bk_856er
join:2007-06-08
Palo Alto, CA
| OK stats, but frequent loss of sync
Hi,
Good stable line for a few years until 2-3 months ago. I compared my stats from two years ago and nothing has really changed, and in fact the downstream noise margin has improved. Now getting very frequent loss of sync usually requiring modem power-cycle to restore (many times a day). No chnages to inside wiring.
Can changing to GDMT mode make things more stable?
Is the "other" Earthlink Zyxel ADSL2+ modem (P660R-D1) more stable with a marginal line like mine?
Here are the current stats:
Earthlink ISP (LPV)
Telesurfer 1.5/384
2005 Zyxel P660R-ELNK stats from NID today:
noise margin upstream: 25 db
output power downstream: 16 db
attenuation upstream: 38 db
noise margin downstream: 14-17 db (range of multiple tests)
output power upstream: 11 db
attenuation downstream: 62 db
CPU Load: 0.26%
Upstream Speed: 383 kbps
Downstream Speed: 1532 kbps
Zyxel normally in bridge mode.
14k feet to CO according to ATT info.
Speed tests from SpeakEasy servers today:
Download Speed: 1295 kbps (161.9 KB/sec transfer rate)
Upload Speed: 319 kbps (39.9 KB/sec transfer rate)
This was my original success story a few years ago (post now too old to add to):
»[General] interpreting Zyxel diagnostic numbers |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
1 edit | I'd suggest a retest of the residence with the AM Radio as appliances, switches, dimmers, ballasts, halogens do degrade over time and can make the Modem lose the DSL signal.
»Ameritech - SBC FAQ »My DSL loses sync regularly. How can I detect interference with an AM Radio?
»SBC DSL FAQ »RF Interference troubleshooting
As to the ZyXEL DSL Modems, all the P660 series use the same T/I AR7 chipset (and all are ADSL2+ Modems) so there is not a dramatic difference between the three that Earthlink has supplied.
Zyxel P-660R-ELNK - Router
Zyxel P-660R-D1 - Router
Zyxel P-660R-61 - Router
The DSL Mode shouldn't cause problems, but if you wanted to try switching modes it can be done in Telnet by changing the unit from Multi-mode to G.DMT manually.
Regards,
Doctor Olds
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bk_856er
join:2007-06-08
Palo Alto, CA
| I did the AM radio retest and I found one obnoxious dimmer about 15ft away from the networking gear and a few noisy Netgear power transformfer bricks relatively close to the modem. An HP laser printer in its idle state was the worst AM radio offender of all, and this device is also near the networking equipment (12 inches). Additionally, I had an in-use 100ft ethernet cable coiled up and stashed behind the printer. Perhaps the coiled cable can collect and introduce noise into the system? I'll collect some more modem data and see if anything is improved.
Question. In cases where you need to live with a suspect RFI emitter, are there any strategies to minimize the effects, such as moving it further away, shielding, etc?
With respect to the 660 zyxel modems, I noticed that my ELNK model has the original ~2005 firmware and I can't find an update. The retail zyxel model has a series of firmware reversions with the most recent one just a month old. Maybe some of those are performance improvements? Looks like I can buy a D1 version for $50 if I want to experiment (rather not spend the cash if I don't need to!).
Bob |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
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join:2001-04-19
1970 442 W30
clubs:
1 edit | You could get one much cheaper by watching eBay for the P660R-D1 Modem.
You would usually move the source of the RFI or remove the Modem from the area of the RFI if you can't remove the source.
Another thing would be to request in the Covad Direct Forum to have your line monitored for 24 hours.
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bk_856er
join:2007-06-08
Palo Alto, CA
| Not much progress, I'm afraid. I rearranged the equipment and re-routed + shortened some wiring, but lost sync a few times in the next hour. Tonight I will collect downstream noise margin data as I cycle the identified RFI generators. I need some data to correlate with the behavior.
Is the actual modem the most susceptible to RFI, or the incoming phone line within the residence? My AM radio testing showed that obstructions (boxes, shelves, etc.) blocked RFI pretty effectively. I needed to move some large boxes to access the incoming line and splitter, which could have compounded my issue by exposing everything since I have not yet replaced the boxes to their former locations. ALL my own wiring is good quality twisted-pair stuff, but not the shielded type. It's only about 8ft from the exterior NID to the splitter and modem. Maybe more clever and less exposed routing will help. Feels like a wild goose chase!
A couple of years ago one of the Covad techs here suggested changing to GDMT mode. Why? I have the procedure for making the change via telnet, but what if it does not work out? How do I change back - presumably to Multi-Mode?
Bob |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
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join:2001-04-19
1970 442 W30
clubs: | Yes, you can try G.DMT Mode or even ANSI T1.413 Mode as those are the original DSL Standards before ADSL2 and ADSL2+. |
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bk_856er
join:2007-06-08
Palo Alto, CA
| And both of those alternatives (G.DMT and ANSI T1.413) are compatible with Earthlink LPV service?
Is is safe to assume that "dropping down" in the standards is OK because I'm only at 1.5/384?
(BTW, thanks for the ongoing input!)
Bob |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
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clubs:
| Correct. ADSL2+ Modems are backwards compatible to the earlier ADSL Standards.
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bk_856er
join:2007-06-08
Palo Alto, CA
| I invested about 3hrs tonight testing the modem noise margins under various conditions. I unplugged virtually everything in the (small) house, monitored the readings for a good bit, and then one by one added things back in. The bottom line is that nothing really made a consistent difference. I did learn that over a longer space of time my downstream noise margins can range between 7db and 16db, and at the low end sync gets iffy. Things are happy at 13db.
On a few occasions the downstream noise margins slowly decreased from 15db to 7db over about 15 minutes with eventual sync loss. Sort of a death spiral. When sync returned automatically a short time later the noise readings were back to normal.
During some periods of consistently low noise margin readings, if I "reset ADSL" with the web interface the noise margins returned to good levels with the new sync. It seems as if some connections are good and some are poor and are doomed.
At one point I thought that things might be correlated with the refrigerator running, but that too proved to be inconsistent. Nonetheless, I think I might benefit from a UPS with a line power conditioner.
I can't find a definitive "in-house" RFI cause for my occasional sync loss, but now I have a better feel for the behavior and I can rule out a bunch of stuff. On the upside, my installation is now very professional looking and strictly according to best practices! That alone might give me the slight edge that I need to stabilize a marginal line.
I tested out the zyxel telnet features. The mode change to GDMT is not a menu item, but is invoked with an undocumented "wan adsl opencmd gdmt" command according to Covad. Anyone know the command to restore ADSL2+ mode? I'm going to hold off on changing the mode until I know how to get back to where I am now.
Bob |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
3 edits | A reset should bring the unit back as delivered. 
»Re: Zyxel P660R-ELNK stability issues...
said by chrp2007  :try this - thanks to e_dub at covad.direct forumopen your command prompt and type: telnet 192.168.1.1 the password should be: 1234 you will see a list of menus, type 24 and hit enter another list of menus will appear, type 8 and hit enter you see a flashing cursor at the bottom of the screen; here you will enter: wan adsl opencmd gdmt hit enter. (once you hit enter your modem will lose sync because of the change. it will regain sync.) you will be taken back to the flashing cursor. type exit to back out, your now done. just exit out of all the menu thus exiting telnet. I also added this info to the Earthlink FAQ:
»EarthLink DSL FAQ »How to set the P660R series to use the G.DMT DSL Standard only? |
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bk_856er
join:2007-06-08
Palo Alto, CA | Nice work!
Wow, the link mentioning the "ring loop imbalance" with gradually decreasing downstream S/N readings sounds very similar to my death spiral.
I'll try the GDMT tomorrow.
Bob |
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DSum
join:2009-07-01
Los Angeles, CA
| Hi,
I don't have a solution for bk_856er, but I have similar problems.
I'm in West Los Angeles, CA, three blocks from the CO. No problems for years with a Zyxel Prestige 645M (yes, a 645M, not some flavor of 660 or a 645-UHP) with Covad/Verizon.
Then two weeks ago I started losing sync randomly, sometimes for a few minutes, sometimes for half a day. No sync for most of Friday, then it worked all weekend when I used it heavily, but then not at all Monday, 50-50 on Tuesday.
I don't want to "hijack" this thread with my problems (I'll start a new thread if needed), but Bob may not be alone and I'm curious to see what eventually works for you.
Dale |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
| Your Modem is a Bridge and you have to use Telnet to obtain the DSL Stats.
»EarthLink DSL FAQ »How do I access my Earthlink/Covad ZyXEL P645 modem (Bridge Model, not UHP)?
The commands to run in Telnet are in bold in the example below.
quote:
ChangeMe> wan adsl chandata
near-end interleaved channel bit rate: 0 kbps
near-end fast channel bit rate: 3008 kbps
far-end interleaved channel bit rate: 0 kbps
far-end fast channel bit rate: 384 kbps
ChangeMe> wan adsl linedata near
relative capacity occupation: 88%
noise margin downstream: 6.5 db
output power upstream: 12.0 dbm
attenuation downstream: 47.5 db
ChangeMe> wan adsl linedata far
relative capacity occupation: 59%
noise margin upstream: 16.0 db
output power downstream: 20.0 dbm
attenuation upstream: 31.5 db
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What’s the point of owning a supercar if you can’t scare yourself stupid from time to time? |
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bk_856er
join:2007-06-08
Palo Alto, CA
| I contacted Zyxel and obtained the last firmware that Earthlink provided to them for the -ELNK flavor modem. After installing the update (twice) the version reported is the same as before. Bin file was "P660R-ELNK-340AHC3D0." I need to contact Earthlink for something more recent if it's available.
Next I put the modem into GDMT mode. The downstream S/N and attenuation improved immediately! The latest stats are below. Time will tell if the connection is more stable, but I like what I see so far!!
System Name:
ZyNOS F/W Version: V3.40(AHC.0) | 11/16/2005
DSL FW Version:TI AR7 05.00.03.e6
Standard:Multi-Mode (does not show G.DMT mode??)
noise margin upstream: 18 db
output power downstream: 16 db
attenuation upstream: 31 db
noise margin downstream: 19 db (highest ever!)
output power upstream: 12 db
attenuation downstream: 60 db (lowest ever!)
SpeakEasy speed test performed today after the changes:
Download Speed: 1288 kbps (161 KB/sec transfer rate)
Upload Speed: 322 kbps (40.3 KB/sec transfer rate)
Bob |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
| There is this, but I don't know what it is for version wise:
»support.earthlink.net/download/broadband/
quote:
EarthLink DSL and Home Phone Service Firmware:
* Zyxel Firmware Upgrade - Windows Download
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What’s the point of owning a supercar if you can’t scare yourself stupid from time to time? |
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bk_856er
join:2007-06-08
Palo Alto, CA
| That's too funny. I just spent 20min with Earthlink support and they were adamant that no firmware update exists, although they were eager to sell me a new modem. I can't get past the password request for that link using my Earthlink info. Anyone know what filename resides there?
Bob |
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Doctor Olds
I Need A Remedy For What's Ailing Me.
Premium,VIP
join:2001-04-19
1970 442 W30
clubs:
| said by bk_856er : I can't get past the password request for that link using my Earthlink info. Anyone know what filename resides there? I can't either. Don't know why and I tried all 8 of my accounts credentials starting with the main account username/password. Strange. Also don't know the filename.
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What’s the point of owning a supercar if you can’t scare yourself stupid from time to time? |
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bk_856er
join:2007-06-08
Palo Alto, CA
| I chatted with support again and tried to get access to that specific page. Waste of time. They insisted that modem firmware is "upgraded on the server end when the modem powers on" and then finally that only their "engineers" can access that page. None of their info was accurate in the least, so I don't believe any of it. That link is taunting me!
At any rate, I now seem to have the original firmware file from Zyxel, so maybe I can risk trying the retail D1 firmware and then downgrade if I run into trouble. Then again I might savor my new connection stability for a while longer. I've bricked a device or two in my time with botched firmware updates...
Bob |
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bk_856er
join:2007-06-08
Palo Alto, CA
| So far, so good with the GDMT mode....
I'm thinking of experimenting with a different modem than the P-660R-ELNK that I'm using now, and possibly "upgrading" to something else for maximum robustness. I already have a good router/gateway, so my needs are simple bridge mode, and I have enough know-how alter the settings.
Is there a superior modem that'll play nicely with the ELNK LPV service?
Bob |
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bk_856er
join:2007-06-08
Palo Alto, CA | Pulled the trigger today on a Covad-approved Innoband ADSL2/2+ VOA Firewall Gateway 8860-C1. Looks like a nice unit that'll cover my router needs. I'll post up after I put it through its paces.
Bob |
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