IP Protocol Numbers
Searchable reference of IP protocol numbers — the IPv4 Protocol field and IPv6 Next Header field — with IPv6 extension-header flagging.
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IP protocol number reference table
| Number | Hex | Keyword | Protocol name | Reference | IPv6 ext. header |
|---|---|---|---|---|---|
| 00x00 | 0x00 | HOPOPT | HOPOPT IPv6 Hop-by-Hop Option IPv6 Hop-by-Hop Options header: options meant for nodes along the path. It must come directly after the IPv6 header. RFC 8200 · IPv6 ext. header: yes | RFC 8200 | yes |
| 10x01 | 0x01 | ICMP | ICMP Internet Control Message Protocol ICMP for IPv4: error reports and diagnostics such as ping and Destination Unreachable. RFC 792 · IPv6 ext. header: no | RFC 792 | no |
| 20x02 | 0x02 | IGMP | IGMP Internet Group Management Protocol IGMP: IPv4 hosts report their multicast group memberships to local routers. RFC 1112 · IPv6 ext. header: no | RFC 1112 | no |
| 30x03 | 0x03 | GGP | GGP Gateway-to-Gateway Protocol An early protocol between Internet gateways; historic and not in current use. RFC 823 · IPv6 ext. header: no | RFC 823 | no |
| 40x04 | 0x04 | IPv4 | IPv4 IPv4 encapsulation An IPv4 packet carried inside another IP packet (IP-in-IP tunneling, RFC 2003). RFC 2003 · IPv6 ext. header: no | RFC 2003 | no |
| 50x05 | 0x05 | ST | ST Internet Stream Protocol An experimental protocol for real-time data streams (ST2+, RFC 1819). RFC 1819 · IPv6 ext. header: no | RFC 1819 | no |
| 60x06 | 0x06 | TCP | TCP Transmission Control Protocol TCP: reliable, ordered, connection-oriented byte streams; used by HTTP, SSH, SMTP and most applications. RFC 9293 · IPv6 ext. header: no | RFC 9293 | no |
| 80x08 | 0x08 | EGP | EGP Exterior Gateway Protocol A historic routing protocol between autonomous systems, replaced by BGP. RFC 888 · IPv6 ext. header: no | RFC 888 | no |
| 90x09 | 0x09 | IGP | IGP any private interior gateway (e.g. Cisco IGRP) Assigned for any private interior gateway protocol; Cisco IGRP used it. IANA · IPv6 ext. header: no | IANA | no |
| 170x11 | 0x11 | UDP | UDP User Datagram Protocol UDP: connectionless datagrams without delivery guarantees; used by DNS, DHCP, QUIC and many others. RFC 768 · IPv6 ext. header: no | RFC 768 | no |
| 270x1B | 0x1B | RDP | RDP Reliable Data Protocol Reliable Data Protocol, an experimental transport (RFC 908). It is not Microsoft's Remote Desktop Protocol, which runs over TCP and UDP. RFC 908 · IPv6 ext. header: no | RFC 908 | no |
| 330x21 | 0x21 | DCCP | DCCP Datagram Congestion Control Protocol DCCP: datagrams with congestion control but without reliable delivery. RFC 4340 · IPv6 ext. header: no | RFC 4340 | no |
| 410x29 | 0x29 | IPv6 | IPv6 IPv6 encapsulation An IPv6 packet carried inside an IP packet, for example IPv6-in-IPv4 (6in4) or IPv6-in-IPv6 tunnels. RFC 2473 · IPv6 ext. header: no | RFC 2473 | no |
| 430x2B | 0x2B | IPv6-Route | IPv6-Route Routing Header for IPv6 IPv6 Routing header: lists nodes the packet should visit on the way, for example for Segment Routing (SRv6). Routing type 0 is deprecated (RFC 5095). RFC 8200 · IPv6 ext. header: yes | RFC 8200 | yes |
| 440x2C | 0x2C | IPv6-Frag | IPv6-Frag Fragment Header for IPv6 IPv6 Fragment header: marks a fragment of a larger packet. In IPv6 only the source fragments, never routers. RFC 8200 · IPv6 ext. header: yes | RFC 8200 | yes |
| 460x2E | 0x2E | RSVP | RSVP Resource Reservation Protocol RSVP: reserves resources along a path; RSVP-TE uses it to set up MPLS traffic-engineering tunnels. RFC 2205, RFC 3209 · IPv6 ext. header: no | RFC 2205, RFC 3209 | no |
| 470x2F | 0x2F | GRE | GRE Generic Routing Encapsulation GRE: carries one protocol inside IP, for example site-to-site tunnels; PPTP also uses a GRE variant. RFC 2784 · IPv6 ext. header: no | RFC 2784 | no |
| 500x32 | 0x32 | ESP | ESP Encapsulating Security Payload IPsec ESP: encryption and/or integrity protection of the payload. RFC 4303 · IPv6 ext. header: yes | RFC 4303 | yes |
| 510x33 | 0x33 | AH | AH Authentication Header IPsec AH: integrity and origin authentication without encryption. RFC 4302 · IPv6 ext. header: yes | RFC 4302 | yes |
| 580x3A | 0x3A | IPv6-ICMP | IPv6-ICMP ICMP for IPv6 ICMPv6: error reports, diagnostics and Neighbor Discovery for IPv6. IPv6 does not work without it. RFC 4443 · IPv6 ext. header: no | RFC 4443 | no |
| 590x3B | 0x3B | IPv6-NoNxt | IPv6-NoNxt No Next Header for IPv6 Nothing follows this header in the IPv6 packet. RFC 8200 · IPv6 ext. header: no — ends the header chain | RFC 8200 | no — ends the header chain |
| 600x3C | 0x3C | IPv6-Opts | IPv6-Opts Destination Options for IPv6 IPv6 Destination Options header: options for the destination, or for each node listed in a Routing header. RFC 8200 · IPv6 ext. header: yes | RFC 8200 | yes |
| 880x58 | 0x58 | EIGRP | EIGRP Enhanced Interior Gateway Routing Protocol EIGRP: Cisco's distance-vector interior routing protocol, published as an informational RFC. RFC 7868 · IPv6 ext. header: no | RFC 7868 | no |
| 890x59 | 0x59 | OSPFIGP | OSPFIGP Open Shortest Path First OSPF: a link-state interior routing protocol; OSPFv2 for IPv4 (RFC 2328) and OSPFv3 for IPv6 (RFC 5340). RFC 2328, RFC 5340 · IPv6 ext. header: no | RFC 2328, RFC 5340 | no |
| 940x5E | 0x5E | IPIP | IPIP IP-within-IP Encapsulation Protocol A separate IP-within-IP assignment. It is a different number from IPv4 encapsulation (4). IANA · IPv6 ext. header: no | IANA | no |
| 970x61 | 0x61 | ETHERIP | ETHERIP Ethernet-within-IP Encapsulation Ethernet frames carried directly in IP (RFC 3378). RFC 3378 · IPv6 ext. header: no | RFC 3378 | no |
| 980x62 | 0x62 | ENCAP | ENCAP Encapsulation Header An early encapsulation header for tunneling (RFC 1241). RFC 1241 · IPv6 ext. header: no | RFC 1241 | no |
| 1030x67 | 0x67 | PIM | PIM Protocol Independent Multicast PIM: multicast routing that builds distribution trees from the unicast routing table. RFC 7761 · IPv6 ext. header: no | RFC 7761 | no |
| 1080x6C | 0x6C | IPComp | IPComp IP Payload Compression Protocol IPComp: compresses IP payloads, often together with IPsec. RFC 3173 · IPv6 ext. header: no | RFC 3173 | no |
| 1120x70 | 0x70 | VRRP | VRRP Virtual Router Redundancy Protocol VRRP: routers share a virtual default-gateway address; the active router sends advertisements with this protocol number. RFC 9568 · IPv6 ext. header: no | RFC 9568 | no |
| 1150x73 | 0x73 | L2TP | L2TP Layer Two Tunneling Protocol version 3 L2TPv3 directly over IP, tunneling layer 2 frames. L2TPv2 runs over UDP instead. RFC 3931 · IPv6 ext. header: no | RFC 3931 | no |
| 1240x7C | 0x7C | ISIS over IPv4 | ISIS over IPv4 IS-IS over IPv4 Assigned for IS-IS carried over IPv4. IS-IS itself normally runs directly over the link layer, not over IP. IANA · IPv6 ext. header: no | IANA | no |
| 1320x84 | 0x84 | SCTP | SCTP Stream Control Transmission Protocol SCTP: reliable message-oriented transport with multi-streaming and multi-homing, used for example in telecom signaling. RFC 9260 · IPv6 ext. header: no | RFC 9260 | no |
| 1330x85 | 0x85 | FC | FC Fibre Channel Assigned for carrying Fibre Channel over IP. RFC 6172 · IPv6 ext. header: no | RFC 6172 | no |
| 1350x87 | 0x87 | Mobility Header | Mobility Header IPv6 Mobility Header IPv6 Mobility header: carries Mobile IPv6 signaling such as Binding Updates. RFC 6275 · IPv6 ext. header: yes | RFC 6275 | yes |
| 1360x88 | 0x88 | UDPLite | UDPLite Lightweight User Datagram Protocol UDP-Lite: a UDP variant whose checksum can cover only part of the payload, so slightly damaged media data can still be delivered. RFC 3828 · IPv6 ext. header: no | RFC 3828 | no |
| 1370x89 | 0x89 | MPLS-in-IP | MPLS-in-IP MPLS-in-IP MPLS packets carried in IP (RFC 4023). RFC 4023 · IPv6 ext. header: no | RFC 4023 | no |
| 1380x8A | 0x8A | manet | manet MANET Protocols A shared number for MANET (mobile ad hoc network) routing protocols. RFC 5498 · IPv6 ext. header: no | RFC 5498 | no |
| 1390x8B | 0x8B | HIP | HIP Host Identity Protocol HIP: separates a host's identity from its IP address (RFC 7401). RFC 7401 · IPv6 ext. header: yes | RFC 7401 | yes |
| 1400x8C | 0x8C | Shim6 | Shim6 Shim6 Protocol Shim6: a multihoming shim layer for IPv6 sites (RFC 5533). RFC 5533 · IPv6 ext. header: yes | RFC 5533 | yes |
| 1410x8D | 0x8D | WESP | WESP Wrapped Encapsulating Security Payload Wrapped ESP: lets middleboxes tell whether ESP traffic is encrypted (RFC 5840). RFC 5840 · IPv6 ext. header: no | RFC 5840 | no |
| 1420x8E | 0x8E | ROHC | ROHC Robust Header Compression ROHC (Robust Header Compression); RFC 5858 covers its use with IPsec. RFC 5858 · IPv6 ext. header: no | RFC 5858 | no |
| 1430x8F | 0x8F | Ethernet | Ethernet Ethernet (SRv6 / segment routing) An Ethernet frame directly after the IPv6 header, used by SRv6 for layer 2 VPN services (RFC 8986). RFC 8986 · IPv6 ext. header: no | RFC 8986 | no |
| 1440x90 | 0x90 | AGGFRAG | AGGFRAG AGGFRAG encapsulation payload for ESP AGGFRAG payload used by IP traffic flow security (IP-TFS) inside ESP (RFC 9347). RFC 9347 · IPv6 ext. header: no | RFC 9347 | no |
| 1450x91 | 0x91 | NSH | NSH Network Service Header NSH: the Network Service Header used for service function chaining. RFC 9491 · IPv6 ext. header: no | RFC 9491 | no |
| 1460x92 | 0x92 | Homa | Homa Homa Homa: a transport protocol designed for remote procedure calls in data centers. IANA · IPv6 ext. header: no | IANA | no |
| 1470x93 | 0x93 | BIT-EMU | BIT-EMU Bit-stream Emulation Assigned for Bit-stream Emulation (RFC 9801). RFC 9801 · IPv6 ext. header: yes | RFC 9801 | yes |
| 2530xFD | 0xFD | — | — Use for experimentation and testing Reserved for experiments and testing (RFC 3692); not for production use. RFC 3692 · IPv6 ext. header: yes | RFC 3692 | yes |
| 2540xFE | 0xFE | — | — Use for experimentation and testing Reserved for experiments and testing (RFC 3692); not for production use. RFC 3692 · IPv6 ext. header: yes | RFC 3692 | yes |
| 2550xFF | 0xFF | Reserved | Reserved Reserved Reserved by IANA. IANA · IPv6 ext. header: no | IANA | no |
How it works
Reference for the 8-bit value in the IPv4 header "Protocol" field and the IPv6 header "Next Header" field, from the IANA Assigned Internet Protocol Numbers registry (registry last updated 2026-03-09; verified 2026-09-15). This table is a curated subset of the values operators meet often; only entries verified as correct are included, and an absent value may still be assigned. Number and keyword follow the registry; the protocol name is a curated display label. Each row also has a short English and Japanese explanation of the protocol's typical role; it describes what the number is assigned for, not what traffic using the number is on a given network. Search by decimal number, by 0x-style hex, or by words in the keyword, the name, or the explanation in either language. In IPv6 the same field is the Next Header field. The IPv6 extension header column mirrors the IPv6 Extension Header attribute of that registry — 0, 43, 44, 50, 51, 60, 135, 139, 140, 147 and the experimental values 253 and 254 are marked there. Value 59 means "no next header": it ends the header chain and is not marked as an extension header, so it is shown separately. Protocol numbers 253 and 254 are reserved for experimentation and testing (RFC 3692); 255 is reserved. The Reference column is a curated protocol reference: the current protocol-specification RFC where a clear one exists (for example RFC 9568 for VRRP, RFC 9260 for SCTP), otherwise the RFCs the registry cites, and IANA when the assignment is backed only by an IANA contact or submission. The full table works without JavaScript; search and the lookup panel need JavaScript.