IPv4 基本报头（20 ~ 60 Byte）
IPv6 基本报头（40 Byte）
IPv4 Header vs IPv6 Header
黄色 为 IPv6 与 IPv4 相同
红色 为 IPv6 删除的
蓝色 为名称不同功能相同
中青色 为新增的
Type of service = Traffic Class （用于 QoS）
Total Length = Ppayload Length （ IPV6 中包头定长，不需要包头长度）
Protocol = Next Header （上层协议）
TTL = Hop Limit （跳数限制 ）
Flow Label 此字段为 IPv6 新增字段，20 bit，可以在无状态和有状态的场景中用作 QoS（Quality of Service，服务质量）控制。只有流标签、源地址以及目标地址三元组完全一致时，才能被认为是同一条流。通过结合流标签、源地址和目标地址三元组，可以准确识别和分类数据流，使得网络能够更高效地分配资源、优化传输路径和提高服务质量。
IPv4 总长度（Total Length)
长度 16 bit，包括报文头部和数据。单位是 Byte，最大数值为 65535。
IPv6 载荷长度（Payload Length）
长度 16 bit，数据包的有效载荷，指基本报头后的数据内容长度，包含扩展头部分。单位是 Byte，最大数值为 65535。
IPv4 总长度（Total Length) 与 IPv6 载荷长度（Payload Length）的字段不同点
IPv4 报头中总长度字段是指报头和数据两部分的长度 ，而 IPv6 的有效载荷字段是指仅数据部分的长度，不包括 IPv6 基本报头。
IP 协议号列表（List of IP Protocol Numbers）
This is a list of the IP protocol numbers found in the field Protocol of the IPv4 header and the Next Header field of the IPv6 header.
It is an identifier for the encapsulated protocol and determines the layout of the data that immediately follows the header.
Both fields are eight bits wide. Protocol numbers are maintained and published by the Internet Assigned Numbers Authority (IANA).
IPv4 报头的 protocol 字段和 IPv6 报头的 Next header 字段中是封装协议的标识符，它决定了紧跟在报头后面的数据的布局。两个字段都是 8 位宽。协议号由互联网号码分配机构 (IANA) 维护和发布。
| Hex | Protocol Number | Keyword | Protocol | References/RFC |
|---|---|---|---|---|
| 0x00 | 0 | HOPOPT | IPv6 Hop-by-Hop Option | RFC 8200 |
| 0x01 | 1 | ICMP | Internet Control Message Protocol | RFC 792 |
| 0x02 | 2 | IGMP | Internet Group Management Protocol | RFC 1112 |
| 0x03 | 3 | GGP | Gateway-to-Gateway Protocol | RFC 823 |
| 0x04 | 4 | IP-in-IP | IP in IP (encapsulation) | RFC 2003 |
| 0x05 | 5 | ST | Internet Stream Protocol | RFC 1190, RFC 1819 |
| 0x06 | 6 | TCP | Transmission Control Protocol | RFC 793 |
| 0x07 | 7 | CBT | Core-based trees | RFC 2189 |
| 0x08 | 8 | EGP | Exterior Gateway Protocol | RFC 888 |
| 0x09 | 9 | IGP | Interior Gateway Protocol (any private interior gateway, for example Cisco's IGRP) | |
| 0x0A | 10 | BBN-RCC-MON | BBN RCC Monitoring | |
| 0x0B | 11 | NVP-II | Network Voice Protocol | RFC 741 |
| 0x0C | 12 | PUP | Xerox PUP | |
| 0x0D | 13 | ARGUS | ARGUS | |
| 0x0E | 14 | EMCON | EMCON | |
| 0x0F | 15 | XNET | Cross Net Debugger | IEN 158[2] |
| 0x10 | 16 | CHAOS | Chaos | |
| 0x11 | 17 | UDP | User Datagram Protocol | RFC 768 |
| 0x12 | 18 | MUX | Multiplexing | IEN 90[3] |
| 0x13 | 19 | DCN-MEAS | DCN Measurement Subsystems | |
| 0x14 | 20 | HMP | Host Monitoring Protocol | RFC 869 |
| 0x15 | 21 | PRM | Packet Radio Measurement | |
| 0x16 | 22 | XNS-IDP | XEROX NS IDP | |
| 0x17 | 23 | TRUNK-1 | Trunk-1 | |
| 0x18 | 24 | TRUNK-2 | Trunk-2 | |
| 0x19 | 25 | LEAF-1 | Leaf-1 | |
| 0x1A | 26 | LEAF-2 | Leaf-2 | |
| 0x1B | 27 | RDP | Reliable Data Protocol | RFC 908 |
| 0x1C | 28 | IRTP | Internet Reliable Transaction Protocol | RFC 938 |
| 0x1D | 29 | ISO-TP4 | ISO Transport Protocol Class 4 | RFC 905 |
| 0x1E | 30 | NETBLT | Bulk Data Transfer Protocol | RFC 998 |
| 0x1F | 31 | MFE-NSP | MFE Network Services Protocol | |
| 0x20 | 32 | MERIT-INP | MERIT Internodal Protocol | |
| 0x21 | 33 | DCCP | Datagram Congestion Control Protocol | RFC 4340 |
| 0x22 | 34 | 3PC | Third Party Connect Protocol | |
| 0x23 | 35 | IDPR | Inter-Domain Policy Routing Protocol | RFC 1479 |
| 0x24 | 36 | XTP | Xpress Transport Protocol | |
| 0x25 | 37 | DDP | Datagram Delivery Protocol | |
| 0x26 | 38 | IDPR-CMTP | IDPR Control Message Transport Protocol | |
| 0x27 | 39 | TP++ | TP++ Transport Protocol | |
| 0x28 | 40 | IL | IL Transport Protocol | |
| 0x29 | 41 | IPv6 | IPv6 Encapsulation (6to4 and 6in4) | RFC 2473 |
| 0x2A | 42 | SDRP | Source Demand Routing Protocol | RFC 1940 |
| 0x2B | 43 | IPv6-Route | Routing Header for IPv6 | RFC 8200 |
| 0x2C | 44 | IPv6-Frag | Fragment Header for IPv6 | RFC 8200 |
| 0x2D | 45 | IDRP | Inter-Domain Routing Protocol | |
| 0x2E | 46 | RSVP | Resource Reservation Protocol | RFC 2205 |
| 0x2F | 47 | GRE | Generic Routing Encapsulation | RFC 2784, RFC 2890 |
| 0x30 | 48 | DSR | Dynamic Source Routing Protocol | RFC 4728 |
| 0x31 | 49 | BNA | Burroughs Network Architecture | |
| 0x32 | 50 | ESP | Encapsulating Security Payload | RFC 4303 |
| 0x33 | 51 | AH | Authentication Header | RFC 4302 |
| 0x34 | 52 | I-NLSP | Integrated Net Layer Security Protocol | TUBA |
| 0x35 | 53 | SwIPe | SwIPe | RFC 5237 |
| 0x36 | 54 | NARP | NBMA Address Resolution Protocol | RFC 1735 |
| 0x37 | 55 | MOBILE | IP Mobility (Min Encap) | RFC 2004 |
| 0x38 | 56 | TLSP | Transport Layer Security Protocol (using Kryptonet key management) | |
| 0x39 | 57 | SKIP | Simple Key-Management for Internet Protocol | RFC 2356 |
| 0x3A | 58 | IPv6-ICMP | ICMP for IPv6 | RFC 4443, RFC 4884 |
| 0x3B | 59 | IPv6-NoNxt | No Next Header for IPv6 | RFC 8200 |
| 0x3C | 60 | IPv6-Opts | Destination Options for IPv6 | RFC 8200 |
| 0x3D | 61 | Any host internal protocol | ||
| 0x3E | 62 | CFTP | CFTP | |
| 0x3F | 63 | Any local network | ||
| 0x40 | 64 | SAT-EXPAK | SATNET and Backroom EXPAK | |
| 0x41 | 65 | KRYPTOLAN | Kryptolan | |
| 0x42 | 66 | RVD | MIT Remote Virtual Disk Protocol | |
| 0x43 | 67 | IPPC | Internet Pluribus Packet Core | |
| 0x44 | 68 | Any distributed file system | ||
| 0x45 | 69 | SAT-MON | SATNET Monitoring | |
| 0x46 | 70 | VISA | VISA Protocol | |
| 0x47 | 71 | IPCU | Internet Packet Core Utility | |
| 0x48 | 72 | CPNX | Computer Protocol Network Executive | |
| 0x49 | 73 | CPHB | Computer Protocol Heart Beat | |
| 0x4A | 74 | WSN | Wang Span Network | |
| 0x4B | 75 | PVP | Packet Video Protocol | |
| 0x4C | 76 | BR-SAT-MON | Backroom SATNET Monitoring | |
| 0x4D | 77 | SUN-ND | SUN ND PROTOCOL-Temporary | |
| 0x4E | 78 | WB-MON | WIDEBAND Monitoring | |
| 0x4F | 79 | WB-EXPAK | WIDEBAND EXPAK | |
| 0x50 | 80 | ISO-IP | International Organization for Standardization Internet Protocol | |
| 0x51 | 81 | VMTP | Versatile Message Transaction Protocol | RFC 1045 |
| 0x52 | 82 | SECURE-VMTP | Secure Versatile Message Transaction Protocol | RFC 1045 |
| 0x53 | 83 | VINES | VINES | |
| 0x54 | 84 | TTP | TTP (Transaction Transport Protocol) (obsoleted March 2023) | |
| 0x54 | 84 | IPTM | Internet Protocol Traffic Manager | |
| 0x55 | 85 | NSFNET-IGP | NSFNET-IGP | |
| 0x56 | 86 | DGP | Dissimilar Gateway Protocol | |
| 0x57 | 87 | TCF | TCF | |
| 0x58 | 88 | EIGRP | EIGRP | Informational RFC 7868 |
| 0x59 | 89 | OSPF | Open Shortest Path First | RFC 2328 |
| 0x5A | 90 | Sprite-RPC | Sprite RPC Protocol | |
| 0x5B | 91 | LARP | Locus Address Resolution Protocol | |
| 0x5C | 92 | MTP | Multicast Transport Protocol | |
| 0x5D | 93 | AX.25 | AX.25 | |
| 0x5E | 94 | OS | KA9Q NOS compatible IP over IP tunneling | |
| 0x5F | 95 | MICP | Mobile Internetworking Control Protocol | |
| 0x60 | 96 | SCC-SP | Semaphore Communications Sec. Pro | |
| 0x61 | 97 | ETHERIP | Ethernet-within-IP Encapsulation | RFC 3378 |
| 0x62 | 98 | ENCAP | Encapsulation Header | RFC 1241 |
| 0x63 | 99 | Any private encryption scheme | ||
| 0x64 | 100 | GMTP | GMTP | |
| 0x65 | 101 | IFMP | Ipsilon Flow Management Protocol | |
| 0x66 | 102 | PNNI | PNNI over IP | |
| 0x67 | 103 | PIM | Protocol Independent Multicast | |
| 0x68 | 104 | ARIS | IBM's ARIS (Aggregate Route IP Switching) Protocol | |
| 0x69 | 105 | SCPS | SCPS (Space Communications Protocol Standards) | SCPS-TP |
| 0x6A | 106 | QNX | ||
| 0x6B | 107 | A/N | Active Networks | |
| 0x6C | 108 | IPComp | IP Payload Compression Protocol | RFC 3173 |
| 0x6D | 109 | SNP | Sitara Networks Protocol | |
| 0x6E | 110 | Compaq-Peer | Compaq Peer Protocol | |
| 0x6F | 111 | IPX-in-IP | IPX in IP | |
| 0x70 | 112 | VRRP | Virtual Router Redundancy Protocol, Common Address Redundancy Protocol (not IANA assigned) | RFC 5798 |
| 0x71 | 113 | PGM | PGM Reliable Transport Protocol | RFC 3208 |
| 0x72 | 114 | Any 0-hop protocol | ||
| 0x73 | 115 | L2TP | Layer Two Tunneling Protocol Version 3 | RFC 3931 |
| 0x74 | 116 | DDX | D-II Data Exchange (DDX) | |
| 0x75 | 117 | IATP | Interactive Agent Transfer Protocol | |
| 0x76 | 118 | STP | Schedule Transfer Protocol | |
| 0x77 | 119 | SRP | SpectraLink Radio Protocol | |
| 0x78 | 120 | UTI | Universal Transport Interface Protocol | |
| 0x79 | 121 | SMP | Simple Message Protocol | |
| 0x7A | 122 | SM | Simple Multicast Protocol | draft-perlman-simple-multicast-03 |
| 0x7B | 123 | PTP | Performance Transparency Protocol | |
| 0x7C | 124 | IS-IS over IPv4 | Intermediate System to Intermediate System (IS-IS) Protocol over IPv4 | RFC 1142 and RFC 1195 |
| 0x7D | 125 | FIRE | Flexible Intra-AS Routing Environment | |
| 0x7E | 126 | CRTP | Combat Radio Transport Protocol | |
| 0x7F | 127 | CRUDP | Combat Radio User Datagram | |
| 0x80 | 128 | SSCOPMCE | Service-Specific Connection-Oriented Protocol in a Multilink and Connectionless Environment | ITU-T Q.2111 (1999) |
| 0x81 | 129 | IPLT | ||
| 0x82 | 130 | SPS | Secure Packet Shield | |
| 0x83 | 131 | PIPE | Private IP Encapsulation within IP | Expired I-D draft-petri-mobileip-pipe-00.txt |
| 0x84 | 132 | SCTP | Stream Control Transmission Protocol | RFC 4960 |
| 0x85 | 133 | FC | Fibre Channel | |
| 0x86 | 134 | RSVP-E2E-IGNORE | Reservation Protocol (RSVP) End-to-End Ignore | RFC 3175 |
| 0x87 | 135 | Mobility Header | Mobility Extension Header for IPv6 | RFC 6275 |
| 0x88 | 136 | UDPLite | Lightweight User Datagram Protocol | RFC 3828 |
| 0x89 | 137 | MPLS-in-IP | Multiprotocol Label Switching Encapsulated in IP | RFC 4023, RFC 5332 |
| 0x8A | 138 | manet | MANET Protocols | RFC 5498 |
| 0x8B | 139 | HIP | Host Identity Protocol | RFC 5201 |
| 0x8C | 140 | Shim6 | Site Multihoming by IPv6 Intermediation | RFC 5533 |
| 0x8D | 141 | WESP | Wrapped Encapsulating Security Payload | RFC 5840 |
| 0x8E | 142 | ROHC | Robust Header Compression | RFC 5856 |
| 0x8F | 143 | Ethernet | Segment Routing over IPv6 | RFC 8986 |
| 0x90 | 144 | AGGFRAG | AGGFRAG Encapsulation Payload for ESP | RFC 9347 |
| 0x91 | 145 | NSH | Network Service Header | draft-ietf-spring-nsh-sr |
| 0x92-0xFC | 146-252 | Unassigned | ||
| 0xFD-0xFE | 253-254 | Use for experimentation and testing | RFC 3692 | |
| 0xFF | 255 | Reserved |
~ From encyclopedia ~