Troubleshooting DSL
Christopher Brooks, 3 Apr 2002
Last updated: 24 Oct 2005

The steps below are directed towards DSL users, but they could be used by anyone having network connectivity issues.

Resources

• GSRC DSL Page
• cvs update is slow
• http://dialup.pacbell.net/dsl/
• http://Cable-DSL.home.att.net/ Troubleshooting guide
• Alcatel 1000 user guide

Tools

• Keynote.com scoreboard
• http://www.visualware.com/visualroute/index.html Shareware visual traceroute
• Yahoo Internet Traffic Links: http://dir.yahoo.com/Computers_and_Internet/Internet/Statistics_and_Demographics/Traffic/
• Internet Traffic report: http://www.internettrafficreport.com

Connectivity problems

1. Take a deep breath
2. Use ping
   Under Windows2k, try ping -t www.gigascale.org Other hosts to try dialup.pacbell.net, your DNS server (use ipconfig /all)
   If you are losing more that 3% of the packets, you are in trouble. Try to narrow down where the delays are by pinging different hosts
3. Use traceroute
   Under Windows2k, traceroute is tracert Take a look at where your packets are going.
4. Check for DNS problems by using IP addresses instead of domain names http://dialup.pacbell.net/dsl/dsl_tcpip.html suggests

                                Primary      Secondary
   Los Angeles/Orange County    206.13.29.12 206.13.30.12
   San Diego                    206.13.30.12 206.13.29.12
   San Francisco/Bay Area       206.13.28.12 206.13.31.12
   Sacramento/Fresno/Stockton   206.13.31.12 206.13.28.12
   

   You might also try changing the last digit to .13 or trying one of the UCB EECS Departmental DNS servers listed in http://www.cs.berkeley.edu/idsg/network/ Three addresses to try are: 128.32.171.23, 128.32.239.23,128.32.156.24
5. Try using a visual traceroute package like one of the ones listed above. See if you can determine what router is dropping your packets.
6. Check the net traffic reports for bad traffic http://www.internettrafficreport.com or http://www.internetpulse.net/
   Look at the traceroute output for routers listed on the traffic report. For example, traceroute shows that my traffic goes through acr1-loopback.SanFranciscosfd.cw.net [206.24.210.16] core1.SanFrancisco.cw.net is worth a look.
   Since traffic is going through Cable & Western, looking at the Cable & Western Traffic site (http://sla.cw.net/) and trying ping and traceroute might indicate if the problem is pacbell, sprint, cw, or uc.
7. Follow the Pac Bell DSL Slowness info notes at http://dialup.pacbell.net/dsl/trouble.html#4:

   I am experiencing slowness on my DSL Internet service.

   Power cycle Alcatel unit:

   1. Unplug your Alcatel unit - do not turn unit off.
   2. Shut down your computer.
   3. After 60 seconds reboot your computer.
   4. Turn the Alcatel unit off and plug the power source back in.
   5. Turn the Alcatel unit on and observe the lights.
   6. Wait 2 minutes for the unit to sync (the Power/Sync indicator light will flash red during the wait). 
   7. If the Power/Sync light does not turn solid green after 5 minutes repeat steps 4, 5, and 6 (up to three times).

   If this does not solve the problem, try the following:

   • Check our System Status page. Any reported Pacific Bell Internet Services Network issue that could affect your performance will be posted here.
   • Go to http://www.internettrafficreport.com. This site will show you if any of the major Internet backbone providers are experiencing packet loss. A serious outage on the part of one provider can affect the performance of others, as traffic is rerouted through the system.
   • Clear the Netscape disk and RAM cache, then restart Netscape. Click here for step-by step instructions.
   • Find and delete all netscape.hst files. The files may have become too large or obsolete. These files are located on your hard drive, in your Netscape directory.

Bandwidth Problems

$ ./iCheckConnection ftp://ic.eecs.berkeley.edu/pub/Octtools/OCT5.1.document.ta
r.Z
PC Pitstop Internet Connection Checker 1.03
Copyright (c) 2000-2 PC Pitstop LLC. All rights reserved.
DHCP Server address not found
DNS is working
Ping ic.eecs.berkeley.edu (128.32.171.49) 32 bytes      30 20 20 30 20
ftp://ic.eecs.berkeley.edu/pub/Octtools/OCT5.1.document.tar.Z returned 1530391 b
ytes in 10 seconds (1194 Kb/s)