Refer to the following sections for explanations and listings of well-known numbers:
• B-1: IP Protocol Numbers
• B-2: ICMP Type and Code Numbers
• B-3: Well-known IP Port Numbers
• B-4: Well-Known IP Multicast Addresses
• B-5: Ethernet Type Codes
A higher-layer protocol is identified with an 8-bit field within an IPv4 packet called Protocol. The IPv4 header format is shown in Figure B-1 with the Protocol field shaded. Figure B-2 shows the IPv6 header format where the protocol number is stored in the shaded Next Header field.
Well-known or ...