A story about fiber to home vs cable

Early this year I converted away from the fiber to home offering that my local telecom provider was servicing the past 2 years back to the dreaded Comcast which 2 years ago proved to be highly unstable at that time, hence why I did the fiber to home instead till recently.

Now why would I gravitate away from the coveted fiber to home internet back to the dreaded Comcast? Network performance instability. Wait, I thought fiber to home doesn’t have network instability? Heh, another devil in the details.

You see even fiber to home is a shared pipe that gets split off between you and your neighbors in the same way cable internet offerings traditionally have, which has earned Comcast in particular some well-deserved stigma for spreading too little bandwidth over too much bread. This is a problem during peak use hours where everyone is pulling on the same shared pipe. There’s nothing wrong between your PoP and your local fiber hub, it’s the ISP fiber backbone itself afterwards that’s the bottleneck as upgrading larger fiber backbones means lots of $$$; city/county permits, and potentially scheduled downtime are expensive and painful, so ISPs are in no hurry to upgrade their backbone, which, to my surprise, Comcast has been lately…

So a bit about how I got here; I’m going to cut down the story a lot as it’s a long one, but, a bit of storytelling here is needed as I’d be willing to bet parts of the story may resonate.

I noted around last November, something changed. All the sudden it seemed like my internet felt slower and I hadn’t changed anything anywhere in my setup. About a month later, I started experiencing complete loss of internet for minutes at a time and me being a computer nerd, I checked every component in my LAN in my house… Clients, Wi-Fi router, cables, EMI interference, you name it. I was left with one possibility, my ISP, which was mind boggling as it was a fiber offering; maybe they had a problem and weren’t aware? So I called and reported the problem, they had me do some far more rudimentary testing but I obliged them as I knew they wouldn’t kick the ticket to someone who could actually do something about it until I did. Later that week a local tech showed up to my house, plugged in his laptop in the middle of the day to my router (outside peak usage) and did a speed test and declared all was good. I indicated all was not and that it wasn’t a fair test as it wasn’t during an outage, IE peak hours. He scoffed thinking he was smarter then I, left my house giving the all clear and closed the ticket. That night it happened again, I called again and reported the issue, after much stronger language this round (instead of obliging and agreeing with every word the representative said) their NOC called me back an hour later and also indicated all was clear and they were seeing green lights across the board. I know from vast experience working with NOCs they all seem to experience either the same ignorance problem, or hot air problem of they either have no clue what they’re doing and rely only on tools that don’t tell a full story, or do know what’s going on but play ignorant because they can’t do anything about something that is their fault but that they can’t fix thus run interference; exactly what just happened.

After a few more escalations and repeats of the issue it was going no-where. I contacted Comcast and arranged to get reconnected. I opt’d to bring my own modem as I wanted to save a couple bucks a month which would pay for itself after a while over their standard rental modem agreement. Sure enough, the problem was resolved when I switched over to Comcast and still hasn’t returned since; guess it’s not my LAN, which my local telecom insisted there must be something wrong with me, or my setup many times throughout the multiple escalations.

Comcast’s evolution (why you should bring your own modem)

So things have changed the past 2 year. Comcast has gone from 4x1 cable bonding 2 years ago to 31x4 cable bonding in my neighborhood now. Say what again?

In layman’s terms, they’ve built wider roads for their internet traffic to accommodate. But, there’s a catch; you need a cable modem capable of negotiating the complex 31x4 link to get the benefit. If you either use a cheaper lower end modem, the default rental one they give you, or have an older one, you’re just not getting the full pipe. Now, there’s more to it than just sheer pipe going on here as most people don’t need (or want to pay for) say a 300mb or more connection. If you have a cable modem capable of negotiating all or most of that pipe, it’s akin to having access to the carpool lanes; your internet traffic can travel on lanes other folks aren’t using, so, even though I only pay for a 60mb cable offering (which is actually 72mb, a bit more on that in a bit), and my 24x8 Netgear CM600 can negotiate up to a 960mb connection which I’m not even remotely interested in paying for, that 60MB connection has access to the lanes that aren’t getting tapped thus at almost any given time I have my full 72MB connection. Worst day I’ve ever had was like 60MB. Wow, that’s really good compared to my fiber offering which I was paying for an 18MB cheap offering but getting somewhere between 0 and 8mb during peak hours, and rarely getting the full 18MB even though it was a true fiber offering towards the end of my time with them.

Couple anecdotes worth mentioning here to stop for…

1.Comcast is offering 1 channel shy of the full DOCSIS 3.1 spec that is 31 of 32 channels, possibly to prevent a DOCSIS 3.1 negotiation from completing before they’re ready for it. 31 channels is no typo.

2.Comcast over-provisions their DOCSIS 3.0 (and earlier) connections by 20% these days to add a cushion as many people still have lower end/older modems and it’s an easy way to mitigate some of the effects of network traffic issues (which they have a stigma for), somewhat cushions though; really you need a beefier modem to shake it loose IE access to the carpool lanes. Raising the speed limit only goes so far which is what they’re doing here. It should be noted, DOCSIS 3.1 does not get overprovisioning, that’s important as say that new Netgear CM1000 or other DOCSIS 3.1 modem will negotiate at 60MB on a 60MB plan vs the 72MB I’m getting on a 60MB plan, granted at the full 31x4 lanes vs my 24x4 lanes that I’m negotiating now, but once you pass into the 24 channels down turf, traffic congestion isn’t the long pole in the tent anymore, it’s once again the speed limit, IE what you’re provisioned for. Thus, my CM600, gets faster speeds at 24x4 and 72MB then a more expensive CM1000 at 31x4 and 60MB. Thus, the only time to get a DOCSIS 3.1 modem, is if you plan to pay for, and your cable provider provides the full DOCSIS 3.1 (gigabit) to your area, otherwise you’re actually missing out and paying more for less. Go figure.

The Netgear CM600, CM700 and PUMA 6 issues

There’s more to this story, if you can believe it…

I noted pretty early on switching to Comcast that although I didn’t have outright outages anymore, certain applications seemed slower than others, particularly complex websites and my FireTV and Roku SmartTV had an odd latency.

Once again I’ll save a bunch of troubleshooting and get to the source: my Netgear CM700 modem at the time.

It’s a DOCSIS 3.0 modem, capable of 32x8 though, seems like a winner based off my prior anecdotes, but, if you noted I’m now at the end of the story using a “lesser” Netgear CM600 capable of 24x8. Yup, there’s a reason. Latency.

Side story on cable splitters, cabling, and signal strength

A little side story though. Part of my troubleshooting that I will get into (and not skip over), I noted that I was only getting 31x2 channels negotiated on my Netgear CM700. I had (past tense) a 3-way cable splitter at my PoP on the side of the house, the two 7db splits weren’t giving enough signal for my CM700 to negotiate the 4 uplinks available, only 2 of the 4, which uplinks are just as important as downlinks for latency purposes. The 3rd 3.5db split (labeled on the splitter), did give enough punch though to negotiate all 4. Uplink packets are often requests for data, not just pushing photos to facebook, they’re very small packets requesting data, then followed by large downstream packets from your ISP fulfilling the request for say loading google.com (or whatever), but it takes an upstream packet to get that downstream flowing. If, you’re ability to request data is once again chocked off due to traffic congestion, it’s a problem for your downstream fulfillment. Thus, it’s important to make sure your cable modem has enough signal to negotiate the full pipe available at your PoP. In my case, I removed the splitter as the only thing I’m using my cable for is internet. If you’re using it for TV too, consider relocation of your modem if possible closer to your PoP, or using a 2-way splitter which gives you 2 3.5db splits if you only need 2 connections, moving your cable modem to the 3.5db split on a 3-way splitter if you need 3, or redoing your coax in your house with higher grade coax to reduce signal loss in worst case scenario (re-wiring is a pain, not just for your ISP, for you too).

Back to the modems

I first relocated my Netgear CM700 to my PoP, it was barely a week old and it went out, dead. I took it back to BestBuy and exchanged it for an ARRIS SB6190. Worst mistake ever.

So now I was getting the full 31x4 negotiation with my newly relocated ARRIS SB6190, but my latency was worse? What is going on here?

Don’t ask me how I figured it out, but after much Google I stumbled upon the PUMA6 problem.

Both the Netgear CM700 and Arris SB6190 use an Intel Puma 6 chipset which isn’t as robust for whatever reason as the Broadcom chipsets in older cable modems. They’re still trying to figure out why and there is a class action lawsuit regarding it. The morale of the story here is, don’t get a PUMA 6 cable modem, and if you have one, you should consider getting one that isn’t if you want a faster internet.

Now I thought you said the SB6190 was worse then the CM700? Correct. The ARRIS SB1690 uses a single core, slower clockspeed variant of the PUMA6 vs the Netgear CM700 uses a dual core, higher clockspeed PUMA6, thus although it’s still PUMA 6, the CM700 is better by a country mile then my former SB6190, and is a viable option if congestion in your neighborhood is so bad, 24x4 isn’t good enough, then, the dual core PUMA 6 CM700 is worth a peek over say the CM600 which isn’t PUMA 6 based, but that’s the exception, in most scenarios, if not every scenario, the latency will be your weak link in the chain choosing between a 24 channel bond broadcom-CM600 and 32 channel bond PUMA-CM700/SB6190.

So after figuring that out, the ARRIS SB6190 went back to BestBuy and after much research, I settled on the Netgear CM600 which although not 32x8 capable, it was 24x8 capable, and no PUMA 6, next best thing. Sadly there is no 32x8 capable broadcom modem, but, 24x8, yes, and only the CM600 at that.

Well I’m happy to say the Netgear CM600 on my no splitter, with my Comcast 60MB plan that I’m getting 72MB for, screams it’s so fast, Roku SmartTV, FireTV and complex websites and all.

There is a slight note though, cable providers have “concentrators” on their end of the spectrum, it’s part of the DOCSIS lifecycle. These concentrators negotiate varying types of modems (including the upcoming / emerging DOCSIS 3.1), they have to have a build for each modem, and each firmware rev, hence when a PUMA 6 “fix” came out, that fix wasn’t rolled out immediately as Comcast and other cable ISPs had to make new software builds on their ends before they could start upgrading modems on the client side with the improved firmware which helps a little bit, but still doesn’t fix the PUMA 6 “bug”.

This is important because the build they have running for the Netgear CM700 is very responsive. Although my Netgear CM600 is better, it’s better in most, but not quite all regards then the dual core PUMA 6 Netgear CM700.

My guess is the CM600 isn’t very popular thus they haven’t given the concentrator/s it’s running on TLC. I’ve noted when I go to open a webpage after no activity for a while it’ll take a good second to respond, but, once it’s “warmed up” man it just goes and subsequent requests are instantaneous. Almost like there is a sleep mode for the Netgear CM600; wish I could turn the sleep mode off. There probably is a sleep mode for it that Comcast controls and I can’t get to from what I gather with my limited insight as the Arris SB6190 did have a sleep mode, which was user accessible so it’s logical. But that’s my only complaint about the Netgear CM600 and Comcast, not bad compared to outages of my fiber to home offering, traffic congestion I had 2 years ago, latency woes of PUMA 6, or not getting overprovisioned (which I avoided) of DOCSIS 3.1 modems.

If there is a cable modem to own, the Netgear CM600 is arguably “the” one to own. If however you’re finding even with a CM600 your data rates are all over the board, then I might suggest a CM700 or CM1000 as those can negotiate the full 32 channels.

If your fiber to home offering is delivering, don’t change it. You like me, may have years of perfect service and then some November your next door neighbor will upgrade to that new gigabit offering, and you’ll be unhappy every time he/she uses it. When that day comes, Comcast hasn’t been standing still to absorb you back into the fold and if you use the right setup, it can be very satisfying to have something that just works.