I work for Zen Internet Ltd and have been monitoring an issue with a couple of sites where the customer is seeing a load of ATM errors.

The customer replaced the Old 2600 series with the new 2820 and then ATM errors have disappeared completely

After a bit of a discussion we feel there maybe an incompatibilty issue with the older series and the new BT firmware on the DSLAMs. It is also not clear if BT have been doing any upgrade work in the affected exchanges for 21CN.

What we are looking for, woudl be your views and also experiences. I dont feel it is a fault of the modem, however over the last 7-8months I have seen more and more errors appear on lines using a 2600series modem.

Any feedback will be greatly appreciated.

I spotted this issue when I was trying to resolve problems using VoIP over these connections. What I found on the affected links was that there were very high rates of ATM Corrected Blocks, which ranged from ~ 4000 to 230000 corrections per minute.

While normal non-time critical data does not fail, it just arrives more slowly, it is not obvious to end users that there is a problem.

I've now swapped out 4 units. Which, as stated, changing the hardware for something with an ADSL2+ chip set (2800, 2820's) resolves the problem.

Alan

2600's are not ADSL2+ capable.
They are excellent units on a standard ADSL line, but they are now getting on a bit, and it's quite likely that they will not be happy with some of the new chipsets in the DSLAM's, which would be only aggravated if ADSL2/2+ was enabled.

runningdeere wrote: 2600's are not ADSL2+ capable.
They are excellent units on a standard ADSL line, but they are now getting on a bit, and it's quite likely that they will not be happy with some of the new chipsets in the DSLAM's, which would be only aggravated if ADSL2/2+ was enabled.

I agree somewhat. in that the modems may be having issues with the new DSLAM chipsets and this is why this post was opened.

The lines they were being used on were DSL Max lines and ficed rate lines. The 2+ mentioned refers to the modem generation and not the lines.

As a follow up...

I still have the odd client with 2600's out there one of which was upgraded onto BT's 21CN over the weekend.

The initial results do not look good. The circuit now appears unusable and the error rate for corrected blocks is over 1,000,000 per second with an uncorrected error rate of just under half that.

Alan

Azzaka wrote: The customer replaced the Old 2600 series with the new 2820 and then ATM errors have disappeared completely

You probably won't find many 2600's still in service as they were discontinued probably 5+ years ago. They didn't support ADSL2+ or INP (predating both in the UK) and also modem code in the newer models will have been tuned for the latest generation of DSLAMs. Most lines will generate some errors, but INP can mask/negate them maybe..