ICMP Messages
Source Quench: Please slow down! I just dropped one of your datagrams.
Time Exceeded: Time to live field in one of your packets became zero.” or “Reassembly timer expired at the destination.
Fragmentation Required: Datagram was longer than MTU and “No Fragment bit” was set.
Address Mask Request/Reply: What is the subnet mask on this net? Replied by “Address mask agent”