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AnthonyW1
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Message 21 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub ...

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AnthonyW1
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Message 22 of 41
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Multiple drop outs every day. Fix it please.

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AnthonyW1
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Message 23 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub ...

Strange. Now i have very bad broadband quality monitor charts - it seems my account has been restricted from uploading pictures...

 

here's the link. Its terrible...

 

https://www.thinkbroadband.com/broadband/monitoring/quality/share/548b4cbeaae6119eb9c2f6f4711035feee...

[url=https://www.thinkbroadband.com/broadband/monitoring/quality/share/548b4cbeaae6119eb9c2f6f4711035feeee4cedd-05-05-2020][img]https://www.thinkbroadband.com/broadband/monitoring/quality/share/thumb/548b4cbeaae6119eb9c2f6f4711035feeee4cedd-05-05-2020.png[/img][/url]

 

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SCA1972
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Message 24 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub ...


@AnthonyW1 wrote:

Strange. Now i have very bad broadband quality monitor charts - it seems my account has been restricted from uploading pictures...


@AnthonyW1 No, your account has not been restricted from uploading pictures.  Images need to be approved before they are visible to everyone.  Normally they should be visible to you as the uploader, but a bug in the current forum code prevents even you seeing them until they are approved.  If you see yellow triangles in place of your images then they are fine and just awaiting approval.  If any of them are showing a red circle with a diagonal line through it then that image has been rejected.

Your latest images contained your WAN IP address which is against the forum rules to protect your privacy, so they were rejected.

Creating multiple thread for the sames issue is also against the rules so I have merged your threads.

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My setup: V6 TV box, M350 Fibre broadband with Hub 3 in modem mode connected to a Netgear R7000 router. Telewest/VM user since 2001.

I'm a Very Insightful Person, I'm here to share knowledge, I don't work for Virgin Media. Learn more

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AnthonyW1
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Message 25 of 41
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Re: drops at my end user level with 'No Ranging Response received - T3 time-out' in the Superhub ...

548b4cbeaae6119eb9c2f6f4711035feeee4cedd-05-05-2020.png

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Robert_P
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Message 26 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 for posting the BQM Anthony, I'm going to send you a Private Message to get some further details from you to look into this further.

 

Thanks

 

Rob

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Eeeps
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Message 27 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.

I suggest you read the DOCSIS 3.0 specification rather than some random interpretation of it if you want to truly understand the communication medium.

In a nutshell it seems from your posts that you have intermittent noise ingress in the upstream channels.

Unfortunately the modulation error ratio (effectively S/N ratio) and bit error rates for upstream signalling is only visible to the CMTS.

In your case, given that your problems occur during daylight hours, I would assume that the noise ingress is created by other CM on your segment or even some external source.
You have to remember that the operating frequencies for upstream channels sit nicely in the radio spectrum.

If you connect to your SH3 during an outage you might get a better idea of what is going on.


@AnthonyW1 wrote:

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 28 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.

That was a little patronising wasn't it...It looks like a well written explanation of DOCSIS to me and matches well with the explain that another forum user  helpfully posted.

"Upstream Noise causing Ranging Requests to not be clearly received by the CMTS."

I will not read the spec thank you. I only wanted to understand T3 timeouts and their causes.

 

So the BQM points to interference / noise in the segment.  Happens only during peak human hours 8AM to 6PM.

Next question - what could be causing that?

  • A neighbours faulty cable modem,
  • birds nesting in the street cabinet ,
  • wrapping the co-ax around a Tesla coil,
  • too many subscribers - bandwidth over allocation...,
  • Aliens
  • or perhaps my neighbour who has 5 HAM radio antennas of various shapes and sizes on their roof and appears to be a teleworker for GCHQ....

 

Place your guesses below...

Someone at Virgin may have a keen eye for the tell tale lead up?

I would hope that the CMTS has monitoring  - perhaps a faulty line card in the switch etc..

 

What equipment is in a street cabinet exactly - make model spec ?

 

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AnthonyW1
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Message 29 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.

Screenshot from 2020-05-06 11-36-43.png

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Eeeps
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Message 30 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.

I wasn't intending been patronising and I apologise if it came across that way.
All I was pointing out was that it's best to go to source material if you want correct and accurate information.

In any case your BQM looks quite good apart from the periods of packet loss so I would assume you don't have a segment congestion problem.

The fact that these periods seem to occur during daylight hours suggest that these are associated some manmade activity. I wouldn't discount amateur radio (even if you though that fatuous).

Do you have an isolator fitted to your incoming coax? Can you check your SH3 status during a disconnect?

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