Hi Pete,
I think something may have happened around here over the last week or two.
After a few seconds of pinging, one of the hops starts dropping packets. I called our ISP to discuss and he started telling me that more and more carriers are not replying.
Is there anything I can do in the engine to try and get around this?
Dave

Hi, Dave.

If it's *just* an intermediate hop that's dropping packets, and downstream hops are not, you can just ignore the results on that hop. We talk about that a bit here:

http://www.nessoft.com/kb/24

There are some possible things you can do, but it depends on exactly the problems.

First, you might try changing packet types. PingPlotter supports several packet types - ICMP, UDP and TCP. The UDP and TCP types are both well-used transport types and carrying these packets is an important part of a router's job (whereas carrying ICMP packets can be down-prioritized). If a router is delaying either the creation or carrying of ICMP TTL Expired packets, then switching to TCP or UDP probably won't help (since all packet types in PingPlotter rely on the TTL expired packet response type), but it's worth a try.

Second, it could be a timing issue. Maybe a router just doesn't like getting packets every second (or whatever your trace interval is). Try changing the trace interval to something higher. Anything over 10 seconds doesn't yield enough useful data, but try intervals up to 10 seconds and see if that makes any difference. Another timing option to play with is the "Packet Send Delay" (in Edit -> Options, Packet). This might be called "Time interval between hop traces" depending on the version you're using, but try increasing this to 250 or 500 and see if that makes any difference in your results.

Let us know if any of this helps.

- Pete