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brouhaha6
Premium Member
join:2013-02-12
Ubiquiti EdgeRouter ER-4
TP-Link Archer C2600

1 edit

brouhaha6

Premium Member

C1000A fails several times a day, has to be power cycled

For a little over a year I've been using a C1000A VDSL2 modem configured to transparent bridging. Several times a day it stops working, in that it passes no traffic, even though it claims that the DSL link is up. I don't think it is overheating as others have suggested, as it still responds to pings to its management interface. I think line noise has somehow confused it, and it should retrain automatically, but apparently doesn't.

The phone line would become unusable every time it rained or snowed, even for voice, so it was clear that water was getting into the line somewhere, but every time CenturyLink sent a technician out, it was working perfectly. Finally in March they happened to send a tech during a snowstorm, he identified the problem, and fixed it by switching me to a different pair. (That had been tried once previously without fixing it, so apparently there's more than one bad pair between me and the FTTC.) Now it works just as well with rain and snow as with dry weather, but still stops working several times a day.

I tried a second C1000A, which behaves in exactly the same way, so I think it's a design flaw rather than a failure of the particular modem.

I've now got the modem plugged into an IP Power 9258 which will power-cycle if it can't get a ping from the CenturyLink PPP gateway address for more than 30 seconds. However, I'm still dissatisfied with the modem. Has anyone else experienced this sort of problem with the C1000A? Is there any more reliable VDSL2 modem that I should try? It looks like it's difficult to find any other VDSL2 modems available for purchase. I'm tempted by the Cisco 877, but I'd rather not spend that much money for a router when all I need is a transparent bridge.

It astounds me that this kind of problem still exists. I've had similar problems with DSL modems and cable modems since first using DSL with Pacific Bell and an Alcatel 1000 modem back in 1999. Having been a firmware engineer for networking products for over 20 years, I fail to understand why they release products with firmware that can't detect when the connection has stopped working and retrain automatically. I guess it's like any other consumer product; once it sort of basically works, the engineering is done and it's shipped to the customer. Pathetic.

TAZ
join:2014-01-03
Tucson, AZ

TAZ

Member

You are not the first to have problems with the C1000A. The ZyXEL products (C1000z, Q100 which has no switch or AP) seem more solid and have fewer reported problems. I use a Q100 myself and have no issues.

Though, if Cisco or Juniper came out with a ~$400-$500 router with 2xVDSL2 & G.998 (or expansion capability for this) + 8-10 GigE switch ports, I'd be _really_ tempted. The SRX110 gets close; the 887VA is kind of pathetic.
gapmn
join:2013-11-10
Saint Paul, MN

gapmn to brouhaha6

Member

to brouhaha6
I have used the C1000a in the past and never had reboot problems. If you tried two different modems and you had the same problem I would look elsewhere. Post your line stats for evaluation.
brad152
join:2006-07-27
Chicago, IL

brad152

Member

The C1000A does suck on unstable lines, i do see this all the time in Phoenix with lines that have low SNR. I've had a few friends that wanted to cancel CenturyLink over it, but once i put a C1000Z or Q100 on there, the problems went away.

The C1000A is just garbage, and to be honest i'm sure you're the only one that i've seen not have issues with it (i even had to swap the one CenturyLink installed at my old job out due to the C1000A causing our VoIP phones to go out)
brouhaha6
Premium Member
join:2013-02-12
Ubiquiti EdgeRouter ER-4
TP-Link Archer C2600

brouhaha6 to gapmn

Premium Member

to gapmn
I'm not sure where you think "elsewhere" might be, but I'm pretty sure that it's badly written firmware that's ultimately to blame. Even if there is something "elsewhere" that is provoking this problem, such as line noise, the modem should be able to recover from it. After all, power cycling recovers, so it's clearly only a transient condition.

I can't get the line stats because the C1000A won't let me access its management interface when in transparent bridging mode. I've got a route configured to get to its management port at 192.168.0.1, and I can ping it, but the web, telnet, etc. ports are only open briefly as it boots, then go away. I'm not sure if that's a bug, or a misguided attempt at security.

When the C1000A is working, I get the full 40/5 speed (verified with several speed test sites), and no significant number of dropped packets.
brouhaha6

brouhaha6 to brad152

Premium Member

to brad152
I have a used Q100, but when I use it I only get 25 Mbps downstream, vs. 40 with the C1000A. Is there some configuration setting in the Q100 that may be limiting the line rate?
brad152
join:2006-07-27
Chicago, IL

brad152

Member

No, my Q100 always has trained faster than the C1000A did (and always had better line stats to boot)

Maybe you got a defective one? what's the SNR and such look like in the Q100?

My Q100 would do 40/3.7 on my "40/5" crap cat-3 line, but the C1000A would only do 32/1.2 on the same jack, and would have the aforementioned non-responsive issue.

TAZ
join:2014-01-03
Tucson, AZ

TAZ to brouhaha6

Member

to brouhaha6
said by brouhaha6:

I have a used Q100, but when I use it I only get 25 Mbps downstream, vs. 40 with the C1000A. Is there some configuration setting in the Q100 that may be limiting the line rate?

What's the SNR? 25M would be ~ the ADSL2+ max, is it possibly in ADSL2+ mode (don't think CL normally allows fallback on the DSLAM side but who knows)?
brouhaha6
Premium Member
join:2013-02-12

brouhaha6

Premium Member

I'll try to dig out the Q100 this weekend, and test it in the wee hours of the morning (so as to minimize disruption to the servers). I'll try resetting it to factory defaults first. If I can get the Q100 to work satisfactorily, that will be great!
gapmn
join:2013-11-10
Saint Paul, MN

gapmn to brouhaha6

Member

to brouhaha6
It appears your logic maybe failed. You stated "I'm pretty sure that it's badly written firmware that's ultimately to blame." If that's the case, every C1000a user would be experiencing the same problem you are. Take the modem out of bridge mode to verify its not your router loosing the PPPoe connection. What do your router logs say? To get the line stats while in bridge mode, Connect a computer directly to the C1000a (wired), set computer to a static ip (192.168.0.2), open up IE, Chrome etc... type in 192.168.0.1 in the address bar and you should get the login page.

TAZ
join:2014-01-03
Tucson, AZ

TAZ

Member

said by gapmn:

It appears your logic maybe failed. You stated "I'm pretty sure that it's badly written firmware that's ultimately to blame." If that's the case, every C1000a user would be experiencing the same problem you are.

Not necessarily. A certain set of conditions (that don't exist in the average user's environment, presumably, or it would be more well-known and hopefully caught during testing) could be triggering this issue.

Though this isn't the exact problem, this is a somewhat similar one that occurred with multiple C1000A units: »C1000A dropping offline. In other words, the C1000A has a reputation for odd behavior like this.
gapmn
join:2013-11-10
Saint Paul, MN

gapmn

Member

I totally agree, "A certain set of conditions (that don't exist in the average user's environment, presumably, or it would be more well-known and hopefully caught during testing) could be triggering this issue." F/W is built for the masses not the "one off." I remember that post in the link you provided. Yet, no line stats were ever posted and a different modem was never even tried to verify it was the modem for sure.

I am not saying it is not the modem, but lets at least do some decent trouble shooting. The OP has not posted his line stats either.

TAZ
join:2014-01-03
Tucson, AZ

TAZ

Member

said by gapmn:

I remember that post in the link you provided. Yet, no line stats were ever posted and a different modem was never even tried to verify it was the modem for sure.

That's true, but he also reported the modem management site being unresponsive when this occurs, which to me points more towards a modem problem.
said by gapmn:

I am not saying it is not the modem, but lets at least do some decent trouble shooting. The OP has not posted his line stats either.

I would tend to agree but OP has already said the modem doesn't report the DSL link dropping, and power cycling the modem resolves the problem. Sure, it's possible the DSL link is dropping but you would think the modem would report this (this is basic functionality and if there were an issue here, it would presumably be caught during even the most basic of testing). Based on this, I don't believe the problem is with the DSL link, or even on the DSLAM -> BRAS end.
brad152
join:2006-07-27
Chicago, IL

brad152 to brouhaha6

Member

to brouhaha6
I've gotta agree with TAZ on this one, as i've had a similar experience with a C1000A on my old single-pair service

Also, since the OP has tried two separate C1000A modems with the same result does tell me it's most likely an issue in the firmware for his line conditions, because if the link is dropping the modem should say so regardless.
gapmn
join:2013-11-10
Saint Paul, MN

gapmn

Member

Okay...so if the OP tried "three" different C1000a's and nothing changed, you would say its even more conclusive at being a bad modem.
brad152
join:2006-07-27
Chicago, IL

brad152

Member

No i'm saying it's just a bad model, as i've had the same issue with a C1000A, and that point has been reiterated several times in the thread, and like i said before, you are the only person i've personally seen not have issues with the C1000A.

I work in IT and have to deal with these garbage modems on a regular basis, and as stated before anytime i've removed the C1000A from the equation and used a XyXEL modem, the issues tend to go away, and i've duplicated this result on several different accounts and locations.

and judging by you standing by the C1000A so much, i'd almost be willing to bet you work in CenturyLink's tech support department
gapmn
join:2013-11-10
Saint Paul, MN

2 edits

gapmn to brouhaha6

Member

to brouhaha6
I like clear results like: I tried a C1000z for 5 days and everything is working perfect. I then reinstalled a C1000a and my problems came back. It appears that many routers have a hard time reestablishing a PPPoE connection after a retrain,(»Router requires frequent power cycles?). Thus, all your modem and router lights might be green, yet no internet connection. If I had to guess, I would say the OP has very marginal line stats causing modem retrains and the router doesn't reestablish a PPPoE connection without the router being rebooted.

brouhaha,

Next time it happens, reboot "only" the router, and see if you get your internet connection back.

I don't care one way or the other about the C1000a and I don't work for CL
brouhaha6
Premium Member
join:2013-02-12
Ubiquiti EdgeRouter ER-4
TP-Link Archer C2600

brouhaha6

Premium Member

When my C1000A stops passing traffic, the router does believe that the PPPoE link has failed, but upon rebooting the router, the PPPoE connection cannot be reestablished, while if I leave the router alone and power-cycle the modem, the router reestablishes PPPoE just fine.
brouhaha6

brouhaha6 to TAZ

Premium Member

to TAZ
said by TAZ:

That's true, but he also reported the modem management site being unresponsive when this occurs, which to me points more towards a modem problem.

Actually the C1000A management interface is unavailable most of the time whether the modem is working properly or not. It seems to be available for only a very brief time after the modem is powered up, then goes away (ports closed). I can still ping it at 192.168.0.1, but nmap shows no ports open. This only occurred after I configured the modems to transparent bridging, and does not occur when I configure them back to "normal" mode. I think this is either a firmware bug or a misguided attempt at security.
brouhaha6

brouhaha6 to gapmn

Premium Member

to gapmn
said by gapmn:

F/W is built for the masses not the "one off."

Even if the condition causing the problem doesn't exist on any other POTS/DSL line in the world, it is still the case that the firmware should detect that the connection has failed, and retrain. I'm not in any way suggesting that the firmware should be able to detect a rare condition unexpected by the firmware developers. I'm only suggesting that it's quite possible to detect that the DSL link has failed, and the C1000A doesn't seem to be doing that.

I've developed firmware for networking products for more than 20 years, including at two well-known router companies, so I do know a little bit about firmware development, and about writing reliable code.

It will definitely be interesting to see whether the Q100 performs better in this situation, since AFAIK it is based on the same Broadcom reference design as the C1000A, though it uses a smaller subset of that design.

billaustin
they call me Mr. Bill
MVM
join:2001-10-13
North Las Vegas, NV

billaustin to brouhaha6

MVM

to brouhaha6
How are you trying to reach the management interface?

I have no issues reaching my C1000A in bridge mode. I use a second interface on a PC with a static IP set in the correct range to reach the modem.

I've tried setting it up in the past to pass it through the router, but only got it to work with one Netgear modem. I'm going to try again after I install my new router.
gapmn
join:2013-11-10
Saint Paul, MN

gapmn to brouhaha6

Member

to brouhaha6
Does this still happen when the modem is not in bridged mode? Also, please post your line stats.
brouhaha6
Premium Member
join:2013-02-12
Ubiquiti EdgeRouter ER-4
TP-Link Archer C2600

brouhaha6 to billaustin

Premium Member

to billaustin
said by billaustin:

How are you trying to reach the management interface?
I have no issues reaching my C1000A in bridge mode. I use a second interface on a PC with a static IP set in the correct range to reach the modem.

I've tried setting it up in the past to pass it through the router, but only got it to work with one Netgear modem. I'm going to try again after I install my new router.

I've done it both with a separate PC statically configured to 192.168.0.10, plugged into a switch between the modem and the router, and using an alias interface on the router. Same results both way: for a very short while (less than a minute) as the modem is booting, I can connect with http or telnet, but after that both ports are closed, though it still responds to ICMP echo requests to 192.168.0.1. Same behavior with two different C1000A units in transparent bridge mode, don't have this problem in "normal" mode.
brouhaha6

brouhaha6 to gapmn

Premium Member

to gapmn
said by gapmn:

Does this still happen when the modem is not in bridged mode?


I don't know. I have servers that I don't want to disrupt for hours, so I'm not going to run it in non-bridge mode long enough to find out.
quote:
Also, please post your line stats.

downstream rate: 45.118 Mbps, SNR: 12 dB, Attenuation: 0 dB, Power: 17 dBm
upstream rate: 5.12 Mbps, SNR: 18 dB, Attenuation: 0 dB, Power: 7.7 dBm

I ran the Java speed test a few times, and got pathetic results (3.2 Mbps down, 3.03 Mbps up). The modem's packet error counts were both zero afterward.

I've seen much better results than that before, nearly matching the modem's reported line rates. However, this is the first time I've run a speed test after a CenturyLink fixed the major problems with water getting into a splice.
gapmn
join:2013-11-10
Saint Paul, MN

gapmn

Member

Are you going to try the Q100 (that has worked well for Taz) today?

billaustin
they call me Mr. Bill
MVM
join:2001-10-13
North Las Vegas, NV

billaustin to brouhaha6

MVM

to brouhaha6
said by brouhaha6:

I've done it both with a separate PC statically configured to 192.168.0.10, plugged into a switch between the modem and the router, and using an alias interface on the router. Same results both way: for a very short while (less than a minute) as the modem is booting, I can connect with http or telnet, but after that both ports are closed, though it still responds to ICMP echo requests to 192.168.0.1. Same behavior with two different C1000A units in transparent bridge mode, don't have this problem in "normal" mode.

Just curious, why are you using a switch between the modem and router when the C1000A has four LAN ports on it?
brouhaha6
Premium Member
join:2013-02-12
Ubiquiti EdgeRouter ER-4
TP-Link Archer C2600

brouhaha6 to gapmn

Premium Member

to gapmn
said by gapmn:

Are you going to try the Q100 (that has worked well for Taz) today?

Couldn't find my Q100, so I bought another one, which should arrive late this week. I'll post stats from that when I get it.
brouhaha6

brouhaha6 to billaustin

Premium Member

to billaustin
said by billaustin:

Just curious, why are you using a switch between the modem and router when the C1000A has four LAN ports on it?

Normally I don't, but due to the locations of the modem and router, it was easier to have the laptop near the router, so I temporarily put a switch there.
brouhaha6

brouhaha6

Premium Member

said by brouhaha6:

for a very short while (less than a minute) as the modem is booting, I can connect with http or telnet, but after that both ports are closed, though it still responds to ICMP echo requests to 192.168.0.1. Same behavior with two different C1000A units in transparent bridge mode, don't have this problem in "normal" mode.

I reset the C1000A that I purchased most recently to factory defaults, configured it to bridging, and now it's not exhibiting the problem with the management interface. The old one still does, even after resetting to factory defaults. That one is rented from CenturyLink, so I'll send it back and stop renting it, and it can be their problem.

Eddie39
@embarqhsd.net

Eddie39 to brad152

Anon

to brad152
After several months having DSL 1 light dropping off, changing modem twice I changed out the green cable with a standard four conductor telephone cable from Radio shack. The problem went away. The module plug on the cable fits loose in the modem along with the cable being stiff causing it not to seat properly.