Alcatel ADSL Modem Sync/NoSurf

Article: 20000626-002
Title: Alcatel ADSL Sync/NoSurf
Created: 06/26/2000
Modified: 01/02/2001
Author: L. Baldwin

If you are experiencing intermittent ability to surf, despite having a solid ADSL sync, the following article may help.

Applicable configurations:

1) Alcatel 1000 Rev. E modem using Feature Group 1 (FG1) firmware
2) Alcatel 1000 Rev. E modem using Feature Group 1 (FG4) firmware
3) Alcatel 1000 Rev. G modem
4) Alcatel Speedtouch Home
5) Alcatel USB (maybe??)

Criteria:

A) Intermittently experience Synch/no-surf symptom

Specifically, Alcatel power/sync light remains STEADY GREEN and the line error light NEVER illuminates, yet you can not surf.

Note: If possible, when you suspect loss of surf capability, issue DOS ping command to your default gateway to confirm.
If you get ping responses, the modem IS properly forwarding traffic and you have a DIFFERENT Synch/Nosurf issue.

AND,

B) You have one of the above Alcatel modems

AND,

C) Rebooting the modem immediately re-establishes surf.

THEN:

You may be experiencing the "Sync/Nosurf" known problem.

Description:

Since Fall 1998 I started experiencing this symptom about once every 30-90 days when using an Alcatel 1000 Rev E (FG1) modem. After a few months I switched to an Efficient 3060 PCI modem and didn't have any further problems. Over the subsequent years I continued to hear reports of this symptom in the Bellsouth support newsgroup and from PacBell users in comp.dcom.xdsl.

I made several unsucessful attempts to escalate this through Alcatel's tech support to no avail. Since the Alcatel 1000 was discontinued in December 1999, I figured it wasn't worth pursuing. Throughout 2000, I now started hearing similar symptoms from users using the new Speedtouch Home modems--I got really concerned and again tried to escalate the issue. Finally, in the Summer of 2000 an Alcatel engineer noticed my posts and helped get my observations escalated to the modem development team in Belgium.

About the same time several European ISPs were also noticing this symptom. The converging reports were finally enough to get Alcatel to take a serious look at this behavior. After about two months, Alcatel was finally able to reproduce the problem in their labs. I don't understand all the details, but my understanding that the bug is in a process called "frequency swapping". Swapping occurs when (if) the modem detect that the current ADSL frequencies that are being used are too noisey. If this process occurs very often, the modem will lock up (stop forwarding traffic and even stop sending ATM idle cells).

This problem likely affects a small percentage of Alcatel modem users (e.g. < 1%), namely, those connected to ADSL lines that are subject to highly variable noise patterns. However, given the number Alcatel modems deployed, the absolute number of affected users may be significant. Additionally, the intermittent nature and inability to reproduce the problem at will is sure to burn a *lot* of ISP helpdesk support hours.

In my case I had 2 ISDN lines, 2 ADSL lines running in the same cable drop to my home office. I also used halogen lamps with the kind of dimmer switches that are also known to induce high amounts of noise. My loop was only 10Kft so I suspect the dimmer switches and/or other digital circuits were triggering this problem from time to time. Those on long loops (e.g. > 15kft) may experience this problem much more frequently.

Resolution:

You can either reboot the modem whenever this problem is triggered (may happen as frequently as hourly, or as infrequently as every few weeks).

For those running the Alcatel 1000 Rev E modem:

This modem is shipped with FG1 firmware by default. On several occasions I have had Bellsouth force FG4 firmware (done on the DSLAM) to the users modem. This seems to significantly reduce and in most cases eliminate the problem. (Don't know why, since as far as Alcatel is concerned this same bug should exist in FG4 as well).

If you are a Bellsouth Internet Services customer (or a customer who obtains DSL through a Bellsouth wholesaler), this can only be accomplished by the Bellsouth DSG (DSL Services Group). These are the folks the manage the DSLAMS (DSL Access Multiplexors) in the central office. Users of other service providers will need to escalate to whichever group manages the DSLAM configurations.

The last I heard Alcatel was working on a DSLAM patch that could detect sync/nosurf (sync, but no inbound ATM idle cells). Then it would manually force a re-sync, clearing the modem lock up. This is of course just a work-around, but necessary as it would be a logistical nightmare to do firmware upgrades for all modems in the field. Unfortunately, I do not know the status of this DSLAM patch or whether it has been deployed in any particular DSL network.

I believe actual fixes for the Alcatel USB and Speedtouch Home have already been released. I don't believe there are plans to provide new firmware for the Alcatel 1000 since it has already been discontinued.

Procedure:

Contact the helpdesk and state that you are experiencing the "Sync/Nosurf" problem and you are tired of having to reboot your modem every XX day/hours. Request that they open a ticket with the DSG (make sure you get the ticket number).

The instructions to the DSG should be as follows:

"Please forward a request to Temnet, or any other DSG Tech that is familar with the process, to upgrade customer from Feature Group 1 to Feature Group 4 on the port associated with ADSL# xxx-xxx-xxxx"