Arris SURFBoard 6141 or 6183 for 25Mbps?

J

jimnms

Gawd
Joined
Mar 15, 2003
Messages
882
For the several months I've been having constant issues with my internet connection crapping out and I have to call and report it every 2-3 weeks. The problem started back in January when a storm knocked down some utility polls that left me without power and internet for 3 days. They finally located the problem and fixed it, then another storm knocked down utility polls on the same damn street last month, and I've been having to go through this crap again.

A couple of techs that have come out to take signal readings have commented on the age of my modem and suggested I upgrade to a DOCSIS 3 modem. I'm still using an old Motorola SB5101. My current plan is 25/3, but bandwidth tests show me getting 30/3. I can't find a list of compatible modems on their site, but the techs say they supply Arris modems.

The specs on the 6183 show it supporting more download channels, so my question is, will the 6183 make a difference with a 25/3 connection? They do offer up to 100/5 for the cost of a few vital organs, but I'm sticking with the basic tier for now.
 
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Are you renting the modem? If so, just upgrade it since your monthly cost shouldn't change.
 
Basically, if you want to buy your own, EITHER of them is fine for a 25/3 connection.
 
A key question that needs answered is - does your ISP support either device? Most ISP's will have a list of compatible devices. If so, the SB6141 hardware is capable of over 300Mbps down, and would be more than enough for your speeds.
 
Either one will make no difference. If you're already having issues with your 5101, then things might actually get worse with a newer modem. You definitely want to glance at http://192.168.100.1 and see what the downstream power level, SNR, and upstream power levels are. I'd take a guess that the upstream power level is already quite high, and once you grab a newer modem that has bonded upstreams it makes the tolerances lower than before. Specifically that SB5101 can operate up to +57dBmV before it drops out, and according to the manuals with 3 bonded channels or more, the max power level can only go up to +51dBmV.

I know several forums where people are enthusiastic about wasting money on overkill hardware, but I'd still stand by saying keep the DOCSIS 2.0 modem until it stops working. A lot of people will hate that suggestion, because you need moar GBs and it will give you all of the magical bonded channels, but I've been watching this stuff unfold for the past 7 years now since they flipped on upstream bonding. I'm still not confident they are capable of actually fixing the issues that have come from it, and see countless issues again and again where the tighter signals have caused problems. (If I wasn't worried the swap from D2 to D3 was going to create more issues, I wouldn't think twice about suggesting to replace the modem)

If you do get a new modem, be sure to be quick to call them again if you have issues and complain up a storm. Because clueless techs love to blame the modem because someone somewhere read that's the magical fix. I don't think I've ever actually seen where a modem swap makes a difference (Assuming it's not dead and doesn't power on or refuses to connect at all), because you'd have to have a modem that was still operating properly, yet somehow lost it's ability to deliver as strong of a signal as it used to. It's either going to be flaky and die, or it's probably still working fine. You might just have to "play ball" because they will clamor up and down it's obviously the modem, so make sure that you monitor it closely if you do replace it because you could very well still have issues. I definitely could be wrong and maybe it will fix something, but I just want to inform you because once you make the jump they likely won't let you just put your SB5101 back into production if the new modem ends up being worse. So then you're basically stuck calling and complaining over and over again until you can finally get someone to admit there is a problem that is on their end.


TL;DR: Check your signal levels to make sure things aren't out of spec before you make a modem swap, so you have ammo ready if the swap doesn't fix anything.
 
Cmustang87 said:
Are you renting the modem? If so, just upgrade it since your monthly cost shouldn't change.
Click to expand...

I own my own modem, they charge too damn much for a rental. If it were a rental, they probably would have replaced it first. I initially used their supplied modem way back when I first got service because it was included for a year (which was a Motorola SB4100). They probably hope people will forget about it and rake in that rental fee. I didn't forget and I bought and have been using this 5101 for well over 10 years now.

bman212121 said:
Either one will make no difference. If you're already having issues with your 5101, then things might actually get worse with a newer modem. You definitely want to glance at http://192.168.100.1 and see what the downstream power level, SNR, and upstream power levels are. I'd take a guess that the upstream power level is already quite high, and once you grab a newer modem that has bonded upstreams it makes the tolerances lower than before. Specifically that SB5101 can operate up to +57dBmV before it drops out, and according to the manuals with 3 bonded channels or more, the max power level can only go up to +51dBmV.

I know several forums where people are enthusiastic about wasting money on overkill hardware, but I'd still stand by saying keep the DOCSIS 2.0 modem until it stops working. A lot of people will hate that suggestion, because you need moar GBs and it will give you all of the magical bonded channels, but I've been watching this stuff unfold for the past 7 years now since they flipped on upstream bonding. I'm still not confident they are capable of actually fixing the issues that have come from it, and see countless issues again and again where the tighter signals have caused problems. (If I wasn't worried the swap from D2 to D3 was going to create more issues, I wouldn't think twice about suggesting to replace the modem)

If you do get a new modem, be sure to be quick to call them again if you have issues and complain up a storm. Because clueless techs love to blame the modem because someone somewhere read that's the magical fix. I don't think I've ever actually seen where a modem swap makes a difference (Assuming it's not dead and doesn't power on or refuses to connect at all), because you'd have to have a modem that was still operating properly, yet somehow lost it's ability to deliver as strong of a signal as it used to. It's either going to be flaky and die, or it's probably still working fine. You might just have to "play ball" because they will clamor up and down it's obviously the modem, so make sure that you monitor it closely if you do replace it because you could very well still have issues. I definitely could be wrong and maybe it will fix something, but I just want to inform you because once you make the jump they likely won't let you just put your SB5101 back into production if the new modem ends up being worse. So then you're basically stuck calling and complaining over and over again until you can finally get someone to admit there is a problem that is on their end.


TL;DR: Check your signal levels to make sure things aren't out of spec before you make a modem swap, so you have ammo ready if the swap doesn't fix anything.
Click to expand...

The SB5101 can only go up to 57dBmV in QPSK modulation. My ISP uses QAM, so it's limited to 55dBmV. I've never seen it operate above 55.2dBmV.

This isn't the first time I have had service drop outs like this. I'm well aware of the modem's signal page and I check on it frequently. I'm probably the first person to report an outage because I'm pretty much always using it, and it probably takes a few days for neighbors to notice and enough people complain before it gets upgraded to an area problem. All of the techs that I've dealt with were knowledgeable and nice. They take the signal reading and see there is a problem and usually within a few hours it's fixed. They never blamed my old modem as the problem, it was just a couple of them that commented on its age. The tech that came Monday seemed surprised that I was getting 25-30Mbps (it's max rating is 38Mbps). The signal was fine when they were here, but they said that they got a lot of reports over the weekend and the issue had been upgraded to an area wide problem.

It went completely out yesterday afternoon for about 2 hours (both TV and internet), and when I called to report it, they said there was an outage in my area that was being worked on. It seems to be fixed now. This is a snapshot I just took, and it looks good now. While the downstream power level is fine, it's usually within -1 to +1 if not right at 0. The upstream power was 37 yesterday when it came up, which is the lowest I have ever seen it. I've seen some say that the optimum is 38-48 and some say it should not be below 42, but I'll take 41.2 over the 53-55 I had over the weekend. It used to always be 46-48, but after they fixed it last month when it started dropping out every time it rained, it has been 44-46. It dropped connection again last week when it rained and since then the power levels would be the usual 44-46 during the day and then go up to 53-55 by around 10pm and drop back down to 44-46 in the afternoon.

In the past, when they've upgraded their speeds, I always notice the speed increase long before they advertise it. Since my current modem is at its max speed, I wouldn't notice or be able to take advantage of any future upgrades, so I think it's time for a new modem. I mistakenly thought the 6183 supported more upload channels than the 6141 and I was wondering if that would make a difference. After getting some sleep I see that they both support the same upload channels, so it won't make any difference. I'll definitely get the cheaper 6141 because at the rate we're getting speed upgrades, both of those modems will be obsolete before I even see speeds that the 6141 can't handle.
 
It looks like your modem is operating 1 channel up and 1 channel down. Definitely dump that thing ASAP.
 
jimnms said:
In the past, when they've upgraded their speeds, I always notice the speed increase long before they advertise it. Since my current modem is at its max speed, I wouldn't notice or be able to take advantage of any future upgrades, so I think it's time for a new modem. I mistakenly thought the 6183 supported more upload channels than the 6141 and I was wondering if that would make a difference. After getting some sleep I see that they both support the same upload channels, so it won't make any difference. I'll definitely get the cheaper 6141 because at the rate we're getting speed upgrades, both of those modems will be obsolete before I even see speeds that the 6141 can't handle.
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That would explain a lot.... If you have enough knowledge about modems to be able to tell me the signal levels and know that a DOCSIS channel maxes out around 38mbits, then asking questions about the difference between two modems wouldn't make any sense.


Depending upon your ISP, you might not even get 4 upstream channels regardless of which modem you have. Same goes for download channels, it's going to be more dependent upon your ISP than anything. Due to the limited bandwidth in upstream, it's very unlikely right now you'll see more than 4 upstream channels, so most new modems are going to be identical on that front. With a paltry 25mbps download, that 5101 single channel is still capable of handling it. Obviously I don't need to tell you about shared bandwidth or any of that, but for completeness to other people who read comments, yes I'm aware that in some scenarios those channels are shared between many people. So back in the DOCSIS 2.0 days it was possible for a few heavy users to saturate the one channel the modem was connected to resulting in slower speeds. This is a bigger issue in the downstream than the upstream, especially with only having 3mbit upload.


If you're signal is that unstable it's swinging 15dB, then chances are good there is a physical compromise in the cabling somewhere. Hopefully a tech will be able to find it and solve your issues. I don't know that I would agree with 38dB being the lowest optimal power levels though. The power level is really just the 2nd hand figure to the uSNR. If you have a really low noise floor, a modem could likely operate just fine at only +30dBmV, because it doesn't need to push much signal at all to keep a quality signal. If you look at the manual it doesn't even state a bottom number, it just says up to +50 something dBmV depending upon what type of encoding is being used. I bet in a lab trial with a 20 foot patch cable between equipment, you could operate at the lowest power level the modem will function at. With the rollout of N+0 it's going to bring the nodes much closer to the end user, which should hopefully bring down the required output levels as the distance back will be significantly less.

I'm really curious to see what kind of improvements are actually seen going N+0, but there definitely have been people who are close to the first person on a node who's signal is regularly lower than 40. But here's the part that most people probably don't understand. If your modem's output window goes up to +50dBmV, and you're getting a nice +35dBmV output, that means you have 15dBmV of headroom to work with. What do we do with this? We turn up the symbol rate. So if 64 qam has a minimum SNR of 24 dB, and we're already getting 30dB SNR, we might be able to tune our parameters on the modem to get it to try to maintain a minimum of say 34 dB SNR. In doing so you'll have plenty of overhead to run at 256 QAM, but it might also require the modem to transmit at a higher power level to get even higher above the noise. But before we can make that switch, you need everyone to have the headroom otherwise a bunch of people's modems will go offline as they can't maintain a connection. So I can understand someone saying the "sweet spot" would be to keep everyone between 42 - 46dBmV because you're making good use of the modems transmit power, while not getting too high that you run out of headroom. There definitely isn't an advantage to being in the 30's, but I don't think there is a disadvantage either. Artificially making your modem work harder but attenuating the signal however definitely doesn't make sense. It would be like having your laptop in the same room as your AP, then putting a book between the two. Your laptop turned down the transmit power because it had more than enough SNR to meet the requirements, so blocking it's path now requires it to turn up the power to get back to the SNR it had previously.
 
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