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Superuser
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Message 11 of 14
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Re: Help please - blue tick light going out on superhub.

Basically it is indicating communication problems between your Hub and VM's Servers (Cable Modem Termination System). The logs are showing the Hub losing connection with VM's CMTS (second T4 error, possibly the first as well) The errors are not normal in a short space of time and IMHO are causing a problem especially if you take your previous logs as well and should be further investigated by VM.

Starting a Broadband Quality Monitor here would show any dropouts and would be useful diagnostic information for VM. You will need to enable respond to ICMP Echo Requests in the Advanced section of the Hub's GUI under Ping.

Longer answer (well you did ask Smiley Happy) Do not read if easily bored

The Hub will send VM's CMTS "keep alive" messages (RNG-REQ) every 30 seconds (or less) as part of the DOCSIS Station Maintenance proceedure. Once VM's CMTS has received the RNG-REQ from the Hub it will analyse the signal and reply to the Hub with a RNG-RSP message containing technical information and information to improve the signal if required like Hub upstream power adjustments, timing adjustments and frequency adjustments if required. It will also issue the Hub a grant for the hub to talk to the CMTS at a given time\duration as many Hub share the same upstream port on the CMTS.

If the Hub has not received a RNG-RSP message from the CMTS within the T3 timeout period (200ms) a T3 timeout no ranging response error is thrown and the Hub will keep sending RNG-REQ messages to the CMTS with increasing frequency. If the Hub has not received a RNG-RSP from 16 consecutive RNG-REQ messages then a T3 timeout retries exhausted reinitialising MAC error or something like that will be thrown and the Hub will give up and drop the connection to VM's CMTS and try connecting again by re-registering with the CMTS.

T3 errors are typically indicative of an upstream problem where some impairment on the upstream has prevented the CMTS from receiving the RNG-REQ message.

A T4 error occurs when the Hub has not received an opportunity to send a RNG-REG to the CMTS within the T4 timeout period of 35 secs, probably caused by, (but not limited to) the hub not receiving a grant to talk the CMTS due to a downstream impairment. The connection is usually reset after a T4 error.

The loss of sync could be due to the hub not receiving timing corrections from the CMTS due to loss of RNG RSP messages

Mac Domain Descriptors are messages that contain the ID of the Primary downstream channel that contains the MAC layer messages (amongst a host of other info), it could be that the hub has locked on to a non primary channel, or a downstream impairment has dropped enough MDD messages to cause the Hub's MDD timer to expire. Note that MAC layer messages like all the ones mentioned above work on a different layer and in parallel to the actual data traffic.

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Forum Team
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Message 12 of 14
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Re: Help please - blue tick light going out on superhub.

Hi Maha,

Thanks for keeping in touch Smiley Happy

Really sorry that you're still struggling with this. I've just taken another look and what's strange is that from our end, you're getting absolutely no time-outs since your last reboot which was over a day and a half ago. Did you do a reboot 1 day and 11 hours ago?

Speak soon,

Take care.

Heather_J

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Maha
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Message 13 of 14
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Re: Help please - blue tick light going out on superhub.

Hello, yes i rebooted the superhub on Wednesday afternoon. The blue tick light went out around midday, but it didn't reconnect so I thought it might be maintanence or something, but after an hour and half, I turned the hub off for 30 sec & back on. Then the blue tick light stayed on.

Thanks for any help.

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Message 14 of 14
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Re: Help please - blue tick light going out on superhub.

Thanks for updating Maha, Smiley Happy

 

Please let us know if we can assist with anything further.

 

Nat_J


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