T3 Timeout
 

Hi, I have just started recieving a daily error,

Started Unicast Maintenance Ranging - No Response received - T3 time-out;

only really started since they upgraded me to 6 downstream channels and the upstream levels dropped to 34.8dBmV.

I clear it daily but it just comes back again.

Prior to this I wasnt recieving any errors.

Re: T3 Timeout
 

yeah t3 errors are upstream related and it is because your upstream power is too low and your modem hasnt got enough juice to send a signal back to the cmts

Re: T3 Timeout
 

Any way it can be increased?

There is only 1 tap in the pit so I cannot be moved into a higher attenuation tap

It used to be 47dBmV but then they started doing upgrades and it dropped to 36dBmV, which was still fine.. But after they switched to 6 downstream channels it dropped further to 34.8 dBmV

Re: T3 Timeout
 

i dont know tbh, the only way I know it can be done it by moving you up a tap point but if that isnt possible for whatever reason I dont know what else they can do. Maybe jb or Seph can bless us with some words of wisdom.

No idea here either lol.

That's only way I know of also. Unless I try to shove a splitter in also. That would attenuate it also.

Fpa probably won't work as that's only supposed to attenuate the forward path.

Re: T3 Timeout
 

Why would you want to increase upstream power? Lower is better.

It is better but at the moment mine is too low so it's causing T3 errors

Re: T3 Timeout
 

I doubt it. 34.8 is low but not too low, and in any case if it's too low the CMTS would simply ask it to go higher.

The CMTS tells the modem to use the lowest upstream transmit power it can while still maintaining a decent signal at the far end. The reason it's low is because it doesn't need to be any higher.

Re: T3 Timeout
 

i thought it had to be between 34 and 58. Mine has always been 48 and most of the good ones I have seen posted are between 42-48.

Re: T3 Timeout
 

Low upstream power is normally associated with high downstream levels. What are your downstream levels at?

Re: T3 Timeout
 

What's your downstream? You might be able to remove your hdu and use a 4 way splitter now.

You can use old wide band attenuators that attenuate upstream and downstream, like a splitter

Re: T3 Timeout
 

Depending on your source between 35-55 is ideal, but anything above 25 and below 60 is fine. When you hit 60 you're at risk of maxing out the modem, since many can't go above 62-64; so when the CMTS commands more output power the modem cannot manage and so signal may drop below acceptable levels. But anything below that, if it's too low the CMTS will just ask for more.

---------- Post added at 11:30 ---------- Previous post was at 11:28 ----------

Exactly. Too little bidirectional attenuation will lead to excessive downstream power levels, which are a problem - since the modem cannot reduce the output power of the CMTS at the other end.

Re: T3 Timeout
 

Long cables have low upstream and low downstream due to the upstream uses a low frequency carrier which doesn't deteriorate over a long distance

Re: T3 Timeout
 

No modem goes above 61.21.

On VM's DOCSIS 3 network no modem should go to 58.21, once upstream bonding is implemented this drops further to 55.21 for 2 x 16QAM channels and 52.21 for 4.

They go to 32 or 64QAM take another 1.21dBmV off this.

There are several other issues that high upstream power causes, mostly focussed on laser clipping - the modems are configured in a mixed mode and talk QPSK for maintenance purposes, if a modem is maxed out it'll be bursting at 58.21dBmV for data grants and 61.21dBmV for maintenance which may overdrive the upstream laser and cause performance degredation.

---------- Post added at 13:39 ---------- Previous post was at 13:37 ----------

I use a bidirectional adjustable attenuator to manage mine.

Downstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked
Locked QAM256 118 55616000 Kbits/sec 299000000 Hz 3.8 dBmV 40.6 dB Hybrid
Locked QAM256 117 55616000 Kbits/sec 291000000 Hz 4.1 dBmV 40.0 dB Hybrid
Locked QAM256 119 55616000 Kbits/sec 307000000 Hz 3.2 dBmV 40.3 dB Hybrid
Locked QAM256 120 55616000 Kbits/sec 315000000 Hz 2.9 dBmV 40.3 dB Hybrid

Upstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power
Locked ATDMA 10 20480 Kbits/sec 27400000 Hz 44.8 dBmV

Re: T3 Timeout
 

Was this a subtle hint? ;)

are we going to see 4 upstreams on 32/64QAM?

Hi agreed low upstream should not be a problem, as the
Cmts should manage those levels and request a higher upstream.

But for whatever reason since they dropped down to 34.8 I started recieving t3 errors.

The reason they dropped seems to coincide with the upgrades and maintenance.. Like I'd read vm sent all their engineers out tightening up the connections In cabinets and things properly.

And I get any tired amps and nodes have also been replaced as part of the upgrades.

Which is why the cmts started requesting a lower upstream power.

I've now removed the hdu and put in a 4 way and 2 way splitter.. 1 on each drop cable.. Will replace though with 2x 3 ways if the t3 errors go away so I have even signal levels around the house.

But upstream is now 41 currently will see if that drops any more

Re: T3 Timeout
 

No and yes, eventually, respectively.

Re: T3 Timeout
 

My bad, I knew it was somewhere around 62-ish...

In that case, the current recommended range of up to 55 is not only incredibly close to the absolute limit already, but will be beyond it soon.

So my guess is the recommended range should change to no more than 50dB now, and 45dB for bonded 64-QAM.

Re: T3 Timeout
 

Is that something he can buy and do himself or would he best ringing up and getting them to take a look at it?

I've been monitoring my
Connection with the hdu removed and upstream at 41 dBmV

And... Im still receiving T3 errors

I guess this is now looking like a networks fault.

Re: T3 Timeout
 

if your power levels are within spec and everything is working alright I wouldnt worry about it. I get the occasional T3 error but I never notice it because my connection is pretty much 100%

Where possible I prefer to fix myself, the engineers around here just lie to me and fob me off. :(

I always use same stuff as vm use, and do to the same standard.. From splitters to triple shielded cable using the same identical f connectors.

Signal levels were perfect until they started doing network work, I've now removed the hdu as the network downstream levels had creeped up slightly, which is how I got the 41dB upstream, as the splitter is now attenuating it.

But still getting the T3 errors

Nothing has changed on my
Installation so it's nothing here I don't think, it was error free for months.

---------- Post added at 07:07 PM ---------- Previous post was at 07:05 PM ----------

It's not occasional though it's several times a day at present :(

Re: T3 Timeout
 

still getting lots of T3 errors :(

connection in terms of downstream is about as perfect as it will get, and upstream is better now.

Connection
Startup Procedure
Procedure Status Comment
Acquire Downstream Channel 315000000 Hz Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File OK
Security Enabled BPI+
Downstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power SNR Docsis/EuroDocsis locked
Locked QAM256 38 55616000 Kbits/sec 315000000 Hz 2.0 dBmV 42.9 dB Hybrid
Locked QAM256 33 55616000 Kbits/sec 283000000 Hz 1.5 dBmV 42.9 dB Hybrid
Locked QAM256 34 55616000 Kbits/sec 291000000 Hz 1.3 dBmV 42.8 dB Hybrid
Locked QAM256 35 55616000 Kbits/sec 299000000 Hz 1.2 dBmV 42.6 dB Hybrid
Locked QAM256 37 55616000 Kbits/sec 307000000 Hz 0.6 dBmV 42.5 dB Hybrid
Locked QAM256 39 55616000 Kbits/sec 323000000 Hz 1.6 dBmV 43.0 dB Hybrid
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV 0.0 dB Unknown
Upstream Channels
Lock Status Modulation Channel ID Max Raw Bit Rate Frequency Power
Locked ATDMA 1 20480 Kbits/sec 35800000 Hz 41.3 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Unlocked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
Primary Downstream Service Flow
Downstream(0)
SFID 1252
Max Traffic Rate 110000000 bps
Max Traffic Burst 10000 bytes
Mix Traffic Rate 0 bps
Primary Upstream Service Flow
Upstream(0)
SFID 1251
Max Traffic Rate 10250000 bps
Max Traffic Burst 16320 bytes
Mix Traffic Rate 0 bps
Max Concatenated Burst 16320 bytes
Scheduling Type Best Effort
Current System Time:Sun May 06 22:03:46 2012

Re: T3 Timeout
 

those power levels are perfect. Have you run some speed tests or done any downloads to see what you get?

Re: T3 Timeout
 

I also get T3 timeouts but I noticed that my US power was all over the place.

http://www.cableforum.co.uk/board/at...1&d=1336376418

What can cause this sort of variation? Can this lead to T3s?

Hi I know they are perfect lol, it took me a lot of hastle last year to get them to that.

This is why I'm sure this is a network problem, my signal levels are fine :)

Re: T3 Timeout
 

just setup a broadband monitor.

looks like im getting some packet loss also

https://www.cableforum.co.uk/images/...2012/05/48.png

Re: T3 Timeout
 

Seems to be behaving so far, I'll see what happens later this evening
http://www.thinkbroadband.com/ping/s...08-05-2012.png

Re: T3 Timeout
 

just been sent a replacement superhub, still getting Timeout errors though and small packet loss :(

https://www.cableforum.co.uk/images/...2012/05/15.png

Re: T3 Timeout
 

Apart from when you just set up the chart, I see virtually zero packet loss on your chart.

Re: T3 Timeout
 

hi, its because I have just setup the chart, had to setup a new one as I got sent a new superhub, and my IP seemed to change.. but as with my previous one over the period of 24 hours the minor packet loss was more visible.

definitely still getting the T3 timeouts as well,

Mon May 21 00:50:51 2012 Critical (3) Started Unicast Maintenance Ranging - No Response received - T3 time-out;

Re: T3 Timeout
 

Well... after 5 months since posting this.

I checked my superhub tonight, and downstream levels have dropped by about 2dB, upstream levels have increased by about 5dB all on their own suddenly.. so VM networks team have done something.

AND.... NO MORE T3 ERRORS!!

But why has it taken them 5 months to fix this? especially after during this time I had made several complaints regarding it... it started when they added more downstream channels and I was getting quite a few every day.

Next month im due to be in a 120mbit ready area as they say upgrades are almost complete... so my guess is they have done something to do with the upgrades which has caused the alteration of my signal levels and fixed the T3s.

just stupid that its taken 5 months.

also noticed that the missing downstream channel in the sequence.. 36 if i can remember has appeared now.

Previously it had always been missing with a gap in the channel numbers.

https://www.cableforum.co.uk/images/local/2012/10/5.jpg

https://www.cableforum.co.uk/images/local/2012/10/6.jpg

https://www.cableforum.co.uk/images/local/2012/10/7.jpg

https://www.cableforum.co.uk/images/local/2012/10/8.jpg