| Attachment | Size |
|---|---|
 Downstream.png | 163.5 KB |
| Upstream 1.png | 146.83 KB |
| Upstream 2.png | 173.79 KB |
Hi everybody!
I have a big problem with my CMTS Cornerstone 1500. Before 4 days, it was necessary to reset the mashine.
After reset everething is going down.:( All adjustment going out.
We are small ISP with very small subscribers.There is 160 modems.I`m not specialist of CMTS andd that was so hard to me, to set right parameters.
Please help me to set right. I`ve not configuration file. :( This is disaster..... I must say: I`m woman :).There is my setting for up and downstream.(Two upstreams 4 and 5)
Downstream:
frequency:423000000 herz
width: 6000000 herz
modulation: qam256
power: 510 dbMv
Upstream 1:
frequency:23000000
width: 3200000
power: 110
input-power-window:60
modulation: QAM 16
Upstream 2:
frequency:26200000
width:3200000
power:110
input-power-window:60
modulation:QAM16
This is general sets for Cable Network. Downstream 6 MHz DOCSIS, Upstream 3,2 MHz
160 modems.
I don`t know how to set MODULATION PROFILE. I just change modulation, and I don`t know how must set other parameters in modulation mode.
Is anybody have idea is welcome.
Friends, help me to set right modulation profile, for this seting of up and downstrem.Thak you previous and sorry for bad english.
Try to oberve a modem is it getting thru ranging? What do You mean by "all adjustments are gone"? Did CMTS "forgot" all settings? Modulation profile is set in upstream configuration mode (upstream-specific/x -> upstr. number. Check what You got under box# admin [enter] then admin# info [enter] -> show that. Is it possible to remotely telnet into Your CMTS? I'll help if possible
Thanks. I know how to set modulation profile in upstream channel, but I don`t know what value must be there. I set just one : modulation be QAM 16, nothing of other values not set correct (modulation-profile 1 example: request-info parameters; data-request; etc.) How it must be please help me
If everything works correctly change it into m-p 2 (QAM16) just to be on a safe side. QPSK is less vulnerable to noise etc. and just works almost always. If there is a problem with RF network it's the way to start. Do not, I say DO NOT, change anything else until You're absolutely sure what are You doing, those are very specific setting not to be changed under normal operation. Setting m-p to 1 or 2 is just enough.
Edit: I just rechecked Your setting and it seems that second upstream has way too low S/N (signal to noise). With modulation-profile set to 2(qam16) You'll be experiencing a lot of problems. Set it into m-p 1 (QPSK) and resolve RF problems in a first place.
Default set ot upstream is QPSK. Upsteream works in this mode 2 days. Trafiic was horroble. When I change modulation to QAM 16 things become normal. Every modem are connected. But traficc qoing up-down up-down. Somethimes is normal, after 10 minutes- not normal.
Then I set the modulation-profile 1 and make some corecctions in other field: example: preamble-len, default is 64, my value is 255!!!!
I don`t know that how must be value with my usptream frequensy, width and etc.
I can`t fill up this fields becouse don`t know wich is coreect value for my upstream channel.
Thanks;
P.S. fields that difficult for me is:
preamble-len
fec-error-correction
scrambler-seed
max-burst-size
last-codeword-shortened ...
with other words I know just rmodulation must be QAM 16
anything else......i don`t know.
If you can help me to set other fields in modulation-mode, please!
Here're values from working CMTS:
1. Info:
Parameter Value
--------- -----
admin-status up
frequency 61000000 hertz
width 3200000 hertz
power 0 tenths-of-dBmV
input-power-window 60 tenths-of-dB
modulation-profile 1 (number)
slot-size 4 (6.25 uSec ticks)
start-ranging-backoff 2 (2 to this power, 16=>special)
end-ranging-backoff 5 (2 to this power, 16=>special)
start-tx-backoff 3 (2 to this power, 16=>special)
end-tx-backoff 10 (2 to this power, 16=>special)
minimum-map-size 32 slots
maximum-map-size 2048 slots
contention-per-map 32 mini-slots
request-data-allowed disallowed
max-data-in-contention 80 mini-slots
initial-ranging-interval 2000 microseconds
high-priority-threshold 75 (number)
guaranteed-threshold 100 percent
link-trap enabled
alias ""
max-cbr-flows -1 flows (-1 = no limit)
2. Show:
Name Value
---- -----
description "cableup1"
mtu 1764 octets
speed 5120000 bits/second
hi-speed 5 megabits/second
operational-status up
last-change 1459616905 100ths-of-seconds
in-octets 1355626544 octets
in-unicast-packets 4177360007 packets
in-non-unicast-packets 0 packets
in-multicast-packets 277632033 packets
in-broadcast-packets 3272975 packets
in-discards 2456 packets
in-errors 2079 packets
id 1 (number)
timing-offset 3836 x (6.25 microseconds/64)
includes-contention true
unerroreds 2875753613 codewords
correcteds 75312 codewords
uncorrectables 11484 codewords
signal-noise 281 (s/n ratio)
microreflections 0 dBc
equalization-data (values)
publication-delay 2214 microseconds
nflow-controlled-maps 0 map PDUs
nnon-flow-controlled-maps 188309618 map PDUs
admitted-cbr 0 flows
cbr-rejected 0 occurrences
mod-iuc-list/1# show
Modulation list
IUC Control Type PreLn DfEnc F-EC F-CL ScrOn ScrSeed BstSz GuardSz LastCW
--- ------- ----- ----- ----- ---- ---- ----- ------- ----- ------- ------
R active qpsk 64 false 0 16 true 338 0 8 false
RD off qpsk 72 false 5 75 true 338 0 8 false
IR active qpsk 128 false 5 34 true 338 0 48 false
PR active qpsk 128 false 5 34 true 338 0 48 false
SD active qpsk 72 false 5 75 true 338 12 8 true
LD active qpsk 80 false 8 220 true 338 0 8 true
End of list
mod-iuc-list/2# show
Modulation list
IUC Control Type PreLn DfEnc F-EC F-CL ScrOn ScrSeed BstSz GuardSz LastCW
--- ------- ----- ----- ----- ---- ---- ----- ------- ----- ------- ------
R active qpsk 64 false 0 16 true 338 0 8 false
RD off qam16 144 false 6 75 true 338 0 8 false
IR active qpsk 128 false 5 34 true 338 0 48 false
PR active qpsk 128 false 5 34 true 338 0 48 false
SD active qam16 144 false 6 75 true 338 7 8 true
LD active qam16 160 false 8 220 true 338 0 8 true
End of list
Your problem is probably in RF network. You have to find it with help of field technician.
I have some questions
1.what is your downstream frequency? my is 423 MHz
2.I have 2 upstream channal, each of them is configured individually. If they are two, may be I must set every ot them in different modulation mode??
May be : first usptream must work in modilation-mode 1
second upsteram modulation-mode 2?????
Do you thik so?
3. In mu setting of hi-speed and speed is 10 megabits, not 5 megabits like your. May be I wrong somewhere.
4.Haw many modems can support just one usptream?
5.If I change modulation-mode with QPSK will change something about speed of upstream. The modulation was QPSK 2 days and the upstream speed was bigger than downstreem speed (in graphs where show traffic of interenet: Incoming speed was bigger than Outgoing that wasn`t normal) than I set modulation QAM16 and now 2 days the traffic going up-down up-down, not normal too but now is tolerable...........
Here are the answers:
1.downstream# info
Parameter Value
--------- -----
admin-status up
frequency 386000000 hertz
width 8000000 hertz
modulation qam256
interleave taps12Increment17
power 560 tenths-of-dBmV
link-trap enabled
alias ""
Caution: I'm using Euro-Docsis so channel width is 8MHz ! So is the frequency step - every 8MHz.
2. Nope. You could set as You wish, different modulation and so on. Frequency of course depends on Your RF network.
3. QAM16 gives You theoretically 10Mbits and QPSK 5Mbits. But in a real world it's less than that ~8-9Mb & 4Mb.
4. It's not so simple - You have to observe traffic and then decide how many modems and if it's time to deploy another upstream. More traffic - less modems. Roughly up to 75 per upstream could be ok.
5. As I said before - QPSK is twice slower than QAM16 but the latter needs really high s/n ratio and RF network should be thoroughly clean. I have no idea about speeds in Your network, at least unless I see the graphs - but what You're saying sounds suspicious. Show me Your modem configuration file, please.
Apparently Your flapping upstream is due to low S/N. Check & fix it in a first place.
I'm leaving until monday. If You need some more help You can drop me an email at : bercik(at)mail.com.
first I want to thank you for attention :)
All of this was so useful for me. Now I have suspisions, that second upsteram doesn`t work. How can be sure in this?!?!?
and how can check this to be sure that not work?!?!?
What command I must use to see modem configuration fille? Thanks again.
Log/telnet onto cmts and use command "modem tot" so You can see how many modems do You have on upstreams. If upstream is working properly You should see some of them online. To encode/decode configuration file use docsis it's freeware also for Win# Try www.docsis.org :) or click Software at left side of this page.
I have another quiestin. How can set valid date-time? I see that the date is not correct......
Try to set, but i can`t. If you can help, write me commads. Thank you:)
box# date ?
Parameter Current Value
--------- -------------
date-time 07/13/2010 12:09:48
Data Type Legal Values
--------- ------------
Date and time string MM/DD/YYYY HH:MM:SS
I do it all by myself, but thanks:) i try it and set alone:)
Your help is important for me!!!!