dpinger pings dropped by some things because of no data payload
The root issue in this thread:
has been shown to be something dropping echo requests with no data payload in his cable modem (likely) or ISP's network. dpinger pings disappear. 'ping -s 0' disappears, -s >= 1 works fine. The echo requests disappear somewhere after leaving his WAN NIC, and before getting to the Internet. That situation is a common Cisco cable modem, next hop router is Casa Systems (same as my TWC at home, which has no issues).
While there's nothing wrong per RFC with excluding a data payload, dpinger is probably the only ping tool that will be widely used that does so by default, so we may trip bugs in other devices in rare edge cases like that. This is likely far from the first that will see issues as 2.3 gets more widely deployed.
Denny offered to add an option to specify a payload size in an email exchange we have going re: the issue. Then we can add an advanced option to gateways to allow configuring it for those who need to.