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Motorola 3100,4100,4200 problem

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Motorola 3100,4100,4200 problem

Hello all,

I have a problem with the Motorola 3100,4100,4200 cable modems. Whenever the power goes out, the power cable on those cable modems need to be unplugged and plugged back in to resync. Is there a firmware upgrade that can fix this? It's a simple fix, but it would sure save a lot of phone calls every time there is a thunder storm?


There is indeed a known

There is indeed a known problem with older firmwares... at least for 3100 modems here is the Advisory from Motorola

Initial Ranging Back-off Not Implemented Correctly. After a Restart of the CMTS or a system wide
outage the SB3100 modems take much longer to reregister than is normally expected.
Early implementations of firmware for the SB3100 did not have the ranging or “binary” back-off
implemented correctly. This would allow large numbers of collisions to occur when attempting initial
ranging with the CMTS. Thus creating a bottleneck that could cause the modems to take many hours
to reregister. The duration would vary depending on system configuration and the number of
modems per upstream port.
Update the modem to code version 3.2.9 or newer corrects this problem.
Updating modems should be done via SNMP. It is not advisable to update the modems via the TFTP/Configuration file as
this updates the modem after it registers with the CMTS and an unexpected loss of downstream signal can lead to the
problem described above.

As for newer firmware versions they can be found on motorola's support site you will need to contact motorola to set up a login, eCHS (their trouble ticket system) would be a good thing to get signed up for as well. You may need to go thru your motorola rep.

Also be sure that ranging backoff is setup properly on your CMTS, what it does is help with congestion when all the modems are rebooting by telling each modem when it can try and come online by using variable backoff times. i.e. 10 modems try to come online at the same time The CMTS will bring on as many as it can then tell the others to wait a variable amount of time and try again. It gives each modem a different usually incremental time so that when it tries to come online there is fewer modems to contend with and they can come online. in this example the first two modems would be able to be brought online the other eight would be given a backoff time to try again, say first one 10 secs, second 20 sec and so on...




You are a gentleman and a scholar.

Thank you,

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