# time to live. This field is mostly used to control the maximum number of hops (routers) visited by the datagram. Each router that processes the datagram decrement this number by one. If this value, after being decremented, is zero, the router discards the datagram
# protocol. This 8 bit field defines the higher-level protocol that uses the service of the IP layer. This field specifies the final destination protocol to which the IP datagram should be delivered