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Cisco 837 randomly drops connection and reconnects (ATM debug output provid

We have a Cisco 837 router at site which appears to be randomly dropping and reconnecting at various times. From looking at the logs, the downtime is only around 15 - 20 seconds, but it is causing issues for the users. I have provided the ATM debug information in a text file attached to this post and would be greatful if someone could help me understand it.

Thanks,

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Re: Cisco 837 randomly drops connection and reconnects (ATM debu

Hello Stuart,

there are two event cycles that appear multiple times and appear multiple times in your log file.

Both event cycles lead to ATM/ADSL interface change state to down

first is:

Nov 17 18:47:33.081: DSL: Defect: LOS LOF LCDf LOM: retraining

Nov 17 18:47:33.081: DSL: Received response: 0x41

Nov 17 18:47:33.769: Resetting ATM0

Nov 17 18:47:35.517: %LINK-3-UPDOWN: Interface ATM0, changed state to down

this tells that an error code has been received on the line and the interface is resetted.

second event cycle :

Nov 18 05:56:46.922: DSL: Using subfunction 0x15

Nov 18 05:56:46.922: DSL: Using subfunction 0x15

Nov 18 05:56:46.922: LOCAL:Max noise margin for power cutoff 31

Nov 18 05:56:46.922: DSL: Sent command 0x3

Nov 18 05:56:47.514: %LINEPROTO-5-UPDOWN: Line protocol on Interface ATM0, changed state to down

In this case the signal to noise ratio here the noise margin has gone under a threshold and this makes the line to be resetted to negotiate again the various line parameters.

I would suggest to ask the provider to perform some test on the line, it looks like that there can be some trouble over it.

There have been also cases where a firmware upgrade solved the issue and this can be achieved also by an IOS upgrade.

However, the line appears with troubles.

Hope to help

Giuseppe

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