Comcast SCIENTIFIC ATLANTA DPC2100

[oscquin]

Hello, I work for an ISP in Latin America and we have bought several DPC2100 Series cablemodems from Comcast but I have the problem that they wait between 8 - 15 minutes to connect. Everything looks fine, when I power it up, all lights turn on, then cable light begins to flash until it finds the connection. any idea will be highly appreciated...modem details are:

DocsDiag v030720 Copyright 2001-3 Robin Walker [email protected]

S-A WebSTAR DPC2100 Series DOCSIS Cable Modem Ethernet+USB <<HW_REV: 2.0; VENDOR

: S-A; BOOTR: 2.1.6; SW_REV: v2.0.2r1242-040825; MODEL: DPC2100>>

System up time                      = 0 days 00h 35m 13.00s

Downstream channel ID                = 1

Downstream channel frequency        = 447000000 Hz

Downstream received signal power    = -0.1 dBmV

Upstream channel ID                  = 2

Upstream channel frequency          = 38000000 Hz

QoS max upstream bandwidth          = 256000 bps

QoS max downstream bandwidth        = 275000 bps

SigQu: Signal to Noise Ratio        = 40.0 dB

Cable modem status                  = Operational

Upstream transmit signal power      = 48.9 dBmV

Date and Time                        = unset

Configuration filename              = 256.cm

thanks in advance.

[FallowEarth]

The only thing I can think of is that the upstream power level, labelled "Upstream transmit signal power" may be a bit high, which can cause problems syncing to the CMTS.

[dn0]

We had an issue a couple of years ago that may be the culprit.

Here is what I can recall:

The SA modems use a different port to download the config file from the TFTP server than other modems, like Motorola for example.

A while back, Motorola had sent out a memo regarding blocking a certain group of ports to prevent attacks from a specific trojan (which I cannot recall which one right now).

Anyways, those ports that Moto recommended we block were the same ports that the SA modems needed to download the config file.(kind of fishy)

The symptoms were that the SA Webstar modems would take an unusually long time to come online. They would come up after about 20 minutes and begin working, but then they would reset every so often and take another 20 minutes to re-sync.

I met with the Scientific Atlanta engineer and we sat down to do some testing.

It turns out that the port blocking was the issue.

I am in the maintenance dept here, it was the data engineers that ultimately figured it out, so it was a little beyond me.

I will try to find more specific info for you, but I would start with contacting SA and verifying which ports the modem needs to contact the TFTP server, and then verify that they are not blocked either through the CMTS or TFTP server, or anywhere in between.

Hope this helps.

Now my brain hurts, need Rum to relax it -