Optimising your broadband connection

I had some problems achieving the expected throughput from my broadband supplier. I have a nominal 24 Mbps ADSL2+ connection and should be achieving downloads of 14 Mbps. These are the steps to follow to improve your downloads.

First, establish whether the problem is upstream or downstream of your router.

  • Find out how far you are from your telephone exchange. The only way to get a true value is by running the line test facility, but BT have restricted this to authorised personnel. So, in the meantime raise a ticket with your provider and get them to find out. Alternately, you can get a rough idea by plugging your phone number and postcode into the Broadband Checker over at DSLZoneUK and you’ll get a pretty map. . I cannot find this on SamKnows anymore…
    Example: 460m
  • Calculate the route using Multimap to drive it for you. This will give you a rough guide of your possible cable length; they don’t always follow the most logical routing and if you’re in a rural environment, the cables will cut across fields.

    Example: 700m
  • Download and run DMT from http://dmt.mhilfe.de/. This page is in German, but just search for your modem and download the right version; this is v7.31 for the Speedtouch 780. You might be able to use this link for a Google translation of their site.
  • Look in the bottom right of the third graph (Channel Characteristics). This will give you the estimated loop length. This should be similar to your twice the cable length.

    Example: 830m-2015m
  • Go to router’s web interface and check what your current Sync speed and Line Attenuation are.

    Example: Bandwidth (Up/Down) [kbps/kbps]:394 / 18,106 —> 18106 kbps –> 17.7 Mbps (18106/1024)
    Line Attenuation (Up/Down) [dB]: 7.5 / 19.5 —> 19.5
  • Look up your expected Sync speed using either this interactive tool or the graphs provided by afster or Internode graph. Take 10% off the figure provided by the interactive tool to get a realistic sync speed.

    Example: Approx 18.2 Mbits/sec according to average graph
  • IF your sync speed is significantly lower than the expected value OR your Line Length is higher than predicted, THEN start looking at wiring issues. If not, then check OS parameters.

This graph shows the real life results from hundreds of users, relating their sync speed to the downstream attenuation reported by their router. Those above the green line are lucky :)

Next optimise your PC’s performance. You will need to be logged on as a user with Adminstrative privileges. If you only have one account, then you will have the required privileges.

  • Download and run TCP Optimiser from SpeedGuide.net. Click on Optimal settings, Apply changes and exit.
  • Reboot your computer.
  • Verify that your Network card is configured for maximum throughput (100 Mbps Full Duplex). To do this, click on
    • Start
    • Control Panel
    • Network and Internet Connections
    • Network Connections
    • Select your network card and click on Change Settings of this Connection or right click on the card and select Properties…
    • Click on the Configure… button next to the Network card name
    • Click on the Advanced tab.
    • Set the appropriate property to 100 Mbps Full-Duplex. On my network card, this is called Media Type
      There are other tweaks that you can do here, such as disable Rx and Tx Checksum Offload. I am not sure of the advisability of doing this.
    • Click on OK
  • Run Microsoft’s Guided Help to maximise your PC’s performance. WARNING! This will disable all themes and turn your PC into retro mode ;) Further details can be found in this knowledgebase article
  • Minimise the window during downloads where possible. It is possible that your graphics processor cannot keep up with the download :)
  • Check CPU usage during downloads and investigate any processes which are consuming too much. Anti Virus packages such as Kaspersky have been known to cause problems during downloads, so try disabling them TEMPORARILY while running any download tests.
    • Right click on a blank area of the taskbar at the bottom of your screen
    • Click on Task Manager
    • Click on the Processes tab and then double click on the column labelled CPU. If the CPU column is not displayed, then click on View and Select columns… then enable the CPU Usage option.
    • The process using the most processor time should be at the bottom of the list
  • Check your memory usage during downloads and investigate any processes which are consuming too much. If the Memory Usage column is not displayed in the task manager, then click on View then Select columns… and enable the Memory Usage option.

All speed checks should be run using a properly shielded Ethernet connection, even if your Wireless connection claims an ‘Excellent’ signal strength. If everything is OK, then we should be able to get download speeds at upto 80% of our sync speed.

NOTE: Speed Tests are to be used as a guideline only. As one commentator said

Speedtest.net shows me at 9000kbps, the Be* test puts me at 9500kbps, Thinkbroadband puts me at 16000kbps and the Virgin Media FTP puts me at about 8000kbps.

All of which are dramatically wrong, since I am synced at over 24000kbps and can download at 2MB/sec from some FTP’s on a single thread, let alone multi threading.