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low upstream :( in thomson tcm420

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Anonymous (not verified)
low upstream :( in thomson tcm420

i'm sorry for my english ;)
I have a modem Motorolla SB3100, and I have a config file below:

Main { /* this is a comment */
/*DownstreamFrequency 123000000;
UpstreamChannelId 1;
/* this is a comment */
NetworkAccess 1;
ClassOfService {
ClassID 1;
MaxRateDown 1100000;
MaxRateUp 2600000;
PriorityUp 1;
GuaranteedUp 2560000;
MaxBurstUp 0;
PrivacyEnable 0;

/* Row 1 */

MaxCPE 1;

In Motorolla SB3100 or SB4100 everything's fine I have upstream about 180kB/s but problem ist with Thomson tcm420 broadband modem, in this modem I have low upstream. Downstram on modem Motorolla and Thomson is OK

Where is the problem?
What i doing wrong?
My CMTS station is Cisco UBR7223 with modem card MC11C

low upstream :( in thomson tcm420

Why such a weird config? GuaranteUp so high - any special purpose?
Maybe just Your upstream bandwidth is not sufficient?

Pozdrawiam :)


reply to old post

I was looking over some old posts and just had to add my two cents worth here.
with a channel width of 3.2Mhz, qpsk is 5 Mbps and 16Qam is 10 Mbps. this is not taking into consideration the docsis overhead and it's shared badwidth. example, with 16Qam and about 200 modems, you'll average about 7 Mbps depending on user traffic.
snr, 18 and higher for qpsk and about 21 and higher for 16 Qam


low upstream :( in thomson tcm420


I meet same problem. The solve: Maximum Traffic Burst = 10000 or Maximum Concatenated Burst = 10000.


Anonymous (not verified)
low upstream :( in thomson tcm420

OK i found the problem. In config in Cisco UBR7223 I change upstream modulation from 16QAM to QPSK. Now is all OK

QPSK faster?

QPSK faster then 16QAM? Why?