That's typically one of the best ways to do it as the signal to the modem is as clean as you can get it. However, depending on the levels coming into the house, you may actually NEED some splits. I know it's not always easy, but the best thing is to have a cable tech come and check signals. They typically have a meter that will let them see the levels. The other way to do this depends on the brand/model of cable modem and the Cable Operator (some are more strict than others.) If the modem supports it, you can statically change your IP address on your computer to 192.168.100.2 and change the gateway to 192.168.100.1. (Sub-interface should let this work too.) Subnet of /24 (255.255.255.0). Now pull up the web page at http://192.168.100.1/. This part varies totally on modem. Surfboards will generally display all the info about levels, Ambit's require a username and password (defaults to root/root if memory serves me) to see levels. The levels will only show when the modem has sync. Now, you can adjust padding/amplification/splitting until you are in the window I mentioned. With splitters, if you take your Reverse from 45 dB to 48.5 dB, your Forward will go from say -1 dB to -4.5 dB approximately. (Directional couplers act differently and vary by model. RSA pads affect only the Reverse padding. Not all companies use them.) If you can't get the levels right inside the house (i.e you have a -10 dB on forward and +30 dB on Reverse, going to +40 dB on Reverse will change the forward to -20 dB which is WAY out of spec) you'll have to have the Cable Operator do some work at the tap or in the field. ============================ Daniel Rysztak, CCNA http://www.druids-grove.net/ -----Original Message----- From: tclug-list-bounces at mn-linux.org [mailto:tclug-list-bounces at mn-linux.org]On Behalf Of Dan Rue Sent: Monday, February 09, 2004 5:53 PM To: TCLUG Mailing List Subject: Re: [TCLUG] New Comcast speeds On Mon, Feb 09, 2004 at 04:30:29PM -0600, Ben Neigebauer wrote: > I have my cable split about 6 ways and get frequent drop-outs. > > Will one of those bi directional broadband amplifiers work? The way I did it (and hopefully the cable company guy will also respond) is by splitting it when it first comes into the house with a good, two way splitter. The one split goes straight to the cable modem. The second, goes to an amplifier, and then to a n-way splitter for the tvs. So, we have a regular amplifier on the line, but it only amplifies the signal for the TVs. hth, dan > > > > > > -----Original Message----- > From: tclug-list-bounces at mn-linux.org [mailto:tclug-list-bounces at mn-linux.org] On Behalf Of Daniel Rysztak > Sent: Monday, February 09, 2004 4:19 PM > To: TCLUG Mailing List > Subject: RE: [TCLUG] New Comcast speeds > > As I work for a cable company and am a Network Engineer, I can attest that > sub-optimal modem levels impact speed. However, this is dependant on the > modem. (Some seem to handle a less clean plant.) Essentially you are > looking for approximately 40 to 50 dB on the Reverse and between 5 to -5 dB > on the Forward. The further you are from those ranges, the more likely you > are to accumulate errors, dropped packets, retransmits and other networking > headaches which chew up your bandwidth. > > Amazingly, that's why those little numbers on splitters and pads are > important. They actually add up to something. > > Except for a directional coupler, every split in a splitter accounts for > approximately 3.5 dB. > > 2 way = (2)3.5dB > 3 way = (1)3.5dB, (2)7dB > 4 way = (4)7dB > > As you can see to make a 3 way, you need to split one that is already split. > > These help pad and adjust the levels in addition to thelevels coming into > the house. (Incoming levels could vary depending on equipment at the > street.) > > Now, if you have a dirty plant where signal to noise is down at 20dB, a 35dB > reverse could be impacted by the noise even though DOCSIS modems supposedly > can handle a reverse down at 8dB to 58dB. That's the difference between a > test bench controlled environment and the real world with snow and cold > weather, cars hitting polls and peds, humidity, and a billion other > variables. > > I think you'll now see, cable is NOT either ON or OFF. > > ============================ > Daniel Rysztak, CCNA > > -----Original Message----- > From: tclug-list-bounces at mn-linux.org > [mailto:tclug-list-bounces at mn-linux.org]On Behalf Of Jack Ungerleider > Sent: Saturday, February 07, 2004 10:49 PM > To: TCLUG Mailing List > Subject: Re: [TCLUG] New Comcast speeds > > > On Saturday 07 February 2004 02:56 pm, David Phillips wrote: > > Jima writes: > > > My immediate guess is that maybe the coax feed to your cable modem is > > > sub-optimal. I'm not a cable expert, though. > > > > Cable is either on or off. A bad signal (often caused by too many > > splitters) will cause failure, not lower speeds. > > The way I understood it from the guy who did the cable check for my cable > modem in Duluth was that there are optimal signal voltage levels for the > data > channels. If the signal is outside that level the modem can have trouble. To > me that implies the possibility of sub-optimal performance. > > But like Jima I'm no cable expert. > > -- > Jack Ungerleider > jack at jacku.com > > > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > http://www.mn-linux.org tclug-list at mn-linux.org > https://mailman.real-time.com/mailman/listinfo/tclug-list > > > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > http://www.mn-linux.org tclug-list at mn-linux.org > https://mailman.real-time.com/mailman/listinfo/tclug-list > > --- > Incoming mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.577 / Virus Database: 366 - Release Date: 2/3/2004 > > > --- > Outgoing mail is certified Virus Free. > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.577 / Virus Database: 366 - Release Date: 2/3/2004 > > > _______________________________________________ > TCLUG Mailing List - Minneapolis/St. Paul, Minnesota > http://www.mn-linux.org tclug-list at mn-linux.org > https://mailman.real-time.com/mailman/listinfo/tclug-list _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota http://www.mn-linux.org tclug-list at mn-linux.org https://mailman.real-time.com/mailman/listinfo/tclug-list _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota http://www.mn-linux.org tclug-list at mn-linux.org https://mailman.real-time.com/mailman/listinfo/tclug-list