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Home Internet Connection Stability Testing
March 7, 2006 5:55 AM   Subscribe

I have a cable modem at home and it seems that I am having periodic outages. I would like to test my connection to the internet from an exterior source. I want to know exactly how often the connection goes down as well as any degraded traffic. Any suggestions?

I have spoken with some neighbors and they seem to be having some of the same problems. I figured I could go down one of a couple of routes.

1 - I have a PC at work that I could load an application to automatically connect to my home pc at a regular basis. Hopefully producing a report covering a week or so that would tell how often the connection failed, for how long, and ideally if I had any degraded service. What would that App be?

2 - Use a resource on the web instead of my work PC.

I would love to hear what you have to say.
posted by wahootim to Technology (5 answers total)
The fact that your connection "goes down" from home may just be that you aren't getting DNS resolution reliably from your cable company's DNS servers. You may, in fact, have full "connectivity" the whole time, in terms of passing packets with acceptable loss rates to Internet addresses. So, "pinging" your home machine from an outside address repeatedly may or may not much correlate to problems you are experiencing from home. That said, you could do several things:

1) Build a list of internet servers that are reliable, and that you can use as ping targets when you experience one of these outages. Ideally, these server names and addresses would be single machine targets at permanent IP addresses. at might or might not be a good one, as it has it's share of intermittent downtime problems...:-) But you get the idea. Save the list in Notepad, where you can get at it quickly. The next time this happens, open a command prompt on your home machine, and try issuing a traceroute command using the name of one of your target servers. The output will look like this:
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.

C:\Documents and Settings\Doobie>tracert

Tracing route to []
over a maximum of 30 hops:

  1     6 ms     1 ms     1 ms
  2    19 ms    16 ms    16 ms
  3    22 ms    12 ms     8 ms
  4    13 ms    16 ms     9 ms
  5    14 ms    22 ms    20 ms
  6    10 ms    13 ms     8 ms
  7    15 ms    10 ms    18 ms
  8    12 ms    14 ms    12 ms
  9    36 ms    40 ms    51 ms []
 10    42 ms    40 ms    43 ms
 11    37 ms    40 ms    48 ms []
 12   587 ms    61 ms    68 ms []
 13     *       58 ms    39 ms []
 14    41 ms    44 ms    58 ms
 15    47 ms    52 ms    35 ms
 16    36 ms    41 ms    41 ms []

 17  1109 ms    72 ms    37 ms []

 18    41 ms    70 ms    76 ms []

 19    43 ms    43 ms    50 ms [

Trace complete.
That tells you that DNS could resolve the server named to an actual IP address, and that your machine could send ICMP packets to that address, and get back packets. And you get to see a lot of machines that handled your traffic on that roundtrip.

If the tracert command fails, it can fail because DNS can't resolve the name you gave, or because of actual connectivity problems. If it's a DNS problem, you can try issuing the tracert command again, but instead of using the name of a target server, use the address for it from your list. If the tracert works, you have proved your problems are DNS failures, and you can complain to your cable company intelligently. You could also add additional DNS servers, outside your cable companies network, to the list of machines you'll look to for DNS when your cable companies servers are down, in the Properties tab for your TCP/IP network connection.

The tracert can also fail because routers in the path to your target servers aren't working, or because links are down. those problems are kind of self-explanatory, but here's a page with some good suggestions for using tracert to figure out connectivity problems.
posted by paulsc at 6:34 AM on March 7, 2006

We were having the same problems with our cable service. Someone suggested plugging the modem into another source. Problem solved.

Apparently cable modems are very sensitive to any fluctuations in power.
posted by DieHipsterDie at 6:37 AM on March 7, 2006

Broadband reports has some tools that are very useful - 'Line Packet Loss Testing' for one - "Packet loss tests on your line, including identification of any problem routers en-route to you.". Also 'SmokePing' and 'Speed Test'.
posted by azlondon at 7:33 AM on March 7, 2006

Also take a look at the signal levels for your modem, particularly if you are experiencing poor TV quality at the lower end of your channels (which is apparently also a warning sign of bad signal levels). We were having some serious but intermittent connection issues that ended up being caused by a bad cable between the cable box itself and the outlet in our house. I gained 2MB down in speed once they had replaced it, and have no more connection issues.

At home, type into your browser window to see if you can bring up a modem diagnostic page. That ip is normally the cable modem address. Check for Signal to Noise ratios (SNR) and the upstream/downstream power levels. SNR should be over 30, downstream power between -15 and 15, and upstream power above 29 or so.

My signal levels fluctuated basically depending on weather (go figure!), so I took screenshots and saved tracert logs for about a week before calling my ISP. That came in really handy for making my case for some sort of repairs.
posted by gemmy at 9:59 AM on March 7, 2006

First, isolate whether the "goes does" is due to an actual loss of connectivity or just the lack of ability to resolve domains in DNS. If the latter, consider bypassing your ISP's DNS servers (which are often slow/overloaded/sucky) and either run your own or use somebody else's.

If it's actual connectivity that goes away, run something like pingplotter and constantly ping a number of sites. The reason you want to be sure that you're pinging a number of sites and not just one or two is that it lets you discriminate between something on your end and problems at one of those sites.
posted by Rhomboid at 7:06 PM on March 7, 2006

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