi and security protocol standards and I don't believe in throwing them out as a solution unless I have no choice. The solution often results in making some compromise and thoughtful workaround. One example is setting the wifi frequency to 2.4GHz as oppose to the less congested 5GHz. All but one of my Windows PC has trouble with 5GHz.

For me even though I am subscribing to Comcast's basic broadband I really cannot take advantage of the channel bonding of DOCSIS 3.0. There is very little difference from DOCSIS 2.0 performance wise except having the redundancy of having multiple channels to carry the data, albeit at a throttled rate. The price I paid is really for a good reputable brand 802.11n gateway/router. Cable ISP will continue to up the Mbps of the lower tier as time goes by. I now have a DOCSIS 3.0 modem that is future-proof and I increased my wifi speed by 1/3.

In closing on a related subject - net neutrality. If there is one single article you should read on the importance of this subject, it is this excellent article on an in depth investigation - The Cliff and the Slope.