2026-03-09 IESG Approval or Standards Action In the Internet Protocol version 4 (IPv4) there is a field called "Protocol" to identify the next level protocol. This is an 8 bit field. In Internet Protocol version 6 (IPv6) , this field is called the "Next Header" field. Values that are also IPv6 Extension Header Types should be listed in the IPv6 Extension Header Types registry at . 0 HOPOPT IPv6 Hop-by-Hop Option Y 1 ICMP Internet Control Message 2 IGMP Internet Group Management 3 GGP Gateway-to-Gateway 4 IPv4 IPv4 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 Boggs, D., J. Shoch, E. Taft, and R. Metcalfe, "PUP: An Internetwork Architecture", XEROX Palo Alto Research Center, CSL-79-10, July 1979; also in IEEE Transactions on Communication, Volume COM-28, Number 4, April 1980. [XEROX] 13 ARGUS (deprecated) ARGUS 14 EMCON EMCON 15 XNET Cross Net Debugger Haverty, J., "XNET Formats for Internet Protocol Version 4", IEN 158, October 1980. 16 CHAOS Chaos 17 UDP User Datagram 18 MUX Multiplexing Cohen, D. and J. Postel, "Multiplexing Protocol", IEN 90, USC/Information Sciences Institute, May 1979. 19 DCN-MEAS DCN Measurement Subsystems 20 HMP Host Monitoring 21 PRM Packet Radio Measurement 22 XNS-IDP XEROX NS IDP "The Ethernet, A Local Area Network: Data Link Layer and Physical Layer Specification", AA-K759B-TK, Digital Equipment Corporation, Maynard, MA. Also as: "The Ethernet - A Local Area Network", Version 1.0, Digital Equipment Corporation, Intel Corporation, Xerox Corporation, September 1980. And: "The Ethernet, A Local Area Network: Data Link Layer and Physical Layer Specifications", Digital, Intel and Xerox, November 1982. And: XEROX, "The Ethernet, A Local Area Network: Data Link Layer and Physical Layer Specification", X3T51/80-50, Xerox Corporation, Stamford, CT., October 1980. [XEROX] 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 Shuttleworth, B., "A Documentary of MFENet, a National Computer Network", UCRL-52317, Lawrence Livermore Labs, Livermore, California, June 1977. 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 SDRP Source Demand Routing Protocol 43 IPv6-Route Routing Header for IPv6 Y 44 IPv6-Frag Fragment Header for IPv6 Y 45 IDRP Inter-Domain Routing Protocol 46 RSVP Reservation Protocol 47 GRE Generic Routing Encapsulation 48 DSR Dynamic Source Routing Protocol 49 BNA BNA Gary Salamon 50 ESP Encap Security Payload Y 51 AH Authentication Header Y 52 I-NLSP Integrated Net Layer Security TUBA 53 SWIPE (deprecated) IP with Encryption 54 NARP NBMA Address Resolution Protocol 55 Min-IPv4 Minimal IPv4 Encapsulation 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 Y 61 any host internal protocol 62 CFTP CFTP Forsdick, H., "CFTP", Network Message, Bolt Beranek and Newman, January 1982. 63 any local network 64 SAT-EXPAK SATNET and Backroom EXPAK 65 KRYPTOLAN Kryptolan Paul Liu 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 David Mittnacht 73 CPHB Computer Protocol Heart Beat David Mittnacht 74 WSN Wang Span Network Victor Dafoulas 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 Brian Horn 84 IPTM Internet Protocol Traffic Manager 85 NSFNET-IGP NSFNET-IGP 86 DGP Dissimilar Gateway Protocol M/A-COM Government Systems, "Dissimilar Gateway Protocol Specification, Draft Version", Contract no. CS901145, November 16, 1987. 87 TCF TCF 88 EIGRP EIGRP 89 OSPFIGP OSPFIGP 90 Sprite-RPC Sprite RPC Protocol Welch, B., "The Sprite Remote Procedure Call System", Technical Report, UCB/Computer Science Dept., 86/302, University of California at Berkeley, June 1986. Bruce Willins 91 LARP Locus Address Resolution Protocol Brian Horn 92 MTP Multicast Transport Protocol 93 AX.25 AX.25 Frames 94 IPIP IP-within-IP Encapsulation Protocol 95 MICP (deprecated) 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 [RXB5] 101 IFMP Ipsilon Flow Management Protocol November 1995, 1997. 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 (deprecated) Simple Multicast Protocol 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 [Hollbach] 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 Y 136 UDPLite 137 MPLS-in-IP 138 manet MANET Protocols 139 HIP Host Identity Protocol Y 140 Shim6 Shim6 Protocol Y 141 WESP Wrapped Encapsulating Security Payload 142 ROHC Robust Header Compression 143 Ethernet Ethernet 144 AGGFRAG AGGFRAG encapsulation payload for ESP 145 NSH Network Service Header N 146 Homa Homa N HomaModule 147 BIT-EMU Bit-stream Emulation Y 148-252 Unassigned 253 Use for experimentation and testing Y 254 Use for experimentation and testing Y 255 Reserved Until March 2023, value 84 was also assigned to TTP (Transaction Transport Protocol). Barry Boehm mailto:boehm&arpa.mil Barry Howard mailto:Howard&nmfecc.llnl.gov Bernard Aboba mailto:bernarda&microsoft.com 1998-04 Bich Nguyen mailto:bitnguyen&gmail.com 2023-01-09 Bill McIntosh mailto:BMcIntosh&fortresstech.com Bob Braden mailto:braden&isi.edu 1997-07 Bob Hinden mailto:bob.hinden&gmail.com 2013-02-17 Brian Kantor mailto:brian&ucsd.edu CJ Lee mailto:cj_lee&novell.com 1997-10 Charlie Perkins mailto:perk&watson.ibm.com 1994-10 Christer Oberg mailto:chg&bull.se 1994-10 Criag Partridge mailto:craig&bbn.com 1999-08 Dave Cheriton mailto:cheriton&pescadero.stanford.edu Dave Presotto mailto:presotto&plan9.att.com 1995-07 David Clark mailto:ddc&lcs.mit.edu David Mills mailto:Mills&huey.udel.edu Deborah Estrin mailto:estrin&usc.edu Dino Farinacci mailto:dino&cisco.com 1996-03 Dirk Fromhein mailto:df&watershed.com Gene Tsudik mailto:tsudik&usc.edu Greg Chesson mailto:Greg&sgi.com Guillermo A. Loyola mailto:LOYOLA&ibm.com Hans-Werner Braun mailto:HWB&mcr.umich.edu Harry Forsdick mailto:Forsdick&bbn.com Howard Hart mailto:hch&hybrid.com Internet Assigned Numbers Authority mailto:iana&iana.org 1995-06 J. Noel Chiappa mailto:JNC&xx.lcs.mit.edu Jack Haverty mailto:jhaverty&oracle.com Jean-Michel Pittet mailto:jmp&gandalf.engr.sgi.com 1998-11 Jim Stevens mailto:jasteven&rockwellcollins.com 2011-01-26 John Ioannidis mailto:ji&tla.org 2015-01-06 John Moy mailto:jmoy&proteon.com John Murphy mailto:john.m.murphy&mci.com 1998-10 John Ousterhout mailto:john.ousterhout&gmail.com 2024-10-24 John Worley mailto:worley&milehigh.net 1998-06 Jon Crowcroft mailto:jon&cs.ucl.ac.uk 1999-06 Jon Postel mailto:postel&isi.edu K. Robert Glenn mailto:glenn&osi.ncsl.nist.gov Kurt Waber mailto:kurt.waber&swisscom.com 1999-08 Leif Ekblad mailto:leif&rdos.net 2012-08-21 Manickam R. Sridhar mailto:msridhar&sitaranetworks.com 1997-09 Mark Hamilton mailto:mah&spectralink.com 1998-11 Marshall T. Rose mailto:mrose&dbc.mtview.ca.us Martha Steenstrup mailto:MSteenst&bbn.com Michael Greenwald mailto:Greenwald&scrc-stony-brook.symbolics.com Michael Hunter mailto:mphunter&qnx.com 1997-07 Michael Welzl mailto:michael&tk.uni-linz.ac.at 1999-08 Mike Little mailto:little&macom4.arpa Murali Rajagopal mailto:murali&gadzoox.com 2000-05 Nancy Feldman mailto:nkf&vnet.ibm.com 1997-01 Peter Lothberg mailto:roll&stupi.se 1999-03 Randall R. Stewart mailto:rrs&lakerest.net 2000-04 Robert Cole mailto:robert&CS.UCL.AC.UK Robert Durst mailto:durst&mitre.org 1997-03 Robert Sautter mailto:rsautter&acdnj.itt.com 1999-08 Robert W. Scheifler mailto:rscheifler&comcast.net 2015-10-06 Robert Woodburn mailto:woody&cseic.saic.com Ross Callon mailto:rcallon&baynetworks.com 1995-12 Steffen Fries mailto:steffen.fries&siemens.com 2026-03-09 Steve Casner mailto:casner&isi.edu Steve Chipman mailto:Chipman&f.bbn.com Steve Deering mailto:deering&parc.xerox.com 1995-03 Steven Blumenthal mailto:BLUMENTHAL&vax.bbn.com Stuart A. Friedberg mailto:stuart&cs.wisc.edu Sue Hares mailto:skh&merit.edu Susie Armstrong mailto:Armstrong.wbst128&xerox.com Tom Markson mailto:markson&osmosys.ingog.com 1995-09 Tony Ballardie mailto:A.Ballardie&cs.ucl.ac.uk Tony Li mailto:tony.li&tony.li 2012-10-17 Tony Przygienda mailto:prz&siara.com 1999-08 Tony Speakman mailto:speakman&cisco.com 1998-01 Trudy Miller mailto:Trudy&acc.com Victor Volpe mailto:vvolpe&smtp.microcom.com 1997-10 Wesley Craig mailto:Wesley.Craig&terminator.cc.umich.edu William Melohn mailto:Melohn&sun.com Zaw-Sing Su mailto:ZSu&tsca.istc.sri.