RFC Editor Abbreviations List December 2023 ---------------------------------------------------------------------- It is common in technical writing to abbreviate complex technical terms by combining the first letters. The resulting abbreviations are often called acronyms. Editorial guidelines for the RFC series generally require expansion of these abbreviations on first occurrence in a title, in an abstract, or in the body of the document. The RFC Editor attempts to keep the use of abbreviations consistent and to point out conflicts to authors. For this purpose, we have built the abbreviation list below. This list contains abbreviations appearing in RFCs and often reflects discussions with authors, WG chairs, and/or ADs. There is no claim of completeness. Note that some abbreviations have multiple expansions. Some abbreviations are so well known that expansion is probably unnecessary. The RFC Editor exercises editorial judgment about whether a particular use of one of the "well-known" abbreviations requires expansion. (For example, strict adherence to the expansion requirement can lead to impossibly ugly titles.) In the following list of abbreviations, those that are usually (but not necessarily) treated as "well known" are marked with asterisks. However, since there are so many different abbreviations and there is a range of knowledge among RFC readers, we tend to expand abbreviations in case of doubt. Finally, this list includes some terms that look like abbreviations but are actually fixed names for things, and hence cannot and should not be expanded. These are noted as "No Expansion". Note: Names of resource records do not need to be expanded (e.g., NAPTR). ---------------------------------------------------------------------- 2G *- Second generation cellular (mobile) (2G) 2.5G *- Enhanced second generation cellular (mobile) (2.5G) 3G *- Third generation cellular (mobile) (3G) 3PCC - Third Party Call Control (3PCC) 3GPP *- Third Generation Partnership Project 3GPP IMS - 3GPP Internet Multimedia System - Third Generation Partnership Project IP Multimedia Subsystem 3PCC - third-party call control (3PCC) 4G *- 4th Generation Mobile network (mobile) (4G) 4rd - IPv4 Residual Deployment (4rd) 5G *- 5th Generation Mobile network (mobile) (5G) 6BBR - 6loWPAN Backbone Router (6BBR) 6CIO - 6LoWPAN Capability Indication (6CIO) 6CO - 6LoWPAN Context Option (6CO) 6LBR - 6LoWPAN Border Router (6LBR) 6LN - 6LoWPAN Node (6LN) 6LoRH - 6LoWPAN Routing Header (6LoRH) 6LoRHC - 6LoRH Critical (6LoRHC) 6LoRHE - 6LoRH Elective (6LoRHE) 6LoWPANs - IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs) 6LR - 6LoWPAN Router (6LR) 6LSA - IPv6 Label Switching Architecture (6LSA) 6P - 6TiSCH Operation Sublayer Protocol (6P) 6PE - IPv6 Provider Edge (6PE) 6rd - IPv6 Rapid Deployment on IPv4 Infrastructures 6TiSCH - IPv6 over the TSCH mode of IEEE 802.15.4e (6TiSCH) 6to4-PMT - 6to4 Provider Managed Tunnel (6to4-PMT) 6top - 6TiSCH Operation Sublayer (6top) A+P - Address plus Port AA - Authoritative Answer (AA) AAA - Authentication, Authorization, and Accounting (AAA) AAC - Advanced Audio Coding (AAC) AAD - additional authenticated data (AAD) AAE - Active-Active Edge (AAE) AAH - Abandoning All Hope (AAH) AAK - Authenticated Anticipatory Keying (AAK) AAL5 - ATM Adaptation Layer 5 (AAL5) AAR - AA-Request (AAR) ABE - Alternative Backoff with ECN (ABE) ABFAB - Application Bridging for Federated Access Beyond web (ABFAB) ABI - application binary interface (ABI) ABNF *- Augmented Backus-Naur form ABNO - Application-Based Network Operations (ABNO) ABR - Area Border Router (ABR) ABRO - Authoritative Border Router Option (ABRO) AC - Access Controller (AC) - Attachment Circuit (AC) - Access Category (AC) ACAP - Application Configuration Access Protocol ACE - Access Control Entry (ACE) - ASCII Compatible Encoding (ACE) ACH - Associated Channel Header ACK - No Expansion (not an abbreviation) ACL - Access Control List (ACL) ACM - access control model (ACM) ACME - Automatic Certificate Management Environment (ACME) ACS - Auto Configuration Server (ACS) ACTN - Abstraction and Control of TE Networks (ACTN) AD - Authentic Data (bit or flag) (AD) ADB - Application Data Block (ADB) ADBN - Application Data Block Number (ADBN) ADC - analog-to-digital converter (ADC) ADGoF - Anderson-Darling Goodness-of-Fit (ADGoF) ADISC - Address Discovery Extended Link Service (ADISC) Pronounced "ay-disk". Adj-RIB *- No Expansion ADK - Anderson-Darling K-sample (ADK) ADM - Add-Drop Multiplexer (as in SONET ADM) ADMD - ADministrative Management Domain ADS - Astrophysics Data System (ADS) ADSL *- Asymmetric Digital Subscriber Line (ADSL) ADSP - Author Domain Signing Practices (ADSP) ADU - Application Data Unit (ADU) ADUI - Application Data Unit Information (ADUI) AEAD - Authenticated Encryption with Associated Data (AEAD) AEC - Acoustic Echo Cancellation (AEC) AERO - Asymmetric Extended Route Optimization (AERO) AES *- Advanced Encryption Standard (AES) AF - Assured Forwarding (as in "Diffserv AF") - Appointed Forwarder (AF) AFBR - Address Family Border Router (AFBR) AFI *- Address Family Identifier (AFI) AFN - Address Family Number AfriNIC *- African Network Information Center AFRF - Authentication Failure Reporting Format (AFRF) AFS *- Authentication File System Typically not expanded Proper name is now AFS; expansion name dropped in the 1990s AFTR - Address Family Transition Router (AFTR) AG - Administrative Group (AG) AGC - Automatic Generation Control (AGC) AGI - Attachment Group Identifier AGN - aggregation node (AGN) AH - Authentication Header (AH) AHS - Additional Header Segment (AHS) - Adaptive HTTP Streaming (AHS) AIA - Authority Information Access (AIA) AIMD - Additive Increase Multiplicative Decrease (AIMD) AIS - Alarm Indication Signal (AIS) AKA - Authentication and Key Agreement (AKA) AMI - Advanced Metering Infrastructure (AMI) AMR - Automatic Meter Reading (AMR) AMT - Automatic Multicast Tunneling (AMT) AKM - Authentication and Key Management (AKM) ALC - Asynchronous Layered Coding (ALC) ALG - Application Level Gateway (ALG) - Application Layer Gateway (ALG) ALOC - Area Locator (ALOC) ALPN - Application-Layer Protocol Negotiation (ALPN) ALT - Alternative Logical Topology (ALT) ALTO - Application-Layer Traffic Optimization (ALTO) AMEI - Association of Musical Electronics Industry (AMEI) AMID - Additive Increase Multiplicative Decrease (AMID) AMR - Adaptive Multi-Rate (AMR) AMR-WB - Adaptive Multi-Rate - WideBand (AMR-WB) AMS - authoritative mapping server (AMS) AMSS - Advanced Mobile Station Software (AMSS) AN - Access Node (AN) ANAT - Alternative Network Address Types (ANAT) ANCP - Access Node Control Protocol (ANCP) ANDSF - Access Network Discovery and Selection Function (ANDSF) ANG - Access Network Gateway (ANG) ANI - Access Network Identifier (ANI) - Autonomic Networking Infrastructure (ANI) ANM - Authentic Neighbours Memory (ANM) - Adaptive Network Management (ANM) ANR - Access Network Router (ANR) ANSI *- American National Standards Institute ANSN - Advertised Neighbor Sequence Number (ANSN) AODV - Ad hoc On-Demand Distance Vector (AODV) AOR - address of record (AOR) AP - Access Point (AP) - Authenticating Party (AP) API *- Application Programming Interface APM - Application Performance Measurement (APM) APN - Access Point Name (APN) APNIC *- Asia Pacific Network Information Centre APP - Application-specific functions APS - Automatic Protection Switching (APS) AQM - Active Queue Management (AQM) AR - Address Resolution (AR) - Access Router (AR) ARAP - Apple Remote Access Protocol (ARAP) ARF - Abuse Reporting Format (ARF) ARIN *- American Registry for Internet Numbers ARL - Authority Revocation List (ARL) ARMv4 *- Advanced RISC Machine version 4 ARO - Access Router Option (ARO) - Address Registration Option (ARO) ARP *- Address Resolution Protocol (ARP) ARQ - Automatic Repeat reQuest AS - Autonomous System (AS) - Applicability Statement (AS) - Authentication Service (AS) - Application Specific (AS) - Application Server (AS) - Authorization Server (AS) ASA - Autonomic Service Agent (ASA) ASBR *- Autonomous System Border Router ASCII *- American Standard Code for Information Interchange ASE - Autonomous System External (ASE) - amplifier spontaneous emission (ASE) ASIC - Application-Specific Integrated Circuit (ASIC) ASLA - Application-Specific Link Attributes (ASLA) ASM *- Any-Source Multicast (ASM) - address-sharing mechanism (ASM) ASN - Access Service Network (ASN) - Autonomous System Number (ASN) ASN.1 *- Abstract Syntax Notation One ASNGW - Access Service Network Gateway (ASNGW) ASON - Automatically Switched Optical Network ASP - Application Service Provider (ASP) ASR - Automatic Speech Recognition (ASR) ATA - Analog Telephone Adaptor (ATA) ATD - Activation Time Delay (ATD) ATM *- Asynchronous Transfer Mode (ATM) *- Automatic Teller Machine (ATM) ATO - arrival time offset (ATO) ATPS - Authorized Third-Party Signatures (ATPS) ATU - ADSL Transceiver Unit (ATU) AU - Access Unit (AU) AUID - Agent or User Identifier (AUID) AVA - Attribute Value Assertion (AVA) AVB - Audio Video Bridging (AVB) AVP - attribute-value pair (AVP) *- Audio-Visual Profile (AVP) AVPF *- Audio-Visual Profile with Feedback (AVPF) AVT - Audio/Video Transport AWG - Arrayed Waveguide Grating (AWG) AXFR - Authoritative Transfer (not full zone transfer or Asynchronous Full Transfer) B-ISDN - Broadband Integrated Services Digital Network (B-ISDN) B-MAC - Backbone MAC (B-MAC) B-VID - Backbone VLAN ID B-VLAN - Backbone VLAN B2BUA - back-to-back user agent (B2BUA) B4 - Basic Bridging BroadBand (B4) BA - Behavior Aggregate (BA) BAB - Bundle Authentication Block (BAB) BACP - Bandwidth Allocation Control Protocol (BACP) - Bonding Aggregation Control Protocol (BACP) BAS - Broadband Access Switch (BAS) - building automation system (BAS) bash - Bourne-Again SHell (bash) BB - Bottleneck Bandwidth (BB) BBF - Broadband Forum (BBF) BC - Boundary Clock (BC) BCB - Backbone Core Bridge (BCB) BCC - Bonding Communication Channel (BCC) BCD - Binary Coded Decimal (BCD) BCE - Bonding Channel Entity (BCE) BCH *- Bose, Ray-Chaudhuri, Hocquenghem Typically not expanded; as in "BCH code" BCP *- Best Current Practice (should only be expanded for introductory docs, e.g., Tao of the IETF) - Bridging Control Protocol (BCP) BDP - Bandwidth-Delay Product (BDP) BDS *- Buchmann, Dahmen, Schneider (name of an algorithm) BE - best-effort (BE) BEB - Backbone Edge Bridge (BEB) BECN - Backward Explicit Congestion Notification (BECN) BEEP - Blocks Extensible Exchange Protocol (BEEP) BEET - Bound End-to-End Tunnel (BEET) BEK - bundle encryption key (BEK) BER *- Basic Encoding Rules - bit error rate (BER) BERT - Block-wise Extension for Reliable Transport (BERT) BEX - Base Exchange (BEX) BFCP - Binary Floor Control Protocol (BFCP) BFD - Bidirectional Forwarding Detection (BFD) BFER - Bit-Forwarding Egress Router (BFER) BFIR - Bit-Forwarding Ingress Router (BFIR) BFR - Bit-Forwarding Router (BFR) BGP *- Border Gateway Protocol BGP-LS - Border Gateway Protocol - Link State BGPsec - Typically not expanded BHS - Basic Header Segment (BHS) BIA - Bump-in-the-API (BIA) BIDIR-PIM - Bidirectional PIM (BIDIR-PIM) BIER - Bit Index Explicit Replication (BIER) BIFT - Bit Index Forwarding Table (BIFT) BIH - Bump-in-the-Host (BIH) BIND/BIND9*- Berkeley Internet Name Domain (BIND) No expansion per Paul Hoffman BIOS *- Basic Input/Output System BIRD *- BIRD Internet Routing Daemon BIRT - Bit Index Routing Table (BIRT) BIS - Bump-in-the-Stack (BIS) BITS - Building Integrated Timing Supply (BITS) BLA - Bridged Line Appearance (BLA) BLE - Bluetooth Low Energy (BLE) BMI - Base MPLS Imposition (BMI) BMP - BGP Monitoring Protocol (BMP) BMR - Basic Mapping Rule (BMR) BN - Bundle Node (BN) - Boundary Node (BN) BNC - Branch Node Capability (BNC) BNF *- Backus-Naur form BNG - Broadband Network Gateway (BNG) BOF *- Birds of a Feather BOM - Byte Order Mark (BOM) BOSH - Bidirectional-streams Over Synchronous HTTP (BOSH) BPDU - Bridge PDU (BPDU) BR - Border Router (BR) BRAS - Broadband Remote Access Server (BRAS) BRDP - Border Router Discovery Protocol (BRDP) BRI - Basic Rate Interface (BRI) BRPC - Backward Recursive PCE-Based Computation (BRPC) BRSKI - Bootstrapping Remote Secure Key Infrastructure (BRSKI) BS - Base Station (BS) BSC - Base Station Controller (BSC) BSD *- [name of operating system; better known by acronym] BSL - BitStringLength (BSL) BSM - Bootstrap Message (BSM) BSO - Basic Security Option (BSO) BSP - Bundle Security Protocol (BSP) BSR - Bootstrap Router (BSR) BSS - Business Support Systems (BSS) - Basic Service Set (BSS) - Base Station System (BSS) BSSID - Basic Service Set Identifier (BSSID) BTLE - Bluetooth Low Energy (BTLE) BTMM - Back to My Mac (BTMM) BTS - Base Tranceiver Station (BTS) BTU - Bonding Transmission Unit (BTU) BUM - Broadcast, Unknown Unicast, and Multicast (BUM) BVT - Bit-rate Variable Transponder (BVT) BW - Bandwidth (BW) BWS - "bad" whitespace (BWS) C-DNS - Compacted-DNS (C-DNS) C-MAC - customer MAC C-PCE - Child PCE C2P - customer-to-provider (C2P) CA - certification authority (CA) - certificate authority (CA) - cryptographic authentication (CA) CAA - Certification Authority Authorization (CAA) CAB - Converged Address Book (CAB) CAC - Connection Admission Control (CAC) CAdES - CMS Advanced Electronic Signatures (CAdES) CAID - Calculation Algorithm ID (CAID) CalDAV - Calendaring Extensions to WebDAV (CalDAV) CALIPSO - Common Architecture Label IPv6 Security Option (CALIPSO) CALS - Computer-Aided Acquisition and Life-Cycle Support (CALS) CAM - Content Addressable Memory (CAM) captcha - Completely Automated Public Turing test to tell Computers and Humans Apart (captcha) CAP - Candidate Access Point (CAP) CAPWAP - Control and Provisioning of Wireless Access Points (CAPWAP) CAPEX - Capital Expenditure (CAPEX) CAR - Committed Access Rate (CAR) CARD - Candidate Access Router Discovery (CARD) CAT-iq - Cordless Advanced Technology - internet and quality (CAT-iq) CATNIP - Common Architecture for Next Generation Internet Protocol (CATNIP) CAVE - Cellular Authentication and Voice Encryption (CAVE) CBC - Cipher Block Chaining (CBC) CBC-MAC - Cipher Block Chaining Message Authentication Code (CBC-MAC) CBHE - Compressed Bundle Header Encoding (CBHE) CBID - Crypto-Based Identifier (CBID) CBOR - Concise Binary Object Representation (CBOR) CBQ - Class-Based Queuing (CBQ) CBR - Constant Bitrate (CBR) CC - Continuity Check (CC) - CSRC count (CC) - Call Completion (CC) - Call Control (CC) CC-V - Continuity Check and Connectivity Verification (CC-V) CCC - CMS Content Constraint (CCC) CCE - Call-Completion Entity (CCE) CCID - Congestion Control Identifier (CCID) - Content Collection IDentifier (CCID) CCM - Counter with CBC-MAC (CCM) - Codec Control Messages (CCM) - Continuity Check Message (CCM) CCNL - Call Completion on Not Logged-in (CCNL) CCNR - Call Completion on No Reply (CCNR) CCMP - Counter Mode with CBC-MAC Protocol (CCMP) - Centralized Conferencing Manipulation Protocol (CCMP) CCS - Change Cipher Spec (CCS) coded character set (CCS) ccTLD - Country Code Top-Level Domain (ccTLD) CCV - Common Communication Vehicle (CCV) CCXML - Call Control XML (CCXML) CD - Congestion Degree CDA - Compression/Decompression Action (CDA) CDDL - Concise Data Definition Language (CDDL) CCDR - Centralized Control Dynamic Routing CDF - Comma-Delimited Format - cumulative distribution function (CDF) CDMA *- Code Division Multiple Access CDMA2000 - No Expansion It is a registered trademark of the Telecommunications Industry Association in the US. CDMF *- Commercial Data Masking Facility CDMI - Cloud Data Management Interface (CDMI) CDN - Call-Disconnect-Notify (CDN) - Content Delivery Network (CDN) - Content Distribution Network (CDN) CDNI - Content Distribution Network Interconnection (CDNI) - Content Delivery Network Interconnection (CDNI) CDP - Content Delivery Protocol (CDP) - CRL Distribution Point (CDP) CDR - Call Data Record (CDR) CDRR - Current Data Rate (Receive) (CDRR) CDRT - Current Data Rate (Transmit) (CDRT) CE - Customer Edge (CE) - Control Element (CE) - Congestion Experienced (CE) CEA - Capabilities-Exchange-Answer (CEA) - Consumer Electronics Association (CEA) CEID - Control Element ID (CEID) CEK - content-encryption key (CEK) CELP - Code-Excited Linear Prediction (CELP) CELT - Constrained-Energy Lapped Transform (CELT) CEMA - Connection Establishment for Media Anchoring (CEMA) CEP - Circuit Emulation over Packet (CEP) CERT *- Computer Emergency Response Team (CERT) CES - Circuit Emulation Service (CES) - Core-Edge Separation (CES) CESoPSN - Circuit Emulation Service over Packet Switched Network (CESoPSN) CFB - Cipher FeedBack (CFB) CFG - context-free grammar (CFG) CFI - Canonical Format Indicator (CFI) CFM - Connectivity Fault Management (CFM) CFWS - comments and/or folding white space (CFWS) CGA - Cryptographically Generated Addresses (CGA) CGI - Common Gateway Interface (CGI) CGN - Carrier-Grade NAT (CGN) CHAP - Challenge Handshake Authentication Protocol (CHAP) CHbH - Critical Hop-by-Hop (CHbH) CHID - Channel Identifier (CHID) CI - Channel Initiator (CI) CI/T - CDNI Control interface / Triggers (CI/T) CIA - Confidentiality, Integrity, and Availability (CIA) CID - Carousel Instance Descriptor (CID) - Connection Identifier (CID) - Content Identifier (CID) - Context Identifier (CID) CIDR - Classless Inter-Domain Routing (CIDR) CIF - Common Intermediate Format (CIF) CIFS - Common Internet File System (CIFS) CIID - Carousel Instance IDentifier (CIID) CIM - Common Information Model (CIM) CIN - Client Identification Name (CIN) CIPID - Contact Information in PIDF (CIPID) CIPSO - Common Internet Protocol Security Option (CIPSO) - Commercial IP Security Option (CIPSO) CIS - Cryptographic Interoperability Strategy (CIS) CISC - Complex Instruction Set Computer (or Computing) CIST - Common and Internal Spanning Tree (CIST) CItE - Critical Ingress-to-Egress (CItE) CL - Controlled Load (CL) CLAS - Cooperating Layered Architecture for SDN (CLAS) CLAT - customer-side translator (CLAT) CLDR - Connectionless Data Response (CLDR) - Common Locale Data Repository (CLDR) CLE - Congestion Level Estimate (CLE) CLEI - Common Language Equipment Identifier (CLEI) CLI - command-line interface (CLI) - Call Level Interface (CLI) - Calling Line Identification (CLI) CLNP - Connectionless Network Protocol (CLNP) - Connectionless-mode Network Protocol (CLNP) (ISO 8473) CLNS - Connectionless Network Service (CLNS) CLP - Cell Loss Priority (CLP) A flag in an ATM cell. CLUE - Controlling Multiple Streams for Telepresence (CLUE) CM - connection manager (CM) CMAC - Cipher-Based Message Authentication Code (CMAC) CMC - Certificate Management over CMS (CMC) CMCC - Conference and Media Control Client (CMCC) CMDB - Configuration Management Database (CMDB) CMS - Cryptographic Message Syntax (CMS) CMT - Coordinated Multicast Trees (CMT) CMTS - cable modem termination system (CMTS) CN - Client Node (CN) - correspondent node (CN) - Common Name (CN) - Comfort Noise (CN) CNAME *- Canonical Name (CNAME) CNC - Customer Network Controller (CNC) CNF - Cache-and-Forward (CNF) CNG - comfort noise generation (CNG) CNP - Checksum Neutrality Preserver (CNP) CNSA - Commercial National Security Algorithm (CNSA) CoA - Care-of Address (CoA) - Change-of-Authorization (CoA) CoAP - Constrained Application Protocol (CoAP) CO - Central Office (CO) - Connection Only (CO) COM - Component Object Module (COM) COMEDIA - Connection-Oriented Media (COMEDIA) COMSEC - Communications Security (COMSEC) CONS - Content distribution Overlay Network Service (CONS) COPS - Common Open Policy Service (COPS) CoRAP - Conditional Random Access Point (CoRAP) CoRE - Constrained RESTful Environments (CoRE) CORS - Cross-Origin Resource Sharing (CORS) Corba - common object request broker architecture (Corba) CoS - Class of Service (CoS) COSE - CBOR Object Signing and Encryption (COSE) CoT - Care-of Test (CoT) CoTI - Care-of Test Init (CoTI) CP - Certificate Policy (CP) - CLUE Participant (CP) CPA - Certification Path Advertisement (CPA) CPE - Customer Premises Equipment (CPE) CPIM - Common Presence and Instant Messaging (CPIM) - Common Profile for Instant Messaging (CPIM) CPL - Call Processing Language (CPL) CPLD - Complex Programmable Logic Device (CPLD) CPM - Converged IP Messaging (CPM) CPP - Common Profile for Presence (CPP) CPRI - Common Public Radio Interface (CPRI) CPS - Certification Path Solicitation (CPS) - Certification Practices Statement (CPS) CPU *- Central Processing Unit CR - Carriage Return (CR) - Correspondent Router (CR) - Channel Receiver (CR) CRC - Cyclic Redundancy Check (CRC) CR-LDP - Constraint-based Routed LDP (CR-LDP) CRIME - Compression Ratio Info-leak Made Easy (CRIME) CRIO - Core Router-Integrated Overlay (CRIO) CRISP - Cross Registry Internet Service Protocol (CRISP) CRL - Certificate Revocation List (CRL) CRLF *- Carriage-Return Line-Feed (ASCII control character sequence) CRM - Customer Relationship Management (CRM) CRMF - Certificate Request Message Format (CRMF) CRS - Coordinate Reference System (CRS) CRT - Chinese Remainder Theorem (CRT) CRUD - Create, Read, Update, Delete (CRUD) CRUDX - Create, Read, Update, Delete, eXec (CRUDX) cRTP - compressed RTP (cRTP) CS - Communication Session (CS) - Class Selector (CS) CSA - Configured Security Association (CSA) CSAIL - Computer Science and Artificial Intelligence Laboratory (CSAIL) CsC - Carriers' Carriers (CsC) CSG - Cell Site Gateways (CSG) CSI - Channel State Information (CSI) CSIRT - Computer Security Incident Response Team (CSIRT) CSM - Capabilities and Settings Message (CSM) CSMA/CD - Carrier Sense Multiple Access with Collision Detection (CSMA/CD) CSNP - Complete Sequence Number PDU (CSNP) CSO - Cross-Stratum Optimization (CSO) CSP - Content Service Provider (CSP) - Content Security Policy (CSP) - Cloud Service Provider (CSP) CSPF - Constrained Shortest Path First (CSPF) CSPRNG - cryptographically secure pseudorandom number generator (CSPRNG) CSR - Certificate Signing Request (CSR) - Clock Synchronization Request (CSR) - control and status registers (CSR) - Customer Service Representative (CSR) CSRC - contributing source (CSRC) CSRF - cross-site request forgery (CSRF) CSS - Cascading Style Sheets (CSS) - Connectivity Specifications Sequence (CSS) - Controlled Slip Seconds (CSS) CT - Certificate Transparency (CT) - Commissioning Tool (CT) - Current Transformer (CT) CT_IU - Common Transport Information Unit (CT_IU) CTO - Congestion Timeout (CTO) CTM - Cellular Text Telephone Modem (CTM) CTR - Counter Mode (CTR) CTS - clear to send (CTS) - Cipher Text Stealing (CTS) CUG - Closed User Group (CUG) CV - Connectivity Verification (CV) CVEs - Common Vulnerabilities and Exposures (CVEs) CVO - Coordination of Video Orientation (CVO) CW - Control Word (CW) - Contention Window (CW) CWDM - Coarse Wavelength Division Multiplexing (CWDM) d-CW - DetNet Control Word (d-CW) DA - Destination Address (DA) - Datamover Architecture (DA) (for iSCSI) DAC - Dynamic Authorization Client (DAC) - Duplicate Address Confirmation (DAC) - Discretionary Access Control (DAC) - digital-to-analog converter (DAC) - Destination Address Compression (DAC) DAD - Duplicate Address Detection (DAD) DAG - Directed Acyclic Graph (DAG) DAM - Destination Address Mode (DAM) DAMA - Demand Assigned Multiple Access (DAMA) DANE - DNS-Based Authentication of Named Entities (DANE) DAO - Destination Advertisement Object (DAO) DAR - dynamic alternate routing (DAR) - Duplicate Address Request (DAR) DARPA - Defense Advanced Research Projects Agency (DARPA) DASH - Dynamic Adaptive Streaming over HTTP (DASH) - synonymous with MPEG-DASH DASS2 - Digital Access Signaling System 2 (DASS2) DBA - Dynamic Bandwidth Allocation (DBA) DC - data center (DC) DCA - Domain Confidentiality Authority (DCA) DCCP - Datagram Congestion Control Protocol (DCCP) dCDN - downstream Content Delivery Network (dCDN) DCE - Data Communications Equipment (DCE) - Distributed Computing Environment (DCE) DCEP - Data Channel Establishment Protocol (DCEP) DCI - Data Center Interconnect (DCI) DCN - Data Center Network (DCN) DCO - Destination Cleanup Object (DCO) DCOM - Distributed Component Object Model (DCOM) DCT - Discrete Cosine Transform (DCT) DD - Database Description (DD) DDDS - Dynamic Delegation Discovery System (DDDS) DDNS - Dynamic DNS (DDNS) DDoS *- Distributed Denial of Service (DDoS) DDP - Device Discovery Protocol (DDP) - Direct Data Placement Protocol (DDP) - Direct Data Placement (DDP) DDT - Delegated Database Tree (DDT) DDUL - Dynamic DNS Update Lease (DDUL) DE - Discard Eligible (DE) [flag in a Frame Relay frame] - Designated Expert (DE) DECADE - DECoupled Application Data Enroute (DECADE) DECT - Digital Enhanced Cordless Telecommunications (DECT) (ETSI EN 300175) DEI - Drop Eligibility Indicator (DEI) DELT - Dual Ended Loop Test (DELT) DER *- Distinguished Encoding Rules DES *- Data Encryption Standard (DES) DetNet - Deterministic Networking (DetNet) DF - Don't Fragment (DF) - Designated Forwarder (DF) - DetNet Flow (DF) DFZ - Default-Free Zone (DFZ) DGIWG - Defence Geospatial Information Working Group (DGIWG) DH - Diffie-Hellman (DH) -or- - Distant Host (DH) DHAAD - Dynamic Home Agent Address Discovery (DHAAD) DHCP *- Dynamic Host Configuration Protocol (DHCP) DHCPv6 *- Dynamic Host Configuration Protocol for IPv6 (DHCPv6) DHT - Distributed Hash Table (DHT) DI - Datamover Interface (DI) DID - Direct Inward Dialing (DID) DIFS - Distributed Interframe Space (DIFS) DIO - DODAG Information Object (DIO) DIS - DODAG Information Solicitation (DIS) - Designated Intermediate System (DIS) DIT - Directory Information Tree (DIT) DKIM - DomainKeys Identified Mail (DKIM) DLC - Data Link Control (DLC) DLCI - Data Link Connection Identifier (DLCI) DLEP - Dynamic Link Exchange Protocol (DLEP) DLP - Discrete Logarithm Problem (DLP) DLSw - Data Link Switching (DLSw) [A forwarding mechanism for the IBM SNA (Systems Network Architecture). It places SNA NPDUs into a TCP connection between two routers, which tunnel them across an IP network.] DLV - DNSSEC Lookaside Validation (DLV) DM - Delay Measurement (DM) - Disconnect Message (DM) DMARC - Domain-based Message Authentication, Reporting, and Conformance (DMARC) DMM - Delay Measurement Message (DMM) - Distributed Mobility Management (DMM) DMR - Default Mapping Rule (DMR) DMS - Distribution Management System (DMS) DMTF - Distributed Management Task Force (DMTF) DN - Distinguished Name (DN) - Data Network (DN) DNA - Detecting Network Attachment (DNA) - Domain Name Association (DNA) DNR - Do Not Revert (DNR) DNS *- Domain Name System DNS-SD - DNS-based Service Discovery (DNS-SD) DNSBL - DNS BlockList - DNS blacklist DNSSEC *- DNS Security *- DNS Security Extensions DNT - Do Not Track (DNT) DOCSIS - Data-Over-Cable Service Interface Specification (DOCSIS) DoD - Downstream-on-Demand (DoD) DODAG - Destination-Oriented Directed Acyclic Graph (DODAG) DoH - DNS (queries) over HTTPS (DoH) DOI - Domain of Interpretation (DOI) - Digital Object Identifier (DOI) DOM - Document Object Model (DOM) DoS *- Denial of Service (DoS) different from DOS (operating system) DoT - DNS over TLS (DoT) DOTS - DDoS Open Threat Signaling (DOTS) DP - Data Plane (DP) - distribution point (DP) - DNSSEC Policy (DS) DPA - Destination Preference Attribute DPI - deep packet inspection (DPI) DPLPMTUD - Datagram Packetization Layer PMTU Discovery (DPLPMTUD) DPNSS - Digital Private Network Signaling System (DPNSS) DPR - Disconnect-Peer-Request (DPR) DPS - Distributed Programming System (DPS) - Domain Pseudonym System (DPS) - DNSSEC Practice Statement (DPS) DR - designated router (DR) DRB - Designated RBridge (DRB) DRBG - deterministic random-bit generator (DRBG) DRC - duplicate request cache (DRC) DRCV - Data Receiver (DRCV) DRO - Discovery Reply Object (DRO) DRR - direct response routing (DRR) DRS - DGIWG Registry System (DRS) DRM - Digital Rights Management (DRM) DS - Diffserv (DS) - Differentiated Services (DS) - Delegation Signer (DS) DS-Lite - Dual-Stack Lite (DS-Lite) DSA *- Digital Signature Algorithm (DSA) DSAA2 - DECT Standard Authentication Algorithm #2 (DSAA2) DSACK - Duplicate Selective Acknowledgement (DSACK) DSAP - Destination Service Access Point (DSAP) DSC - DECT Standard Cipher (DSC) - DNS Statistics Collector (DSC) DSC2 - DECT Standard Cipher #2 DSCP - Differentiated Services Code Point (DSCP) DSDL - Document Schema Definition Languages (DSDL) DSE - DSA-Specific Entry (DSE) DSL *- Digital Subscriber Line (DSL) DSLAM - Digital Subscriber Line Access Multiplexer DSM - Demand-Side Management (DSM) DSN - Delivery Status Notification (DSN) - Data Sequence Number (DSN) DSND - Data Sender (DSND) DSP - Digital Signal Processor (DSP) - Digital Signal Processing (DSP) DSRC - Dedicated Short-Range Communication (DSRC) DSRCS - Dedicated Short-Range Communications Services (DSRCS) DSRK - Domain-Specific Root Key (DSRK) DSRL - Document Semantics Renaming Language DSS - Digital Signature Standard (DSS) - Data Sequence Signal (DSS) DSUSRK - Domain-Specific Usage-Specific Root Keys (DSUSRK) DT - Density Threshold (DT) DTCP - Digital Transmission Content Protection (DTCP) DTD *- Document Type Definition - Deactivation Time Delay (DTD) DTE - Data Terminal Equipment (DTE) DTLS *- Datagram Transport Layer Security (DTLS) DTMF - dual-tone multi-frequency (DTMF) DTN - Delay-Tolerant Networking (DTN) DTOS - Distributed Trusted Operating System (DTOS) DTS - decoding time stamp (DTS) - decode time stamp (DTS) DTSN - Destination Advertisement Trigger Sequence Number (DTSN) DTX - Discontinuous Transmission (DTX) DUA - DASS 2 Extensions (DUA) DUID - DHCP Unique Identifier (DUID) DUNS - Data Universal Numbering System (DUNS) DUPACK - Duplicate Acknowledgment (DUPACK) DupThresh - Duplicate Acknowledgment Threshold (DupThresh) DUT - Device Under Test (DUT) DVB - Digital Video Broadcasting (DVB) DVI - No Expansion DVMRP - Distance Vector Multicast Routing Protocol (DVMRP) DWDM - Dense Wavelength Division Multiplexing (DWDM) E.164 - No Expansion Refers to a telephone numbering plan as specified by the ITU-T E.164 specification E-L1CS - Extended Level 1 Circuit Scope (E-L1CS) E-L1FS - Extended Level 1 Flooding Scope (E-L1FS) E-LAN - Bidirectional Logical Connectivity between >2 UNIs (E-LAN) - Ethernet LAN, provides multipoint connectivity E-LINE - Ethernet point-to-point connectivity E-LMI - Ethernet Local Management Interface (E-LMI) E-LSP - Explicitly TC-encoded-PSC LSP (E-LSP) (note: expansion in RFC 3270 was updated by RFC 5462) E-UTRAN - Evolved Universal Terrestrial Radio Access Network (E-UTRAN) E-VLAN - Ethernet Virtual Private LAN (E-VLAN) E2E - end to end (E2E) EA - Embedded Address (EA) EAG - Extended Administrative Group (EAG) EAI - Email Address Internationalization (EAI) EAP - Extensible Authentication Protocol (EAP) EAP-AKA - EAP Authentication and Key Agreement (EAP-AKA) EAP-GSPK - Extensible Authentication Protocol - Generalized Pre-Shared Key (EAP-GPSK) EAP-SIM - EAP Subscriber Identity Module (EAP-SIM) EAP-TTLS - Extensible Authentication Protocol Tunneled Transport Layer Security (EAP-TTLS) EARO - Extended Address Registration Option (EARO) EATF - Emergency Access Transfer Function (EATF) EBCDIC *- Extended Binary Coded Decimal Interchange Code (EBCDIC) EBGP - External BGP (EBGP) EBM - Equipped Bit Mask (EBM) EC - Elliptic Curve (EC) - Extended Communities (EC) - Exchange Complete (EC) ECAM - European Committee for Academic Middleware (ECAM) EC2N - elliptic curve group over GF[2^N] (as in EC2N group) ECC - Elliptic Curve Cryptography (ECC) ECC CDH - Elliptic Curve Cryptography Cofactor Diffie-Hellman (ECC CDH) ECCSI - Elliptic Curve-Based Certificateless Signatures for Identity-Based Encryption (ECCSI) ECDH - Elliptic Curve Diffie-Hellman ECDSA - Elliptic Curve Digital Signature Algorithm (ECDSA) ECM - Error Correction Mode (ECM) - Encapsulated Control Message (ECM) ECMP *- Equal-Cost Multipath (ECMP) ECMQV - Elliptic Curve Menezes-Qu-Vanstone (ECMQV) EC2N - Elliptic Curve Group over GF[2^N] (as in EC2N group) ECN - Explicit Congestion Notification (ECN) ECP - Elliptic Curve Group over GF[P] (as in ECP group) - Electronic CodeBook (ECP) - Encryption Control Protocol (ECP) eCPRI - enhanced CPRI (eCPRI) ECRTP - Enhanced Compressed RTP (ECRTP) ECS - EDNS Client Subnet (ECS) ECT - ECN-Capable Transport (ECT) - Encapsulating Content Type (ECT) EDAC - Extended Duplicate Address Confirmation (EDAC) EDAR - Extended Duplicate Address Request (EDAR) EDCA - Enhanced Distributed Channel Access (EDCA) EdDSA - Edwards-curve Digital Signature Algorithm (EdDSA) EDF - empirical distribution function (EDF) EDGE - Enhanced Data rates for GSM Evolution (EDGE) EDI - Electronic Data Interchange (EDI) EDIINT - Electronic Data Interchange - Internet Integration (WG name) EDN - Extended Diagnostic Notation (EDN) EDNS(0) - Extension Mechanisms for DNS (EDNS(0)) EDNS0 - Extension Mechanisms for DNS (EDNS0) From Paul Hoffman (10/24/2018): People in the DNS world these days are also using "EDNS0" because it is more readable. EE - End Entity (EE) EENA - European Emergency Number Association (EENA) EF - Expedited Forwarding (as in "Diffserv EF") EFCI - Explicit Forward Congestion Indication (EFCI) EFM - Ethernet First Mile (EFM) EFR - Enhanced Full Rate (EFR) EGP *- Exterior Gateway Protocol EHLO *- Extended Hello For the template in RFC 5321, "EHLO" is specified a term of art, not an abbreviation. EHV - Extra-High Voltage (EHV) EID - Endpoint Identifier (EID) - Extension Header ID (EID) EIP - Extended Internet Protocol (EIP) EISS - Extended Internal Sublayer Service (EISS) EIR - Equipment Identity Register (EIR) EIRP - Equivalent Isotropic Radiated Power (EIRP) - Effective Isotropically Radiated Power (EIRP) EKM - Exported Keying Material (EKM) EKT - Encrypted Key Transport (EKT) EKU - extended key usage (EKU) EL - Entropy Label (EL) ELI - Entropy Label Indicator (ELI) ELOC - Endpoint Locator (ELOC) EMA - External Measurement Agent (EMA) eMBB - enhanced Mobile Broadband (eMBB) eMMC - embedded Multimedia Chip (eMMC) EMS - Energy Management Systems (EMS) (Smart Grid) EMSK - Extended Master Session Key (EMSK) eNB - Evolved Node B (eNB) ENT - Empty Non-Terminal (ENT) ENUM - No Expansion Refers generally to a telephone numbering plan. However, the term ENUM is universal, whereas Telephone Number Mapping is not. There are ENUM activities and organizations all over the world. The "long name" of the ENUM WG long name is the anomaly, because ENUM is not an abbreviation, despite appearances. EOF *- End of File (EOF) EOF - Extended Options and Flags (EOF) EoR - End-of-Row (EoR) EOR *- exclusive or [In logical operations, the exclusive disjunction, also called exclusive or, (symbolized XOR or EOR), is a type of logical disjunction on two operands that results in a value of "true" if and only if exactly one of the operands has a value of "true." (wikipedia)] - End of Rib (EoR) EPA - Explicit Path Attribute (EPA) EPC - Electronic Product Code (EPC) - Evolved Packet Core (EPC) EPD - Endpoint Discriminator (EPD) - EtherType Protocol Discrimination (EPD) EPI - Educational Policy Institute (EPI) EPON - Ethernet Passive Optical Network (EPON) EPP - Extensible Provisioning Protocol (EPP) EPS - Evolved Packet System (EPS) EPUB *- electronic publication (EPUB) ER - EAP Re-authentication (ER) - Explicit Route (ER) ERE - Extended Regular Expressions (ERE) ERLD - Entropy Readable Label Depth (ERLD) ERO - Explicit Route Object (ERO) ERP - EAP Re-authentication Protocol (ERP) - Enterprise Resource Provision (ERP) - Enterprise Resource Planning (ERP) ERT - Expected Residual Time (ERT) ERU - Effective Request URI (ERU) ERX - EAP Re-authentication Extension (ERX) ES - Errored Seconds (ES) - Ethernet Segment (ES) ES-IS - End System to Intermediate System ESA - Effective Security Association (ESA) ESADI - End-Station Address Distribution Information (ESADI) ESB - Extension Security Block (ESB) ESC - Event State Compositor (ESC) ESI - Error Source Identifier (ESI) - Entity Status Inquiry - Encoding Symbol ID - Energy Services Interface (ESI) (Smart Grid) - Ethernet Segment Identifier (ESI) ESMC - Ethernet Synchronization Messaging Channel (ESMC) ESMTP *- Extended Simple Mail Transfer Protocol ESN - Electronic Serial Number (ESN) - Extended Sequence Number Per Errata 3615, the N (of ESN) can also be "Numbers", but the abbreviation should not be plural (i.e., the abbreviation shoul still be ESN). ESO - Extended Security Option (ESO) ESP - Encapsulating Security Payload (ESP) ESRP - Emergency Service Routing Proxy (ESRP) ESS - Extended Service Set (ESS) - Enhanced Security Services (ESS) EST - Enrollment over Secure Transport (EST) ETag - entity-tag (ETag) ETLD - Effective Transport Label-Stack Depth (ETLD) ETM - excess-traffic-marked (ETM) ETR - Egress Tunnel Router (ETR) ETS - Emergency Telecommunications Service (ETS) ETSI *- European Telecommunications Standards Institute (ETSI) ETX - Expected Transmission Count (ETX) EUI - Extended Unique Identifier (EUI) EUI-64 - 64-bit Extended Unique Identifier (EUI-64) EVB - Edge Virtual Bridging (EVB) - Edge Virtual Bridge (EVB) EVDO - Evolution-Data Optimized (EVDO) EVI - EVPN Instance EVPL - Ethernet Virtual Private Line (EVPL) EVPN *- Ethernet VPN (EVPN) EVRC - Enhanced Variable Rate CODEC (EVRC) EVRC-NW - Enhanced Variable Rate Narrowband-Wideband Codec (EVRC-NW) EVS - Extended-Vendor-Specific (EVS) EWMA - exponentially weighted moving average (EWMA) EXI - Efficient XML Interchange (EXI) F-BM - Forwarding Bit Mask (F-BM) FA - forwarding adjacency (FA) - Foreign Agent (FA) FAD - feature and attribute data (FAD) FAN ELS - Fabric Address Notification Extended Link Service (FAN ELS) Pronounced "fan ee el es". FARP - Fibre Channel Address Resolution Protocol (FARP) Pronounced "farp". FAT - flow-aware transport (FAT) FBL - Feedback Loop (FBL) FCAG - Frequency Control Automatic Generation (FCAG) FCAPS - Fault, Configuration, Accounting, Performance, and Security (FCAPS) FCC - Floor Control Chair (FCC) - File Carbon Copy (FCC) FCFS - First come, first served (FCFS) FCI - Feedback Control Information (FCI) - Footprint & Capabilities Advertisement interface (FCI) FCIP - Fibre Channel Over TCP/IP (FCIP) FCP - Fibre Channel Protocol (FCP) - Floor Control Participant (FCP) FCS - Frame Check Sequence (FCS) - Floor Control Server FDB - Filtering Database (FDB) FDDI - Fiber Distributed Data Interface (FDDI) FDMA - Frequency-Division Multiplex (FDMA) FDT - File Delivery Table (FDT) FE - Forwarding Element (FE) FEC - Forward Error Correction (FEC) - Forwarding Equivalence Class (FEC) - Forward Erasure Correction (FEC) FECN - Forward Explicit Congestion Notification (FECN) FedFS - Federated File System (FedFS) FEM - Forwarding Element Manager (FEM) FF - Fixed-Filter (FF) FFC - Finite Field Cryptography (FFC) FFCI - FEC Framework Configuration Information (FFCI) FFD - Full Function Device (FFD) ffs - for further study FFT - Fast Fourier Transform (FFT) FG - forest guide (FG) FGL - Fine-Grained Labeling (FGL) - Fine-Grained Labeled (FGL) - Fine-Grained Label (FGL) FHR - First-Hop Router (FHR) FI - Forwarding Indicator (FI) FIA - form interpretation algorithm (FIA) (W3C VoiceXML 2.0) FIB *- Forwarding Information Base (FIB) FID - Flow ID (FID) FIFO *- First In, First Out [This is listed in Merriam Websters Dictionary.] FII - Forked Instance Identifier (FII) FILS - Fast Initial Link Setup (FILS) FIN - Not expanded TCP flag bit name; see SYN. FIPS *- Federal Information Processing Standards (FIPS) FIR - Full Intra Request (FIR) FLAC - Free Lossless Audio Codec (FLAC) FLISR - Fault Location, Isolation, and Service Restoration (FLISR) FLR - Frame Loss Ratio (FLR) FLUTE - File Delivery over Unidirectional Transport (FLUTE) FM - forwarding management (FM) - Fault Management (FM) FMIPv6 - Fast Handovers for Mobile IPv6 (FMIPv6) FMR - Forwarding Mapping Rules (FMR) FMT - feedback message type (FMT) FNV - Fowler/Noll/Vo (FNV) ForCES - Forwarding and Control Element Separation (ForCES) FP - Fixed Part (FP) FPGA - Field-Programmable Gate Array (FPGA) FPS - Frames Per Second (FPS) FQ - Fair Queuing (FQ) FQDN - Fully Qualified Domain Name (FQDN) FR - Frame Relay (FR) FRAND - fair, reasonable, and non-discriminatory (FRAND) FRER - Frame Replication and Elimination for Redundancy (FRER) FRR - Fast Reroute (FRR) F-RTO - Forward RTO-Recovery FS-LSP - Flooding Scope LSP (FS-LSP) FSID - File System ID (FSID) FSM - Finite State Machine (FSM) FSPF - Fabric Shortest Path First (FSPF) FSSI - FEC-Scheme-Specific Information (FSSI) FT - feedback target (FT) FTN - FEC-to-NHLFE (FTN) FTP *- File Transfer Protocol FTTH - fiber to the home (FTTH) FWS - folding white space (FWS) G-ACh - Generic Associated Channel (G-ACh) GAL - Generic Associated Channel Label (GAL) G-ACh Label (GAL) GAP - Generic Access Profile (GAP) GARP - Generic Attribute Registration Protocol (GARP) GAS - Generic Advertisement Service (GAS) GbE - Gigabit Ethernet (GbE) GBR - Guaranteed Bit Rate (GBR) GBS - Generic Bonding Sub-layer (GBS) GCKS - Group Controller/Key Server (GCKS) GCM - Galois/Counter Mode (GCM) GCO - Global Concurrent Optimization (GCO) GDOI - Group Domain of Interpretation (GDOI) GERAN - GSM/EDGE Radio Access Network (GERAN) GFP - Generic Framing Procedure (GFP) GGSN - Gateway GPRS Support Node (GGSN) GHC - Generic Header Compression (GHC) GID - Group Identifier (GID) - Global Identifier (GID) GIST - General Internet Signaling Transport (GIST) GLB - Global Locator Block (GLO) GLONASS - Global Orbiting Navigation Satellite System (GLONASS) GLOP - No Expansion GMA - Generalized Modulus Algorithm (GMA) GMAC - Galois Message Authentication Code (GMAC) GMII - Gigabit Media Independent Interface (GMII) GML - Geography Markup Language (GML) GMPLS *- Generalized Multiprotocol Label Switching GMRP - GARP Multicast Registration Protocol (GMRP) GNSS - Global Navigation Satellite System GOOSE - Generic Object Oriented Substation Events (GOOSE) GPL - General Public License (GPL) GPMD - General-Purpose Media Descriptor (GPMD) GPRS - General Packet Radio Service (GPRS) - General Packet Radio System (GPRS) GPS *- Global Positioning System (GPS) GPU - Graphics Processing Unit (GPU) GRASP - Generic Autonomic Signaling Protocol (GRASP) GRE *- Generic Routing Encapsulation (GRE) GRUU - Globally Routable User Agent URI (GRUU) GSAKMP - Group Secure Association Key Management Protocol (GSAKMP) GSE - Generalized Structure Element (GSE) GSI - Grid Security Infrastructure (GSI) GSLB - Global Server Load Balancing (GSLB) GSM *- Global System for Mobile Communications (GSM) GSMA - Global System for Mobile Communications Association (GSMA) GSPD - Group Security Policy Database (GSPD) GSPM - Generic Secure Password Method (GSPM) GSS-API - Generic Security Service Application Program Interface (GSS-API) GSTN - General Switched Telephone Network (GSTN) - Global Switched Telephone Network (GSTN) GTK - Group Temporal Key (GTK) gTLD - Generic Top-Level Domain (gTLD) GTP - Generic Tunneling Protocol (GTP) - GPRS Tunnelling Protocol (GTP) GTSM - Generalized TTL Security Mechanism (GTSM) GUA - Global Unicast Address (GUA) GUI *- Graphical User Interface GUID - Globally Unique Identifier (GUID) GVRP - Generic VLAN Registration Protocol (GVRP) H-PCE - Hierarchical PCE (H-PCE) H-VPLS - Hierarchical Virtual Private LAN Service (H-VPLS) HA - Home Agent (HA) HAAA - Home AAA (HAAA) HAC - Home Agent Controller (HAC) HAS - HTTP Adaptive Streaming (HAS) HBA - Host Bus Adapter (HBA) - Host-Based Authentication (HBA) - Hash-Based Addresses (HBA) HbH - Hop-by-Hop (HbH) HC - high capacity (HC) - Header Compression (HC) HCA - Host Channel Adapter (HCA) HD *- High Definition HDCP - High-bandwidth Digital Content Protection (HDCP) HDLC - High-Level Data Link Control (HDLC) HELD - HTTP-Enabled Location Delivery (HELD) HET - Header Extension Type (HET) HFC - Hybrid Fiber Coaxial (HFC) HFS+ - Hierarchical File System Plus (HFS+) HG - home gateway (HG) HI - Host Identifier (HI) - Host Identity (HI) HIP - Host Identity Protocol (HIP) hIPv4 - hierarchical IPv4 HIT - Host Identity Tag (HIT) HKDF - HMAC-based Key Derivation Function (HKDF) HL - Hop Limit (HL) HLR - Home Location Register (HLR) HMAC - Hashed Message Authentication Code (HMAC) - Hash-Based Message Authentication Code (HMAC) HMI - Human-Machine Interface (HMI) HMIPv6 - Hierarchical Mobile IPv6 (HMIPv6) HNCP - Home Networking Control Protocol (HNCP) HoA - Home Address (HoA) HOBA - HTTP Origin-Bound Authentication (HOBA) HoT - Home Test (HoT) HoTI - Home Test Init (HoTI) HOKEY - Handover Keying (HOKEY) HPC - High-Performance Computing (HPC) HPKP - HTTP Public Key Pinning (HPKP) HPTP - HTTP-based Peer to Peer (HPTP) - HTTP-based Peer-to-Peer (HPTP) (adj.) hSFC - Hierarchical Service Function Chaining (hSFC) HSM - Hardware Security Module (HSM) HSMP - Hub and Spoke Multipoint (HSMP) HSPA - High Speed Packet Access (HSPA) (No hyphen, not our term to define) HSR - High-availability Seamless Redundancy (HSR) HSS - Home Subscriber Server (HSS) HSTS - HTTP Strict Transport Security (HSTS) HTTP *- HyperText Transfer Protocol HTTPS *- Hypertext Transfer Protocol Secure HTML *- HypterText Markup Language HV - High Voltage (HV) I-JSON - Internet JSON (I-JSON) I-PMSI - Inclusive PMSI (I-PMSI) I2NSF - Interface to Network Security Functions (I2NSF) I2RS - Interface to the Routing System (I2RS) IaaS - Infrastructure as a Service (IaaS) IA - Identity Association (IA) IA-RWA - Impairment-Aware Routing and Wavelength Assignment (IA-RWA) f IA_PD - Identity Association for Prefix Delegation (IA_PD) IAB *- Internet Architecture Board (should only be expanded for introductory docs, e.g., Tao of the IETF) IACD - Interface Adjustment Capability Descriptor (IACD) IACS - Industrial Automation and Control System (IACS) IAID - Identity Association IDentifier (IAID) IAMM - In-line Aware MRB Mode (IAMM) IANA *- Internet Assigned Numbers Authority (should only be expanded for introductory docs, e.g., Tao of the IETF) IAOC - IETF Administrative Oversight Committee (IAOC) IAP - Intercept Access Point (IAP) - Internet Access Provider (IAP) - Intermediate Anonymization Process (IAP) IASA - IETF Administrative Support Activity (IASA) IAX - Inter-Asterisk eXchange (IAX) IBAKE - Identity-Based Authenticated Key Exchange (IBAKE) IBCF - Interconnection Border Control Function (IBCF) IBE - Identity-Based Encryption (IBE) IBGP - Internal BGP (IBGP) ICANN *- Internet Corporation for Assigned Names and Numbers (ICANN) ICC - ITU Carrier Code (ICC) (https://www.itu.int/oth/T0201) ICCP - Inter-Chassis Communication Protocol (ICCP) ICE - Interactive Connectivity Establishment (ICE) ICE PAC - Interactive Connectivity Establishment Patiently Awaiting Connectivity ICMP *- Internet Control Message Protocol ICP - Internet Content Provider (ICP) I-CPI - Intermediate-Controller Plane Interface (I-CPI) ICRP - Incoming-Call-Reply (ICRP) ICRQ - Incoming-Call-Request (ICRQ) ICS - IMS Centralized Services (ICS) ICSA - International Computer Security Association (ICSA) ICT - Inner Content Type (ICT) - Information and Communications Technology (ICT) ICV - Integrity Check Value (ICV) I-D - Internet-Draft (I-D) I-SID - Service Instance Identifier (I-SID) (IEEE) IDEA - International Data Encryption Algorithm (IDEA) IDevID - Initial Device Identifier (IDevID) IDN - Internationalized Domain Name (IDN) IDNA - Internationalizing Domain Names in Applications (IDNA) - Internationalized Domain Names for Applications (IDNA) IdP - Identity Provider (IdP) IDR - Instantaneous Decoding Refresh (IDR) IDRP - Inter-Domain Routing Protocol (IDRP) (ISO/IEC 10747) IDS - Intrusion Detection System (IDS) IDSN - Initial Data Sequence Number (IDSN) IE - Information Element (IE) - Internet Explorer (IE) IEA - Ingress Egress Aggregate (IEA) IEC *- International Electrotechnical Commission IED - Intelligent Electronic Device (IED) IEEE *- Institute of Electrical & Electronics Engineers IESG *- Internet Engineering Steering Group (should only be expanded for introductory docs, e.g., Tao of the IETF) IETF *- Internet Engineering Task Force (should only be expanded for introductory docs, e.g., Tao of the IETF) IETF LLC - IETF Administration Limited Liability Company (IETF LLC) IF - intermediate frequency (IF) iff *- if and only if (from mathematical logic) IFG - Inter-Frame Gap (IFG) IGD - Internet Gateway Device (IGD) IGP *- Interior Gateway Protocol (IGP) IGMP *- Internet Group Management Protocol IHL - Internet Header Length (IHL) IID - Instance ID (IID) - Interface Identifier (IID) i.i.d - independent and idenitically distributed (i.i.d) IIH - IS-IS Hello (IIH) IIR - infinite impulse response (IIR) IKE - Internet Key Exchange Protocol (IKE) IKEv2 - Internet Key Exchange Protocol Version 2 (IKEv2) IKM - input keying material (IKM) ILM - Incoming Label Map ILMI - Integrated Local Management Interface (ILMI) ILNP - Identifier-Locator Network Protocol (ILNP) - Interim LNP (ILNP) ILV - Index-Length-Value (ILV) IMA - Inverse Multiplexing for ATM (IMA) IMAP *- Internet Message Access Protocol IMDN - Instant Message Disposition Notification (IMDN) IMEI - International Mobile Equipment Identity (IMEI) International Mobile station Equipment Identity (per 3GPP) IMEISV - International Mobile station Equipment Identity and Software Version number (IMEISV) IMG - Inter-domain Multicast Gateway (IMG) iMIP - iCalendar Message-Based Interoperability Protocol (iMIP) IMPP - Instant Messaging and Presence Protocol (IMPP) IMS - IP Multimedia Subsystems (IMS) IMSI - International Mobile Subscriber Identity (IMSI) INCITS - INternational Committee for Information Technology Standards INR - Internet Number Resource (INR) INT - In-Band Network Telemetry (INT) I/O *- Input/Output (I/O) IO - information object (IO) - Initialize Only (IO) IOAM - In situ Operations, Administration, and Maintenance (IOAM) (RFC 9197) IODEF - Incident Object Description Exchange Format (IODEF) IOI - Item of Interest (IOI) - Inter Operator Identifier (IOI) ION - IETF Operational Notes (ION) IOS *- Internetwork Operating System (IOS); as in Cisco IOS IoT - Internet of Things (IoT) IoTSU - Internet of Things Software Update (IoTSU) IP *- Internet Protocol IP-OBU - IP On-Board Unit (IP-OBU) IP-RSU - IP Road-Side Unit (IP-RSU) IPBX - IP Private Branch Exchange (IPBX) IPEI - International Portable Equipment Identity (IPEI) IPCP - IP Control Protocol (IPCP) IPDV - Inter-Packet Delay Variation (IPDV) IP Packet Delay Variation (IPDV) IPFIX - IP Flow Information Export IPFRR - IP Fast Reroute (IPFRR) IPHC - IP Header Compression (IPHC) IPLS - IP-only LAN Service (IPLS) IPng *- IP Next Generation IPoE - IP over Ethernet (IPoE) IPoIB - IP over InfiniBand (IPoIB) IPP - Internet Printing Protocol (IPP) IPPM - IP Performance Metrics (IPPM) IPR *- Intellectual Property Rights (IPR) IPRAN - IP Radio Access Network (IPRAN) IPS - Intrusion Prevention System (IPS) IPsec *- IP Security (IPsec) IPSO - IP Security Option (IPSO) - Internet Protocol for Smart Objects (IPSO) IPTV - No Expansion A service that delivers television signals over an RTP/UDP/IP video stream. It is read "IP TV". IPv4 *- Internet Protocol version 4 IPv6 *- Internet Protocol version 6 IPX - Internetwork Packet Exchange (IPX) - IP Packet eXchange IPWAVE - IP Wireless Access in Vehicular Environments (IPWAVE) IQN - iSCSI Qualified Name (IQN) IR - Initiation and Refresh (IR) - Internet Registry (IR) - Ingress Replication (IR) IRB - Integrated Routing and Bridging (IRB) (RFC 8317) IRC - Internet Relay Chat (IRC) IRD - Information Resource Directory (IRD) IRI - Internationalized Resource Identifier (IRI) IRIG - Inter-Range Instrumentation Group (IRIG) IRO - Include Route Object (IRO) IRON - Internet Routing Overlay Network (IRON) IRR - Internet Routing Registry IRTF *- Internet Research Task Force (should only be expanded for introductory docs, e.g., Tao of the IETF) IS - Information Service (IS) *- Intermediate System (IS) IS-IS *- Intermediate System to Intermediate System (routing protocol) ISAKMP - Internet Security Association and Key Management Protocol (ISAKMP) ISATAP - Intra-Site Automatic Tunnel Addressing Protocol (ISATAP) ISC - Internet Systems Consortium (ISC) ISCD - Interface Switching Capability Descriptor iSCSI - Internet Small Computer System Interface (iSCSI) ISE - Independent Submissions Editor (ISE) ISDN *- Integrated Services Digital Network (ISDN) iSER - iSCSI Extensions for RDMA (iSER) ISI - Information Sciences Institute (ISI) ISID - Initiator Session Identifier (ISID) iSNS - Internet Storage Name Service (iSNS) ISO *- International Organization for Standardization ISOC *- Internet Society ISP *- Internet Service Provider iSPF - incremental Shortest Path First (iSPF) ISS - Internal Sublayer Service ISSN *- International Standard Serial Number (ISSN) ISSU - In-Service Software Upgrade (ISSU) IST - Internal Spanning Tree (IST) ISUP - ISDN User Part (ISUP) iTIP - iCalendar Transport-independent Interoperability Protocol (iTIP) ITR - Ingress Tunnel Router (ITR) ITS - Intelligent Transport Systems (ITS) ITT - Initiator Task Tag (ITT) ITU *- International Telecommunication Union (Please note the singular "Telecommunication" per http://www.itu.int/en/about/Pages/default.aspx -- not the plural "Telecommunications" that authors often use) ITU-T *- ITU Telecommunication standardization sector IU - Information Unit (IU) IUA - ISDN Q.921-User Adaptations Layer (IUA) IUMM - In-line Unaware MRB Mode (IUMM) IV - Initialization Vector (IV) - Impairment Validation (IV) IVL - Independent VLAN Learning (IVL) IVR - Interactive Voice Response (IVR) IW - Initial Window (IW) IWF - Interworking Function (IWF) IWLAN - Interworking Wireless LAN IXFR - Incremental Zone Transfer (IXFR) IXP - Internet Exchange Point (IXP) JA - Joining Assistant (JA) JCR - JSON Content Rules (JCR) JID - Jabber Identifier (JID) (Peter Saint-Andre prefers "Jabber ID" for exp.) JOSE - JSON Object Signing and Encryption (JOSE) J-PAKE - Juggling PAKE (J-PAKE) JPEG *- Joint Photographic Experts Group JRD - JSON Resource Descriptor (JRD) JSEP - JavaScript Session Establishment Protocol (JSEP) JSON *- JavaScript Object Notation JWA - JSON Web Algorithms (JWA) JWE - JSON Web Encryption (JWE) JWK - JSON Web Key (JWK) JWS - JSON Web Signature (JWS) JWT - Joint Working Team (JWT) - JSON Web Token (JWT) - JavaScript Object Notation Web Token (JWT) KAM3 - Key Agreement Mechanism 3 (KAM3) KARP - Keying and Authentication for Routing Protocols (KARP) KCI - Key Compromise Impersonation (KCI) KDA - Key Distribution Authority (KDA) KDC - Key Distribution Center (KDC) KDF - Key Derivation Function (KDF) KE - key establishment (KE) KEK - key encryption key (or key-encryption key) (KEK) KEM - Key Encapsulation Mechanism KIM - Key Identifier Mode (KIM) KINK - Kerberized Internet Negotiation of Keys (KINK) KLV - Key-Length-Value (KLV) KMP - Key Management Protocol (KMP) KMS - Key Management Service (KMS) KPAK - Key Management Service Public Authentication Key (KPAK) KPI - Key Performance Indicator (KPI) KPML - Key Press Markup Language (KPML) KSA - Key Source Authority (KSA) KSAK - Key Management Service Secret Authentication Key (KSAK) KSK - Key Signing Key (KSK) KTA - Key Trust Anchor (KTA) L2CP - Layer 2 Control Protocol (L2CP) L2F - Layer 2 Forwarding (L2F) L2SS - L2-Specific Sublayer (L2SS) L2TP - Layer 2 Tunneling Protocol (L2TP) L2VPN *- Layer 2 Virtual Private Network (L2VPN) L3VPN *- Layer 3 Virtual Private Network (L3VPN) L-LSP - Label-Only-Inferred-PSC LSP (L-LSP) LAALP - Local Active-Active Link Protocol (LAALP) LAC - L2TP Access Concentrator (LAC) LACNIC *- Latin American and Caribbean Internet Addresses Registry LACP - Link Aggregation Control Protocol (LACP) LAG - Link Aggregation Group (LAG) LAMP - Link Aggregation Marker Protocol (LAMP) LAN *- Local Area Network (LAN) LATM - Low-overhead MPEG-4 Audio Transport Multiplex (LATM) LBR - LLN Border Router (LBR) LbyR - Location-by-Reference (LbyR) LbyV - Location-by-Value (LbyV) LC - Local Controller (LC) - Link Connection (LC) - Line Card (LC) LCAF - LISP Canonical Address Format (LCAF) LCAS - Link Capacity Adjustment Scheme (LCAS) LCCE - Logical Cluster Computing Environment (LCCE) - L2TP Control Connection Endpoint LCG - Linear Congruential Generator (LCG) LCI - Location Configuration Information (LCI) LCP - Location Configuration Protocol (LCP) - large content providers (LCP) - Link Control Protocol (LCP) LCT - Layered Coding Transport (LCT) LDAP - Lightweight Directory Access Protocol (LDAP) LDH - letter-digit-hyphen (LDH) LDI - Link Down Indication (LDI) LDML - Locale Data Markup Language (LDML) LDN - Local Domain Name (LDN) LDP *- Label Distribution Protocol (LDP) LDPC - Low-Density Parity Check (LDPC) LDR - Link Delivery Ratio (LDR) LDRA - Lightweight DHCPv6 Relay Agent (LDRA) LE - Lower Effort (LE) LEDBAT - Low Extra Delay Background Transport (LEDBAT) LEC - Loss Estimation Counter (LEC) - Local Exchange Carrier (LEC) LER - Label Edge Router (LER) LF *- Line Feed LFA - Loop-Free Alternate (LFA) LFB - Logical Functional Block (LFB) - Logical Function Block (LFB) LFE - Low Frequency Effects (LFE) LFIB - Label Forwarding Information Base (LFIB) LFN - Long Fat Network (LFN) - Local Fixed Node (LFN) LFS - Label Format Specifier (LFS) LFSR - linear feedback shift register (LFSR) LGR - Label Generation Ruleset (LGR) LIFO - last-in-first-out (LIFO) LIG - LISP Internet Groper (LIG) LIME - Layer-Independent OAM Management in the Multi-Layer Environment (LIME) LIP - Loop Initialization Primitive Sequence (LIP) Pronounced "lip". LIPA - Local IP Access (LIPA) LIR - Local Internet Registry (LIR) LIS - Location Information Server (LIS) LISP - Locator-Identifier Split Protocol (LISP) Locator/ID Separation Protocol (LISP) LKH - Logical Key Hierarchy (LKH) LLC - Logical Link Control (LLC) - Local Link Connectivities (LLC) LLC_SAP - Logical Link Control Service Access Point (LLC_SAP) LLC/SNAP - Logical Link Control/Subnetwork Access Protocol (LLC/SNAP) Pronounced "el el see snap". LLCL - Local Link Connectivity List (LLCL) LLDP - Link Layer Discovery Protocol (LLDP) (ANSI/TIA-1057) LLDP-MED - Link Layer Discovery Protocol - Media Endpoint Discovery (LLDP-MED) LLID - Logical Link Identifier (LLID) LLME - Lower Layer Management Entity (LLME) LLMNR - Link-Local Multicast Name Resolution (LLMNR) LLN - Low-Power and Lossy Network (plural LLNs) LLQC - Last Listener Query Count (LLQC) LLQI - Last Listener Query Interval (LLQI) LLQT - Last Listener Query Timer (LLQT) LLS - Link-Local Signaling (LLS) LM - Loss Measurement (LM) - location management LMA - Local Mobility Anchor (LMA) LMAA - Local Mobility Anchor Address (LMAA) LMAP - Large-scale Measurement of Broadband Performance (LMAP) LMDS - Local Multipoint Distribution Service (LMDS) LMP - Link Management Protocol (LMP) LMQC - Last Member Query Count (LMQC) LMQI - Last Member Query Interval (LMQI) LMQT - Last Member Query Timer (LMQT) LMTP - Local Mail Transfer Protocol (LMTP) LNE - logical network element (LNE) LO - Leading Only (LO) Loc-RIB *- No Expansion LOPS - Loss of Packet Synchronization (LOPS) LORAN-C - Long Range Navigation System Version C LoST - Location-to-Service Translation (LoST) LoWPAN - Low-Power Wireless Personal Area Network (LoWPAN) LPC - linear-predictive coding (LPC) LPWAN - Low-Power WAN (LPWAN) LQI - Link Quality Indication (LQI) LRA - Localized Routing Acknowledge (LRA) - Local Registration Authority (LRA) LRDD - Link-based Resource Descriptor Document (LRDD) LRI - Localized Routing Initialization (LRI) LRM - Link Resource Manager (LRM) LRU - Least Recently Used (LRU) LS - Lip Synchronization (LS) LSA - Link State Advertisement (LSA) LSAP - Link Service Access Point (LSAP) LSB - least significant bit (LSB) - Locator-Status-Bit (LSB) LSC - Link State Control (LSC) - Lambda Switch Capable (LSC) - Lambda Switching Capable (LSC) LSDB - Link State Database (LSDB) LSE - Label Stack Entry (LSE) LSF - Line Spectral Frequency (LSF) LSI - Local Scope Identifier (LSI) LSN - Large-Scale NAT (LSN) LSP - Label Switched Path (LSP) - Label Switching Path (LSP) -- RARELY USED - Link State Packet (LSP) - Link State PDU (LSP) (or Link State Protocol Data Unit) (Note: Link State PDU whenever referring to IS-IS; per Janos Farkas re: RFC 7813) - Location Service Provider (LSP) LSPA - LSP Attributes (LSPA) LSPDB - Link State PDU Database (LSPDB) LSR - Label Switching Router (LSR) - Loose Source Routing (LSR) LSRR - Loose Source and Record Route (LSRR) LSU - Link State Update (LSU) LSW - Least Significant Word (LSW) LTE *- Long Term Evolution (LTE) (No hyphen; not our term to define) LTP - Licklider Transmission Protocol (LTP) - Link Termination Point (LTP) LU - Logical Unit (LU) LUN - Logical Unit Number (LUN) LW-IGMPv3 - Lightweight IGMPv3 (LW-IGMPv3) LW-MLDv2 - Lightweight MLDv2 (LW-MLDv2) lw4o6 - Lightweight 4over6 (lw4o6) LW46 - LightWeight 46 (LW46) lwAFTR - Lightweight AFTR (lwAFTR) lwB4 - Lightweight B4 (lwB4) LwM2M - Lightweight Machine-to-Machine LWSP - linear whitespace (LWSP) LZ77 - Lempel-Ziv (LZ77) LZQ - Lempel-Ziv-Welch (LZQ) M2M - machine-to-machine (M2M) mAFTR - Multicast AFTR (mAFTR) mB4 - Multicast Basic Bridging BroadBand (mB4) MA - Multicast Acquisition (MA) - multiple attachment (MA) - Measurement Agent (MA) - Maintenance Association (MA) MA/RA - Maintenance Agency/Registration Authority (MA/RA) MAC - Media Access Control (MAC) - Medium Access Control (MAC) - Message Authentication Code (MAC) - Mandatory Access Control (MAC) Caution when expanding these. Alfred provides the following info: a) IEEE 802.2 (et al.) : MAC == Media Access Control -- Sublayer of the Link Layer; most frequently used in combination with "address". I pose the rule of thumb: Whenever "MAC" appears in context with "address", it has to be expanded in the IEEE sense. b) Legacy cryptographic terminology : MAC == Message Authentication Code c) Media/Medium dependent upon plural/singular. Per Dan Romascanu for RFCs 5412-5418. MACE - Middleware Architecture Committee for Education (MACE) MACsec - Media Access Control Security (MACsec) MAE - Metropolitan Area Ethernet (MAE) MAG - Mobile Access Gateway (MAG) MAID - Maintenance Association Identifier (MAID) MAN *- Metropolitan Area Network MANET - Mobile Ad Hoc Network (MANET) MAP - Mobility Anchor Point (MAP) - Mobile Application Part (MAP) MAP-E - Mapping of Address and Port with Encapsulation (MAP-E) MAP-T - Mapping of Address and Port using Translation (MAP-T) MAS - Mobile Access Station (MAS) MBB - Make-Before-Break (MBB) MBGP - Multicast BGP (MBGP) - Multiprotocol BGP (MBGP) MBMS - Multimedia Broadcast/Multicast Service (MBMS) MBZ - MUST be zero MC - Motion Compensation (MC) - Media Consumer (MC) MC-LAG - Multi-Chassis Link Aggregation (MC-LAG) MCA - Multiple Call Appearance (MCA) MCC - Mobile Country Code (MCC) - Management Communication Channel (MCC) MCLT - Maximum Client Lead Time (MCLT) MCU - Multipoint Control Unit (MCU) MCMS - Multimedia Cable Network System (MCNS) MD - Maintenance Domain (MD) MD5 *- Message Digest 5 (Typically not expanded MDA - Mail Delivery Agent (MDA) MDC - Modification Detection Code (MDC) MDL - maximum datagram lifetime (MDL) mDNS - Multicast DNS (mDNS) MDNs - Message Disposition Notifications (MDNs) MDRR - Maximum Data Rate (Receive) (MDRR) MDRT - Maximum Data Rate (Transmit) (MDRT) MDS - Maximal Separable Distance (MDS) - MetaData Server (MDS) MDSC - Multi-Domain Service Coordinator (MDSC) MDT - Multicast Distribution Tree (MDT) ME - Maintenance Entity (ME) MED - Multi-Exit Discriminator (MED) MEDIACTRL *- Media Server Control MEF - MEF Forum (MEF) (no longer "Metro Ethernet Forum (MEF)") MEG - Maintenance Entity Group (MEG) MEID - Mobile Equipment Identity (MEID) MELPe - Mixed Excitation Linear Prediction Enhanced MEP - Maintenance Entity Group End Point (MEP) MES - Manufacturing Execution System (MES) MF - More Fragments (MF) MFIB - Multicast Forwarding Information Base (MFIB) MG - Media Gateway (MG) MGC - Media Gateway Controller (MGC) MGCP - Media Gateway Control Protocol (MGCP) MGF - mask generation function (MGF) MHAE - Mobile-Home Authentication Extension (MHAE) MHD - multihomed device (MHD) MHN - multihomed network (MHN) MHP - Multimedia Home Platform (MHP) - Multi-Homed Prefix (MHP) MI-PMSI - Multidirectional Inclusive PMSI (MI-PMSI) MIB *- Management Information Base MIC - Message Integrity Check (MIC) - Message Integrity Code (MIC) MID - Media Identification (MID) MIDCOM - Middlebox Communications (midcom) MIDI - MIDI (Musical Instrument Digital Interface) Typically not expanded. If expand, make MIDI primary, that is, use "MIDI (Musical Instrument Digital Interface)", not "Musical Instrument Digital Interface (MIDI)". (per RFC Editor note for RFCs 4695 and 4696) MIF - multiple interfaces (MIF) MIKEY - Multimedia Internet KEYing (MIKEY) MIME *- Multipurpose Internet Mail Extensions MIMO - Multiple Input Multiple Output (MIMO) MIN - Mobile Identification Number (MIN) MINC - multicast inference of network characteristics (MINC) MINE - Minimal Encapsulation in IP (MINE) MIP - Mobile IP - Maintenance Entity Group Intermediate Point MIPv6/MIP6 - Mobile IPv6 (MIPv6 or MIP6) MIPS *- Million Instructions Per Second MITM - man in the middle (MITM) [typically hyphenated as adj. before "attack"] MKI - Master Key Identifier (MKI) MKT - Master Key Tuple (MKT) ML - Metadata Label (ML) MLA - Multiple Call Line Appearance MLD - Multicast Listener Discovery (MLD) MLDv2 - Multicast Listener Discovery Version 2 (MLDv2) mLDP - Multipoint LDP (mLDP) not as defined in RFC 6388 (mLDP: Multipoint extensions for LDP) confirmed by WG chair and AD MLDv2 - Multicast Listener Discovery Version 2 (MLDv2) MLE - Mesh Link Establishment (MLE) MLI - Message Length Indicator (MLI) - Metadata Label Indicator (MLI) MLM - Mailing List Manager (MLM) MLPP - Multilevel Precedence and Preemption (MLPP) MLS - Multi-Level Secure (MLS) - Multi-Level Security (MLS) MM - Mobility Management (MM) MMA - MIDI Manufacturers Association MMDEF - Malware Metadata Exchange Format (MMDEF) MME - Mobile Management Entity (MME) Mobility Management Entity (MME) MMORPG - Massively Multiplayer Online Role-Playing Game (MMORPG) MMRP - Multiple MAC Registration Protocol (MMRP) MMS - Multimedia Messaging Service (MMS) mMTC - massive Machine Type Communications (mMTC) MN - Mobile Node (MN) MN-FA - Mobile Node - Foreign Agent (MN-FA) MNC - Mobile Network Code (MNC) MNG - Mobile Network Gateway (MNG) MO - Measurement Object (MO) MOBIKE - IKEv2 Mobility and Multihoming (MOBIKE) MoCA - Multimedia over Coax Alliance (MoCA) MODP - modular exponentiation (MODP) (often MODP group) MOP - Mode of Operation (MOP) MOS - mean opinion score (MOS) MOSPF - Multicast Extensions to OSPF (MOSPF) MP - Multiprotocol (MP) - Maintenance Point (MP) - Merge Point (also "MPT" in this list) - Media Provider (MP) MP-BGP - Multiprotocol BGP MP2P - Multi-Point to Point (MP2P) MP2PE - Multi-Point to Point Emulation (MP2PE) MP2MP - Multipoint-to-Multipoint (MP2MP) MPA - Marker PDU Aligned Framing for TCP MPD - Media Presentation Description (MPD) MPEG *- Motion Picture Experts Group Typically not expanded. MPEG-DASH - MPEG Dynamic Adaptive Streaming over HTTP (MPEG-DASH) - synonymous with DASH MPI - Minimum Picture Interval (MPI) - Multiprecision Integer (MPI) - Metadata Present Indicator (MPI) MPL - Multicast Protocol for Low-Power and Lossy Networks (MPL) MPLS *- Multiprotocol Label Switching Use "Multiprotocol" wherever "Multi Protocol" or "MultiProtocol" occur MPLS-TE *- MPLS Traffic Engineering (MPLS-TE) MPLS-TP - MPLS Transport Profile (MPLS-TP) MPNTP - Multipath Network Time Protocol (MPNTP) MPPTP - Multipath Precision Time Protocol (MPPTP) MPR - multipoint relay (MPR) MPS - Maximum Packet Size (MPS) MPT - Merge Point (MPT) MPTCP - Multipath TCP (MPTCP) MQTT - Message Queuing Telemetry Transport (MQTT) MR - Mobile Router (MR) - Map Resolver (MR) MRB - Media Resource Broker (MRB) MRD - Multicast Router Discovery (MRD) MRIB - Multicast Routing Information Base (MRIB) MRRU - Maximum Reconstructed Reception Unit (MRRU) MRT - Multi-threaded Routing Toolkit (MRT) - Maximally Redundant Tree (MRT) MRTG - Multi Router Traffic Grapher (MRTG) MRU - Maximum Receive Unit (MRU) MS - Media Server (MS) - Mobile Station (MS) - Message Store (MS) - Manual Switch (MS) MS-PW - Multi-Segment Pseudowire (MS-PW) MSA - Mail Submission Agent (MSA) - Message Submission Agent (MSA) - Mobility Service Authorizer (MSA) MSB - most significant bit (MSB) MSC - Mobile Switching Center (MSC) MSCML - Media Server Control Markup Language (MSCML) MSD - Maximum SID Depth (MSD) MSDP - Multicast Source Discovery Protocol (MSDP) MSID - Media Stream Identifier (MSID) MSISDN - Mobile Station International Subscriber Dial Number (MSISDN) - Mobile Subscriber Integrated Services Digital Network number (MSISDN) MSL - maximum segment lifetime (MSL) MSM - Mobile Station Modem (MSM) MSML - Media Server Markup Language (MSML) MSN - Master Sequence Number (MSN) MSP - Mail Service Provider (MSP) - Mapping Service Provider (MSP) MSRP - Message Session Relay Protocol (MSRP) MSS - Maximum Segment Size (MSS) - Mobile Support Station (MSS) MSTI - Multiple Spanning Tree Instance (MSTI) [802.1q] MSTP - Multiple Spanning Tree Protocol (MSTP) - Mobility Service Transport Protocol (MSTP) MSW - Most Significant Word (MSW) MT - Message Transfer (MT) - Mobile Terminal (MT) - Multiplier (MT) - Multi-Topology (MT) - Mersenne Twister (MT) MTA - Mail Transport Agent (MTA) - Mail Transfer Agent (MTA) - Message Transfer Agent (MTA) MTTR - mean time to repair (MTTR) MTU *- Maximum Transmission Unit MTU-s - Multi-Tenant Unit switch (MTU-s) MU - Merging Unit (MU) MUA - Mail User Agent (MUA) - Message User Agent (MUA) MUC - Multi-User Chat (MUC) MUD - Manufacturer Usage Description (MUD) MV - Medium Voltage (MV) MVPN - Multicast VPN (MVPN) MVRP - Multiple VLAN Registration Protocol (MVRP) (IEEE 802.1ak) MWI - Message-Waiting Indicator (MWI) MXF - Material Exchange Format (MXF) NA - Neighbor Advertisement (NA) NAA - Network Address Authority (NAA) NACK *- Negative ACKnowledgement NACM - NETCONF Access Control Model (NACM) NADA - Network-Assisted Dynamic Adaptation (NADA) NAI - Network Access Identifier (NAI) NAL - Network Abstraction Layer (NAL) NANPA - North American Numbering Plan Administration (NANPA) NAPT *- Network Address Port Translator (NAPT) *- Network Address and Port Translator (NAPT) (can use Translator or Translation - both are fine) NAPTR *- Naming Authority Pointer (NAPTR) (resource record) NAR - New Access Router (NAR) NAS - Network Access Server (NAS) - Network-Attached Storage (NAS) NASREQ - Network Access Server Requirements (NASREQ) NAT *- Network Address Translation (NAT) *- Network Address Translator (NAT) NAT64 - Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers NAT64-CGN - NAT64 Carrier-Grade NAT (NAT64-CGN) NAT64-FE - NAT64 server Front End (NAT64-FE) NAT-PMP - NAT Port Mapping Protocol (NAT-PMP) NAT-PT - Network Address Translation - Protocol Translation (NAT-PT) - Network Address Translator - Protocol Translator (NAT-PT) NAT-T - Network Address Translation Traversal (NAT-T) NBMA - Non-Broadcast Multi-Access (NBMA) NC - Neighbor Cache (NC) NC - Network Controller (NC) NCE - Network Connection Endpoint (NCE) - Neighbor Cache Entry (NCE) NCP - Network Control Protocol (NCP) NCR - Non-Congestion Robustness (NCR) NCS - Network Control Signaling (NCS) ND - Neighbor Discovery (ND) NDN - Named Data Networking (NDN) NDP - Neighbor Discovery Protocol (NDP) - Neighbor Discovery Process (NDP) NE - Network Element (NE) NEA - Network Endpoint Assessment (NEA) NEMO - Network Mobility (NEMO) NENA - National Emergency Number Association (NENA) NETCONF - Network Configuration Protocol (NETCONF) [Not typically expanded in titles, but expand in abstract] NetInf - Network of Information (NetInf) NEWPRED - No Expansion Refers to error resilience in MPEG-4 version 2 regarding which frame should be used as the reference for the next prediction. NFC - Normalization Form C (NFC) -- Unicode Normalization Form C - Near Field Communication (NFC) NFKC - Normalization Form KC (NFKC) NFS *- Network File System NFV - Network Function Virtualization (NFV) NFVI - NFV Infrastructure (NFVI) NGN - Next Generation Network (NGN) NGW - Network Gateway (NGW) NHC - Next Header Compression (NHC) NHDP - Neighborhood Discovery Protocol NHLFE - Next Hop Label Forwarding Entry NI - Named Information (NI) - network instance (NI) NIC - Network Interface Card (NIC) - Network Information Center (NIC) (as in AfriNIC, APNIC, LACNIC) - Network Interface Controller (NIC) NID - Network Interface device (NID) - Network Identifier (NID) - Namespace Identifier (NID) NIDS - Network Intrusion Detection System NIH - Named Information for Humans (NIH) NIR - National Internet Registry (NIR) NIS - Network Information Service (NIS) NIST *- National Institute of Standards and Technology (NIST) NLM - Network Lock Manager (NLM) NLP - nonlinear processing (NLP) NLPID - Network Layer Protocol Identifier (NLPID) NLRI - Network Layer Reachability Information (NLRI) nMAG - new Mobility Access Gateway (nMAG) NMDA - Network Management Datastore Architecture (NMDA) NME - Network Management Entity (NME) NMP - Network Musical Performance (NMP) NMS - Network Management System (NMS) - Network Management Station (NMS) NNI - Network-Network Interface (NNI) NNTP - Network News Transfer Protocol (NNTP) NOC - Network Operations Center (NOC) NOP - No Operation (NOP) NORM - NACK-Oriented Reliable Multicast (NORM) NOS/OLS - Not_Operational Primitive Sequence / Offline Primitive Sequence (NOS/OLS) N-PE - Network-facing PE NP *- nondeterministic polynomial time NPDAO - No-Path Destination Advertisement Object (NPDAO) NPT - Normal Play Time (NPT) NPTv6 - IPv6-to-IPv6 Network Prefix Translation (NPTv6) NR-LDH - Non-Reserved LDH (NR-LDH) NREN - National Research and Education Network (NREN) NRPN - Non-Registered Parameter Numbers (NRPN) Note: the plural is used in MIDI documents NRS - Name Resolution Service (NRS) NRZ - Non-Return-to-Zero (NRZ) NS - No Expansion as in "NS simulator" is network simulator, but should not be expanded - Neighbor Solicitation (NS) NSA - National Security Agency (NSA) NSAP - Network Service Access Protocol (NSAP) - Network Service Access Point (NSAP) NSC - Network Simulation Cradle (NSC) NSD *- No Expansion NSH - Network Service Header (NSH) NSCP - Name Server Control Protocol (NSCP) NSE - Named Signaling Event (NSE) NSEC *- NextSECure (NSEC) NSF *- National Science Foundation NSI - non-service initialized (NSI) NSID - Name Server Identifier (NSID) NSIS - Next Steps in Signaling (NSIS) NSLP - NSIS Signaling Layer Protocol (NSLP) NSP - native service processing (NSP) - Network-Specific Prefix (NSP) - Network Service Provider (NSP) NSR - Non-Stop Routing (NSR) NSS - Namespace Specific String (NSS) - Number of Source Symbols (NSS) NSSA - Not-So-Stubby Area (NSSA) NTFS - New Technology File System (NTFS) NTP *- Network Time Protocol NTSC *- National Television Standards Committee NUD - Neighbor Unreachability Discovery NUT - Network Under Test (NUT) NVA - Network Virtualization Authority (NVA) NVC - Number of Virtual Components (NVC) NVE - Network Virtualization Edge (NVE) NVFS - Network Virtual File System (NVFS) NVGRE - Network Virtualization Using Generic Routing Encapsulation (NVGRE) NVT - Network Virtual Terminal (NVT) NVO3 - Network Virtualization over Layer 3 (NVO3) NVT - Network Virtual Terminal (NVT) NWK - Network Layer (NWK) OA - Ordered Aggregate (OA) OACK - Option Acknowledgment (OACK) OAM - Operations, Administration, and Maintenance (OAM) (BCP 161 (RFC 6291)) OASIS - Organization for the Advancement of Structured Information Standards (OASIS) OATC - Open Authentication Technology Committee (OATC) OAuth *- [seems to be more of a name rather than an abbreviation] O&M - OAM and Management (O&M) (BCP 161 (RFC 6291)) OC - Ordinary Clock OCB - No Expansion OCB was initially an acronym of Offset Codebook but is now the algorithm's full name (see RFC 7253) OCF - Open Connectivity Foundation (OCF) OCh - Optical Channel (OCh) OCP - Objective Code Point (OCP) OCR - optical character recognition (OCR) OCRP - Outgoing-Call-Reply (OCRP) OCRQ - Outgoing-Call-Request (OCRQ) OCSP - Online Certificate Status Protocol (OCSP) ODU - Optical Data Unit (ODU) ODM - Original Device Manufacturer (ODM) OEM - original equipment manufacturer (OEM) OEO - optical-electronic-optical (OEO) OF - Objective Function (OF) OFB - Output FeedBack (OFB) OFDM - Orthogonal Frequency Division Multiplexing (OFDM) oFIB - ordered forwarding information base (oFIB) OGA - ORCHID Generation Algorithm (OGA) OGC - Open Geospatial Consortium (OGC) OGF - Open Grid Forum (OGF) OID *- Object Identifier oif - outgoing interface OIPF - Open IPTV Forum (OIPF) OKM - Output Keying Material (OKM) OLS - Optical Line System (OLS) OLSR - Optimized Link State Routing (OLSR) OLT - Optical Line Terminal (OLT) (Server unit of the EPON) OM - Overlay Multicast (OM) OMA - Open Mobile Alliance (OMA) OMAP - Online Multimedia Authorization Protocol (OMAP) OMP - Optical Multi-Point (OMP) ONC - Open Network Computing (ONC) OOMF - Overload Originated Multi-destination Frame (OOMF) OpenPGP - No Expansion OPES - Open Pluggable Edge Services (OPES) OPEX - Operating Expenses (OPEX) - Operational Expediture (OPEX) OPML - Outline Processor Markup Language (OPML) ORCHID - Overlay Routable Cryptographic Hash Identifiers (ORCHID) ORO - Option Request Option (ORO) OS *- Operating System - Outbound Streams (OS) - Opportunisitic Security (OS) OSCORE - Object Security for Constrained RESTful Environments (OSCORE) OSI *- Open Systems Interconnection OSN - Original Sequence Number (OSN) OSPF *- Open Shortest Path First (routing protocol) OSS - Operational Support System (OSS) - Operations Support System (OSS) (an author objected to the former) OSSI - Open Source Software Institute (OSSI) OT - Operation Technology (OT) OTAF - Over-the-Air Functionality (OTAF) OTASP - Over-the-Air Service Provisioning (OTASP) OTI - Object Transmission Information (OTI) OTN - Optical Transport Network (OTN) OTP - One-Time Password (OTP) OTT - Over the Top (OTT) OU - Organizational Unit (OU) OUI - Organizationally Unique Identifier (OUI) OVN - Open Virtual Networking (OVN) OVS - Open vSwitch (OVS) OWD - One-Way Delay (OWD) OWE - Opportunistic Wireless Encryption (OWE) OWS - optional whitespace (OWS) OXC - Optical Cross-Connect (OXC) OWAMP - One-Way Active Measurement Protocol P-GW - Packet Data Network Gateway (P-GW) P-PCE - Parent PCE (P-PCE) P2MP - Point-to-Multipoint (P2MP) - Peer-to-Multipeer P2C - provider-to-customer (P2C) P2P - peer-to-peer (P2P) - point-to-point (P2P) P2PE - Point-to-Point Emulation (P2PE) P2PSIP - Peer-to-Peer SIP (P2PSIP) P3P - Platform for Privacy Preferences (P3P) PA - provider-aggregated (PA) - provider assigned (PA) - Posture Attribute (PA) PaaS - Platform as a Service (PaaS) PAA - PANA Authentication Agent PaC - PANA Client (PaC) PAC *- Proxy Auto-Configuration (PAC) Not typically expanded; e.g., "the PAC file" or "Microsoft PAC" - PPTP Access Concentrator (PAC) - privilege attribute certificate (PAC) PACE - Password Authenticated Connection Establishment (PACE) PAD - Peer Authorization Database (PAD) - principal authentication data (PAD) PAG - Policy Association Group (PAG) PAI - P-Asserted-Identity (PAI) PAKE - password-authenticated key exchange (PAKE) PAL *- Phase Alternation Line - Package Availability List (PAL) PANA - Protocol for Carrying Authentication for Network Access PAR - previous access router (PAR) PASSporT - Personal Assertion Token (PASSporT) PAT - Port Address Translation (PAT) - Policy Association Type (PAT) PAWS - Protocol to Access White-Space (PAWS) Databases - Protection Against Wrapped Sequences (PAWS) PB - Provider Bridge (PB) (IEEE 802.1ad) - Posture Broker PBA - Proxy Binding Acknowledgement (PBA) PBAC - Policy-Based Admission Control (PBAC) PBB - Provider Backbone Bridge (PBB) (IEEE 802.1ah) (or Bridging or Bridges per past usage) PBKDF2 - Password-Based Key Derivation Function 2 (PBKDF2) PBBN - Provider Backbone Bridged Network PBU - Proxy Binding Update (PBU) PBX - Private Branch Exchange (PBX) PC - Protocol Controller (PC) - Posture Collector (PC) PCAP - Packet Capture (PCAP) PCAP-NG - PCAP Next Generation (PCAP-NG) PCB - Payload Confidentiality Block (PCB) - Protocol Control Block (PCB) PCC - Path Computation Client (PCC) - Policy and Charging Control (PCC) PCE *- Path Computation Element (PCE) PCECC - PCE as a Central Controller (PCECC) PCED - PCE Discovery (PCED) PCEP - Path Computation Element Communication Protocol (PCEP) PCIM - Policy Core Information Model (PCIM) PCM *- Pulse Code Modulation (PCM) (noun) *- Pulse Code Modulated (PCM) (adjective) PCMU *- Pulse Coded Modulation Pronounced 'mu-law' Not typically expanded PCN - Pre-Congestion Notification PCP - Port Control Protocol (PCP) PCR - Path Control and Reservation (PCR) PCRE - Perl Compatible Regular Expressions (PCRE) PCRF - Policy and Charging Rule Function (PCRF) PD - Prefix Delegation PDA *- Personal Digital Assistant PDC *- Personal Digital Cellular (mobile phone standard) Similar to CDMA; should not be expanded. PDF *- Portable Document Format (PDF) PDH - Plesiochronous Digital Hierarchy (PDH) PDM - Performance and Diagnostic Metrics (PDM) PDN - Packet Data Network (PDN) PDN-GW - Packet Data Network Gateway (PDN-GW) PDP - Packet Data Protocol (PDP) PDS - Parameter Data Structure (PDS) PDSN - Packet Data Serving Node (PDSN) PDU *- Packet Data Unit - Protocol Data Unit - Power Distribution Unit (PDU) PDV - Packet Delay Variation (PDV) PE - Provider Edge (PE) PEAP - Protected Extensible Authentication Protocol (PEAP) PEF - Packet Elimination Function (PEF) PEG - Parsing Expression Grammar (PEG) PEM - Privacy-Enhanced Mail (PEM) PEM1 - No Expansion PEM-1 is not an abbreviation, it is an acronym, and cannot be expanded. PEN - Private Enterprise Number (PEN) PEP - Policy Enforcement Point (PEP) PER - Packed Encoding Rules (PER) PERA - Purdue Enterprise Reference Architecture (PERA) PERC - Private Media in Privacy-Enhanced RTP Conferencing (PERC) PETR - Proxy Egress Tunnel Router (PETR) PEX - Peer Exchange (PEX) PFS - Perfect Forward Secrecy (PFS) PFX - Personal inFormation eXchange (PFX) PGM - Pragmatic General Multicast (PGM) PGP - Pretty Good Privacy (PGP) PGW - Packet Data Network Gateway (PGW) PHB - Per-Hop Behavior (PHB) PHIB - Previous Hop Insertion Block (PHIB) PHOP - previous hop (PHOP) PHP - Penultimate Hop Popping (PHP) PHR - Per Hop Reservation (PHR) PHY - Physical Layer (PHY) PI - Provider Independent (PI) - Protocol Instantiation (PI) - protocol interpreter (PI) - Policy Identifier (PI) PIB - Payload Integrity Block (PIB) PIC - Prefix Independent Convergence (PIC) (commonly BCP PIC) PID - Provider-defined Identifier (PID) - Packet ID (PID) PIDF - Presence Information Data Format (PIDF) PIDF-LO - Presence Information Data Format Location Object (PIDF-LO) PIE - Proportional Integral controller Enhanced (PIE) PII - Personally Identifiable Information (PII) PIM *- Protocol Independent Multicast PIM-DM - PIM - Dense Mode (PIM-DM) PIM-SM - PIM - Sparse Mode (PIM-SM) PIM-SSM *- PIM Source-Specific Multicast (PIM-SSM) PIN *- Personal Identification Number (PIN) PIO - Prefix Information Option (PIO) PITR - Proxy Ingress Tunnel Router (PITR) PKCS *- Public-Key Cryptography Standards (PKCS) [remove the expansion if refers to series of standards, e.g., PKCS #8] PKG - Private Key Generator (PKG) PKI *- Public Key Infrastructure (PKI) PKINIT - Public Key Cryptography for Initial Authentication in Kerberos (PKINIT) PKIX *- Public Key Infrastructure using X.509 PL - Protocol Layer (PL) - Packetization Layer (PL) PLAT - provider-side translator (PLAT) PLC - Packet Loss Concealment (PLC) - Policy (Rule) Lifetime Change (PLC) - Power Line Communication (PLC) (Communication can be singular or plural) - Programmable Logic Controller (PLC) PLCP - Physical Layer Convergence Procedure (PLCP) PLI - Picture Loss Indication (PLI) PLR - Point of Local Repair (PLR) - Packet Loss Rate (PLR) PLMN - Public Land-based Mobile Network (PLMN) PLPMTUD - Packetization Layer Path MTU Discovery PLSP-ID - PCEP-specific identifier for the LSP PM - Pervasive Monitoring (PM) - Performance Monitoring (PM) pMAG - previous Mobility Access Gateway (pMAG) PMC - Probability of Missing Commands (PMC) PMD - Physical Medium Dependent (PMD) PMF - Performance Measurement Function (PMF) PMID - Portable MAC Identity (PMID) PMIPv6 - Proxy Mobile IPv6 PMS - Physical Media Specific (PMS) PMSI - P-Multicast Service Interface (PMSI) - Provider Multicast Service Interface PMTU - Path MTU (PMTU) PMTUD - Path MTU Discovery (PMTUD) PMU - Phasor Measurement Unit (PMU) PNC - Provisioning Network Controller (PNC) PNF - Physical Network Function (PNF) pNFS - Parallel NFS (pNFS) PNG *- Portable Network Graphics (PNG) PNNI - Private Network-Network Interface (PNNI) PNS - Push Notification Service (PNS) PoE - Power over Ethernet (PoE) POF - Packet Ordering Function (POF) POI - Purge Originator Identification PON - Passive Optical Network (PON) POP - Point of Presence (POP) - Post Office Protocol (POP) - proof of possession (PoP) POS - PPP over SONET (POS) - Packet over SONET (POS) POSH - PKIX over Secure HTTP (POSH) POSIX *- Portable Operating System Interface (POSIX) POTS - Plain Old Telephone Service PP - Portable Part (PP) PPID - Payload Protocol Identifier (PPID) PPP *- Point-to-Point Protocol PPPoA - Point-to-Point Protocol over ATM (PPPoA) PPPoE - Point-to-Point Protocol over Ethernet (PPPoE) PPS - Packets Per Second (PPS) PPSP - Peer-to-Peer Streaming Portocol (PPSP) PPTP - Point-to-Point Tunneling Protocol (PPTP) PR - Persistent Reservation (PR) PRID - Push Resource ID (PRID) PR-SCTP - Partially Reliable Stream Control Transmission Protocol (PR-SCTP) PRA - Purported Responsible Address (PRA) PRACK - Provisional Response Acknowledgement (PRACK) PRC - Provisioning Class (PRC) - Partial Route Computation (PRC) PRE - Packet Replication and Elimination (PRE) PRECIS - Preparation, Enforcement, and Comparison of Internationalized Strings (PRECIS) PREOF - Packet Replication, Elimination and Ordering Functions (PREOF) PRF - Pseudorandom Function (PRF) - Packet Replication Function (PRF) PRL - Potential Router List (PRL) Parameter Request List (PRL) PRNG - Pseudorandom Number Generator (PRNG) ProAV - professional audio and video industry (ProAV) PRP - Parallel Redundancy Protocol (PRP) PRR - Port-Range Router (PRR) - Policy Reserve Rule (PRR) PRTC - Primary Reference Time Clock (PRTC) PS - Parametric Stereo (PS) - Proxy Signature PSAMP - Packet Sampling (PSAMP) PSAP - Public Safety Answering Point (PSAP) PSC - Packet Switch Capable (PSC) - Packet Switching Capable (PSC) - PHB Scheduling Class (PSC) - Protection State Coordination (PSC) PSD - Power Spectral Density (PSD) PSID - Port Set Identifier (PSID) PSK - Pre-Shared Key (PSK) PSKC - Portable Symmetric Key Container (PSKC) PSN *- Public Switched Network - Packet Switched Network PSNP - Partial Sequence Number PDU (PSNP) - Partial Sequence Numbers PDU (PSNP) - Packet Sequence Number (PSN) PSS - Packet-switched Streaming Service (PSS) (3GPP) - Probabilistic Signature Scheme (PSS) (as in RSASSA-PSS) PSTN - Public Switched Telephone Network (PSTN) PT - payload type (PT) - posture transport - Protection Type (PT) PTA - PMSI Tunnel Attribute (PTA) PTB - Packet Too Big (PTB) PTI - Payload Type Identifier (PTI) PTK - Pairwise Transient Key (PTK) PTM - Packet Transfer Mode (PTM) - Pulse-Time Modulation (PTM) PTO - Probe Timeout (PTO) PTP - Precision Time Protocol (PTP) PTS - presentation time stamp (PTS) PTSW - payload type switch (PTSW) PtM - Point to Multipoint (PtM) PtP - Point to Point (PtP) PUC - Probability of Unwanted Commands (PUC) PURR - Proxy Unique Registration Reference (PURR) PV - Posture Validator (PV) PVC - Permanent Virtual Circuit (PVC) PVP - Permanent Virtual Path (PVP) PVT - Public Validation Token (PVT) PW - pseudowire PW-RED - Pseudowire Redundancy (PW-RED) PWE3 - Pseudowire Emulation Edge-to-Edge (PWE3) QNAME *- query QoE - Quality of Experience (QoE) QoP - Quality of Protection (QoP) QoS *- Quality of Service (QoS) QQIC - Querier's Query Interval Code (QQIC) QR - Quick Response (QR) QRV - Querier's Robustness Variable (QRV) QUIC *- not an acronym per the WG QSIG - Q-signaling protocol [No Expansion] R2T - request-to-transmit (R2T) - Ready to Transfer (R2T) R2TSN - Ready to Transfer Sequence Number (R2TSN) RA - Router Advertisement (RA) - Router Alert (RA) - Routing Area (RA) - registration authority (RA) RAA - Re-Auth-Answer (RAA) RACK - Recent Acknowledgment RADIUS *- Remote Authentication Dial-In User Service (RADIUS) Year 2006+ docs don't expand RADIUS in title RAID - Redundant Array of Independent Disks (RAID) RAL - RPL-Aware Leaf (RAL) RAM *- Random-Access Memory RAMS - Rapid Acquisition of Multicast Sessions (RAMS) RAMS-R - RAMS Request (RAMS-R) RAMS-T - RAMS Termination (RAMS-T) RAN - Radio Access Network (RAN) - Regional Access Network (RAN) - RPL-Aware Node (RAN) RANAP - Radio Access Network Application Protocol (RANAP) RANGER - Routing and Addressing in Networks with Global Enterprise Recursion (RANGER) RAO - Router Alert Option (RAO) RAP - Random Access Point (RAP) RAQMON - Real-time Application Quality-of-Service Monitoring (RAQMON) RAR - Re-Auth-Request (RAR) RBAC - Resource-Based Admission Control (RBAC) RBNF - Routing Backus-Naur Form (RBNF) RBR - Realm Border Router (RBR) RBridge - Routing Bridge (RBridge) *- RBridge Channel (not an abbreviation - is a name of a facility per Donald Eastlake) RC - Routing Controller (RC) RC4 *- Rivest Cipher #4 - not common, but no expansion required RCODE - No Expansion RCS - Rich Communication Services (RCS) RD - Route Distinguisher (RD) - Router Discovery (RD) RDDP - Remote Direct Data Placement Protocol (RDDP) RDE - Registry Data Escrow (RDE) RDF - Resource Description Framework (RDF) RDI - Remote Defect Indicator (RDI) - Remote Defect Indication (RDI) RDM - Replay Detection Method (RDM) RDMA - Remote Direct Memory Access (RDMA) RDN - Relative Distinguished Name (RDN) rDNS - reverse DNS (rDNS) RDNSS - Recursive DNS Server (RDNSS) RDO - Route Discovery Option (RDO) RDP *- Reliable Data Protocol (RDP) RDS - Resolution Discovery System (RDS) RE - Redundancy Elimination (RE) REAP - Reachability Protocol (REAP) RED - Random Early Detection (RED) REE - Rich Execution Environment (REE) RELAX NG *- Regular Language for XML Next Generation (do not expand; better known by RELAX NG) RELOAD - REsource LOcation And Discovery (RELOAD) REMB - Receiver Estimated Maximum Bitrate (REMB) REST - Representational State Transfer (REST) RESTCONF - No Expansion RESTful - [Ideally includes a sentence to define RESTful, e.g., “RESTful” refers to the Representational State Transfer (REST) architecture.] RF - radio frequency (RF) RFB - Remote Framebuffer (RFB) RFC *- Request for Comments RFD - Reduced Function Device (RFD) - Route Flap Damping (RFD) RFID - Radio Frequency Identification (RFID) RFPI - Radio Fixed Part Identity (RFPI) RGB *- red, green, blue RGP - Redemption Grace Period RGRP - Reporting Group (RGRP) RGRS - Reporting Group Reporting Sources (RGRS) RGW - routing gateway (RGW) RH3 - type 3 Routing Header for IPv6 (RH3) RHO - Redirected Header Option (RHO) RI - Router Information (RI) - CDNI Request Routing Redirection interface (RI) RIB *- Routing Information Base (RIB) RID - Real-time Inter-network Defense (RID) - restriction identifier (RID) RIG - Referral Internet Groper (RIG) RIID - Rendezvous Point Interface ID RIP *- Routing Information Protocol RIPE NCC *- Reseaux IP Europeens Network Coordination Centre RIPng - Routing Information Protocol Next Generation (RIPng) RIR - Regional Internet Registry (RIR) RISC - Reduced Instruction Set Computer (or Computing) RJRS - Recovery Journal Receiver Structure (RJRS) RJSS - Recovery Journal Sending Structure (RJSS) RKAP - Reconfiguration Key Authentication Protocol (RKAP) RLE *- Run Length Encoding RLMI - Resource List Meta-Information (RLMI) RLOC - Routing Locator (RLOC) RLQR - Relative Link Quality (Receive) (RLQR) RLQT - Relative Link Quality (Transmit) (RLQT) RLS - Resource List Server (RLS) RMCAT - RTP Media Congestion Avoidance Techniques (RMCAT) RMON - remote (network) monitoring (RMON) RMS - root mean square (RMS) RMT - Reliable Multicast Transport (RMT) RNC - Radio Network Controller (RNC) - Relax NG Compact Notation RNIC - RDMA-enabled Network Interface Controller (RNIC) - RDMA Network Interface Card (RNIC) ROA - Route Origin Authorization (ROA) ROADM - Reconfigurable Optical Add/Drop Multiplexer (ROADM) ROC - Rollover Counter (ROC) RoCE - RDMA over Converged Ethernet (RoCE) Per RFC 7609 author Mike Fox, "RoCE" is pronounced "Rocky" RoE - Radio over Ethernet (RoE) ROHC - RObust Header Compression (ROHC) ROLIE - Resource-Oriented Lightweight Information Exchange (ROLIE) ROLL - Routing Over Low-Power and Lossy Network (ROLL) ROM *- Read-Only Memory ROVR - Registration Ownership Verifier (ROVR) RP - Rendezvous Point (RP) - Relying Party (RP) - Reply Path (RP) - Routing Processor (RP) - Request Parameters (RP) - Reverse Path (RP) RPA - Rendezvous Point Address (RPA) RPC *- remote procedure call (RPC) (Remote Procedure Call protocol) - RFC Production Center (RPC) RPCSEC_GSS *- RPC security protocol RPC-over-RDMA Version 1 - Remote Direct Memory Access Transport for Remote Procedure Call Version 1 (no need to expand if RFC 8166 is referenced) RPF - Reverse Path Forwarding (RPF) RPI - RPL Packet Information (RPI) RPKI - Resource Public Key Infrastructure (RPKI) RPL - Routing Protocol for Low-Power and Lossy Networks (RPL) Rendezvous Point Link (RPL) RPN - Registered Parameter Numbers (RPN) Note: the plural is used in MIDI documents RPR - relay peer routing (RPR) RPT - Rendezvous Point Tree (RPT) RPSI - Reference Picture Selection Indication (RPSI) RPSL - Routing Policy Specification Language (RPSL) RR - Resource Record (RR) - receiver report (RR) - Route Reflector (RR) (as used by BGP) RRH - Remote Radio Head (RRH) RRL - Response Rate Limiting (RRL) RRO - Record Route Object (RRO) RRT - Return Routability Test (RRT) RS - Retransmission Server (RS) - Router Solicitation (RS) - Resource Server (RS) - Recording Session (RS) RSA *- Rivest, Shamir and Adleman Routing and Spectrum Assignment (RSA) RSAES-OAEP - RSA Encryption Scheme - Optimal Asymmetric Encryption Padding (RSAES-OAEP) RSASSA-PSS - RSA Probabilistic Signature Scheme (RSASSA-PSS) RSC - Receive Segment Coalescing (RSC) RSE - RFC Series Editor (RSE) RSG - Radio Network Controller Site Gateway (RSG) RSI - Receiver Summary Information (RSI) RSIP - Realm Specific IP (RSIP) RSN - Reservation Sequence Number (RSN) RSOO - Relay-Supplied Options option (RSOO) RSP - Rendered Service Path (RSP) RSS *- Rich Site Summary (RSS) - Read Sequence Status Block (RSS) - Received Signal Strength (RSS) - Resident Set Size (RSS) RSSI - Received Signal Strength Indication (RSSI) RSTP - Rapid Spanning Tree Protocol (RSTP) (IEEE 802.1t) RSVP *- Resource Reservation Protocol RSVP-TE *- RSVP - Traffic Engineering RT - Route Target (RT) RTBH - Remote Triggered Black Hole (RTBH) RTCP *- RTP Control Protocol (RTCP) if RTP in RTCP needs to be expanded, should be expanded as: *- Real-time Transport Control Protocol (RTCP) RTCWEB *- Web Real-Time Communication RTMFP - Real-Time Media Flow Protocol (RTMFP) RTMP - Real Time Messaging Protocol (RTMP) RTO - retransmission timeout (RTO) RTP *- Real-time Transport Protocol RTS - request to send (RTS) RTSP - Real-Time Streaming Protocol (RTSP) RTT *- round-trip time RTX *- Retransmission RUL - RPL-Unaware Leaf (RUL) RVS - Rendezvous Server (RVS) RW - Restart Window (RW) RWA - Routing and Wavelength Assignment (RWA) RWS - required whitespace (RWS) RZ - Return-to-Zero (RZ) S-BFD - Seamless Bidirectional Forwarding Detection (S-BFD) S-BGP - Secure Border Gateway Protocol (S-BGP) S-GW - Serving Gateway (S-GW) S-NAPTR - Straightforward-Naming Authority Pointer (S-NAPTR) S-PE - Switching Provider Edge (S-PE) S-PLC - supervisory PLC (S-PLC) S-PMSI - Selective PMSI (S-PMSI) S-VLAN - Service VLAN (S-VLAN) S2L - source-to-leaf (S2L) S46 - Softwire46 (S46) SaaS - Software as a Service (SaaS) - Storage as a Service (SaaS) SA - security association (SA) - Source-Active (SA) - Source Address (SA) SAC - Source Address Compression (SAC) State Advertisement Control (SAC) SACK - selective acknowledgment (SACK) SACM - Security Automation and Continuous Monitoring (SACM) SACRED - Securely Available Credentials (SACRED) SAD - Security Association Database (SAD) SAFI *- Subsequent Address Family Identifier (SAFI) SAI - Service Activation Interface (SAI) SAID - Security Association ID Historically (back to early drafts "SAId" is being used in MIB object Names, also in enumeration values like "Said" are being used; can leave them as is mainly because: a) NMS vendors and operators are familiar with that syntax for OBJECT names involving SAIDs b) It is risky to make global replace that could lead to SNMP syntax errors on deployment (e.g., global replace of SAId for SAID Fix in DESCRIPTION Clauses ONLY: "(SAID)" instead of "(SAId)" "SAID" instead of "SAId" SALT - Speech Application Language Tags (SALT) SAM - Scalable Adaptive Multicast (SAM) - Source Address Mode (SAM) SAM2 - SCSI Architecture Model - 2 (SAM2) SAML - Security Assertion Markup Language (SAML) SAN - System Area Network (SAN) - Subject Alternative Name (SAN) SANA - Space Assigned Numbers Authority (SANA) SAOL - Structured Audio Orchestra Language (SAOL) SAP - Session Announcement Protocol (SAP) - Service Access Point (SAP) - Serving Access Point (SAP) SAR - Segmentation and Reassembly (SAR) SAS - Serial Attached SCSI (SAS) - Sequential Aggregate Signature (SAS) - Short Authentication String (SAS) SASL - Simple Authentication and Security Layer (SASL) SAToP - Structure-Agnostic Time Division Multiplexing over Packet (SAToP) SAVI - Source Address Validation Improvement (SAVI) SAVP *- Secure Audio-Visual Profile (SAVP) SAVPF *- Secure Audio-Visual Profile with Feedback (SAVPF) SB - Source Block (SB) SBC - Session Border Controller (SBC) SBD - Shared Bottleneck Detection (SBD) SBE - Signaling Path Border Element (SBE) SBG - Session Border Gateway (SBG) SBM - Subnet Bandwidth Manager (SBM) SBN - Source Block Number (SBN) SBR - Spectral Band Replication (SBR) SC - Softwire Concentrator (SC) - Switched Connection (SC) SCADA - Supervisory Control and Data Acquisition (SCADA) SCCRP - Start-Control-Connection-Reply (SCCRP) SCCRQ - Start-Control-Connection-Request (SCCRQ) SCHAC - Schema for Academia (SCHAC) SCHC - Static Context Header Compression (SCHC) SCI - Structured Cybersecurity Information (SCI) SCIM - System for Cross-domain Identity Management (SCIM) SCRAM - Salted Challenge Response Authentication Mechanism (SCRAM) SCReAM - Self-Clocked Rate Adaptation for Multimedia (SCReAM) SCS - Secure Cookie Sessions (SCS) SCSI - Small Computer System Interface (SCSI) - Switching Capability Specific Information (SCSI) SCT - Sender Current Time (SCT) - Signed Certificate Timestamp (SCT) SCTP - Stream Control Transmission Protocol (SCTP) SCVP - Simple Certificate Validation Protocol (SCVP) - Server-Based Certificate Validation Protocol (SCVP) S/D - Source/Destination (S/D) SD - Standard Definition (SD) - sub-domain (SD) SDAT - Simple DNA address table (SDAT) SDES - source description (SDES) SDH - Synchronous Digital Hierarchy (SDH) SDID - Signing Domain Identifier (SDID) SDK *- software development kit SDN - Software-Defined Networking (SDN) SDNV - Self-Delimiting Numeric Value (SDNV) SDO - Standards Development Organization (SDO) SDP - Session Description Protocol (SDP) SDSI - Simple Distributed Security Infrastructure (SDSI) SDU - service data unit (SDU) SEAL - Subnetwork Encapsulation and Adaptation Layer (SEAL) SECG - Standards for Efficient Cryptography Group (SECG) SEI - Supplemental Enhancement Information (SEI) SEND - Secure Neighbor Discovery (SEND) SERO - Secondary Explicit Route Object (SERO) SES - Severely Errored Seconds (SES) SESPAKE - Security Evaluated Standardized Password Authenticated Key Exchange (SESPAKE) SF - Scheduling Function (SF) - Service Function (SF) SFC - Service Function Chaining (SFC) - Service Function Chain (SFC) SFF - Service Function Forwarder (SFF) SFGMP - Source Filtering Group Management Protocol (SFGMP) SFL - Synonymous Flow Label (SFL) SFMT - sub-feedback message type (SFMT) SFP - Service Function Path (SFP) SFU - Selective Forwarding Units (SFU) SGML - Standard Generalized Markup Language (SGML) SGSN - Serving GPRS Support Node (SGSN) SGW - Serving Gateway (SGW) SHA *- Secure Hash Algorithm SHDSL - Single-pair High-speed Digital Subscriber Line (SHDSL) SHIM - Stanza Headers and Internet Metadata (SHIM) Shim6 *- Site Multihoming by IPv6 Intermediation (Shim6) *- Level 3 Multihoming Shim Protocol for IPv6 (Shim6) SI - softwire initiator (SI) - Set Identifier (SI) - Service Index (SI) SIA - Subject Information Access (SIA) SID - Schema IDentifier (SID) (in YANG and OAM context) - segment identifier (SID) From RFC 8402: SID: a segment identifier. Note that the term SID is commonly used in place of the term "Segment", though this is technically imprecise as it overlooks any necessary translation. - session ID or server ID or sender ID - Silence Descriptor (SID) From Ingemar Johansson (author) There seems to be two definitions: "Silence Descriptor" and "Silence Insertion Description". The 3GPP and ETSI definition seems to be "Silence Descriptor" - Silence Insertion Descriptor (SID) SIDR - Secure Inter-Domain Routing (SIDR) SIFS - Short Interframe Space (SIFS) SIIT - Stateless IP/ICMP Translation Algorithm (SIIT) SILK - Not an acronym. See usage in RFC 6716 SIMCO - Simple Middlebox Configuration (SIMCO) SIMD - single instruction, multiple data (SIMD) SIMPLE - SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE) SIP *- Session Initiation Protocol - Simple Internet Protocol (SIP) SIPBRANDY - SIP Best-practice Recommendations Against Network Dangers to privacY (SIPBRANDY) SIPP - Simple Internet Protocol plus (SIPP) SIPREC - SIP-Based Media Recording (SIPREC) SIPS - Session Initiation Protocol Secure (SIPS) SIPTO - Selected IP Traffic Offload (SIPTO) SIR - Source Intermediary Recipient (SIR) - Signal-to-Interference Ratio (SIR) SIV - Synthetic Initialization Vector (SIV) SKFC - Session Key Far Component (SKFC) SKI - Subject Key Identifier (SKI) SKNC - Session Key Near Component (SKNC) SLA - Service Level Agreement (SLA) SLAAC - Stateless Address Autoconfiguration (SLAAC) SLD - Second-Level Domain (SLD) SLI - Set-Link-Info (SLI) (includes hyphens) - Slice Lost Indication (SLI) SLLA - Source Link-Layer Address (SLLA) SLLAO - Source Link-Layer Address Option (SLLAO) SLO - Service Level Objective (SLO) SLP - Service Location Protocol (SLP) SLURM - Simplified Local Internet Number Resource Management with the RPKI (SLURM) SM - Single Marking (SM) SMB - Session Management Broker (SMB) - Server Message Block (SMB) SMDS - Switched Multimegabit Data Service (SMDS) SMF - Standard MIDI File (SMF) S/MIME *- Secure/Multipurpose Internet Mail Extensions SMI - Structure of Management Information (SMI) SMIL - Synchronized Multimedia Integration Language (SMIL) SMIv2 - Structure of Management Information Version 2 (SMIv2) SMP - Shared Mesh Protection (SMP) SMPTE - Society of Motion Picture and Television Engineers (SMPTE) SMR - Solicit-Map-Request (SMR) SMS *- Short Message Service SMSS - Sender Maximum Segment Size (SMSS) SMTP *- Simple Mail Transfer Protocol SMUX - SNMP Multiplex (SMUX) SN - Sequence Number (SN) Sn - No Expansion number value Sn in mathematical equations SNA - Systems Network Architecture (SNA) SNACK - Selective Negative Acknowledgment (SNACK) - Sequence Number Acknowledgement (SNACK) SNAP - Subnetwork Access Protocol (SNAP) - Simple Notification and Alarm Protocol (SNAP) SNI - Server Name Indication (SNI) SNIA - Storage Networking Industry Association (SNIA) SNID - subnamespace identifier (SNID) SNMP *- Simple Network Management Protocol SNP - Subnetwork Point (SNP) - Sequence Number Packet (SNP) - Sequence Number PDU (SNP) SNPA - Subnetwork Point of Attachment (SNPA) SNR - Signal-to-Noise Ratio (SNR) - Serial Number (SNR) SNTP - Simple Network Time Protocol (SNTP) SOA - Start of Authority - Source of Authority (SOA) SOAP *- Simple Object Access Protocol But "a Web services messaging protocol; originally the acronym for Simple Object Access Protocol, the term is no longer defined in common use" -IEEE Computer Society "In previous versions of this specification the SOAP name was an acronym. This is no longer the case." - W3C (http://www.w3.org/TR/2007/REC-soap12-part1-20070427/) SoC - System on Chip (SoC) SOCKS - No Expansion. name of protocol. SODP - Secure Object Delivery Protocol (SODP) SOHO - Small Office, Home Office (SOHO) SOI - SESSION-OF-INTEREST (SOI) SONET - Synchronous Optical Network (SONET) SOP - Start of Packet (SOP) - Same-Origin Policy (SOP) SP - Service Provider (SP) SPB - Shortest Path Bridging (SPB) SPBM - Shortest Path Bridging MAC mode (SPBM) (IEEE 802.1aq) SPC - Service Provider Code (SPC) - Soft Permanent Connection (SPC) SPD - Security Policy Database (SPD) SPE - Synchronous Payload Envelope (SPE) SPEKE - Simple Password Exponential Key Exchange (SPEKE) SPF - Sender Policy Framework (SPF) - Shortest Path First (SPF) 9/8/08 - SPF should be expanded in most if not all IS-IS documents as "Shortest Path First" rather than "Sender Policy Framework" SPHINCS - No Expansion SPI - Security Parameter Index (SPI) - Service Path Identifier (SPI) SPICE - Secure Protocol for Internet Content Exchange (SPICE) SPID - Service Provider ID (SPID) SPIT - Spam over Internet Telephony (SPIT) SPKI - Simple Public Key Infrastructure (SPKI) - SubjectPublicKeyInfo (SPKI) - Subject Public Key Info (SPKI) SPKM - Simple Public-Key GSS-API Mechanism (SPKM) SPM - Secure Password Method (SPM) SPME - Sub-Path Maintenance Element (SPME) SPND - Secure Proxy Neighbor Discovery (SPND) SPNEGO - Simple and Protected GSS-API Negotiation SPT - shortest path tree (SPT) SPVC - Switched Permanent Virtual Circuit (SPVC) SQL *- Structured Query Language SR - sender report (SR) - Segment Routing (SR) SR OS - Service Router Operating System (SR OS) SR-VCC - Single Radio Voice Call Continuity (SR-VCC) SRC - Session Recording Client (SRC) SRG - Shared Risk Group (SRG) SRGS - Speech Recognition Grammar Specification (SRGS) SRH - Source Routing Header (SRH) SRLG - Shared Risk Link Group (SRLG) SRP - Secure Routing Protocol (SRP) - Secure Remote Password (SRP) - Stateful PCE Request Parameter (SRP) SRR - status report request (SRR) - symmetric recursive routing (SRR) SRRO - Secondary Record Route Object (SRRO) SRS - Session Recording Server (SRS) SRTCP - Secure Real-time Transport Control Protocol (SRTCP) SRTE - Segment Routing Traffic Engineering (SRTE) SRTP - Secure Real-time Transport Protocol (SRTP) ("Realtime" also okay) SRTT - Smoothed Round-Trip Time (SRTT) SRV *- Service Record (SRV) (resource record) SS7 - Signaling System 7 (SS7) SS-FSSI - Sender-Side FEC-Scheme-Specific Information (SS-FSSI) SS-PW - Single-Segment Pseudowire (SS-PW) SSAP - Source Service Access Point (SSAP) SSE - Server Session End (SSE) - State Signaling Event (SSE) SSH - Secure Shell (SSH) [note: may need to add protocol; e.g., Secure Shell (SSH) protocol] SSID - Service Set Identifier (SSID) - Session ID (SSID) - STAMP Session Identifier (SSID) SSK - Secret Signing Key (SSK) SSL *- Secure Sockets Layer (SSL) SSL/TLS *- Secure Sockets Layer/Transport Layer Security (SSL/TLS) SSM *- source-specific multicast (SSM) - Single-Source Multicast (SSM) SSN - Server Sequence Number (SSN) - subsystem number (SSN) - Stream Sequence Number (SSN) - Station Serial Number (SSN) SSO - Single Sign-On (SSO) SSON - Spectrum-Switched Optical Network (SSON) SSP - scheme-specifc part (SSP) - SIP Service Provider (SSP) SSPI - Security Support Provider Interface (SSPI) SSRC - synchronization source (SSRC) SSRR - Strict Source and Record Route (SSRR) SSU - Synchronization Supply Unit (SSU) SSV - Shared Secret Value (SSV) - Secret State Verifier (SSV) ST-PE - Source Terminating Provider Edge (ST-PE) STag - Steering Tag (STag) STAMP - Simple Two-way Active Measurement Protocol (STAMP) STB - Set-Top Box (STB) STIR - Secure Telephone Identity Revisited (STIR) STP - Spanning Tree Protocol (STP) - Secure Transfer Protocol (STP) STS - Synchronous Transport Signal (STS) - Security Token Service (STS) STUN - Session Traversal Utilities for NAT (STUN) - Simple Traversal of the UDP Protocol through NAT (STUN) SUT - System Under Test (SUT) SVC - Switched Virtual Circuit (SVC) SVEC - Synchronization Vector (SVEC) *SVG - Scalable Vector Graphics (SVG) SVL - Shared VLAN Learning (SVL) SVN - Software Version Number (SVN) SW - Session Wide (SW) SWID - Software Identification (SWID) SWIMA - Software Inventory Message and Attributes (SWIMA) SWS - silly window syndrome (SWS) SYN - No Expansion TCP flag bit name. See FIN. syncE - synchronous Ethernet (syncE) T-MPLS - Transport MPLS (T-MPLS) T-PE - Terminating Provider Edge (T-PE) TA - Trust Anchor (TA) TAC - Type Allocation Code (TAC) TAE - Timing Alignment Error (TAE) TAL - Trust Anchor Locator (TAL) TAMP - Trust Anchor Management Protocol (TAMP) TAPI - Telephony Application Programming Interface (TAPI) - Transport API (TAPI) TC - Textual Convention (TC) Topology Control (TC) - messages Traffic Class (TC) Transmission Convergence (TC) Transparent Clock (TC) TCA - Target Channel Adapter (TCA) TCAM - Ternary Content-Addressable Memory (TCAM) TCB - Transmission Control Block (TCB) - Trusted Computing Base (TCB) TCN - Topology Change Notification (TCN) TCP *- Transmission Control Protocol TCP-AO - TCP Authentication Option (TCP-AO) TDD - Telecommunication Device for the Deaf (TDD) - Time-Division Duplex (TDD) TDIM - Time-Division Inverse Multiplexing (TDIM) TDM - Time-Division Multiplexer (TDM) - Time-Division Multiplexing (TDM) TDMA *- Time-Division Multiple Access See also CDMA - Time Division Multiplex (TDMA) TDMoIP - Time-Division Multiplexing over IP (TDMoIP) TE *- Traffic Engineering (TE) *- Traffic Engineered (TE) TEAP - Tunnel Extensible Authentication Protocol (TEAP) TED - Traffic Engineering Database (TED) TEE - Trusted Execution Environment (TEE) TEI - Terminal Endpoint Identifier (TEI) TEP - tunnel endpoint (TEP) TERENA - Trans-European Research and Education Networking Association (TERENA) TESLA - Timed Efficient Stream Loss-Tolerant Authentication (TESLA) TF - transport format (TF) TF-EMC2 - Task Force on European Middleware Coordination and Collaboration (TF-EMC2) TFC - Traffic Flow Confidentiality (TFC) TFO - TCP Fast Open (TFO) TFRC - TCP Friendly Rate Control (TFRC) TFS - Time and Frequency Synchronization (TFS) *TFTP - Trivial File Transfer Protocol TGS - Ticket-Granting Server (TGS) - Ticket-Granting Service (TGS) TGT - Ticket-Granting Ticket (TGT) THD - Total Harmonic Distortion (THD) TI-LFA - Topology Independent Loop-Free Alternate (TI-LFA) TIAS - Transport Independent Application Specific (Maximum) (TIAS) TIB - Tree Information Base (TIB) TIMIP - Terminal Independent Mobile IP (TIMIP) TIO - Transit Information Option (TIO) TKIP - Temporal Key Integrity Protocol (TKIP) TLD - Top-Level Domain (TLD) tLDP - Targeted LDP (tLDP) (not T-LDP as used in several other RFCs, e.g., RFC 6373) confirmed by WG Chair TLLA - Target Link-Layer Address (TLLA) TLLAO - Target Link-Layer Address Option (TLLAO) TLP - Tail Loss Probe (TLP) TLS *- Transport Layer Security (TLS) - Transparent LAN Services (TLS) TLSA - No exp TLSP - TRILL Link State Protocol (TLSP) TLV *- Type-Length-Value (self-describing data) TMCE - Traffic-Managed Controlled Environment (TMCE) TMF - Task Management Function (TMF) TML - Transport Mapping Layer TMMBR - Temporary Maximum Media Stream Bit Rate Request (TMMBR) TMMBN - Temporary Maximum Media Stream Bit Rate Notification (TMMBN) TMTU - Tunnel MTU (TMTU) TNC - Trusted Network Connect (TNC) TNCP - TRILL Network Control Protocol (TNCP) TNP - TRILL Network Protocol (TNP) TO - Tagged Offset (TO) ToIP - Real-time Text over Internet Protocol (ToIP) TOE - TCP Offload Engine (TOE) - target of evaluation (TOE) TOFU - trust-on-first-use (TOFU) TOI - Transmission Object Identifier (TOI) ToR - Top-of-Rack (ToR) TOS - Type of Service (TOS) TPA - Trust Provisioning Authority (TPA) TPGT - Target Portal Group Tag (TPGT) TPDU - Transport Protocol Data Unit (TPDU) TPM - Transport Performance Metrics (TPM) or TPM Trusted Platform Module (TPM) TPS - Transport Protocol Specific (TPS) TPUI - Temporary Portable User Identity (TPUI) TR - Tunnel Router (TR) TRILL - Transparent Interconnection of Lots of Links (TRILL) TS - Traffic Selector (TS) - Transport Stream (TS) - Tenant System (TS) TSA - Time Stamping Authority TSCH - Time-Slotted Channel Hopping (TSCH) TSDM - Trusted System Development Methodology (TSDM) TSecr - Timestamp Echo Reply (TSecr) TSI - Transport Session Identifier (TSI) - Tenant System Interface (TSI) TSM - Transport Security Model TSN - Trunk Switched Network (TSN) - Test Support Network (TSN) - Transmission Sequence Number (TSN) - Time-Sensitive Networking (TSN) TSO - TCP Segmentation Offload (TSO) TSTN - Temporal-Spatial Trade-off Notification (TSTN) TT-PE - Target Terminating Provider Edge (TT-PE) TTD - Throughput Test Device (TTD) TTL *- Time to Live TTP - Tunnel Termination Point (TTP) TTSI - Text-To-Speech Interface (TTSI) TTT - Target Transfer Tag (TTT) TU - Time Unit (TU) - transaction user (TU) TUG - Tributary Unit Group (TUG) TURN - Traversal Using Relay NAT (TURN) - Traversal Using Relays around NAT (TURN) TV - Type/Value (TV) TWAMP - Two-Way Active Measurement Protocol (TWAMP) TX *- Transmission UA - User Agent (UA) UAC - User Agent Client (UAC) UAK - User Authentication Key (UAK) UAL - Unused Association Lifetime (UAL) UAM - Universal Access Method (UAM) UART - Universal Asynchronous Receiver Transmitter (UART) UAS - User Agent Server (UAS) - Unavailable Seconds (UAS) uCDN - upstream Content Delivery Network (uCDN) UCMP - Unequal-Cost Multipath (UCMP) UCS - Uniform Client ID String (UCS) - Universal Multiple-Octet Coded Character Set (UCS) - Universal Coded Character Set (UCS) UDA - User Defined Application (UDA) UDDI - Universal Description, Discovery, and Integration (UDDI) UDP *- User Datagram Protocol UDP-Lite *- User Datagram Protocol Lite UDPTL - UDP Transport Layer (UDPTL) UDRP - Uniform Domain-Name Dispute-Resolution Policy (UDRP) UDVM - Universal Data/Voice Multiplexer (UDVM) UE - User Equipment (UE) UHF *- Ultra High Frequency UHP - Ultimate Hop Popping (UHP) UHR - Ultra-High Reliability (UHR) UI *- User Interface UICC - Universal Integrated Circuit Card (UICC) UID - Unique Identifier (UID) - User Identifier (UID) U/L - Universal/Local (U/L) ULA - Unique Local Addressing (ULA) - Unique Local Address (ULA) ULB - Upper Layer Binding (ULB) ULE - Ultra Low Energy (ULE) ULID - Upper-Layer Identifier (ULID) ULL - Ultra-Low Latency (ULL) ULP - Unequal Loss Protection (ULP) - Upper-Level Protocol (ULP) - Upper-Layer Protocol (ULP) UMA - Unlicensed Mobile Access (UMA) UMB - Ultra Mobile Broadband (UMB) UMH - Upstream Multicast Hop (UMH) UML - Unified Modeling Language (UML) UMTS - Universal Mobile Telecommunications System (UMTS) U-NAPTR - URI-Enabled NAPTR (U-NAPTR) UNC - Universal Naming Convention (UNC) UNI - User-Network Interface (UNI) U-NII - Unlicensed National Information Infrastructure (U-NII) UNSAF - UNilateral Self-Address Fixing (UNSAF) U-PE - User-facing PE (U-PE) UPA - Update Notification Acknowledgement (UPA) UPF - User Plane Function (UPF) UPN - Update Notification (UPN) UPnP - Universal Plug and Play (UPnP) URI *- Uniform Resource Identifier URL *- Uniform Resource Locator URLLC - Ultra-Reliable and Low Latency Communications (URLLC) URN *- Uniform Resource Name uRPF - unicast reverse path forwarding (uRPF) USB *- Universal Serial Bus USC - University of Southern California (USC) US-CERT - US Computer Emergency Readiness Team (CERT) USM - User-based Security Model USRK - Usage Specific Root Keys (USRK) UTC *- Coordinated Universal Time UTF-8 *- Unicode transformation format 8. UTI - Universal Transport Interface (UTI) Note: Cisco - Uniform Type Identifier (UTI) UTRAN - Universal Terrestrial Radio Access Network (UTRAN) UUCP - Unix-to-Unix Copy (UUCP) UUI - User-to-User Information (UUI) UUID - Universally Unique Identifier (UUID) V2V - vehicle to vehicle (V2V) V2X - vehicle to everything (V2X) VACM - View-based Access Control Model (VACM) VAD - Voice Activity Detection (VAD) VAP - Virtual Access Point (VAP) VAPID - Voluntary Application Server Identification (VAPID) VBCM - Video Back Channel Message (VBCM) VBD - Voiceband Data (VBD) VBR - Vouch By Reference (VBR) - Variable Bitrate (VBR) VBR-NRT - Variable Bit Rate - Non Real Time VBR-RT - Variable Bit Rate - Real Time VC - Virtual Circuit (VC) vCard *- No Expansion VCAT - Virtual Concatenation (VCAT) VCC - Virtual Channel Connection (VCC) VCCV - Virtual Circuit Connectivity Verification (VCCV) VCI - Virtual Channel Identifier (VCI) - Virtual Circuit Identifier (VCI) VDL - Valid Data Length (VDL) VDP - Virtual Station Interface (VSI) Discovery and Configuration Protocol (VDP) VDSL - Very high bit-rate Digital Subscriber Line (VDSL) - Very high speed Digital Subscriber Line (VDSL) VE - VPLS Edge (VE) VET - Virtual Enterprise Traversal (VET) VHF *- Very High Frequency VI - Virtual Interface (VI) VID - VLAN ID (VID) vIP *- virtual IP address (vIP) VL - VLAN labeled (VL) VLAN *- Virtual Local Area Network VLB - Valiant Load-Balancing (VLB) VM - Virtual Machine (VM) VMR - Variable Multi Rate (VMR) VMR-WB - Variable Multi Rate WideBand (VMR-WB) VMS - Virtual Memory System (VMS) VN - Virtual Network (VN) VNC - Virtual Network Computing (VNC) VNF - Virtual Network Function (VNF) VNI - VXLAN Network Identifier - Virtual Network Identifier (VNI) VNTM - Virtual Network Topology Manager (VNTM) VoD - Video on Demand (VoD) VoIP - Voice over IP (VoIP) VoLTE - Voice over LTE (VoLTE) VO - Virtual Organization (VO) VOP - Video Object Plane (VOP) VOQ - Virtual Output Queueing (VOQ) VPC - Virtual Path Connection (VPC) VPD - Vital Product Data (VPD) VPI - Virtual Path Identifier (VPI) VPIM - Voice Profile for Internet Mail (VPIM) VPN *- Virtual Private Network (VPN) VPLS - Virtual Private LAN Service (VPLS) VPMS - Virtual Private Multicast Service (VPMS) VPWS - Virtual Private Wire Service (VPWS) VR - Virtual Reality (VR) VRF - VPN Routing and Forwarding (VRF) - Virtual Routing and Forwarding (VRF) VRID - Virtual Router Identifier (VRID) VRP - VLAN Registration Protocol (VRP) - Versatile Routing Platform (VRP) VRRP - Virtual Router Redundancy Protocol (VRRP) VSA - Vendor-Specific Attribute (VSA) VSI - Virtual Switch Instance (VSI) - Virtual Station Interface (VSI) VSP - Voice Service Provider (VSP) VSS - Virtual Subnet Selection (VSS) VT - Virtual Tributary (VT) - Voltage Transformer (VT) VTEP - VXLAN Tunnel End Point (VTEP) VXLAN - Virtual eXtensible Local Area Network (VXLAN) VXML - VoiceXML (VXML) W3C *- World Wide Web Consortium (W3C) WAMS - Wide-Area Management System (WAMS) WAN *- Wide Area Networks WAP - Wireless Application Protocol (WAP) W-CDMA - Wideband Code Division Multiple Access (W-CDMA) WCE - Write Cache Enable (WCE) WDM - Wavelength Division Multiplexing (WDM) WebDAV - Web Distributed Authoring and Versioning (WebDAV) WEBRC - Wave and Equation Based Rate Control (WEBRC) WebRTC *- Web Real-Time Communication (WebRTC) WEP - Wired Equivalent Privacy (WEP) WF - Wildcard-Filter (WF) WFQ - Weighted Fair Queuing (WFQ) WG *- Working Group WGLC - Working Group Last Call WGS 84 - World Geodetic System 1984 (WGS 84) WHT - Walsh-Hadamard transform (WHT) WiLD - WiFi-based Long Distance (WiLD) WiMAX - Worldwide Interoperability for Microwave Access (WiMAX) WKP - Well-Known Prefix (WKP) - Well-Known Port (WKP) WLAN *- Wireless Local Area Network (WLAN) WLE - Whole Label Evaluation (WLE) WM - Wireless Medium (WM) WMN - Wireless Mesh Network (WMN) WOTS - Winternitz One-Time Signature (WOTS) WPA2 - Wi-Fi Protected Access 2 (WPA2) WRAP - Web Resource Authorization Profiles (WRAP) WRED - Weighted Random Early Detection (WRED) WRR - Weighted Round Robin (WRR) WS - White Space (WS) WSDL - Web Services Description Language (WSDL) WSON - Wavelength Switched Optical Network (WSON) WSP - whitespace (WSP) WSR - Window Size Ratio (WSR) WSS - Wavelength Selective Switch (WSS) - Secure WebSocket (WSS) - Web Services Security (WSS) WTP - Wireless Termination Point (WTP) WTR - Wait to Restore (WTR) WWN - World Wide Name (WWN) WWNN - World Wide Node Name (WWNN) WWPN - World Wide Port Name (WWPN) WWW *- World Wide Web XACML - eXtensible Access Control Markup Language (XACML) XCAP - XML Configuration Access Protocol (XCAP) Xcast - Explicit Multicast (Xcast) XCON - Centralized Conferencing (XCON) XDR - External Data Representation (XDR) XEID - Extended Endpoint Identifier (XEID) XHTML *- Extensible Hypertext Markup Language (XHTML) XID - Transaction ID XIP - Execute in Place (XIP) XLAT - translator (XLAT) XML *- Extensible Markup Language XML-DA - XML-Data Access (XML-DA) XML-RPC - Extensible Markup Language-Remote Procedure Calling (XML-RPC) XMLDSIG - XML Digital Signatures (XMLDSIG) XMLSIG - XML-Signature Syntax and Processing (XMLSIG) XMP - Extensible Metadata Platform (XMP) XMPP - Extensible Messaging and Presence Protocol (XMPP) XNQ - eXtended Network Quality (XNQ) XOR *- exclusive or (see EOR above) XPath - XML Path Language (XPath) XR - Extended Report (XR) XRD - Extensible Resource Descriptor (XRD) XRI - Extensible Resource Identifier (XRI) XRO - Exclude Route Object (XRO) XSD - XML Schema Definition (XSD) XSF - XMPP Standards Foundation (XSF) XTP - Xpress Transfer Protocol (XTP) - Xpress Transport Protocol (XTP) XUI - XCAP User Identifier (XUI) YADIFA *- No Expansion YAML *- do not expand YANG *- Do not expand YIN - YANG Independent Notation (YIN) ZWP - Zero Window Probe (ZWP) zsh - Z SHell (zsh) ZKPP - Zero-Knowledge Password Proof (ZKPP) ZRTP - No Expansion ZSK - Zone Signing Key (ZSK)