Glossary
I
133 terms.
- I_T nexus
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.
Like I'm five The private line between one computer and one disk that all their messages travel on.
- I-SID
The Service Instance Identifier, a 24-bit value that is global within a PBB network and identifies a service.
Like I'm five A ticket number that says which service a message belongs to.
- IAB
The Internet Architecture Board, which provides architectural oversight and is the final stop in the appeals ladder for process questions.
Like I'm five A group of senior advisers who watch the big picture and settle the last argument about whether the club followed its rules.
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 1594 RFC 1602 RFC 1603 RFC 1610 RFC 1640 RFC 1720 RFC 1780 RFC 1787 and 78 more
- IAC (Interpret as Command)
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.
Like I'm five A secret knock that says the next thing is an instruction, not part of the message.
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 2355
- IAID
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.
Like I'm five A number that identifies which of a device's network connections is asking for an address.
- IANA
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.
Like I'm five The group that keeps the master list of who may use which numbers.
Used in RFC 758 RFC 770 RFC 790 RFC 870 RFC 990 RFC 1060 RFC 1070 RFC 1118 RFC 1155 RFC 1174 RFC 1310 RFC 1340 RFC 1466 RFC 1495 RFC 1505 RFC 1518 RFC 1590 RFC 1591 RFC 1594 RFC 1601 RFC 1602 RFC 1630 RFC 1651 RFC 1700 and 1096 more
- IANA registry
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.
Like I'm five An official list of agreed code numbers, with rules for adding new ones.
- IBGP and EBGP
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.
Like I'm five Talking to teammates in your own network versus talking to neighbours in another network.
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 53 more
- iCalendar
The text format defined by RFC 5545 for exchanging events, to-dos, journal entries and free/busy time between calendar programs.
Like I'm five A common way to write down plans so every calendar app can read them.
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 6557 RFC 6638 RFC 6868 RFC 7095 RFC 7265 RFC 7529 RFC 7808 RFC 7809 RFC 7953 RFC 7986 and 7 more
- ICANN
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.
Like I'm five The group that hands out domain names and Internet address numbers.
- ICE (Interactive Connectivity Establishment)
A protocol that helps two endpoints find a working network path between them despite NATs. It tries candidate addresses and picks one that works.
Like I'm five Trying different doors until you find one that opens so two people can meet.
Used in RFC 5768 RFC 6314 RFC 6679 RFC 6940 RFC 7584 RFC 7675 RFC 8421 RFC 8445 RFC 8656 RFC 8826 RFC 8831 RFC 8835 RFC 8839 RFC 8841 RFC 8843 RFC 8863 RFC 9429 RFC 9725
- ICE candidate
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.
Like I'm five One possible door that a computer tells its friend about.
Used in RFC 5245 RFC 6544 RFC 8445 RFC 8838 RFC 8839 RFC 8840 RFC 9429
- ICMP
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".
Like I'm five The postal service's note that says, "We could not deliver your parcel, and here is why."
Used in RFC 777 RFC 778 RFC 791 RFC 792 RFC 814 RFC 816 RFC 823 RFC 840 RFC 844 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 RFC 1016 RFC 1070 and 113 more
- ICMP Extension Structure
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.
Like I'm five Extra pages stapled to the back of an error note.
- ICMPv6
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.
Like I'm five The internet's way of sending back short notes about what went wrong, or asking "are you there?"
Used in RFC 1885 RFC 1970 RFC 1981 RFC 2461 RFC 2463 RFC 2466 RFC 2473 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 RFC 4443 and 72 more
- Idempotent method
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.
Like I'm five Pressing the elevator button twice does the same as pressing it once.
Used in RFC 955 RFC 1045 RFC 1094 RFC 2068 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 RFC 9110 and 2 more
- Identifier
In ILNP, a stable name or identity for a node, independent of its current network location. Identifiers persist across network movements.
Like I'm five Your actual name, which stays the same no matter where you move.
- Identifier alignment
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).
Like I'm five Checking that the name on the envelope matches the name on the proof.
- Identity Association
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.
Like I'm five A labelled box that holds the addresses you have borrowed.
- Identity Provider
A system that manages identity information and tells other systems, such as relying parties, who a user is.
Like I'm five The place that vouches for who you are when another website asks.
Used in RFC 6595 RFC 7832 RFC 7833 RFC 8176 RFC 8473 RFC 8827
- Identity-Based Encryption
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.
Like I'm five Your public key is made from your name, not from a certificate.
Used in RFC 5091 RFC 5408 RFC 5409 RFC 6267 RFC 6508 RFC 6509 RFC 6539
- IDN (Internationalized Domain Name)
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.
Like I'm five A web address you can write in your own alphabet instead of just English letters.
- IDNA
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.
Like I'm five The rules that let your browser show website names in your own language while the internet still uses plain letters underneath.
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 4690 RFC 4952 RFC 5122 RFC 5144 RFC 5178 RFC 5301 RFC 5564 RFC 5729 RFC 5890 RFC 5891 RFC 5892 RFC 5893 and 41 more
- IEEE 1394
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.
Like I'm five A fast cable standard that lets gadgets plug into one shared line and talk to each other.
- IEEE 754
The standard for binary floating-point numbers used by most languages. A double can represent integers exactly only up to 2^53.
Like I'm five A way computers store numbers that is exact for small whole numbers but blurry for huge ones.
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
- IESG
The Internet Engineering Steering Group, which oversees IETF technical work and approves standards actions.
Like I'm five A small committee that checks new rules and says yes or no.
Used in RFC 1160 RFC 1251 RFC 1264 RFC 1280 RFC 1336 RFC 1391 RFC 1396 RFC 1435 RFC 1500 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 RFC 1984 RFC 2026 and 106 more
- IETF (Internet Engineering Task Force)
The open community of engineers that develops and standardizes Internet protocols, working mostly through mailing lists and meetings.
Like I'm five The big open club of people who write the rules computers use to talk to each other.
Used in RFC 758 RFC 1052 RFC 1083 RFC 1109 RFC 1118 RFC 1120 RFC 1160 RFC 1174 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 1396 RFC 1410 RFC 1462 RFC 1500 and 230 more
- IETF Administrative Oversight Committee
The seven-member committee that provides oversight and control of the IASA on behalf of the IETF community.
Like I'm five The committee that watches over the IETF's office and makes sure it works well.
- IETF Administrative Support Activity (IASA)
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.
Like I'm five The office team that looks after the paperwork and money for the IETF.
- IETF Review
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.
Like I'm five A careful approval process where the whole internet community gets to review and agree before something important is decided.
- IETF Trust
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.
Like I'm five A special box, with trusted keepers, that holds the IETF's important ideas and lets others use them.
- IGMP
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.
Like I'm five How computers tell the teacher which clubs they are in.
Used in RFC 988 RFC 1011 RFC 1075 RFC 1112 RFC 1546 RFC 1584 RFC 1585 RFC 1667 RFC 2022 RFC 2113 RFC 2205 RFC 2236 RFC 2432 RFC 2490 RFC 2710 RFC 2896 RFC 2933 RFC 3228 RFC 3376 RFC 3569 RFC 3678 RFC 3738 RFC 3810 RFC 3918 and 59 more
- IGMP querier
The single multicast router on a subnet that sends the periodic General Queries. It is elected by IP address, with the lowest address winning.
Like I'm five The one router chosen to keep asking the neighborhood who wants what.
- IGMP snooping
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.
Like I'm five A switch eavesdrops on who wants which show so it only sends the show to those people.
- IHL (Internet Header Length)
The 4-bit IPv4 field giving the header length in 32-bit words. The smallest valid value is 5, which is 20 octets.
Like I'm five A note saying how long the label on the package is.
Used in RFC 791
- IKE
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.
Like I'm five The quick whispered meeting where two computers agree on a secret code.
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 141 more
- ILMI
The Integrated Local Management Interface, an ATM Forum mechanism based on SNMP version 1 that lets ATM hosts, routers and switches exchange management information.
Like I'm five A way for a device and its switch to chat about settings and facts.
- Image File Directory
In TIFF format, a data structure containing metadata tags describing an image, including compression type, resolution, dimensions, and pointers to the actual image data.
Like I'm five A table of contents inside a TIFF file that describes what the image data is and where it is located.
- IMAP
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.
Like I'm five A mailbox you can look into from many places, without taking the letters home.
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 114 more
- IMEI
International Mobile station Equipment Identity, a 15-digit unique identifier for 3GPP (GSM/LTE) mobile devices, defined in RFC 7254.
Like I'm five The unique ID number for phones using GSM or LTE networks.
- IMP
Interface Message Processor. The early ARPANET used dedicated computers called IMPs to route messages between hosts.
Like I'm five The machines that carried messages around the early network.
Used in RFC 1 RFC 41 RFC 331 RFC 381 RFC 432 RFC 440 RFC 547 RFC 548 RFC 622 RFC 642 RFC 647 RFC 660 RFC 878
- IMP
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.
Like I'm five The network box that sits between a computer and the rest of the network, handling all messages.
- Implicit Keep
The default Sieve behavior of filing a message into the user's main mailbox when no action has cancelled it. Some actions cancel it.
Like I'm five If no rule says otherwise, the letter just goes in your main mailbox.
- Implicit TLS
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.
Like I'm five Using a door that is always locked, so you start the secret handshake before saying anything else.
- IMS (IP Multimedia Subsystem)
A 3GPP architecture for delivering voice, video and messaging services over IP networks, built on top of SIP.
Like I'm five A system for making calls and sending messages using the internet instead of traditional cellular networks.
- In situ OAM (IOAM)
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.
Like I'm five Each stop along the way writes a note on the parcel itself.
Used in RFC 9197 RFC 9322 RFC 9326 RFC 9359 RFC 9452 RFC 9617 RFC 9630
- In-Network Storage
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.
Like I'm five Putting storage lockers inside the network instead of only at the far endpoints.
- Independent Submission
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.
Like I'm five A note you send straight to the editor instead of through the big club.
- Index mesh
A network of interconnected index servers that cooperate to guide search queries toward relevant data sources.
Like I'm five Networked library catalogs that share information about what they index.
- Indicator of compromise
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.
Like I'm five A clue left behind by a bad actor that helps you spot them.
- Information Element
A named, numbered field in IPFIX that describes one kind of data, such as an address or a delay, together with its data type.
Like I'm five One labelled box on a report form, like Name or Age.
Used in RFC 1755 RFC 2331 RFC 5102 RFC 5471 RFC 5472 RFC 5477 RFC 6313 RFC 7012 RFC 7013 RFC 7270 RFC 8038 RFC 8137 RFC 9487 RFC 9740 RFC 9870 RFC 9951
- Information model
A conceptual model of managed objects and their relationships that hides protocol and implementation details.
Like I'm five The idea drawing of what exists and how it fits together.
Used in RFC 3060 RFC 3444 RFC 3585 RFC 3644 RFC 3670 RFC 5706 RFC 8193 RFC 8477
- Information Resource Directory
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.
Like I'm five A menu that lists everything the server can serve.
- Information-Centric Networking
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.
Like I'm five Asking for things by what they are called instead of where they live.
Used in RFC 7476 RFC 7927 RFC 7933 RFC 7945 RFC 8569 RFC 8763 RFC 8884 RFC 9138 RFC 9139 RFC 9531
- Informational RFC
An RFC that provides useful information, guidance, or documentation without specifying or advancing standards. Informational RFCs do not go through the standards track process.
Like I'm five A helpful document published by the RFC process that gives advice or explains something, but is not an official standard.
- Ingress filtering
Checking at the network edge that outgoing packets have source addresses belonging to the local network.
Like I'm five The router checks that packets leaving the network actually came from someone in that network.
Used in RFC 2267 RFC 2344 RFC 2827 RFC 2893 RFC 3013 RFC 3024 RFC 3704 RFC 3964 RFC 4213 RFC 4948 RFC 5177 RFC 5210 RFC 5220 RFC 5358 RFC 5881 RFC 7039 RFC 7157 RFC 8043
- Ingress replication
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.
Like I'm five Making a separate copy for every person instead of sharing one.
Used in RFC 6389 RFC 6513 RFC 7117 RFC 7524 RFC 7740 RFC 7988 RFC 9574 RFC 9685 RFC 10018
- Initial window
The number of data segments a TCP sender may send into a new connection before it receives any acknowledgement. Classic practice used one segment.
Like I'm five How many packets TCP is allowed to send in its very first burst.
- Initialization vector
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.
Like I'm five A fresh starting twist for each message so the same lock never works the same way twice.
Used in RFC 1829 RFC 1851 RFC 2405 RFC 2410 RFC 2420 RFC 2451 RFC 2773 RFC 3370 RFC 3414 RFC 3537 RFC 3602 RFC 3657 RFC 3686 RFC 3826 RFC 4010 RFC 4106 RFC 4196 RFC 4312 RFC 4503 RFC 5282 RFC 5830 RFC 6054 RFC 6896 RFC 7008 and 3 more
- Instance ID
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.
Like I'm five A permanent ID for a specific phone device, separate from your phone number or account.
- Integrated Services
An internet service model that adds reserved-resource services, such as Guaranteed Service and Controlled-Load Service, on top of ordinary best effort delivery.
Like I'm five Letting some traffic book a special lane while everyone else still uses the normal road.
- Integrity check value (ICV)
The value carried with a packet that lets the receiver check it was not altered. With AES-GCM it is the authentication tag.
Like I'm five A little seal on the package that shows whether it was tampered with.
- Intellectual Property Rights
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.
Like I'm five The legal protection that says who owns an idea or document and what others are allowed to do with it.
- Interactive Voice Response
An automated phone service that plays recorded prompts and collects a caller's key presses or speech. It is often shortened to IVR.
Like I'm five A phone menu run by a machine that says press 1 for this and press 2 for that.
- Interception proxy
A proxy that transparently redirects client traffic without the client's knowledge or configuration, also known as a transparent proxy.
Like I'm five A hidden helper that sits in the middle of your messages without you knowing it's there.
- Interchange Key
A longer-lived cryptographic key shared between a sender and recipient, used to encrypt the DEK for transmission with a message.
Like I'm five A key that two people share, used to lock up the message key.
- Interest
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.
Like I'm five A request that asks for something by its name.
- Interface identifier
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.
Like I'm five The part of the address that is like the apartment number, naming one door on the street.
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 49 more
- Interface to the Routing System (I2RS)
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.
Like I'm five A way for apps to ask a router what it knows and tell it where to send traffic.
- Interface Token
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.
Like I'm five A unique number each end of the phone line gets, so they can tell each other apart.
- Interior gateway protocol
A routing protocol used inside a single network or routing domain. IS-IS and OSPF are link-state examples.
Like I'm five The way routers inside one organization's network tell each other how to reach things.
- Interior Gateway Protocol (IGP)
A routing protocol used inside a single autonomous system, as opposed to an exterior protocol between them. RIP, OSPF and IS-IS are IGPs.
Like I'm five The rules for giving directions inside one town.
Used in RFC 827 RFC 898 RFC 904 RFC 911 RFC 985 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 RFC 1370 RFC 1371 and 99 more
- Interleaving
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.
Like I'm five Mixing up the order of bits so that a noisy burst does not destroy one message, but takes slightly longer to arrive.
Used in RFC 2354 RFC 2658 RFC 3558 RFC 3640 RFC 4679 RFC 5404
- Internationalization
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.
Like I'm five Making internet protocols work with languages and alphabets from all over the world.
- Internet
A global network of interconnected computer networks that communicate using the TCP/IP protocol suite, enabling exchange of data, services, and applications worldwide.
Like I'm five A giant network of computers connected together so people all over the world can share information.
- Internet checksum
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.
Like I'm five A check number on the envelope that lets the receiver tell if the letter was damaged.
Used in RFC 528 RFC 700 RFC 768 RFC 792 RFC 793 RFC 809 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 RFC 1221 and 93 more
- Internet Exchange Point
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.
Like I'm five A big meeting hall where many networks plug in so they can pass messages to each other.
- Internet Number Resource
An IP address block or Autonomous System number. Internet Number Resources are what the RPKI certifies authority over.
Like I'm five The numbers that name networks on the internet, like street addresses for whole neighborhoods.
- Internet Printing Protocol
An application-level protocol for distributed printing using Internet tools and technologies, carried over HTTP/1.1 in IPP/1.0.
Like I'm five A newer way for computers to ask printers across a network to print things.
- Internet Printing Protocol
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.
Like I'm five A shared language that computers use to ask printers to print and to ask how the printing is going.
- Internet Routing Registry
A shared database in which network operators register routing information, such as the routes they originate and their routing policies, as objects.
Like I'm five A public filing cabinet where networks leave cards saying which roads are theirs and how they share them.
- Internet Service Provider
An organization that provides Internet connectivity and services to customers, such as dial-up access, email hosting, or web server hosting.
Like I'm five A company that lets you plug into the Internet.
- Internet Society (ISOC)
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.
Like I'm five The big club that helps look after the IETF and lets it choose some of its board members.
- Internet Standard
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.
Like I'm five A rule that has been tested and approved and everyone should use it.
- Internet Standards Process
The formal procedure, defined in RFC 2026, by which Internet protocols and specifications are proposed, reviewed, tested, and approved for standardization.
Like I'm five The official steps that Internet rules must go through to become approved.
- Internet-Draft
A working document circulated for review. It has no formal status and may be changed or removed at any time.
Like I'm five A rough draft that anyone can read and comment on but nobody should treat as final.
Used in RFC 967 RFC 1111 RFC 1120 RFC 1160 RFC 1206 RFC 1310 RFC 1391 RFC 1539 RFC 1543 RFC 1550 RFC 1594 RFC 1602 RFC 1603 RFC 1645 RFC 1718 RFC 1899 RFC 2026 RFC 2223 RFC 2418 RFC 2500 RFC 2700 RFC 2800 RFC 2900 RFC 2939 and 52 more
- Interoperability
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.
Like I'm five Two toys from different shops that still fit together.
Used in RFC 942 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 RFC 6053 RFC 6205 and 25 more
- Interworking function
A component that translates messages and behavior between two different protocols so that systems using each can work together.
Like I'm five A translator that stands between two people who speak different languages.
- Intra-frame
Compression within a single frame without referencing other frames in a video sequence.
Like I'm five Each picture is compressed on its own, not by comparing it to nearby pictures.
- Intrusion Detection
The process of monitoring networks or hosts for signs of unauthorized access or malicious activities, and reporting detected incidents.
Like I'm five Watching for bad guys trying to break in, then reporting what you see.
- Intrusion detection system
A tool that watches network traffic, system logs or application records for suspicious activity and reports what it finds as alerts.
Like I'm five A security guard that watches for suspicious behaviour and raises an alarm.
- Inverse ARP
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.
Like I'm five Instead of asking which room a name lives in, you know the room and ask who lives there.
- Invoking packet
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.
Like I'm five The original package that got into trouble. The note includes a photo of it so you know which one it was.
- IODEF
Incident Object Description Exchange Format; an XML-based standard (RFC 5070) for exchanging structured incident management data, including observations, impact assessments, and expected responses.
Like I'm five A standard form for describing security incidents so different organizations can swap incident reports and understand each other.
- IP (Internet Protocol)
The protocol that addresses and forwards datagrams between networks. RFC 791 defines version 4.
Like I'm five The addressing and routing system of the Internet's postal service.
Used in RFC 791 RFC 792 RFC 800 RFC 801 RFC 815 RFC 840 RFC 872 RFC 873 RFC 875 RFC 880 RFC 893 RFC 899 RFC 908 RFC 914 RFC 939 RFC 945 RFC 961 RFC 963 RFC 968 RFC 986 RFC 1011 RFC 1015 RFC 1016 RFC 1017 and 53 more
- IP address
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.
Like I'm five A home address for a computer, so mail knows where to go.
Used in RFC 208 RFC 608 RFC 791 RFC 793 RFC 796 RFC 814 RFC 819 RFC 826 RFC 844 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 RFC 966 and 174 more
- IP datagram
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.
Like I'm five One envelope with the address on the front and your letter inside.
Used in RFC 781 RFC 782 RFC 815 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 2098 RFC 2344 and 11 more
- IP Fast Reroute
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.
Like I'm five Having a backup road ready so you can switch the instant the main road closes.
- IP flow
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.
Like I'm five A group of network packets that look alike, such as all the letters between the same two houses.
- IP fragmentation
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.
Like I'm five Cutting a big picture into puzzle pieces so it fits through a small door, then having to rebuild it on the other side.
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 1242 RFC 1294 RFC 1326 RFC 1332 RFC 1390 RFC 1448 and 203 more
- IP header option
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.
Like I'm five An extra note stuck on a package that asks the post office to do something special.
- IP Precedence
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.
Like I'm five The old three-square priority marking that came before the newer sticker.
- IP spoofing
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.
Like I'm five Writing a fake return address on a letter.
- IP tunnel
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.
Like I'm five Putting a letter inside a second envelope for part of its trip, then throwing the outer envelope away.
- IP-in-IP encapsulation
Wrapping an IP packet inside another IP packet so the outer header can carry extra routing information; the far end removes the outer header.
Like I'm five Putting a letter inside a bigger envelope with a different address on it.
- IP-VRF
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.
Like I'm five A private road map that only one customer's traffic is allowed to use.
- IPFIX
IP Flow Information Export, a protocol for sending records about IP traffic flows from an Exporting Process to a Collecting Process.
Like I'm five A standard way for network gear to send summaries of the traffic it saw to a counting machine.
Used in RFC 5102 RFC 5153 RFC 5471 RFC 5476 RFC 5655 RFC 6183 RFC 6313 RFC 6526 RFC 6615 RFC 6727 RFC 6728 RFC 7013 RFC 7014 RFC 7125 RFC 7373 RFC 8038 RFC 9387 RFC 9740 RFC 9870 RFC 9951
- IPFIX Information Element
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.
Like I'm five One labeled box in a traffic report, like 'sender' or 'number of packets'.
- IPFIX Mediator
An IPFIX Device that receives a record stream, transforms it with one or more Intermediate Processes, and exports the result as IPFIX Messages.
Like I'm five A middleman that tidies up traffic reports before passing them along.
- IPFIX Template
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.
Like I'm five A blueprint that says "the first field is the source address, the second is the destination, the third is the port," so both sides agree on the format.
- IPng
IP the Next Generation; the protocol that would eventually become IPv6, designed to replace IPv4's addressing and routing limitations.
Like I'm five The new version of the IP protocol that fixes the problems with the old one.
- IPsec
A set of protocols that protect IP packets with encryption and integrity checks, using ESP or AH. IKE sets up the keys it uses.
Like I'm five A way to put every packet in a locked, tamper-proof envelope.
Used in RFC 1825 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 RFC 2406 and 445 more
- IPv4
Version 4 of the Internet Protocol (RFC 791), with 32-bit addresses. Still widely used alongside IPv6.
Like I'm five The older, shorter Internet addresses that are nearly used up.
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 1560 RFC 1597 RFC 1606 RFC 1607 RFC 1621 RFC 1622 RFC 1627 RFC 1668 RFC 1669 RFC 1670 and 376 more
- IPv4-as-a-Service
A family of transition technologies that let an ISP with an IPv6-only access or core network still give its customers IPv4 connectivity.
Like I'm five A way to keep the old kind of internet working on a network built for the new kind.
- IPv4-compatible address
An IPv6 address with an all-zeros 96-bit prefix and an IPv4 address in the low-order 32 bits, used for automatic tunneling.
Like I'm five A new-style address with an old-style address hidden inside it.
- IPv4-embedded IPv6 address
An IPv6 address that carries a 32-bit IPv4 address inside it, so the original IPv4 address can be recovered without keeping any state.
Like I'm five A long new address with the short old address tucked inside it.
- IPv4-mapped IPv6 address
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.Like I'm five An IPv6 address with an old-style IPv4 address tucked into its last part.
- IPv6
Internet Protocol version 6, the successor to IPv4. It uses 128-bit addresses and has no broadcast, relying on multicast instead.
Like I'm five The newer, much bigger phone book for the internet, with enough numbers that nobody should run out.
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 858 more
- IPv6 Transition
The process and mechanisms by which the Internet gradually shifts from IPv4 to IPv6, including various compatibility and translation techniques.
Like I'm five The gradual change from the old internet language to the new one while keeping everything working.
- IPv6 tunneling
Encapsulation of IPv6 packets inside IPv4 packets so IPv6 traffic can traverse IPv4-only networks until native IPv6 connectivity is available.
Like I'm five Wrapping a new-style letter in an old-style envelope to get it through the old mail system.
- IRB interface
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.
Like I'm five A little gate that lets traffic pass from one neighborhood's street map to the big city map.
- IRI
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.
Like I'm five A web address that can use letters from many languages.
- IRIS
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.
Like I'm five A common way to ask registries questions, with each registry adding its own kinds of questions.
- IRTF
The Internet Research Task Force, a community of researchers organized by the Internet Architecture Board to investigate long-term issues relevant to the Internet.
Like I'm five A group of researchers who study long-term Internet questions separately from the main standards groups.
- IS-IS
Intermediate System to Intermediate System, a routing protocol for exchanging routing information within a network domain.
Like I'm five A way for routers to tell each other which paths work best.
Used in RFC 2966 RFC 3277 RFC 3563 RFC 5089 RFC 5303 RFC 5307 RFC 5310 RFC 6213 RFC 7810 RFC 8202 RFC 8243 RFC 8706 RFC 8918 RFC 9130 RFC 9194 RFC 9885
- iSCSI
A SCSI transport protocol that maps the SCSI family of protocols onto TCP/IP, so storage commands can travel over an IP network.
Like I'm five A way to send disk commands across a normal network.
Used in RFC 3347 RFC 3723 RFC 3980 RFC 4018 RFC 4171 RFC 5047 RFC 7144 RFC 7145
- Island of security
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.
Like I'm five A sealed neighborhood that the town hall doesn't vouch for.
- iSNS
The Internet Storage Name Service, a protocol that lets IP-based storage devices register themselves and discover other storage devices on the network.
Like I'm five A phone book that storage machines use to find each other.
- ISO 8601
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.
Like I'm five A rule book for writing dates, with so many choices that RFC 3339 picks just one.
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
- Isochronous
A delivery mode in which packets are guaranteed to arrive with bounded latency. In IEEE 1394 these packets are not individually acknowledged.
Like I'm five A way of sending data on a strict schedule, like a bus that always leaves on time.
- Issuer identifier
The URL, using the https scheme and no query or fragment, that names an authorization server and appears as its issuer value in metadata.
Like I'm five The web address that works as the server's name.
- ISUP
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.
Like I'm five The set of messages that phone company switches use to start and end calls.