Cisco Access List Protocol Numbers And Assignment

Access control lists (ACLs) perform packet filtering to control which packets move through the network and where. Such control can restrict the access of users and devices to the network, providing a measure of security. Access lists can save network resources by reducing traffic. Access lists provide diverse benefits, depending on how they are used. Many of the benefits fall into the following categories:

Block Unwanted Traffic or Users

Access lists can filter incoming or outgoing packets on an interface, thereby controlling access based on source addresses, destination addresses, or user authentication. You can also use access lists to determine which types of traffic are forwarded or blocked at the router interfaces. For example, you can permit e-mail traffic to be routed, but at the same time block all Telnet traffic.

Reduce the Chance of DOS Attacks

There are a number of ways to reduce the chance of denial-of-service attacks. For example, by specifying IP source addresses, you can control whether traffic from hosts, networks, or users access your network. By configuring the TCP Intercept feature, you can prevent servers from being flooded with requests for a connection.

Control Access to Virtual Terminal Lines

You can place an access list on inbound vty (Telnet) line access from certain nodes or networks. You can also place an access list on outbound vty access, blocking or permitting Telnet access to other devices.

Restrict the Content of Routing Updates

Access lists can control routing updates being sent, received, or redistributed.

Provide Bandwidth Control

An access list on a slow link can prevent excess traffic.

Identify or Classify Traffic for QoS Features

Access lists can provide congestion avoidance by setting IP precedence for WRED or CAR. It can provide congestion management for class-based weighted fair queuing (WFQ), priority queuing, and custom queuing.

Trigger Dial-on-Demand (DDR) Calls

An access list can enforce dialing and disconnect criteria.

Limit Debug Command Output

An access list can limit debug output based on an address or protocol.

Provide NAT Control

Access lists can control which addresses are translated by Network Address Translation (NAT).

Authenticate Incoming RSH and RCP Requests

To enable the Cisco IOS software to receive incoming remote shell (rsh) protocol and remote copy (rcp) protocol requests, customers must configure an authentication database to control access to the router. Access lists can simplify the identification of local users, remote hosts, and remote users in the database authentication configuration.

Protocol Numbers

Last Updated
Available Formats

Plain text

Registry included below

Assigned Internet Protocol Numbers

Registration Procedure(s)
IESG Approval or Standards Action
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) [RFC8200], 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 [IANA registry ipv6-parameters].
Available Formats

DecimalKeywordProtocolIPv6 Extension HeaderReference
0HOPOPTIPv6 Hop-by-Hop OptionY[RFC8200]
1ICMPInternet Control Message[RFC792]
2IGMPInternet Group Management[RFC1112]
4IPv4IPv4 encapsulation[RFC2003]
6TCPTransmission Control[RFC793]
8EGPExterior Gateway Protocol[RFC888][David_Mills]
9IGPany private interior gateway (used by Cisco for their IGRP)[Internet_Assigned_Numbers_Authority]
10BBN-RCC-MONBBN RCC Monitoring[Steve_Chipman]
11NVP-IINetwork Voice Protocol[RFC741][Steve_Casner]
12PUPPUP[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]]
13ARGUS (deprecated)ARGUS[Robert_W_Scheifler]
14EMCONEMCON[<mystery contact>]
15XNETCross Net Debugger[Haverty, J., "XNET Formats for Internet Protocol Version 4", IEN 158, October 1980.][Jack_Haverty]
17UDPUser Datagram[RFC768][Jon_Postel]
18MUXMultiplexing[Cohen, D. and J. Postel, "Multiplexing Protocol", IEN 90, USC/Information Sciences Institute, May 1979.][Jon_Postel]
19DCN-MEASDCN Measurement Subsystems[David_Mills]
20HMPHost Monitoring[RFC869][Bob_Hinden]
21PRMPacket Radio Measurement[Zaw_Sing_Su]
22XNS-IDPXEROX 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]]
27RDPReliable Data Protocol[RFC908][Bob_Hinden]
28IRTPInternet Reliable Transaction[RFC938][Trudy_Miller]
29ISO-TP4ISO Transport Protocol Class 4[RFC905][<mystery contact>]
30NETBLTBulk Data Transfer Protocol[RFC969][David_Clark]
31MFE-NSPMFE Network Services Protocol[Shuttleworth, B., "A Documentary of MFENet, a National Computer Network", UCRL-52317, Lawrence Livermore Labs, Livermore, California, June 1977.][Barry_Howard]
32MERIT-INPMERIT Internodal Protocol[Hans_Werner_Braun]
33DCCPDatagram Congestion Control Protocol[RFC4340]
343PCThird Party Connect Protocol[Stuart_A_Friedberg]
35IDPRInter-Domain Policy Routing Protocol[Martha_Steenstrup]
37DDPDatagram Delivery Protocol[Wesley_Craig]
38IDPR-CMTPIDPR Control Message Transport Proto[Martha_Steenstrup]
39TP++TP++ Transport Protocol[Dirk_Fromhein]
40ILIL Transport Protocol[Dave_Presotto]
41IPv6IPv6 encapsulation[RFC2473]
42SDRPSource Demand Routing Protocol[Deborah_Estrin]
43IPv6-RouteRouting Header for IPv6Y[Steve_Deering]
44IPv6-FragFragment Header for IPv6Y[Steve_Deering]
45IDRPInter-Domain Routing Protocol[Sue_Hares]
46RSVPReservation Protocol[RFC2205][RFC3209][Bob_Braden]
47GREGeneric Routing Encapsulation[RFC2784][Tony_Li]
48DSRDynamic Source Routing Protocol[RFC4728]
49BNABNA[Gary Salamon]
50ESPEncap Security PayloadY[RFC4303]
51AHAuthentication HeaderY[RFC4302]
52I-NLSPIntegrated Net Layer Security TUBA[K_Robert_Glenn]
53SWIPE (deprecated)IP with Encryption[John_Ioannidis]
54NARPNBMA Address Resolution Protocol[RFC1735]
55MOBILEIP Mobility[Charlie_Perkins]
56TLSPTransport Layer Security Protocol using Kryptonet key management[Christer_Oberg]
58IPv6-ICMPICMP for IPv6[RFC8200]
59IPv6-NoNxtNo Next Header for IPv6[RFC8200]
60IPv6-OptsDestination Options for IPv6Y[RFC8200]
61any host internal protocol[Internet_Assigned_Numbers_Authority]
62CFTPCFTP[Forsdick, H., "CFTP", Network Message, Bolt Beranek and Newman, January 1982.][Harry_Forsdick]
63any local network[Internet_Assigned_Numbers_Authority]
64SAT-EXPAKSATNET and Backroom EXPAK[Steven_Blumenthal]
65KRYPTOLANKryptolan[Paul Liu]
66RVDMIT Remote Virtual Disk Protocol[Michael_Greenwald]
67IPPCInternet Pluribus Packet Core[Steven_Blumenthal]
68any distributed file system[Internet_Assigned_Numbers_Authority]
69SAT-MONSATNET Monitoring[Steven_Blumenthal]
70VISAVISA Protocol[Gene_Tsudik]
71IPCVInternet Packet Core Utility[Steven_Blumenthal]
72CPNXComputer Protocol Network Executive[David Mittnacht]
73CPHBComputer Protocol Heart Beat[David Mittnacht]
74WSNWang Span Network[Victor Dafoulas]
75PVPPacket Video Protocol[Steve_Casner]
76BR-SAT-MONBackroom SATNET Monitoring[Steven_Blumenthal]
77SUN-NDSUN ND PROTOCOL-Temporary[William_Melohn]
78WB-MONWIDEBAND Monitoring[Steven_Blumenthal]
80ISO-IPISO Internet Protocol[Marshall_T_Rose]
83VINESVINES[Brian Horn]
84TTPTransaction Transport Protocol[Jim_Stevens]
84IPTMInternet Protocol Traffic Manager[Jim_Stevens]
86DGPDissimilar Gateway Protocol[M/A-COM Government Systems, "Dissimilar Gateway Protocol Specification, Draft Version", Contract no. CS901145, November 16, 1987.][Mike_Little]
90Sprite-RPCSprite 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]
91LARPLocus Address Resolution Protocol[Brian Horn]
92MTPMulticast Transport Protocol[Susie_Armstrong]
93AX.25AX.25 Frames[Brian_Kantor]
94IPIPIP-within-IP Encapsulation Protocol[John_Ioannidis]
95MICP (deprecated)Mobile Internetworking Control Pro.[John_Ioannidis]
96SCC-SPSemaphore Communications Sec. Pro.[Howard_Hart]
97ETHERIPEthernet-within-IP Encapsulation[RFC3378]
98ENCAPEncapsulation Header[RFC1241][Robert_Woodburn]
99any private encryption scheme[Internet_Assigned_Numbers_Authority]
101IFMPIpsilon Flow Management Protocol[Bob_Hinden][November 1995, 1997.]
102PNNIPNNI over IP[Ross_Callon]
103PIMProtocol Independent Multicast[RFC7761][Dino_Farinacci]
107A/NActive Networks[Bob_Braden]
108IPCompIP Payload Compression Protocol[RFC2393]
109SNPSitara Networks Protocol[Manickam_R_Sridhar]
110Compaq-PeerCompaq Peer Protocol[Victor_Volpe]
111IPX-in-IPIPX in IP[CJ_Lee]
112VRRPVirtual Router Redundancy Protocol[RFC5798]
113PGMPGM Reliable Transport Protocol[Tony_Speakman]
114any 0-hop protocol[Internet_Assigned_Numbers_Authority]
115L2TPLayer Two Tunneling Protocol[RFC3931][Bernard_Aboba]
116DDXD-II Data Exchange (DDX)[John_Worley]
117IATPInteractive Agent Transfer Protocol[John_Murphy]
118STPSchedule Transfer Protocol[Jean_Michel_Pittet]
119SRPSpectraLink Radio Protocol[Mark_Hamilton]
121SMPSimple Message Protocol[Leif_Ekblad]
122SM (deprecated)Simple Multicast Protocol[Jon_Crowcroft][draft-perlman-simple-multicast]
123PTPPerformance Transparency Protocol[Michael_Welzl]
124ISIS over IPv4[Tony_Przygienda]
126CRTPCombat Radio Transport Protocol[Robert_Sautter]
127CRUDPCombat Radio User Datagram[Robert_Sautter]
130SPSSecure Packet Shield[Bill_McIntosh]
131PIPEPrivate IP Encapsulation within IP[Bernhard_Petri]
132SCTPStream Control Transmission Protocol[Randall_R_Stewart]
133FCFibre Channel[Murali_Rajagopal][RFC6172]
135Mobility HeaderY[RFC6275]
138manetMANET Protocols[RFC5498]
139HIPHost Identity ProtocolY[RFC7401]
140Shim6Shim6 ProtocolY[RFC5533]
141WESPWrapped Encapsulating Security Payload[RFC5840]
142ROHCRobust Header Compression[RFC5858]
253Use for experimentation and testingY[RFC3692]
254Use for experimentation and testingY[RFC3692]


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