Thread: 100M T3 Timeout
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Old 06-05-2012, 14:39   #14
Ignitionnet
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Re: T3 Timeout

Quote:
Originally Posted by qasdfdsaq View Post
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
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 ----------

Quote:
Originally Posted by RB2004 View Post
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
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
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