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) (RFC1883 and RFC2460) this field is called the "Next Header" field.
Protocol Numbers
- 0 HOPOPT IPv6 Hop-by-Hop Option
- 1 ICMP Internet Control Message
- 2 IGMP Internet Group Management
- 3 GGP Gateway-to-Gateway
- 4 IP IP in IP (encapsulation)
- 5 ST Stream
- 6 TCP Transmission Control
- 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
- 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 SEP Sequential Exchange 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
- 42 SDRP Source 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 MHRP Mobile Host Routing Protocol
- 49 BNA BNA
- 50 ESP Encapsulating 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
- 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 Protocol
- 96 SCC-SP Semaphore Communications Sec. Protocol
- 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
- 135-254 Unassigned
- 255 Reserved
