IP
Internet Protocol (IP) is the primary part of the Network Layer of the OSI Model that is responsible for routing traffic across network boundaries. It is the protocol that is responsible for addressing. IPv4 is probable the version that most people are familiar with and it has been around since 1974. IPv6 is its current successor and due to a shortage of available IPv4 addresses compared to the explosive increase in the number of devices that use IP addresses, IPv6 is rapidly increasing in use.
When IP is chosen as the protocol type the available option to further specify the protocol is the protocol number. This is used to narrow down which protocol within the Internet Protocol Suite and provide a more granular control.
Protocol number
IP is responsible for more than the address that it is most commonly associated with and there are a number of associated protocols that make up the Network Layer. While there are not 256 of them, the field that identifies them is a numeric value between 0 and 256.
In the Internet Protocol version 4 (IPv4) [RFC791] there is a field called “Protocol” to identify the next level protocol. This is an 8 bit field. In Internet Protocol version 6 (IPv6) [RFC2460], this field is called the “Next Header” field.
Protocol numbers
| # | Protocol | Protocol's Full Name |
|---|---|---|
| 0 | HOPOPT | IPv6 Hop-by-Hop Option |
| 1 | ICMP | Internet Control Message Protocol |
| 2 | IGMP | Internet Group Management |
| 3 | GGP | Gateway-to-Gateway |
| 4 | IPv4 | IPv4 encapsulation Protocol |
| 5 | ST | Stream |
| 6 | TCP | Transmission Control Protocol |
| 7 | CBT | CBT |
| 8 | EGP | Exterior Gateway Protocol |
| 9 | IGP | Any private interior gateway (used by Cisco for their IGRP) |
| 10 | BBN-RCC-MON | BBN RCC Monitoring |
| 11 | NVP-II | Network Voice Protocol |
| 12 | PUP | PUP |
| 13 | ARGUS | ARGUS |
| 14 | EMCON | EMCON |
| 15 | XNET | Cross Net Debugger |
| 16 | CHAOS | Chaos |
| 17 | UDP | User Datagram Protocol |
| 18 | MUX | Multiplexing |
| 19 | DCN-MEAS | DCN Measurement Subsystems |
| 20 | HMP | Host Monitoring |
| 21 | PRM | Packet Radio Measurement |
| 22 | XNS-IDP | XEROX NS IDP |
| 23 | TRUNK-1 | Trunk-1 |
| 24 | TRUNK-2 | Trunk-2 |
| 25 | LEAF-1 | Leaf-1 |
| 26 | LEAF-2 | Leaf-2 |
| 27 | RDP | Reliable Data Protocol |
| 28 | IRTP | Internet Reliable Transaction |
| 29 | ISO-TP4 | ISO Transport Protocol Class 4 |
| 30 | NETBLT | Bulk Data Transfer Protocol |
| 31 | MFE-NSP | MFE Network Services Protocol |
| 32 | MERIT-INP | MERIT Internodal Protocol |
| 33 | DCCP | Datagram Congestion Control Protocol |
| 34 | 3PC | Third Party Connect Protocol |
| 35 | IDPR | Inter-Domain Policy Routing Protocol |
| 36 | XTP | XTP |
| 37 | DDP | Datagram Delivery Protocol |
| 38 | IDPR-CMTP | IDPR Control Message Transport Proto |
| 39 | TP++ | TP++ Transport Protocol |
| 40 | IL | IL Transport Protocol |
| 41 | IPv6 | IPv6 encapsulation |
| 42 | IPv6 | SDRPSource Demand Routing Protocol |
| 43 | IPv6-Route | Routing Header for IPv6 |
| 44 | IPv6-Frag | Fragment Header for IPv6 |
| 45 | IDRP | Inter-Domain Routing Protocol |
| 46 | RSVP | Reservation Protocol |
| 47 | GRE | General Routing Encapsulation |
| 48 | DSR | Dynamic Source Routing Protocol |
| 49 | BNA | BNA |
| 50 | ESP | Encap Security Payload |
| 51 | AH | Authentication Header |
| 52 | I-NLSP | Integrated Net Layer Security TUBA |
| 53 | SWIPE | IP with Encryption |
| 54 | NARP | NBMA Address Resolution Protocol |
| 55 | MOBILE | IP Mobility |
| 56 | TLSP | Transport Layer Security Protocol using Kryptonet key management |
| 57 | SKIP | SKIP |
| 58 | IPv6-ICMP | ICMP for IPv6 |
| 59 | IPv6-NoNxt | No Next Header for IPv6 |
| 60 | IPv6-Opts | Destination Options for IPv6 |
| 61 | any host internal protocol | |
| 62 | CFTP | CFTP |
| 63 | any local network | |
| 64 | SAT-EXPAK | SATNET and Backroom EXPAK |
| 65 | KRYPTOLAN | Kryptolan |
| 66 | RVD | MIT Remote Virtual Disk Protocol |
| 67 | IPPC | Internet Pluribus Packet Core |
| 68 | any distributed file system | |
| 69 | SAT-MON | SATNET Monitoring |
| 70 | VISA | VISA Protocol |
| 71 | IPCV | Internet Packet Core Utility |
| 72 | CPNX | Computer Protocol Network Executive |
| 73 | CPHB | Computer Protocol Heart Beat |
| 74 | WSN | Wang Span Network |
| 75 | PVP | Packet Video Protocol |
| 76 | BR-SAT-MON | Backroom SATNET Monitoring |
| 77 | SUN-ND | SUN ND PROTOCOL-Temporary |
| 78 | WB-MON | WIDEBAND Monitoring |
| 79 | WB-EXPAK | WIDEBAND EXPAK |
| 80 | ISO-IP | ISO Internet Protocol |
| 81 | VMTP | VMTP |
| 82 | SECURE-VMTP | SECURE-VMTP |
| 83 | VINES | VINES |
| 84 | TTP | TTP |
| 84 | IPTM | Protocol Internet Protocol Traffic |
| 85 | NSFNET-IGP | NSFNET-IGP |
| 86 | DGP | Dissimilar Gateway Protocol |
| 87 | TCF | TCF |
| 88 | EIGRP | EIGRP |
| 89 | OSPFIGP | OSPFIGP |
| 90 | Sprite-RPC | Sprite RPC Protocol |
| 91 | LARP | Locus Address Resolution Protocol |
| 92 | MTP | Multicast Transport Protocol |
| 93 | AX.25 | AX.25 Frames |
| 94 | IPIP | IP-within-IP Encapsulation Protocol |
| 95 | MICP | Mobile Internetworking Control Pro. |
| 96 | SCC-SP | Semaphore Communications Sec. Pro. |
| 97 | ETHERIP | Ethernet-within-IP Encapsulation |
| 98 | ENCAP | Encapsulation Header |
| 99 | any private encryption scheme | |
| 100 | GMTP | GMTP |
| 101 | IFMP | Ipsilon Flow Management Protocol |
| 102 | PNNI | PNNI over IP |
| 103 | PIM | Protocol Independent Multicast |
| 104 | ARIS | ARIS |
| 105 | SCPS | SCPS |
| 106 | QNX | QNX |
| 107 | A/N | Active Networks |
| 108 | IPComp | IP Payload Compression Protocol |
| 109 | SNP | Sitara Networks Protocol |
| 110 | Compaq-Peer | Compaq Peer Protocol |
| 111 | IPX-in-IP | IPX in IP |
| 112 | VRRP | Virtual Router Redundancy Protocol |
| 113 | PGM | PGM Reliable Transport Protocol |
| 114 | any 0-hop protocol | |
| 115 | L2TP | Layer Two Tunneling Protocol |
| 116 | DDX | D-II Data Exchange (DDX) |
| 117 | IATP | Interactive Agent Transfer Protocol |
| 118 | STP | Schedule Transfer Protocol |
| 119 | SRP | SpectraLink Radio Protocol |
| 120 | UTI | UTI |
| 121 | SMP | Simple Message Protocol |
| 122 | SM | SM |
| 123 | PTP | Performance Transparency Protocol |
| 124 | ISIS over IPv4 | |
| 125 | FIRE | |
| 126 | CRTP | Combat Radio Transport Protocol |
| 127 | CRUDP | Combat Radio User Datagram |
| 128 | SSCOPMCE | |
| 129 | IPLT | |
| 130 | SPS | Secure Packet Shield |
| 131 | PIPE | Private IP Encapsulation within IP |
| 132 | SCTP | Stream Control Transmission Protocol |
| 133 | FC | Fibre Channel |
| 134 | RSVP-E2E-IGNORE | |
| 135 | Mobility Header | |
| 136 | UDPLite | |
| 137 | MPLS-in-IP | |
| 138 | manet | |
| 139 | HIP | |
| 140 | Shim6 | |
| 141 | WESP | |
| 142 | ROHC | |
| 143 − 252 | Unassigned | Unassigned |
| 253 | Use for experimentation and testing | |
| 254 | Use for experimentation and testing | |
| 255 | Reserved |
Further information can be found by researching RFC 5237.