I

The SCSI relationship between an initiator port and a target port. In iSCSI it is represented by a session, which may span several TCP connections.

Plain language SCSI relationship between initiator and target ports represented by sessions in iSCSI.

Used in RFC 3783 RFC 7144

The Service Instance Identifier, a 24-bit value that is global within a PBB network and identifies a service.

Plain language Service Instance Identifier, a 24-bit value globally identifying a service in a PBB network.

Used in RFC 7080 RFC 7623 RFC 9541

The Internet Architecture Board, which provides architectural oversight and is the final stop in the appeals ladder for process questions.

Plain language Internet Architecture Board providing architectural oversight and appeals process.

Used in RFC 1052 RFC 1109 RFC 1118 RFC 1120 RFC 1160 RFC 1174 RFC 1199 RFC 1251 RFC 1264 RFC 1311 RFC 1336 RFC 1358 RFC 1391 RFC 1396 RFC 1410 RFC 1462 RFC 1560 RFC 1594 RFC 1602 RFC 1603 RFC 1610 RFC 1640 RFC 1720 RFC 1780 and 83 more

The Telnet escape byte, value 255. It marks the next byte as a command rather than data; a real data byte of 255 is sent as IAC IAC.

Plain language Telnet escape byte (255) marking the next byte as a command rather than data.

Used in RFC 580 RFC 729 RFC 732 RFC 854 RFC 885 RFC 1041 RFC 1043 RFC 1073 RFC 1079 RFC 1205 RFC 1572 RFC 1576 RFC 2355

Identity Association Identifier. A value that identifies a particular address association (such as a network interface) on a client, used to manage multiple address leases.

Plain language Identity Association Identifier identifying a specific address association on a client.

Used in RFC 4361 RFC 7943

The Internet Assigned Numbers Authority, which maintains the registries of protocol parameters and address space. RFC 1918 records that IANA reserved the three private blocks.

Plain language Internet Assigned Numbers Authority maintaining registries of protocol parameters and addresses.

Used in RFC 758 RFC 770 RFC 790 RFC 870 RFC 990 RFC 1060 RFC 1065 RFC 1070 RFC 1118 RFC 1155 RFC 1174 RFC 1310 RFC 1340 RFC 1345 RFC 1466 RFC 1495 RFC 1505 RFC 1518 RFC 1590 RFC 1591 RFC 1594 RFC 1601 RFC 1602 RFC 1630 and 1123 more

An official list of protocol values, such as codes, flags and numbers, kept by IANA. Each registry has a policy that says how new values may be added.

Plain language Official list of protocol values maintained by IANA with policies for adding new entries.

Used in RFC 1060 RFC 3406 RFC 3553 RFC 3942 RFC 4288 RFC 5646 RFC 6255 RFC 6761 RFC 6954 RFC 7214 RFC 7803 RFC 8137 RFC 8553 RFC 9436 RFC 9553 RFC 9778 RFC 9904

Internal BGP is a session between routers in the same autonomous system, and External BGP is a session between routers in different autonomous systems. The two are treated differently, for instance in the decision process an EBGP-learned route is preferred over an IBGP-learned one.

Plain language Internal BGP for same-network routers and External BGP for different networks.

Used in RFC 1105 RFC 1164 RFC 1267 RFC 1268 RFC 1745 RFC 1771 RFC 1773 RFC 1998 RFC 2260 RFC 2439 RFC 2547 RFC 2772 RFC 2796 RFC 2858 RFC 3107 RFC 3219 RFC 3345 RFC 3446 RFC 3618 RFC 4098 RFC 4223 RFC 4271 RFC 4273 RFC 4364 and 54 more

The text format defined by RFC 5545 for exchanging events, to-dos, journal entries and free/busy time between calendar programs.

Plain language Text format from RFC 5545 for exchanging calendar events between applications.

Used in RFC 2445 RFC 2446 RFC 2447 RFC 2739 RFC 3880 RFC 4324 RFC 4480 RFC 4791 RFC 5239 RFC 5333 RFC 5545 RFC 5546 RFC 6047 RFC 6321 RFC 6501 RFC 6557 RFC 6638 RFC 6868 RFC 7095 RFC 7265 RFC 7529 RFC 7808 RFC 7809 RFC 7953 and 8 more

Internet Corporation for Assigned Names and Numbers, the organization responsible for managing the Internet's Domain Name System, IP address allocations, and protocol parameter assignments.

Plain language Internet Corporation for Assigned Names and Numbers managing DNS and IP allocation.

Used in RFC 2690 RFC 2691 RFC 7305

A protocol that helps two endpoints find a working network path between them despite NATs. It tries candidate addresses and picks one that works.

Plain language Interactive Connectivity Establishment protocol helping endpoints find working paths through NATs.

Used in RFC 5128 RFC 5766 RFC 5768 RFC 6314 RFC 6679 RFC 6940 RFC 7345 RFC 7478 RFC 7584 RFC 7675 RFC 8421 RFC 8445 RFC 8656 RFC 8825 RFC 8826 RFC 8827 RFC 8831 RFC 8835 RFC 8839 RFC 8841 RFC 8843 RFC 8863 RFC 9143 RFC 9429 and 1 more

A transport address that an ICE agent offers to its peer as a possible way to reach it. Candidates are paired and tested with connectivity checks.

Plain language A transport address offered by an ICE agent as a possible way to reach it.

Used in RFC 5245 RFC 5766 RFC 6544 RFC 8445 RFC 8838 RFC 8839 RFC 8840 RFC 9429

The Internet Control Message Protocol (RFC 792). Routers and hosts use it to send error and status messages about IP datagrams, such as "destination unreachable".

Plain language Routers and hosts send ICMP messages to report errors about data packets, such as when they cannot reach a destination.

Used in RFC 777 RFC 778 RFC 791 RFC 792 RFC 800 RFC 814 RFC 816 RFC 823 RFC 840 RFC 844 RFC 869 RFC 879 RFC 880 RFC 888 RFC 889 RFC 896 RFC 904 RFC 917 RFC 924 RFC 944 RFC 985 RFC 991 RFC 1009 RFC 1011 and 127 more

A block appended to certain ICMP error messages, made of one extension header followed by one or more objects. It carries additional information beyond the original ICMP content.

Plain language Block appended to ICMP error messages containing an extension header and objects.

Used in RFC 4884 RFC 5837 RFC 8335

The Internet Control Message Protocol for IPv6, defined in RFC 4443. It carries error reports and diagnostic messages such as Echo Request and Reply, and is identified by IPv6 Next Header value 58.

Plain language ICMPv6 carries error reports and diagnostic messages between IPv6 devices, identified by protocol value 58.

Used in RFC 1885 RFC 1970 RFC 1981 RFC 2461 RFC 2463 RFC 2466 RFC 2473 RFC 2521 RFC 2675 RFC 2710 RFC 2780 RFC 2893 RFC 2894 RFC 3122 RFC 3542 RFC 3756 RFC 3810 RFC 3971 RFC 4007 RFC 4193 RFC 4286 RFC 4293 RFC 4294 RFC 4389 and 77 more

A request method for which several identical requests have the same intended effect as one. PUT, DELETE and the safe methods are idempotent, which lets clients retry them after a connection failure.

Plain language A request method like PUT or DELETE where making the same request multiple times has the same effect as making it once.

Used in RFC 955 RFC 1045 RFC 1094 RFC 2068 RFC 2801 RFC 2832 RFC 4825 RFC 4918 RFC 5389 RFC 5661 RFC 5730 RFC 5734 RFC 5789 RFC 5995 RFC 6546 RFC 6886 RFC 7231 RFC 7237 RFC 7252 RFC 7959 RFC 8132 RFC 8489 RFC 8790 RFC 8881 and 3 more

In ILNP, a stable name or identity for a node, independent of its current network location. Identifiers persist across network movements.

Plain language In ILNP, a stable identity for a network node that remains the same even when the node's network location changes.

Used in RFC 2101 RFC 6677 RFC 6740 RFC 6743 RFC 6744 RFC 6745 RFC 6746 RFC 6748 RFC 6973 RFC 7819

A match between the domain in a message's From header and a domain that SPF or DKIM has authenticated. It can be relaxed (same organizational domain) or strict (exact match).

Plain language A match between the sender's domain and a domain that SPF or DKIM has authenticated, either exact or at the organizational level.

Used in RFC 7489 RFC 7960 RFC 9989

A group of related leases (addresses or prefixes) that a DHCP client and server manage together. Each one has a client-chosen identifier called an IAID and holds one type of lease.

Plain language A group of related DHCP leases (addresses or prefixes) that a client and server manage together with a unique identifier.

Used in RFC 3315 RFC 8415 RFC 9915

A system that manages identity information and tells other systems, such as relying parties, who a user is.

Plain language A system that verifies who a user is and tells other systems whether to trust that identity.

Used in RFC 6595 RFC 6973 RFC 7523 RFC 7831 RFC 7832 RFC 7833 RFC 8176 RFC 8473 RFC 8827

A public-key encryption system where the public key is derived directly from a user's identity string (e.g., email address) without requiring a separate certificate.

Plain language A public-key encryption system where the public key is derived directly from a user's identity, like an email address, without a certificate.

Used in RFC 5091 RFC 5408 RFC 5409 RFC 6267 RFC 6507 RFC 6508 RFC 6509 RFC 6539

A domain name that uses characters from scripts other than ASCII Latin, such as Cyrillic, Arabic, or Chinese, allowing domain names to be written in many languages.

Plain language A domain name using characters from non-English scripts such as Arabic, Chinese, or Cyrillic instead of only ASCII letters.

Used in RFC 3490 RFC 3491 RFC 4713 RFC 5890 RFC 5992

Internationalizing Domain Names in Applications. An architecture in which applications convert non-ASCII domain labels to ASCII compatible encoding (ACE) labels, so the DNS itself does not change.

Plain language A system that lets applications convert non-ASCII domain names to ASCII encoding so the DNS system itself doesn't need to change.

Used in RFC 3454 RFC 3490 RFC 3491 RFC 3492 RFC 3743 RFC 3982 RFC 3987 RFC 4185 RFC 4282 RFC 4290 RFC 4501 RFC 4524 RFC 4681 RFC 4690 RFC 4713 RFC 4952 RFC 5122 RFC 5144 RFC 5178 RFC 5301 RFC 5564 RFC 5729 RFC 5890 RFC 5891 and 44 more

IEEE Std 1394 is a standard for a High Performance Serial Bus. Devices on the bus have node identifiers and can exchange asynchronous and isochronous packets.

Plain language A standard for a high-speed serial bus that lets devices exchange data with each other directly.

Used in RFC 2734 RFC 3146

The standard for binary floating-point numbers used by most languages. A double can represent integers exactly only up to 2^53.

Plain language The standard for how computers represent decimal numbers; double-precision numbers can represent integers exactly only up to 2^53.

Used in RFC 1014 RFC 2212 RFC 3212 RFC 4506 RFC 5307 RFC 6340 RFC 7035 RFC 7139 RFC 7373 RFC 7493 RFC 7813 RFC 8259 RFC 8330 RFC 8428 RFC 8610 RFC 8625 RFC 8746 RFC 8785 RFC 8794 RFC 8949 RFC 9843 RFC 10005

The Internet Engineering Steering Group, which oversees IETF technical work and approves standards actions.

Plain language The Internet Engineering Steering Group, which oversees IETF technical work and approves standards.

Used in RFC 1160 RFC 1246 RFC 1251 RFC 1264 RFC 1280 RFC 1336 RFC 1391 RFC 1396 RFC 1435 RFC 1500 RFC 1560 RFC 1594 RFC 1600 RFC 1601 RFC 1602 RFC 1603 RFC 1640 RFC 1720 RFC 1752 RFC 1796 RFC 1800 RFC 1818 RFC 1871 RFC 1915 and 111 more

The open community of engineers that develops and standardizes Internet protocols, working mostly through mailing lists and meetings.

Plain language The open community of engineers who develop and standardize Internet protocols, working mostly through mailing lists and meetings.

Used in RFC 758 RFC 1052 RFC 1083 RFC 1109 RFC 1118 RFC 1120 RFC 1160 RFC 1174 RFC 1175 RFC 1200 RFC 1206 RFC 1211 RFC 1242 RFC 1251 RFC 1280 RFC 1310 RFC 1336 RFC 1358 RFC 1360 RFC 1369 RFC 1391 RFC 1392 RFC 1396 RFC 1410 and 242 more

The seven-member committee that provides oversight and control of the IASA on behalf of the IETF community.

Plain language IETF Administrative Oversight Committee providing oversight of IASA.

Used in RFC 4071 RFC 4089 RFC 7437 RFC 8715

The structure that handles the administrative, legal and financial support of the IETF. It was defined in 2005 and revised in 2018 as IASA 2.0.

Plain language IETF Administrative Support Activity handling administrative and financial support.

Used in RFC 4071 RFC 4089 RFC 8712 RFC 8718

An approval process for IANA registrations that requires publication in the standards track (typically as an RFC) and approval by the IESG after community review.

Plain language An approval process requiring publication in the standards track and IESG approval after community review.

Used in RFC 9756 RFC 9812

A trust formed to acquire, hold, maintain and license certain intellectual property and other property used in the administration of the IETF. The IETF as a whole is its Beneficiary.

Plain language An organization that manages the IETF's intellectual property and licenses it for use by the community.

Used in RFC 4371 RFC 5378 RFC 8179 RFC 8713 RFC 8714

The number that uniquely identifies one network interface, or one sub-layer of an interface, in a managed system. It must stay constant at least until the management system is next re-initialized.

Used in RFC 1229 RFC 1573 RFC 2494 RFC 2863 RFC 5837

The Internet Group Management Protocol, carried in IP protocol 2, by which hosts tell neighbouring multicast routers which groups they belong to. RFC 1112 defines version 1.

Plain language A protocol that lets computers tell nearby multicast routers which multicast groups they want to join.

Used in RFC 988 RFC 1011 RFC 1075 RFC 1112 RFC 1546 RFC 1584 RFC 1585 RFC 1667 RFC 2022 RFC 2113 RFC 2189 RFC 2201 RFC 2205 RFC 2236 RFC 2432 RFC 2490 RFC 2710 RFC 2887 RFC 2896 RFC 2933 RFC 3228 RFC 3376 RFC 3569 RFC 3678 and 64 more

The single multicast router on a subnet that sends the periodic General Queries. It is elected by IP address, with the lowest address winning.

Plain language The single multicast router on a subnet elected to periodically query which hosts want to receive multicast traffic.

Used in RFC 3918 RFC 4605 RFC 9776

A technique where a layer-2 switch listens to group membership messages to decide which ports should receive multicast traffic. MLD snooping is the IPv6 equivalent.

Plain language A switch listens to membership messages to know which ports should receive multicast traffic, avoiding unnecessary broadcasting.

Used in RFC 3488 RFC 4286 RFC 5790 RFC 9166

The 4-bit IPv4 field giving the header length in 32-bit words. The smallest valid value is 5, which is 20 octets.

Plain language The Internet Header Length field in IPv4 that specifies the header size in 32-bit words, with a minimum value of 5 (20 octets).

Used in RFC 791

The Internet Key Exchange. The protocol IPsec peers use to authenticate each other and to negotiate and refresh the keys and algorithms that protect their traffic. IKEv2 is the current version.

Plain language The Internet Key Exchange protocol that establishes the keys and algorithms IPsec peers use to protect their traffic.

Used in RFC 2401 RFC 2402 RFC 2409 RFC 2410 RFC 2412 RFC 2719 RFC 2764 RFC 3104 RFC 3173 RFC 3193 RFC 3329 RFC 3456 RFC 3457 RFC 3473 RFC 3526 RFC 3554 RFC 3579 RFC 3585 RFC 3586 RFC 3602 RFC 3664 RFC 3686 RFC 3715 RFC 3723 and 147 more

The Internet Key Exchange Protocol version 2, described in RFC 7296. It negotiates security associations and can carry host configuration information, so it is one of the ways a node might learn about a Provisioning Domain.

Plain language The protocol a VPN uses to set up its secure tunnel and exchange settings with the server.

Used in RFC 4543 RFC 4754 RFC 4868 RFC 5149 RFC 5193 RFC 5374 RFC 5380 RFC 5856 RFC 6023 RFC 6027 RFC 6071 RFC 6380 RFC 6954 RFC 7427 RFC 7556 RFC 7619 RFC 7815 RFC 8784 RFC 9370 RFC 9838

The Integrated Local Management Interface, an ATM Forum mechanism based on SNMP version 1 that lets ATM hosts, routers and switches exchange management information.

Plain language An ATM Forum mechanism based on SNMP that lets ATM devices exchange management information.

Used in RFC 2601 RFC 2602

The Identifier-Locator Network Protocol, an experimental enhancement to IP that separates a node's stable identifier from the locators used to reach it. A node may hold several locators at once, and the set changes when it moves or multihomes. RFC 6740 gives the architecture and RFC 6743 the message ILNPv6 nodes use to advertise those changes.

Plain language A way of giving a computer a permanent name while letting the addresses that reach it change, so a conversation survives a move.

Used in RFC 6743 RFC 6744

In TIFF format, a data structure containing metadata tags describing an image, including compression type, resolution, dimensions, and pointers to the actual image data.

Plain language In TIFF format, a metadata structure containing compression type, resolution, dimensions, and pointers to the image data.

Used in RFC 1314 RFC 2306 RFC 2879 RFC 3949

The Internet Message Access Protocol. A more capable mail-access protocol that keeps mail and folders on the server so several devices can share them.

Plain language An email protocol that keeps mail and folders on a server so you can access them from multiple devices.

Used in RFC 1056 RFC 1064 RFC 1176 RFC 1203 RFC 1731 RFC 1732 RFC 1733 RFC 1844 RFC 1939 RFC 2060 RFC 2061 RFC 2062 RFC 2086 RFC 2087 RFC 2088 RFC 2095 RFC 2177 RFC 2180 RFC 2192 RFC 2193 RFC 2195 RFC 2221 RFC 2222 RFC 2244 and 116 more

International Mobile station Equipment Identity, a 15-digit unique identifier for 3GPP (GSM/LTE) mobile devices, defined in RFC 7254.

Plain language A unique 15-digit identifier for GSM and LTE mobile devices.

Used in RFC 6155 RFC 7254 RFC 7255 RFC 8464

Interface Message Processor. The early ARPANET used dedicated computers called IMPs to route messages between hosts.

Plain language Dedicated computers that routed messages between hosts in the early ARPANET.

Used in RFC 1 RFC 41 RFC 101 RFC 107 RFC 331 RFC 381 RFC 432 RFC 440 RFC 547 RFC 548 RFC 622 RFC 642 RFC 647 RFC 660 RFC 878 RFC 928

Interface Message Processor; a specialized computer that served as the node of the ARPANET, connecting host computers to the network and handling message routing and delivery.

Plain language A specialized computer that served as a network node on ARPANET, handling message routing between hosts.

Used in RFC 271 RFC 878 RFC 3109

The default Sieve behavior of filing a message into the user's main mailbox when no action has cancelled it. Some actions cancel it.

Plain language In Sieve, the default action that files a message to your main mailbox if no filtering rule cancels it.

Used in RFC 3028 RFC 5228 RFC 5429 RFC 9122

Starting TLS negotiation immediately when a connection opens on a port dedicated to the secured protocol. No plaintext is exchanged first, unlike a STARTTLS upgrade.

Plain language Starting TLS encryption immediately when a connection opens on a dedicated port, with no plaintext exchange first.

Used in RFC 8143 RFC 8314

The process where a device obtains the cryptographic key material it needs to identify and trust future interactions with a network. An equivalent is learning the fingerprint of the network's root certification authority certificate.

Used in RFC 7397 RFC 8366

A 3GPP architecture for delivering voice, video and messaging services over IP networks, built on top of SIP.

Plain language A 3GPP architecture for delivering voice, video, and messaging services over IP networks using SIP.

Used in RFC 3455 RFC 4457 RFC 7315 RFC 7651 RFC 7875 RFC 9878

IOAM records operations and telemetry data inside the packet itself as it crosses a particular network domain. Nodes along the path add or read this data.

Plain language A technique where each node along a path writes telemetry data into the packet itself.

Used in RFC 9197 RFC 9232 RFC 9322 RFC 9326 RFC 9359 RFC 9452 RFC 9617 RFC 9630

A storage service placed inside a network (rather than at endpoints or external cloud) to reduce traffic on congested links and improve performance for applications sharing that network. DECADE is an architecture for in-network storage.

Plain language Storage placed inside a network rather than only at endpoints, reducing traffic and improving performance.

Used in RFC 6392 RFC 7069

A traffic pattern in which many ingress ports send to one or a few egress ports at the same time. It uses up buffer memory on the device.

Used in RFC 8238 RFC 8239 RFC 8257

An RFC proposed directly to the RFC Editor rather than produced through the IETF standards process. It is reviewed under the RFC Editor's own process.

Plain language An RFC proposed directly to the RFC Editor instead of through the IETF standards process.

Used in RFC 4844 RFC 4846 RFC 5742 RFC 7841 RFC 8730

A network of interconnected index servers that cooperate to guide search queries toward relevant data sources.

Plain language A network of interconnected index servers that cooperate to guide search queries to relevant data sources.

Used in RFC 1913 RFC 2651 RFC 2655 RFC 2657

An observable sign, such as a file hash, a domain name or an address, that helps detect or confirm malicious activity on a system or network.

Plain language An observable sign such as a file hash or domain name that helps detect malicious activity.

Used in RFC 7970 RFC 9424

A named, numbered field in IPFIX that describes one kind of data, such as an address or a delay, together with its data type.

Plain language A named field in IPFIX that describes one kind of data, such as an address or delay, with its data type.

Used in RFC 1755 RFC 2331 RFC 3955 RFC 5102 RFC 5471 RFC 5472 RFC 5476 RFC 5477 RFC 6313 RFC 7011 RFC 7012 RFC 7013 RFC 7270 RFC 8038 RFC 8137 RFC 9487 RFC 9740 RFC 9870 RFC 9951

A conceptual model of managed objects and their relationships that hides protocol and implementation details.

Plain language A conceptual model of managed objects and their relationships, hiding protocol and implementation details.

Used in RFC 1274 RFC 3060 RFC 3444 RFC 3460 RFC 3585 RFC 3644 RFC 3670 RFC 5070 RFC 5706 RFC 8193 RFC 8477 RFC 9016

The ALTO resource, called the IRD, that lists the other resources a server offers, with their media types and capabilities. Clients read it to find out what they can ask for.

Plain language The ALTO resource listing the other resources a server offers, with their media types and capabilities.

Used in RFC 7285 RFC 8895 RFC 9240

A networking approach where data is requested by name rather than by the address of the host that holds it. CCNx is one such protocol.

Plain language A networking approach where data is requested by name rather than by the host address that holds it.

Used in RFC 7476 RFC 7927 RFC 7933 RFC 7945 RFC 8569 RFC 8763 RFC 8884 RFC 9064 RFC 9138 RFC 9139 RFC 9531

An RFC that provides useful information, guidance, or documentation without specifying or advancing standards. Informational RFCs do not go through the standards track process.

Plain language An RFC providing useful information or guidance without advancing standards through the standards track.

Used in RFC 1550 RFC 2199 RFC 2223 RFC 2599 RFC 3099 RFC 4844 RFC 7841

Checking at the network edge that outgoing packets have source addresses belonging to the local network.

Plain language Checking at the network edge that outgoing packets have source addresses belonging to the local network.

Used in RFC 2267 RFC 2344 RFC 2827 RFC 2893 RFC 3013 RFC 3024 RFC 3704 RFC 3964 RFC 4213 RFC 4832 RFC 4948 RFC 5177 RFC 5210 RFC 5220 RFC 5358 RFC 5881 RFC 6620 RFC 6959 RFC 7039 RFC 7157 RFC 8043

Sending a separate copy of a packet to each downstream neighbor instead of one shared copy. RFC 6389 avoids it on a LAN for LDP P2MP LSPs.

Plain language Sending a separate copy of a packet to each downstream neighbor instead of one shared copy.

Used in RFC 6389 RFC 6513 RFC 7117 RFC 7524 RFC 7740 RFC 7988 RFC 9574 RFC 9685 RFC 10018

A LISP router that takes a packet from inside a site and prepends an outer header using its own locator as the source. In LISP multicast it is the root of the core distribution tree.

Used in RFC 6830 RFC 6831 RFC 6835 RFC 9299

A group of PCN flows that share the same ingress node and the same egress node. PCN meters the traffic, reports it and makes its admission and termination decisions separately for each such group.

Plain language All the flows that travel from one entry point to one exit point of the PCN domain. The decisions are made for the group, not for each flow on its own.

Used in RFC 6661 RFC 6662

The number of data segments a TCP sender may send into a new connection before it receives any acknowledgement. Classic practice used one segment.

Plain language The number of data segments a TCP sender may transmit into a new connection before receiving an acknowledgement.

Used in RFC 2415 RFC 2416 RFC 3390 RFC 6928 RFC 9040

A starting value fed into a block cipher mode along with the key. It must be unique for each message encrypted under the same key.

Plain language A unique starting value fed into a cipher with the key, ensuring the same key never produces identical output twice.

Used in RFC 1829 RFC 1851 RFC 2040 RFC 2405 RFC 2410 RFC 2420 RFC 2451 RFC 2773 RFC 3217 RFC 3370 RFC 3394 RFC 3414 RFC 3537 RFC 3602 RFC 3657 RFC 3686 RFC 3826 RFC 4010 RFC 4106 RFC 4196 RFC 4312 RFC 4503 RFC 5084 RFC 5282 and 8 more

A URN that uniquely identifies a single User Agent (phone) instance, used in SIP to distinguish between multiple registrations or devices of the same user.

Plain language A URN that uniquely identifies a single phone or user device instance in SIP.

Used in RFC 5838 RFC 7255 RFC 7770 RFC 8465 RFC 9300

An internet service model that adds reserved-resource services, such as Guaranteed Service and Controlled-Load Service, on top of ordinary best effort delivery.

Plain language An internet service model adding reserved-resource services such as guaranteed delivery on top of best-effort delivery.

Used in RFC 2188 RFC 2208 RFC 2215 RFC 2381 RFC 2382 RFC 2386 RFC 2688 RFC 2689 RFC 2816 RFC 2990

The value carried with a packet that lets the receiver check it was not altered. With AES-GCM it is the authentication tag.

Plain language A value carried with a packet that lets the receiver verify the packet was not altered.

Used in RFC 2402 RFC 2406 RFC 2750 RFC 2773 RFC 3394 RFC 4106 RFC 4230 RFC 4302 RFC 4309 RFC 4543 RFC 5856 RFC 5858 RFC 7182 RFC 7183

Legal rights that protect original creative works, including documents, software, and inventions. In the context of the IETF, these rights determine what others may do with IETF standards.

Plain language Legal rights protecting original creative works, determining what others may do with IETF standards.

Used in RFC 3978 RFC 3979 RFC 5377 RFC 6701 RFC 8179

The part of a telephone network that is under software control. A switching point detects a condition such as a busy line and asks a separate control point, which holds the service logic, what to do with the call.

Plain language The software-controlled part of the telephone network. The switch notices a problem with a call and asks a separate computer what to do about it.

Used in RFC 2995 RFC 3136

An abstract, high-level policy that defines network behavior at the domain level, such as 'optimize for energy efficiency' or 'prioritize security', without specifying implementation details.

Used in RFC 7575 RFC 9315

An automated phone service that plays recorded prompts and collects a caller's key presses or speech. It is often shortened to IVR.

Plain language An automated phone service that plays recorded messages and collects key presses or speech input.

Used in RFC 4722 RFC 5022 RFC 6231 RFC 6562 RFC 7478

A proxy that transparently redirects client traffic without the client's knowledge or configuration, also known as a transparent proxy.

Plain language A proxy that transparently redirects client traffic without the client's knowledge or configuration.

Used in RFC 3040 RFC 3143

A longer-lived cryptographic key shared between a sender and recipient, used to encrypt the DEK for transmission with a message.

Plain language A longer-lived cryptographic key shared between sender and recipient, used to encrypt the message key.

Used in RFC 989 RFC 1040 RFC 1113 RFC 1421

In content-centric networking, a request message that names the Content Object it wants. Any Content Object whose name and attributes match is said to satisfy it.

Plain language In content-centric networking, a request message that names the content object it wants.

Used in RFC 7945 RFC 8609 RFC 8793 RFC 9064 RFC 9531

The low-order bits of an IPv6 unicast address that identify an interface on a link. For most unicast addresses it is 64 bits long and in Modified EUI-64 format.

Plain language The low-order bits of an IPv6 unicast address identifying an interface on a link, typically 64 bits in EUI-64 format.

Used in RFC 2373 RFC 2374 RFC 2462 RFC 2464 RFC 2467 RFC 2470 RFC 2472 RFC 2491 RFC 2492 RFC 2497 RFC 2526 RFC 2529 RFC 2590 RFC 3041 RFC 3146 RFC 3162 RFC 3513 RFC 3572 RFC 3587 RFC 3592 RFC 3972 RFC 4201 RFC 4291 RFC 4338 and 51 more

The number that the operating system uses to identify a network interface. A human-readable zone identifier, such as an interface name, is mapped to this number by the host, usually through the socket API.

Plain language The number the operating system gives to a network interface, which is what it actually uses behind the name you type.

Used in RFC 1573 RFC 9844

A proposed interface that lets network applications read and change routing system state through an I2RS client talking to an I2RS agent on the router.

Plain language Interface to the Routing System, allowing network applications to read and modify routing state.

Used in RFC 7920 RFC 7922 RFC 8242

A 32-bit unique value negotiated between the two ends of an IPv6 PPP link. It is used as the lower portion of the link-local address, ensuring each end gets a distinct address.

Plain language A 32-bit unique value negotiated between the two ends of an IPv6 PPP link for the link-local address.

Used in RFC 1971 RFC 2023

A routing protocol used inside a single network or routing domain. IS-IS and OSPF are link-state examples.

Plain language A routing protocol used within a single network domain, such as OSPF or IS-IS.

Used in RFC 1126 RFC 1723 RFC 3210 RFC 5302 RFC 5443 RFC 5671 RFC 5919 RFC 7297 RFC 7431 RFC 7897 RFC 8279 RFC 8405 RFC 8541 RFC 9552 RFC 9843 RFC 9917

A routing protocol used inside a single autonomous system, as opposed to an exterior protocol between them. RIP, OSPF and IS-IS are IGPs.

Plain language A routing protocol used within a single autonomous system, such as RIP, OSPF, or IS-IS.

Used in RFC 827 RFC 898 RFC 904 RFC 911 RFC 975 RFC 985 RFC 995 RFC 1009 RFC 1058 RFC 1069 RFC 1074 RFC 1075 RFC 1126 RFC 1133 RFC 1136 RFC 1142 RFC 1222 RFC 1245 RFC 1246 RFC 1247 RFC 1267 RFC 1268 RFC 1287 RFC 1364 and 101 more

A technique that rearranges data to trade latency for error correction. By spreading data over time, bursty noise on the line becomes tolerable, but the cost is added delay.

Plain language A technique that rearranges data to trade added delay for better error correction during transmission.

Used in RFC 2354 RFC 2658 RFC 3558 RFC 3640 RFC 4348 RFC 4679 RFC 5404 RFC 7826

In the IETF context, adding or improving the handling of non-ASCII text in a protocol so that it can work with any human language and script.

Plain language Adding support for non-ASCII text in a protocol so it can work with any human language and script.

Used in RFC 1345 RFC 3536 RFC 3997 RFC 4646 RFC 5646 RFC 6365 RFC 7622 RFC 8264 RFC 8398

A global network of interconnected computer networks that communicate using the TCP/IP protocol suite, enabling exchange of data, services, and applications worldwide.

Plain language A global network of interconnected computer networks that communicate using TCP/IP.

Used in RFC 1392 RFC 1432 RFC 1462 RFC 1941 RFC 2150 RFC 2664 RFC 3935

The 16-bit one's complement sum used in IP, TCP, UDP and ICMP headers to detect corruption. Because it is a simple sum, a NAT can update it incrementally when it changes a field.

Plain language A 16-bit checksum in IP, TCP, UDP, and ICMP headers that detects corruption during transmission.

Used in RFC 528 RFC 700 RFC 768 RFC 792 RFC 793 RFC 809 RFC 815 RFC 817 RFC 869 RFC 888 RFC 905 RFC 916 RFC 935 RFC 994 RFC 998 RFC 1010 RFC 1045 RFC 1071 RFC 1141 RFC 1144 RFC 1145 RFC 1146 RFC 1151 RFC 1186 and 99 more

A shared switched network, often a Layer 2 fabric, where many networks connect to exchange traffic with each other. It is commonly shortened to IXP.

Plain language A shared network, often a Layer 2 fabric, where many networks connect to exchange traffic.

Used in RFC 5632 RFC 7454 RFC 7947 RFC 7948 RFC 8327

An IP address block or Autonomous System number. Internet Number Resources are what the RPKI certifies authority over.

Plain language An IP address block or Autonomous System number certified by the RPKI.

Used in RFC 6484 RFC 8897 RFC 9255

An application-level protocol for distributed printing using Internet tools and technologies, carried over HTTP/1.1 in IPP/1.0.

Plain language An application protocol for distributed printing over the Internet using HTTP/1.1.

Used in RFC 2569 RFC 2911 RFC 3196 RFC 3380

An application-level protocol for distributed printing over the Internet. Clients send operations such as creating a job or querying a Printer object to a server.

Plain language An application protocol that lets computers ask printers to print and check printing status.

Used in RFC 3381 RFC 3995 RFC 3997 RFC 3998 RFC 8011

The group that works like an editorial review board for the IRTF. It reviews and approves every IRTF-stream document before it goes to the RFC Editor.

Used in RFC 1336 RFC 5743

A shared database in which network operators register routing information, such as the routes they originate and their routing policies, as objects.

Plain language A shared database where network operators register routing information and policies.

Used in RFC 1879 RFC 2622 RFC 4948 RFC 7454 RFC 7682

An organization that provides Internet connectivity and services to customers, such as dial-up access, email hosting, or web server hosting.

Plain language An organization providing Internet connectivity and services such as email hosting or web hosting.

Used in RFC 1690 RFC 1775 RFC 1941 RFC 5632

The Internet Society is the organization that provides organizational and financial support for the IETF. Its by-laws give the IETF the right to name three Trustees to its Board.

Plain language The Internet Society, which provides organizational and financial support for the IETF.

Used in RFC 1396 RFC 1602 RFC 3233 RFC 3677 RFC 3716 RFC 8712 RFC 8714

A protocol that has completed the full Internet Standards Process and been approved by the IESG and IAB for widespread deployment. Assigned an STD number.

Plain language A protocol approved by the IESG and IAB after completing the full Internet Standards Process.

Used in RFC 1602 RFC 2500 RFC 2600 RFC 2700 RFC 2800 RFC 2900 RFC 6410 RFC 8700

The formal procedure, defined in RFC 2026, by which Internet protocols and specifications are proposed, reviewed, tested, and approved for standardization.

Plain language The formal procedure defined in RFC 2026 for proposing, reviewing, testing, and approving Internet protocols.

Used in RFC 1174 RFC 3000 RFC 3300 RFC 3427 RFC 3683 RFC 3978 RFC 3979

A working document circulated for review. It has no formal status and may be changed or removed at any time.

Plain language A working document circulated for review with no formal status and no guarantee of permanence.

Used in RFC 967 RFC 1111 RFC 1120 RFC 1160 RFC 1206 RFC 1310 RFC 1391 RFC 1396 RFC 1539 RFC 1543 RFC 1550 RFC 1594 RFC 1602 RFC 1603 RFC 1645 RFC 1718 RFC 1899 RFC 2014 RFC 2026 RFC 2223 RFC 2418 RFC 2500 RFC 2700 RFC 2800 and 62 more

The ability of independently written implementations to work together. RFC 2119 says its key words should be used only where actually required for interoperation or to limit harmful behavior.

Plain language The ability of independently written implementations to work together correctly.

Used in RFC 942 RFC 1270 RFC 1560 RFC 1727 RFC 1911 RFC 2061 RFC 2119 RFC 2360 RFC 2438 RFC 2446 RFC 2825 RFC 3283 RFC 3584 RFC 3773 RFC 3859 RFC 3935 RFC 4231 RFC 4485 RFC 4646 RFC 4775 RFC 5463 RFC 5657 RFC 5774 RFC 5897 and 28 more

A component that translates messages and behavior between two different protocols so that systems using each can work together.

Plain language A component that translates between two different protocols so systems using each can work together.

Used in RFC 2955 RFC 4123 RFC 4553 RFC 5086 RFC 5087 RFC 6970

Compression within a single frame without referencing other frames in a video sequence.

Plain language Video compression within a single frame without comparing it to other frames.

Used in RFC 5168 RFC 8593 RFC 9043 RFC 9626

The process of monitoring networks or hosts for signs of unauthorized access or malicious activities, and reporting detected incidents.

Plain language Monitoring networks or hosts for signs of unauthorized access or malicious activities.

Used in RFC 4732 RFC 4767 RFC 8329

A tool that watches network traffic, system logs or application records for suspicious activity and reports what it finds as alerts.

Plain language A tool that watches for suspicious network activity and reports alerts when detected.

Used in RFC 4765 RFC 4766 RFC 9411

A variant of ARP in which a node that already knows the other party's hardware address asks for its protocol (IP) address instead of the other way round.

Plain language A variant of ARP where a node that knows the other party's hardware address asks for its IP address.

Used in RFC 1294 RFC 1586 RFC 1755 RFC 2225 RFC 2390 RFC 2834

The packet that caused an ICMPv6 error. The error message quotes as much of it as will fit without exceeding the minimum IPv6 MTU, so the sender can tell which program and connection it belongs to.

Plain language The original packet that caused an ICMPv6 error; the error message includes enough of it for the sender to identify the problem.

Used in RFC 1885 RFC 4443 RFC 8883

Incident Object Description Exchange Format; an XML-based standard (RFC 5070) for exchanging structured incident management data, including observations, impact assessments, and expected responses.

Plain language An XML format for exchanging structured incident management data between organizations.

Used in RFC 5070 RFC 5901 RFC 6545 RFC 6546 RFC 6684 RFC 8134 RFC 8727

The protocol that addresses and forwards datagrams between networks. RFC 791 defines version 4.

Plain language The protocol that addresses and forwards packets between networks.

Used in RFC 791 RFC 792 RFC 800 RFC 801 RFC 815 RFC 817 RFC 840 RFC 872 RFC 873 RFC 875 RFC 879 RFC 880 RFC 887 RFC 893 RFC 899 RFC 908 RFC 914 RFC 939 RFC 942 RFC 945 RFC 961 RFC 963 RFC 968 RFC 986 and 86 more

A number that identifies a network interface on an IP network. IPv4 addresses are 32 bits, written as four decimal bytes such as 192.0.2.1. IPv6 addresses are 128 bits.

Plain language A number identifying a network interface; IPv4 addresses are 32 bits, IPv6 addresses are 128 bits.

Used in RFC 208 RFC 608 RFC 791 RFC 793 RFC 796 RFC 814 RFC 819 RFC 826 RFC 844 RFC 887 RFC 895 RFC 903 RFC 917 RFC 919 RFC 922 RFC 923 RFC 925 RFC 940 RFC 943 RFC 946 RFC 950 RFC 951 RFC 952 RFC 953 and 194 more

The unit of data that the Internet Protocol sends: a header with source and destination addresses followed by a payload. Each datagram is handled independently of the others.

Plain language The unit of data the Internet Protocol sends, consisting of a header with addresses and a payload.

Used in RFC 781 RFC 782 RFC 815 RFC 823 RFC 877 RFC 879 RFC 894 RFC 895 RFC 914 RFC 998 RFC 1042 RFC 1044 RFC 1055 RFC 1071 RFC 1149 RFC 1188 RFC 1209 RFC 1356 RFC 1490 RFC 1701 RFC 1819 RFC 1858 RFC 2003 RFC 2004 and 18 more

A family of techniques in which a router prepares backup paths in advance and switches to them quickly after a link or node failure, before routing has fully reconverged.

Plain language A technique where routers prepare backup paths in advance and switch quickly after a link fails.

Used in RFC 6571 RFC 7490 RFC 7916 RFC 8518 RFC 9403

A set of IP packets that pass an observation point in the network during a certain time interval and share a set of common properties. Flow records summarize each such set.

Plain language A set of IP packets sharing common properties that pass through an observation point during a time interval.

Used in RFC 3917 RFC 5101 RFC 5470 RFC 5472

Splitting one IP datagram into several smaller pieces so it can cross a link with a small MTU. The receiving host has to put the pieces back together, and losing any one piece loses the whole datagram.

Plain language Splitting an IP datagram into smaller pieces to cross links with small MTUs.

Used in RFC 675 RFC 760 RFC 791 RFC 815 RFC 879 RFC 894 RFC 955 RFC 963 RFC 994 RFC 998 RFC 1001 RFC 1002 RFC 1063 RFC 1070 RFC 1108 RFC 1188 RFC 1191 RFC 1201 RFC 1241 RFC 1242 RFC 1294 RFC 1326 RFC 1332 RFC 1390 and 207 more

An optional extra field in the IPv4 header, such as Record Route or Router Alert. Options make the header longer than 20 octets and are often handled by a slower path in routers.

Plain language An optional field in the IPv4 header, such as Record Route, that often takes a slower processing path.

Used in RFC 815 RFC 1826 RFC 2113 RFC 2385 RFC 4283 RFC 6178 RFC 6274 RFC 6967 RFC 7126 RFC 9326

The three-bit priority field in bits 0-2 of the IPv4 TOS octet defined in RFC 791. The DS field's Class Selector codepoints keep partial compatibility with it.

Plain language The three-bit priority field in the IPv4 TOS octet, predating the DS field.

Used in RFC 794 RFC 2474 RFC 2859 RFC 4222 RFC 8436

Sending packets with a forged source address, so that they appear to come from somewhere else, often to hide an attacker or to aim replies at a victim.

Plain language Sending packets with a forged source address to hide an attacker or redirect replies to a victim.

Used in RFC 2267 RFC 2827 RFC 4832 RFC 4948 RFC 6959

A path where an original IP packet is wrapped inside a new outer IP header. In a simple tunnel the outer header is discarded at the tunnel exit.

Plain language A path where an original IP packet is wrapped inside a new outer IP header for part of its journey.

Used in RFC 2667 RFC 2746 RFC 2983 RFC 3168 RFC 4087 RFC 5177 RFC 5569 RFC 6333 RFC 9599 RFC 9601

Wrapping an IP packet inside another IP packet so the outer header can carry extra routing information; the far end removes the outer header.

Plain language Wrapping an IP packet inside another IP packet so the outer header can carry extra routing information.

Used in RFC 1853 RFC 2004 RFC 2189 RFC 2201 RFC 2746 RFC 3024 RFC 3843 RFC 4459 RFC 5558 RFC 5565 RFC 5720 RFC 6438 RFC 8138 RFC 9008 RFC 9914

A Virtual Routing and Forwarding table for IP routes on a PE. It is the PE's instantiation of a Layer 3 VPN for one tenant.

Plain language A Virtual Routing and Forwarding table on a PE that instantiates a Layer 3 VPN for one customer.

Used in RFC 9135 RFC 9136 RFC 9572

Inter-Packet Delay Variation: the difference between the delay of one packet and the delay of the packet before it. RFC 3432 computes it as IPDV[i] = Delay[i] - Delay[i-1], and it may be negative, zero or positive.

Plain language How much the delay jumped between one packet and the next.

Used in RFC 3393 RFC 3432

IP Flow Information Export, a protocol for sending records about IP traffic flows from an Exporting Process to a Collecting Process.

Plain language IP Flow Information Export, a protocol for sending records about IP traffic flows.

Used in RFC 3955 RFC 4948 RFC 5101 RFC 5102 RFC 5153 RFC 5471 RFC 5472 RFC 5473 RFC 5475 RFC 5476 RFC 5477 RFC 5655 RFC 6183 RFC 6235 RFC 6313 RFC 6526 RFC 6615 RFC 6632 RFC 6727 RFC 6728 RFC 7011 RFC 7012 RFC 7013 RFC 7014 and 10 more

A named, typed field that IPFIX can put in a flow record, such as a source address or a packet count. The set of elements is kept in an IANA registry.

Plain language A named, typed field that IPFIX puts in flow records, such as source address or packet count.

Used in RFC 5101 RFC 5473 RFC 5477 RFC 5610 RFC 6235 RFC 6615 RFC 7013 RFC 8549

An IPFIX Device that receives a record stream, transforms it with one or more Intermediate Processes, and exports the result as IPFIX Messages.

Plain language An IPFIX device that receives flow records, transforms them, and exports the result.

Used in RFC 5473 RFC 5982 RFC 6183 RFC 6615 RFC 7013 RFC 7119

A message that defines the structure and order of information elements in subsequent data records, allowing the exporter and collector to agree on what data will be exchanged.

Plain language A message defining the structure and order of information elements in subsequent data records.

Used in RFC 1835 RFC 3955 RFC 5471 RFC 7013

IP the Next Generation; the protocol that would eventually become IPv6, designed to replace IPv4's addressing and routing limitations.

Plain language IP the Next Generation; the eventual name for IPv6, designed to fix IPv4's limitations.

Used in RFC 1550 RFC 1560 RFC 1677 RFC 1726

The IP Performance Metrics framework and the IETF working group that maintains it. It defines the measurements used to describe how an IP network performs, such as one-way delay and packet loss.

Plain language The IETF's family of definitions for measuring how an IP network performs.

Used in RFC 2678 RFC 2679 RFC 2680 RFC 2681 RFC 3357 RFC 3432 RFC 3763 RFC 5560 RFC 6808 RFC 7312 RFC 7497 RFC 8924

A public filing that records intellectual property rights a participant reasonably and personally knows may cover a Contribution to the IETF. It must name the patents or applications, the inventors, the document or activity affected and the Internet-Draft version, and it is filed at the IETF rather than inside the document itself.

Plain language The official public note saying which of your patents might apply to a piece of work the IETF is doing.

Used in RFC 2350 RFC 6701 RFC 8179

A set of protocols that protect IP packets with encryption and integrity checks, using ESP or AH. IKE sets up the keys it uses.

Plain language A set of protocols that protect IP packets with encryption and integrity checks.

Used in RFC 1825 RFC 1826 RFC 1827 RFC 1828 RFC 1829 RFC 1851 RFC 1852 RFC 2085 RFC 2205 RFC 2207 RFC 2222 RFC 2230 RFC 2316 RFC 2331 RFC 2356 RFC 2367 RFC 2393 RFC 2394 RFC 2395 RFC 2401 RFC 2402 RFC 2403 RFC 2404 RFC 2405 and 480 more

Version 4 of the Internet Protocol (RFC 791), with 32-bit addresses. Still widely used alongside IPv6.

Plain language Version 4 of the Internet Protocol with 32-bit addresses.

Used in RFC 790 RFC 810 RFC 943 RFC 1010 RFC 1020 RFC 1062 RFC 1219 RFC 1236 RFC 1365 RFC 1367 RFC 1380 RFC 1481 RFC 1518 RFC 1533 RFC 1547 RFC 1560 RFC 1597 RFC 1606 RFC 1607 RFC 1621 RFC 1622 RFC 1627 RFC 1668 RFC 1669 and 385 more

A family of transition technologies that let an ISP with an IPv6-only access or core network still give its customers IPv4 connectivity.

Plain language A transition technology letting ISPs with IPv6-only networks still provide IPv4 connectivity.

Used in RFC 9313 RFC 9386

An IPv6 address with an all-zeros 96-bit prefix and an IPv4 address in the low-order 32 bits, used for automatic tunneling.

Plain language An IPv6 address with an all-zeros 96-bit prefix and an IPv4 address inside.

Used in RFC 2185 RFC 2373 RFC 2893

An IPv6 address that carries a 32-bit IPv4 address inside it, so the original IPv4 address can be recovered without keeping any state.

Plain language An IPv6 address carrying a 32-bit IPv4 address so the original address can be recovered.

Used in RFC 4798 RFC 6052 RFC 6992 RFC 8114

An IPv6 address that carries an IPv4 address in its low-order 32 bits. It can be written in mixed notation, such as ::ffff:192.0.2.1.

Plain language An IPv6 address carrying an IPv4 address in its last 32 bits.

Used in RFC 2373 RFC 2553 RFC 4038 RFC 5952 RFC 6724

Internet Protocol version 6, the successor to IPv4. It uses 128-bit addresses and has no broadcast, relying on multicast instead.

Plain language Internet Protocol version 6, with 128-bit addresses and no broadcast.

Used in RFC 1545 RFC 1560 RFC 1668 RFC 1669 RFC 1670 RFC 1671 RFC 1672 RFC 1673 RFC 1674 RFC 1675 RFC 1676 RFC 1678 RFC 1679 RFC 1680 RFC 1682 RFC 1687 RFC 1688 RFC 1710 RFC 1719 RFC 1726 RFC 1752 RFC 1776 RFC 1809 RFC 1810 and 877 more

The process and mechanisms by which the Internet gradually shifts from IPv4 to IPv6, including various compatibility and translation techniques.

Plain language The process and mechanisms by which the Internet gradually shifts from IPv4 to IPv6.

Used in RFC 3142 RFC 3338 RFC 3750 RFC 4029 RFC 4038 RFC 4057 RFC 4852 RFC 5569 RFC 6908 RFC 7596 RFC 7597 RFC 7599 RFC 8219

Encapsulation of IPv6 packets inside IPv4 packets so IPv6 traffic can traverse IPv4-only networks until native IPv6 connectivity is available.

Plain language Wrapping IPv6 packets inside IPv4 packets so IPv6 traffic can cross IPv4-only networks.

Used in RFC 3053 RFC 3068 RFC 3750 RFC 3904 RFC 4779 RFC 4852

Internet Packet eXchange, the network protocol used by Novell NetWare for local and wide-area networking before the industry standardized on TCP/IP.

Used in RFC 1234 RFC 1552 RFC 1553 RFC 1634

A Layer 3 interface on a PE that connects a bridge table (one subnet) to an IP-VRF. It acts as the default gateway for the hosts on that subnet.

Plain language A Layer 3 interface on a PE that connects a subnet to an IP-VRF.

Used in RFC 9135 RFC 9625

An Internationalized Resource Identifier, a form of URI that can contain characters from a wider range of writing systems. Every URI is also an IRI.

Plain language An Internationalized Resource Identifier, a form of URI that can contain characters from many writing systems.

Used in RFC 3987 RFC 4287 RFC 5122 RFC 5988

The Internet Registry Information Service, a protocol for querying registries. Each kind of registry plugs in its own XML schema defining the queries and results it supports.

Plain language The Internet Registry Information Service, a protocol for querying registries.

Used in RFC 3982 RFC 3983 RFC 4414 RFC 4698

The Internet Research Task Force, a community of researchers organized by the Internet Architecture Board to investigate long-term issues relevant to the Internet.

Plain language The Internet Research Task Force, a community of researchers investigating long-term Internet issues.

Used in RFC 1160 RFC 1336 RFC 2028 RFC 4440 RFC 5742 RFC 5743 RFC 7305 RFC 7841 RFC 8700 RFC 8729

Intermediate System to Intermediate System, a routing protocol for exchanging routing information within a network domain.

Plain language Intermediate System to Intermediate System, a routing protocol for exchanging routing information within a domain.

Used in RFC 1574 RFC 2966 RFC 3277 RFC 3359 RFC 3563 RFC 3784 RFC 3787 RFC 3906 RFC 5089 RFC 5302 RFC 5303 RFC 5307 RFC 5310 RFC 5817 RFC 6119 RFC 6165 RFC 6213 RFC 6862 RFC 7356 RFC 7399 RFC 7576 RFC 7579 RFC 7645 RFC 7810 and 19 more

A SCSI transport protocol that maps the SCSI family of protocols onto TCP/IP, so storage commands can travel over an IP network.

Plain language A protocol that maps SCSI commands onto TCP/IP for sending storage commands over a network.

Used in RFC 3347 RFC 3723 RFC 3980 RFC 4018 RFC 4171 RFC 4173 RFC 4174 RFC 5046 RFC 5047 RFC 7144 RFC 7145

Integrated Services Digital Network, a digital telephone service that offers switched circuits called B-channels for data and a separate D-channel for signaling and limited data.

Used in RFC 1356 RFC 1618 RFC 4233 RFC 6567

A signed zone for which no authentication chain can be built from its parent, so a validator needs some other way to get its key.

Plain language A signed DNS zone with no authentication chain from its parent, so validators need another way to verify it.

Used in RFC 1687 RFC 3090 RFC 4035

The Internet Storage Name Service, a protocol that lets IP-based storage devices register themselves and discover other storage devices on the network.

Plain language The Internet Storage Name Service, a protocol letting storage devices register and discover each other.

Used in RFC 4171 RFC 4172 RFC 4174 RFC 4939

The international standard for writing dates and times. It allows many forms, so Internet protocols usually pick a narrow profile of it, as RFC 3339 does.

Plain language The international standard for writing dates and times, with many forms.

Used in RFC 2445 RFC 3339 RFC 3862 RFC 4765 RFC 5733 RFC 6350 RFC 7095 RFC 7265 RFC 7493 RFC 7529 RFC 8984 RFC 9553 RFC 9554 RFC 9557 RFC 9581

A delivery mode in which packets are guaranteed to arrive with bounded latency. In IEEE 1394 these packets are not individually acknowledged.

Plain language A delivery mode where packets are guaranteed to arrive with bounded latency.

Used in RFC 1257 RFC 2734

The URL, using the https scheme and no query or fragment, that names an authorization server and appears as its issuer value in metadata.

Plain language The https URL that names an authorization server and appears in its metadata.

Used in RFC 8414 RFC 9207

ISDN User Part, a telephone network signaling protocol used between switches to set up and release calls. Its messages include IAM, ACM, ANM, REL and RLC.

Plain language ISDN User Part, a telephone network signaling protocol used between switches.

Used in RFC 3372 RFC 3398 RFC 3482 RFC 3666 RFC 4190

The iCalendar Transport-independent Interoperability Protocol, defined in RFC 5546. It describes the scheduling messages calendar users exchange, such as requests and replies, without tying them to a transport.

Used in RFC 6047 RFC 6638

A suite of wire protocols made up of RDMAP, DDP and MPA. It may be layered above TCP, SCTP or other transport protocols.

Plain language A suite of wire protocols (RDMAP, DDP, MPA) for moving data directly into memory.

Used in RFC 5040 RFC 5041 RFC 5046 RFC 6581