50M : Connection loss

[foddy]

Occasionally, I have a problem where I lose Internet connection completely. Everything looks like it's working, my router has its IP address, I can see the 192.168.100.1 web site, but nothing beyond it.

Shutting down and bringing up the external interface forces things to work again (it probably causes the DHCP lease to be renewed). But it's the same IP address. Does the cable modem (VMNG300) maintain some sort of connection state that it's losing?

There were a few errors in the CM log at around the same time over a period of around a minute:

• SYNC Timing Synchronization failure - Loss of Sync
• Received Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out
• No Ranging Response received - T3 time-out
• MIMO Event MIMO: Stored MIMO=0 post cfg file MIMO=-1;

Any ideas?

Thanks.



---------- Post added at 10:35 ---------- Previous post was at 10:08 ----------

I should add - 64QAM, 7.04-8.17 dBmV downstream power levels, 16QAM 46.96 dBmV upstream.

I have a 3.5dB forward-path attenuator, a two-way splitter and a 8dB forward-path equaliser between VM and the cable modem (in that order, the equaliser being plugged into the modem).

[pip08456]

Downstreams on the high side.
SNR?

[foddy]

Originally Posted by pip08456

Downstreams on the high side.
SNR?

I assume that's RxMER - 37.30 - 37.88 dB.

[Peter_]

If you can see a valid public ip address then the may be an outage "Valid ip no throughput" which only support can advise you about.

[foddy]

Originally Posted by Masque

If you can see a valid public ip address then the may be an outage "Valid ip no throughput" which only support can advise you about.

Quite possibly, but I'm guessing the first thing I'll be asked to do is turn it off and on again, which I know will fix it...

One interesting thing is that it seems to have got a little worse since I had Tivo installed. I took PDFs of the modem pages before that, and there's almost no difference - if anything, the downstream power is lower now.

[Peter_]

Originally Posted by foddy

Quite possibly, but I'm guessing the first thing I'll be asked to do is turn it off and on again, which I know will fix it...

A reboot usually does not clear the fault I stated as it is an issue on the network which would affect many more customers.

[foddy]

Originally Posted by Masque

A reboot usually does not clear the fault I stated as it is an issue on the network which would affect many more customers.

Ah no, I don't think it's that, then - a reboot (or even just taking the external interface down/up) will clear the problem.

[Peter_]

Originally Posted by foddy

Ah no, I don't think it's that, then - a reboot (or even just taking the external interface down/up) will clear the problem.

If that is how you fix the issue then the modem is at fault.

[foddy]

Originally Posted by Masque

If that is how you fix the issue then the modem is at fault.

Could it not be the UBR? I thought the modems didn't maintain any state. The IP address doesn't change, the modem doesn't get a reboot, the ethernet would have stayed up - essentially it's the DHCP renew which fixes it.

[Peter_]

Originally Posted by foddy

Could it not be the UBR? I thought the modems didn't maintain any state. The IP address doesn't change, the modem doesn't get a reboot, the ethernet would have stayed up - essentially it's the DHCP renew which fixes it.

It sounds more like a modem issue if you lose connection with a valid ip but to check would involve a engineer and a probable swap to a Superhub.

[foddy]

Originally Posted by Masque

It sounds more like a modem issue if you lose connection with a valid ip but to check would involve a engineer and a probable swap to a Superhub.

In that case, I think I'll keep quiet. Thanks for your help.