Hello everyone,

I'm trying to understand my poor VOIP performance. Ping Plotter Pro has shed much light, and what I see in the light has created confusion. For background, my network consists of a Zywall 110 router, and a Zonet gigabit switch. Comcast just replaced my modem with a brand new one. I'm in Aurora CO, a suburb of Denver.

To troubleshoot, initially I pinged my modem at 10.1.10.1. No packet loss and very minimal latency. So it seems like my hardware is OK.

Then I pinged Phone.com, my voip provider of the moment. Lots of packet loss, and lots of latency, that seem to originate a few hops in on Comcast's network.

Then I plugged directly into the modem. Much less packet loss, and still quite a bit of latency, but not much variation in latency. The latency I'm seeing seems much higher than what others are seeing.

It doesn't matter what I ping, this pattern holds. Also, there are 2 or 3 Comcast servers/routers that I hit every time I ping something.

So is it possible that my router is doing something to my packets that is somehow causing packet loss?

Should Comcast's network be better, or is it as good as it gets?

Thank you all in advance,

Ross

Here are some screen shots:

Hey DaVikes,

It is really hard to say based on your screenshots (due to only have about 30 second samples), but it *does* look like this is on Comcast's side.

It *does* look pretty similar to bandwidth saturation (as seen here: http://www.pingplotter.com/commonnetworkproblems/#bandwidthsat). At this point, it may prove helpful to continue monitoring for a longer period of time (if you could let PingPlotter run continuously for 24 hours - that would be great). This would allow you to see if the pattern here happens to be time based (do the spikes in latency/packet loss drop during non-peak hours - when no one is using the internet?), which may help provide more clues to what is happening here.

We do also have a great guide to troubleshooting network issues that you may find useful here:

http://www.pingplotter.com/netnirvana/

If it is shown to be Comcast's network, this guide will show you how you can prove it to them by building a good case.

Hopefully, that will point you in the right direction to start solving this. Please let us know what happens with a longer monitored timeframe.

Cheers!

-Phillip

Hello Phillip,

Thanks for your reply. After some more experimenting, I have determined that my network is somehow causing downstream packet loss. If I plug my laptop directly into the cable modem, I get livable, but not great results. Packet loss at the final hop over 3-4 hours in the middle of the day was at 1.7%. Average latencey was around 250ms, which is not good. If I plug my laptop into my network switch, behind my router, packet loss will jump 5% to 15%. My router is relatively lightly loaded, so I'm going to see about updating the firmware. Do you have any thoughts about why my router could be causing downstream packet loss? Ping plotter is not showing any loss in my network, but something is definitely going wrong downstream.

Also, the problem gets worse when traffic moves from comcast to level 3. I think that might be that level 3 is de-prioritizing ping plotters test packets, but I'm not sure.

Also, Comcast seems to be routing my traffic differently this week than they have the past couple of weeks. One of their worst routers is no longer in the path. So perhaps I will get my voip phones working after all.

Also, I am running the mac version of Ping Plotter. Is there a way to expand the graph time from 1 minute?


Thanks,

Ross