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gary_dexter
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Message 11 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub 2 logs.

Thought you were the network guru?


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AnthonyW1
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Message 12 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub 2 logs.

Drop outs happening 2 to 5 times every day. Guaranteed to be during something important my wife is doing...

Waiting a few days didn't cure the problem.

 

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AnthonyW1
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Message 13 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub 2 logs.

No I am not a network guru. Just 25 years in Tech - at the application level. 

I understand IP networks to some extent.

--No Ranging Response received - T3 time-out -   is caused by what?

What is the protocol used between cable modem and virgin mothership ?

Does t3 time-out indicate that virgin network is not responding to the cable modem? 

Or has cable modem lost its lock on the channels bouncing up and down the co-ax ?

 

 

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Lisa_CC
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Message 14 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub ...

Hi AnthonyW1, I've had a peek at your network details and can see a problem in that it's only showing one upstream channel. I'm going to send you a Private Message so I can grab some details, please reply to it so I can help.

 

Thanks,

 

Lisa

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AnthonyW1
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Message 15 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub ...

Thank you. I've replied on private message.

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jem101
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Message 16 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub 2 logs.


@AnthonyW1 wrote:

No I am not a network guru. Just 25 years in Tech - at the application level. 

I understand IP networks to some extent.

Unfortunately it's not really an IP network at this point

--No Ranging Response received - T3 time-out -   is caused by what?

In a nutshell every 30 seconds or so the Hub sends out a Ranging Request packet to the CMTS (that's the equipment at the far end of the cable in what's called a 'headend' The CMTS has to send a response back within 200ms which tells the hub if it needs to adjust timing, frequency centres etc. If the hub sends out a request and doesn't get the Ranging Response back, it resets the timer and flags a T3 error, if it misses 16 consecutive REQ/RESP cycles the Hub will reset itself to try and improve things (it starts the initial ranging process again), and the CMTS will assume that the Hub has gone offline and no longer try to communicate with it. The cause is usually problems with upstream communication, the CMTS never gets the REQ message so never sends the RESP back, the upstreams all run at lower frequencies than the downstream and are much more susceptible to interference mostly from bad or loose connections.

What is the protocol used between cable modem and virgin mothership ?

DOCSIS 3.0 (mostly; there are some areas which are on 3.1), the upstream consists of up to four bonded RF channels with the data encoded within them using 64 QAM. That's between the Hub and the CMTS after that it's an IP network out to VM's infrastructure.

Does t3 time-out indicate that virgin network is not responding to the cable modem? 

Sort of (see above)

Or has cable modem lost its lock on the channels bouncing up and down the co-ax ?

Not really no

 

 


 

Lisa_CC
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Message 17 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub ...

Thanks for the details Anthony and can confirm that they are correct.

 

I've had a look at your details again and I'm unsure what you've done or changed any equipment but I can see the upstream channels now and all the stats are showing and they are all fine. I can confirm that I cannot see any errors or anything that may suggest that there is an issue.

 

Have you always had your Hub set up in modem mode and using a third party router? Can you try and keep the Hub in router mode and monitor it to see if your connection still drops?

 

Thanks,

 

Lisa

 

 

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AnthonyW1
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Message 18 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub 2 logs.

T3 ( Ranging Request Retries Exhausted )

Explanation: The cable modem has sent 16 Ranging Request (RNG-REQ) messages without receiving a Ranging Response (RNG-RSP) message in reply from the CMTS. The cable modem is therefore resetting its cable interface and restarting the registration process. This typically is caused by noise on the upstream that causes the loss of MAC-layer messages. Noise could also raise the signal-to-noise ratio (SNR) on the upstream to a point where the cable modem’s power level is insufficient to transmit any messages. If the cable modem cannot raise its upstream transmit power level to a level that allows successful communication within the maximum timeout period, it resets its cable interface and restarts the registration process. This error message is DOCSIS event message is R03.0, Ranging Request.

T3 timeouts result when a Cable Modem, that is locked into the downstream, transmits a Ranging Request(RNG-REQ) to the CMTS(Cable Modem Termination System) and 200 milliseconds passes without the CM receiving a Ranging Response(RNG-RSP) from the CMTS. Indeed, maintaining a PING(Packet InterNet Groper) less than 200ms is important to a healthy DOCSIS network. When 10 T3s occur in succession (a period of 20 seconds passes without the CM receiving a Ranging Response, the CM will cease attempting to communicate with the HFC(Hybrid Fiber Optic Coaxial) network and reset its DOCSIS interface. In this case the RESET statistic on the modem log will increment but not all T3s will cause a reset if communication is restored within 10 T3 periods or 20 seconds. When T3 timeouts occur, but not enough occur in succession to trigger a reset, slow speeds are often a symptom as these timeouts slow down the TCP/IP handshakes necessary to maintain internet connections.

T3 Timeouts are typically caused by Upstream Noise causing Ranging Requests to not be clearly received by the CMTS. T3 problems can often be intermittant in nature as they may be the result of noise originating in any part of the plant that shares the same line card at the CMTS with the subscriber impacted. In fact, T3s can even be caused by noise originating on other neighboring nodes if resources are shared at the headend. Speed issues and intermittant connectivity issues are some of the most common problems encounted on our Trouble Calls.

T3 Timeouts can also be encountered when the plant's noise floor is so severe that the CM cannot overtalk it (SNR is bad and Noise power level is higher than your modem's signal). This can affect a single leg of the plant or even entire nodes. When a high noise floor results in several modems resetting their DOCSIS interface because 10 T3 timeouts have occured in succession, as we covered above, this is referred to as a noise outage. Noise outages frequently occur node-wide and while some may self-clear, many continue until a Plant Maintenence Technician locates and repairs the offending source of noise. This is why we ALL must be vigilant about preventing noise from entering the plant.

Occurrence: Extremely common in the customer homes

Symptom: Will cause intermittent disconnections. If you see couple of them, it is fine. If you quite a few of them consecutively, then it will lead to disconnections.

Example:
2017-6-14, 00:05:06 Critical (3) No Ranging Response received - T3 time-out;CM-MAC=**:**:**:**:**:**;CMTS-MAC=**:**:**:**:**:**;CM-QOS=1.0;CM-VER=3.0

Fixes:
1. Check for the loose or Bad cables. This is by far most neglected and most common fix.
2. Remove extra splitters in house
3. Buy powered amplifier to boost your upstream power
4. Buy better coaxial cables
5. Call for a technician visit to inspect and fix cables outside and inside home (could be rain damage, fire damage, animal damage, construction damage, etc)

See our Blog Post on how to fix your power issues by installing powered amplifier to boost your cabl...

See out Blog Posts on Understanding DOCSIS 3.0/3.1 Signal Issues at your home and maintaining optimu...

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AnthonyW1
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Message 19 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub ...

Horrid uptime T3 timeoutsHorrid uptime T3 timeouts

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AnthonyW1
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Message 20 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub ...

 

https://www.thinkbroadband.com/broadband/monitoring/quality/share/fe8a9a23a1ae063e31c9cee9dc81b26a5b... 

 

Screenshot from 2020-05-03 19-39-45.png

Network works great when everyone's asleep.  Please confine your use to 1am to 9am...

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