I'm trying to understand the PDU sizes as it traverse the TCP/IP model.
RFC 791 says the IP protocol is required to accept datagrams of 576 octets. ( 512 octets, plus up to 64 header octets). I know the IHL (Internet Header Length) field is 4 bits long and specifies the header length in 32 bit words.
So the IP Header has a max size of 60 bytes.... Can someone explain where this 64 octet header comes from and how it differs from the 60 byte header?