Resync/disconnect issue

Mar · 17-10-2008, 10:09

Greetings.

For the last month i am having an issue with VM 2mb service.
Issue: everything works as intendet until "infinite latency" apear, which result in modem resync. It is a random issue which may, or may not apear during single day, but it happens (like today) to be as frequent as 8-10 times an hour, making my internet connection unusable.
I have been calling VM a couple times, one tech said everything is fine, the other one said he will upload something and i'l get my internet up and running, ofcourse, the problem ist still here.
some data:
York, Acomb.

ModemL ntl250
Boot Code Version : 3.1.6d
Software Version : 2.94.1014
Hardware Version : 1.19

Downstream Frequency : 586750000 Hz
Downstream Modulation : QAM64
Downstream Symbol Rate : 6952 Ksym/sec
Downstream Interleave Depth : taps12Increment17
Downstream Receive Power Level : 0.9 dBmV
Downstream SNR : 37.9 dB

Upstream Channel ID : 4
Upstream Frequency : 46200000 Hz
Upstream Modulation : QPSK
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 37.5 dBmV
Upstream Mini-Slot Size : 2

Event Log:
Fri Oct 17 09:24:05 2008 Fri Oct 17 09:24:05 2008 Information (7) The s/w filename specified in the config file is the same as ...
Fri Oct 17 09:24:05 2008 Fri Oct 17 09:24:05 2008 Information (7) A software upgrade filename was specified in the config file.
Fri Oct 17 09:24:05 2008 Fri Oct 17 09:24:05 2008 Information (7) Authorized
Fri Oct 17 09:24:05 2008 Fri Oct 17 09:24:05 2008 Information (7) Registration complete!
Fri Oct 17 09:24:05 2008 Fri Oct 17 09:24:05 2008 Information (7) We registered with a DOCSIS 1.0 config file!
Fri Oct 17 09:24:05 2008 Fri Oct 17 09:24:05 2008 Information (7) Received a REG-RSP message from the CMTS...
Fri Oct 17 09:24:05 2008 Fri Oct 17 09:24:05 2008 Information (7) Sending a REG-REQ to the CMTS...
Fri Oct 17 09:24:05 2008 Fri Oct 17 09:24:05 2008 Information (7) CableModem SNMP configure complete
Fri Oct 17 09:24:03 2008 Fri Oct 17 09:24:03 2008 Information (7) IP init completed ok
Fri Oct 17 09:24:03 2008 Fri Oct 17 09:24:03 2008 Information (7) CableModem TFTP init ok
Fri Oct 17 09:24:00 2008 Fri Oct 17 09:24:00 2008 Error (4) ToD request sent- No Response received
Fri Oct 17 09:24:00 2008 Fri Oct 17 09:24:00 2008 Information (7) CableModem DHCP client init ok
Fri Oct 17 09:24:00 2008 Fri Oct 17 09:24:00 2008 Critical (3) DHCP WARNING - Non-critical field invalid in response.
Fri Oct 17 09:23:53 2008 Fri Oct 17 09:23:53 2008 Information (7) MAP w/initial maintenance region received
Fri Oct 17 09:23:52 2008 Fri Oct 17 09:23:52 2008 Critical (3) No Ranging Response received - T3 time-out
Fri Oct 17 09:23:52 2008 Fri Oct 17 09:23:52 2008 Information (7) MAP w/initial maintenance region received
Fri Oct 17 09:23:51 2008 Fri Oct 17 09:23:51 2008 Critical (3) No Ranging Response received - T3 time-out
Fri Oct 17 09:23:51 2008 Fri Oct 17 09:23:51 2008 Information (7) MAP w/initial maintenance region received
Fri Oct 17 09:23:51 2008 Fri Oct 17 09:23:51 2008 Information (7) Downstream sync ok
Fri Oct 17 09:23:51 2008 Fri Oct 17 09:23:51 2008 Information (7) Beginning initial ranging...
Fri Oct 17 09:23:51 2008 Fri Oct 17 09:23:51 2008 Information (7) downstream time sync acquired...
Fri Oct 17 09:23:51 2008 Fri Oct 17 09:23:51 2008 Information (7) Downstream sync ok
Fri Oct 17 09:23:50 2008 Fri Oct 17 09:23:50 2008 Information (7) starting ds time sync acquisition...
Fri Oct 17 09:23:47 2008 Fri Oct 17 09:23:47 2008 Information (7) Locked on the downstream. Waiting for UCDs...
Fri Oct 17 09:23:47 2008 Fri Oct 17 09:23:47 2008 Information (7) Downstream lock ok
Fri Oct 17 09:23:46 2008 Fri Oct 17 09:23:46 2008 Information (7) Sync Start
Fri Oct 17 09:23:46 2008 Fri Oct 17 09:23:46 2008 Critical (3) Received Response to Broadcast Maintenance Request, But no Un...
Fri Oct 17 09:23:46 2008 Fri Oct 17 09:23:46 2008 Information (7) Reset downstream scanning state!
Fri Oct 17 09:23:13 2008 Fri Oct 17 09:23:13 2008 Critical (3) Started Unicast Maintenance Ranging - No Response received - ...

I've been monitoring event log and signals levels for the last week, and noticed that 95% of resyncs happens after
Critical (3) Started Unicast Maintenance Ranging - No Response received - ...
as i bolded it, there is around 30 sec window of "infinite latecy" and after that
Information (7) Reset downstream scanning state!

During "infinite latency" signal levels are steady and at apropriate level, SNR goes low exactly when resync start, but is quickly set at apropriate level.

If anyone knows what kind of argument i could use to make VM fix the problem, i would realy apriciate it.

Regards.

Axegrinder · 17-10-2008, 10:35

Power levels look fine there, how low does the SNR drop? If it goes below 30 then that will cause problems

Mar · 17-10-2008, 11:38

Greetings.

When
Fri Oct 17 11:20:52 2008 Fri Oct 17 11:20:52 2008 Information (7) Reset downstream scanning state!
Start, SNR drops to around 30, and Downstream Receive Power Level goes up to 14 for a milisec - looks like normal procedure during synchronizing to me.

But i assume it's not where the problem is. I belive the problem start exactly here
Fri Oct 17 11:20:20 2008 Fri Oct 17 11:20:20 2008 Critical (3) Started Unicast Maintenance Ranging - No Response received - ...
at this point, my connection is cut of, ping won't go any further then my modem, same tracerout. I looks like modem can't get any response from "exchange"? for around 30 sec and try to reestablish connection by resync - if that make any sense.

Maybe i should ask for a new firmware? i'm just tired listening to that music on the phone, just to get "Your modem is up for 99% of the time, that is realy good!" response from tech. Yes, for the last year and a half, my modem was 100% up, for the last month it is unusable service.

Axegrinder · 17-10-2008, 12:17

I'm guessing they may be doing work on your UBR.