It's a little diffcult to say without seeing more details about the question but from what you have supplied it looks like you are referring to a device that has sent a ping to another device and now has received a reply from the device ie. echo reply.
What the last line is saying is that if a device receives an echo reply and it has not sent out an echo then it drops the packet. In more general terms -
if you receive a response to a ping but you haven't sent out a ping request in the first place then you should drop the packet.
ICMP echo/echo replies are matched to each other by -
1) sending the same data back in the datagram as was sent
2) using sequence numbers to match the echo requests against the eho replies.
If you stopped the ICMP process on the WS2 before the echo reply was received then WS2 simply sees it as an echo reply packet but it has nothing to match it against because you stopped the ICMP process from running.
For me at least, this is a very difficult question since we're not seeing the context from where it was pulled from. What is this in regards to? My first thought is that if a device receives an icmp reply, but the device didn't send an icmp echo, the icmp process should drop it.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...