Here is the graph that was sent:



It looks like the *first* place you should look is between you and hop 1. The latencies I see in the graph you sent are pretty unacceptable. Do these happen constantly, or just during high load times? If you run Ping Plotter for 24 hours and look at a 24 hour graph of hop 1, how does it look? If 4am looks different than 8pm, then you might have too many subscribers on your local segment (a problem with cable sometimes - but not as often as one might think). If you consistently have problems throughout the entire 24 hour period at hop 1, then there's probably something wrong with either your cable modem's connection to the network, or possibly even something inside your own home network. Based on your description of your home network (BEFSR41, 100 megabit card), I'd suspect that it's not your local network, unless there's a bad cable involved. It's also possible your PC may have some configuration option set on it that is causing problems - but I'm no expert on troubleshooting local PC problems. If you have another PC that has similar results, then you can eliminate your PC as a problem.

Another thing you should be sure to check is to make sure your PC isn't using excessive bandwidth. It may be that you have some kind of a trojan installed that is accessing the network and overwhelming your connection - or you may be intentionally running a program that uses a lot of bandwidth. Either of these things could cause results similar to what you're seeing.

Make sure you check with DSL Reports to see if others in your area are reporting problems. Also, if your ISP has a local support forum, or there are newsgroups where local users may hang out, check to see if others on your local cable system are having problems. Next, contact your Cable provider and complain about poor performance. You shouldn't be getting 150 ms average pings to hop 1 - so you should express this to them. Email them Ping Plotter graphs and have them send someone to troubleshoot your connection (actually, you should expect that your support person will be helpful and will suggest good things to try - so go through everything your support person suggests until they give up. Many times, they will determine the correct fix for the problem without you having to push them to do so).

Once you've troubleshot your local hop 1 latency problems, then you can look beyond to downstream problems, if you still have them. The "oversubscribed" term can be taken in several contexts - one being that they have too many subscribers on your local segment - and the local segment's bandwidth capability is being oversaturated. This problem would be local to your neighborhood only. Another definition of "oversubscribed" is that they don't have enough bandwidth exiting their facility to service all their requirements. Usually, this happens on a broader scale - ie: the size of a large city. Based on your description of problems, I can't point at either of these as problems (mostly, because of the timing of the problem you're seeing). Usually, oversubscription manifests itself as periodic high latency and packet loss - and that period is almost always from 8pm till 1am on a consumer system. Running Ping Plotter continuously for days will help you see if there is a pattern to your problems.

I hope this gives you some ideas on next steps. If you've already talked to your ISP about this problem, feel free to shoot back your response here and maybe I can come up with some additional suggestions for you. Also, saving the data (in .pp2 format) with a goodly amount of data collected would allow me to analyze it a bit (24 or 48 hours, possibly, zipped up and emailed to me).