I've seen this occasionally on lower bandwidth connections. If this always happens when you start Ping Plotter and trace to a target (or does *most* of the time), then for certain it's not the network specifically, but the way data is being delivered to the network via Ping Plotter.

The first sample with Ping Plotter has significantly more bandwidth usage than subsequent ones.

First off, the first sample *always* sends out 35 packets. Ping Plotter has no idea how long the actual route is - and it wants to return data as fast as possible, so it sends out 35 packets - each separated by a small time period (as specified in "Advanced Options" / Packet Option tab / Time interval between hop traces. This defaults to 25ms - which means with a 56 byte packet, you're looking at a bit over 2 K/s of bandwidth used. If you have more than a 56 byte packet specified, this is higher. Once Ping Plotter knows the route length (ie: sample 2 and beyond), it only sends out as many packets as is necessary to make the final destination. There is some chance that this will impact your bandwidth (I'm leaving out a TON of things here - in ideal situations, this actually wouldn't impact anything - but it's hard to know under non-ideal sitations).

Second, as individual results come back on the first sample, the routers that have responded also need to have their names looked up. This happens immediately as each hop responds back. This means that there is additional bandwidth being used at this point - as Ping Plotter talks to the DNS server(s). This handshaking doesn't take a lot of time, but it can overlap and has a chance to impact the first sample set's times.

If you want to see if this is impacting you at all, there are several ways to set Ping Plotter. First off, to disable the impact of the reverse DNS lookups, there's an option (on the same page of options as we discussed earlier) to disable threaded (concurrent) DNS lookups. Reset your trace and see if the behavior is any different.

Another way to minimize the impact of Ping Plotter's network usage is to change the time interval between hop traces. If you've got it set to 25, try changing it to 75 or 100. This will slow the rate at which Ping Plotter uses network resources.

If you're still seeing the same behavior when you've throttled down Ping Plotter's network usage, then it could possibly be a networking issue. If this is the case, I'd expect to see this happen only after a period of time when you hadn't contacted the final destination. Shutting down Ping Plotter and restarting it won't affect any ARP lookups on the network - so if it's reproducible within a matter of a few minutes, I'd look more at Ping Plotter's usage of network resources than I would at network itself.

Note that the issues talked about here *mostly* impact people on dial-up modems - or slow connections.

Let us know if this makes sense - and if changing any of the suggested settings changes the results you're seeing.

- Pete