Hi all,

I am trying to indentify the reason for a regular ping spike. Having recently changed ISPs and modems, I am baffled as to what is causing the problem (if it is indeed a problem, or just some reporting anomaly).

The facts:
- about every minute, the ping to my 2nd hop (1 hop past my gateway) spikes rapidly up from the normal 10ms or so up to 400-700ms then subsides to normal, over the course of 5 seconds

- this occured with my previous ISP (SBC/PacBell) and still occurs with my current ISP (DSLExtreme, which still uses SBC lines)

- this occured with my previous modem (Alcatel ADSL 1000) as well as my new modem (Westell WireSpeed)

- this occurs whether I test from my PC or my Mac, using PingPlotter, or any other ping/traceroute tool

- I connect directly to the DSL modem when testing, no LAN router involved

- speeds are good, about 2090 up / 345 down

- the only device on my side of the connection that remains the same is the Siecor DSL splitter, originally installed several years ago with my SBC installation.

I'm baffled. Anyone have any idea what is causing this, and whether it affects my connection at all? I am attaching a PingPlotter graph.

Thank you!

Bernie

Hi, Bernie.

Do you see anything at the downstream hops? Do they exhibit similar spikes? What do you see in the final destination? Do these latency spikes change to packet loss at any point in your downstream tree?

I suspect that another constant in your connection is the phone line and hardware at the phone company office. Can you share with us who your phone company is, and your physical location (ie: City)? We've heard another report of something similar (although different as well) in the last several weeks, and it'd be interesting to correlate the facts in these two cases to see if there are any similarities we can figure out.

It would be interesting to see some longer pathed instances as well - using a known target (like www.google.com, or even one of our servers) to see what the downstream hops look like.

If you're *only* seeing this at hop 2 (unlikely or you'd not be bringing it up as an issue), make sure you check out our knowledgebase article on the topic of intermediate hops.

- Pete

Hi Pete,
I have the same problem as this guy. I have a latency spike at jump 1, but then get packet loss all the way down the row of about 30%. I was told by my ISP that my first hop is my modem, but when I disconnected the cable connection (I have cable internet w/sb5100 mot) I can't ping the first hop. That would mean it is not at my location I believe. Any way, the spike in latency and packet loss happen at nearly exact 1 minute intervals, almost 24 hours per day. It takes a break sometimes for 10 to 30 minutes and then starts again. While there is packet loss my VOIP phone has complete drop out of voices for about 3 seconds, but usually maintains connection. It makes no difference what final destination I use.

Is there any way to ping any other host on your network (e.g., your gateway, or another computer), to eliminate most other sections of your network?

It sounds like you need to convince your ISP that the problem is with their connection, not your network. To do that, remove as much of your network as possible - try using a wired connection directly to the cable modem. If that has the same symptoms, have the cable company come out and help you troubleshoot. There's not a lot more you can do there.

- Pete

OK, well my cable company changed providers and the problem went away immediately so there is no way it was my equipment. I guess the thing that bothers me the most is when they know its their fault and they continue to have me searching for answers on my end. At least with Ping Plotter they couldn't deny there was a problem.