 Then, similar to IPv4, any device along the path whose MTU is smaller than the packet will drop the packet and send back an ICMPv6 "Packet Too Big" (Type 2) message containing its MTU, allowing the source host to reduce its Path MTU appropriately.The process is repeated until the MTU is small enough to traverse the entire path without fragmentation.If the Path MTU changes after the connection is set up and is lower than the previously determined Path MTU, the first large packet will cause an ICMP error and the new, lower Path MTU will be found.