Appendix BWell-known Protocol, Port, and Other Numbers
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
B-1: IP Protocol Numbers
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.
Figure B-1 IPv4 Header Format Showing the Protocol Field
Figure B-2 IPv6 Base Header Format Showing the Next Header Field
Well-known or ...
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