Sometime back I wrote a script for user who wanted to check if the ESXi servers in his network are alive in a given range. Basically the script uses vmkping -c 2 <IP_RANGE> from one ESXi box.
i will dust out the older threads and provide the script if found.. fingers crossed..
Found it..
Since you know the IP range, you can change the 192.168.x.x to your setup:
for i in `seq 255`; do for j in `seq 255`; do echo 192.168.$i.$j; esxcli network diag ping -H 192.168.$i.$j -I vmk0 -c 1 | grep -i Recieved | awk '{if($2 == 1) {print "Alive"} else print "Dead"}' >> Discovery.txt; done; done