juniper@R2> ping 12.1.1.1 rapid size 10000   
PING 12.1.1.1 (12.1.1.1): 10000 data bytes
!.!!.
--- 12.1.1.1 ping statistics ---
5 packets transmitted, 3 packets received, 40% packet loss
round-trip min/avg/max/stddev = 6.301/6.972/7.606/0.533 ms


//////After I set the MTU///

juniper@R2> ping 12.1.1.1 rapid size 10000    
PING 12.1.1.1 (12.1.1.1): 10000 data bytes
.....
--- 12.1.1.1 ping statistics ---
5 packets transmitted, 0 packets received, 100% packet loss

juniper@R2>