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4 Performance

If you haven't tweaked your computer to its optimum settings, it's possible you may not be getting the best throughput from your connection. You can head over to our »Broadband Tweaks forum for personalized assistance in getting your system optimized for your cable connection.

If you want to try to hack your cable modem to increase your upload or download speed, please see »Cable Users FAQ »Can I uncap my cable modem to get higher speeds?

Feedback received on this FAQ entry:
  • im already using aable connection but still im always loosing or internet connection.

    2010-06-21 22:17:39

by wheelert$93 See Profile edited by big greg See Profile
last modified: 2006-08-22 17:48:57

USB 2.0 interfaces can operate at up to 400 Mbps. A fixed amount of USB bandwidth is shared between all devices that are plugged in to your computer. USB is used to connect your computer to a wide variety of devices.

An Ethernet interface, on the other hand, is intended for network traffic only. It connects directly to the computer's bus so that high speed transfers occur with the lowest possible CPU overhead. Ethernet interfaces are included with most modern motherboards. Older machines need a PCI-based Ethernet adaptor. Ethernet interfaces can typically connect at 10 Mbps or 100 Mbps (Fast Ethernet). Newer Ethernet interfaces connect at 10, 100, or 1000 Mbps (Gig Ethernet).

In most cases, you will want to use a wireless or wired router behind your cable modem. In this case, you must use Ethernet for the modem to router connection.

What about speed? Your cable modem will typically operate at 3 megabits per second or less. This speed can easily be handled by the slowest USB or Ethernet connection. Most cable modems can connect with USB 2.0 (up to 400 Mbps) or Fast Ethernet (100 Mbps).

The Ethernet interface is usually preferred, as this frees your USB ports (and bandwidth) for other peripherals.

Feedback received on this FAQ entry:
  • The major cable internet service providers have tiered their services and advertise download speed in excess of 10Mbps for most service levels. Let us presume that a cable internet service subscriber can obtain download speeds to the cable modem averaging 10-15Mbps. Would a USB 1.1 connection to the cable modem (throughputting data at a maximum of 12Mbps) bottleneck the cable modem download speed? Does USB have some overhead so that actual throughput in this case would be even somewhat less than the theoretical 12Mbps?

    2011-07-09 21:06:30 (valuequest See Profile)

by steven500 See Profile edited by Lex Luthor See Profile
last modified: 2010-06-24 08:00:43

It depends. Determining your RWIN (TCP Receive Window) is not an exact science, and one size does not fit all.

You can go to our Tweaks Forum for assistance in determining the best RWIN for your computer and connection, or visit the Tweaks FAQ for reference information.

by wheelert$93 See Profile edited by big greg See Profile
last modified: 2005-08-01 08:13:41

You can view your signal levels using the cable modem's web interface. You should see readings like this

Receive/Downstream: -15dbmV to +15dbmV
Transmit/Upstream: 30dbmV to 55dbmV
Signal to Noise Ratio (SNR): 30dB or Greater

If your signals are out of spec, you may experience packet loss or retransmissions. Either can lead to slow speeds.

Feedback received on this FAQ entry:
  • says this information is outdated due to lack of DOCSIS 3.

    2014-06-01 13:40:21 (antdude See Profile)

  • According to the TW tech I just spoke with, acceptable downstream power levels are -9dBmV to +9dBmV. I am having problems with my digital phone service and the tech said my downstream power was +12dBmV and that was +3dBmV over max so he scheduled a truck to come out and see what's causing the excess power level.

    2009-03-25 07:20:23 (socalblitz See Profile)

by drake See Profile edited by big greg See Profile
last modified: 2005-08-01 08:22:05