Modem Keeps Dropping Signal

Modem Keeps Dropping Signal
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Subject Author Date
Modem Keeps Dropping Signal Bruce 12-15-2005
Posted by Bruce on December 15, 2005, 1:02 am
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I'm in the SF Bay Area, zip 94070. I swapped out my RCA DCM245, which
couldn't handle the new, higher speeds, for a Motorola SB5101 at the
Comcast walk-in store. I now have the new speeds, but every hour or so,
the modem drops the signal. The online light stays solid, but I'm no
longer connected to the internet. I have to power cycle.

Here's my modem stats for the new SB5101:
Downstream
Frequency 705000000 Hz
Signal To Noise Ratio 27.8 dB (RCA was 35.2)
Power Level -5.5 dBmV (RCA was -7.5)

Upstream
Channel ID 4
Frequency 24800000 Hz
Power 34.0 dBmV (RCA was 32)

I've got a truck roll for Saturday morning to check line (that's what
Comcast wants to do), but it seems odd that this happened immediately
after putting the new SB5101 into service.

I don't understand if this is a coincidence that the S/N dropped, or if
the new modem could be the problem.

Posted by Dr Feelgood on December 15, 2005, 1:53 am
Chances are it was not provisioned properly. Could be the mac address was input
wrong. Try giving service a call again and have them double check it.


> I'm in the SF Bay Area, zip 94070. I swapped out my RCA DCM245, which
> couldn't handle the new, higher speeds, for a Motorola SB5101 at the
> Comcast walk-in store. I now have the new speeds, but every hour or so,
> the modem drops the signal. The online light stays solid, but I'm no
> longer connected to the internet. I have to power cycle.
>
> Here's my modem stats for the new SB5101:
> Downstream
> Frequency 705000000 Hz
> Signal To Noise Ratio 27.8 dB (RCA was 35.2)
> Power Level -5.5 dBmV (RCA was -7.5)
>
> Upstream
> Channel ID 4
> Frequency 24800000 Hz
> Power 34.0 dBmV (RCA was 32)
>
> I've got a truck roll for Saturday morning to check line (that's what
> Comcast wants to do), but it seems odd that this happened immediately
> after putting the new SB5101 into service.
>
> I don't understand if this is a coincidence that the S/N dropped, or if
> the new modem could be the problem.



Posted by Bruce on December 15, 2005, 1:58 am

> Chances are it was not provisioned properly. Could be the mac address
> was input wrong. Try giving service a call again and have them double
> check it.
>
>
If that were the case, I don't think I'd even get a connection.

Crap, just dropped again. Won't come back online without a power cycle.

Posted by Warren on December 15, 2005, 4:43 am
Bruce wrote:
> "Dr Feelgood" wrote:
>> Chances are it was not provisioned properly. Could be the mac address
>> was input wrong. Try giving service a call again and have them double
>> check it.
>>
>>
> If that were the case, I don't think I'd even get a connection.
>

Not necessarily.

Remember that both your computer and the modem have their own IP addresses.
Your computer may be getting a valid IP address because it's MAC address is
already on your account. When the modem comes online for the first time, it
should get an IP address that will only allow local access, but once it's
provisioned, it will get an IP address that will allow access to the
Internet. The problem is that the IP address is initially assigned at the
direction of the provisioning system. It is a very short lease. When it
comes time to renew the lease, if the provisioning process has not finished,
the regular DHCP server won't recognize the modem as being allowed to have a
full-access IP address. Your online light will remain lit, but you'll have
no access to the Internet.

It should be easy for this to be fixed. A customer service rep can repush,
or refresh, the information on the account, after which the DHCP server for
your node will now know to give your modem a full-access IP. Assuming your
modem's MAC is correct in the records (which it probably is if you are able
to get, and re-get, the temporary IP address that allows you to keep getting
online over and over again for that hour time period.)

--
Warren H.

==========
Disclaimer: My views reflect those of myself, and not my
employer, my friends, nor (as she often tells me) my wife.
Any resemblance to the views of anybody living or dead is
coincidental. No animals were hurt in the writing of this
response -- unless you count my dog who desperately wants
to go outside now.

This fall, vacuum up your leaves instead of raking:
http://www.holzemville.com/mall/blackanddecker/blowers.html





Posted by Bruce on December 15, 2005, 9:19 am

> Bruce wrote:
>> "Dr Feelgood" wrote:
>>> Chances are it was not provisioned properly. Could be the mac
>>> address was input wrong. Try giving service a call again and have
>>> them double check it.
>>>
>>>
>> If that were the case, I don't think I'd even get a connection.
>>
>
> Not necessarily.
>
> Remember that both your computer and the modem have their own IP
> addresses. Your computer may be getting a valid IP address because
> it's MAC address is already on your account. When the modem comes
> online for the first time, it should get an IP address that will only
> allow local access, but once it's provisioned, it will get an IP
> address that will allow access to the Internet. The problem is that
> the IP address is initially assigned at the direction of the
> provisioning system. It is a very short lease. When it comes time to
> renew the lease, if the provisioning process has not finished, the
> regular DHCP server won't recognize the modem as being allowed to have
> a full-access IP address. Your online light will remain lit, but
> you'll have no access to the Internet.
>
> It should be easy for this to be fixed. A customer service rep can
> repush, or refresh, the information on the account, after which the
> DHCP server for your node will now know to give your modem a
> full-access IP. Assuming your modem's MAC is correct in the records
> (which it probably is if you are able to get, and re-get, the
> temporary IP address that allows you to keep getting online over and
> over again for that hour time period.)
>

Thanks Warren and Dr. FG. I have had them push a new config file twice,
but this time I asked them to check the MAC. It was correct. Comcast
suggests possibly a bad modem out of the box, and to swap before the
truck roll on Saturday. I'll try to get back to the Comcast store before
then...

Thanks again.

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