Abbreviation
|
Meaning
|
Primary Applicability[4]
|
Normative Reference
|
ACK
|
Acknowledgement
|
Transport and other layers
|
TCP/IP, for example. RFC 793
|
ACL
|
Access control list
|
Security, application layer
|
Access control list, Cisco overview
|
ADSL
|
Asymmetric digital subscriber line
|
Telecom
|
ITU-T G.992.5 Annex M, for example
|
AES
|
Advanced Encryption Standard
|
Security
|
U.S. FIPS PUB 197
|
ANSI
|
American National Standards Institute
|
Organization
|
ANSI
|
API
|
Application Programming Interface
|
Software
|
API
|
ARP
|
Address Resolution Protocol
|
Link layer
|
RFC 1122
|
ATM
|
Asynchronous Transfer Mode
|
Telecom
|
ATM cell description
|
BGP
|
Border Gateway Protocol (routing protocol)
|
Application layer, Routers
|
RFC 4271
|
BSS
|
Basic service set (Wi-Fi)
|
Wireless
|
IEEE Std 802.11-2007
|
CAT
|
Category (e.g. CAT-5 cable)
|
Physical layer
|
ANSI/TIA/EIA-568-B.1-2001
|
CCITT (obs.)
|
Standards organization that has been replaced by ITU-T
|
Organization
|
ITU-T
|
CHAP
|
Challenge-Handshake Authentication Protocol (PPP)
|
Security, telecom
|
RFC 1994
|
CIDR
|
Classless Inter-Domain Routing
|
Architecture
|
RFC 1518 RFC 1519
|
CIR
|
Committed Information Rate (Frame Relay)
|
Telecom
|
RFC 1490 RFC 1973 RFC 2427
|
CLI
|
Command line interpreter
|
Hardware
|
Catalyst 6500 Series Command Reference, 7.6, for example
|
CPE
|
Customer premises equipment
|
Telecom
|
Telecom Glossary
|
CPU
|
Central processing Unit
|
Microprocessor
|
Wikipedia
|
CRC
|
Cyclic redundancy check
|
Link and other layers
|
24 References here.
|
CRC-16-CCITT
|
Cyclic redundancy check (X.25, HDLC)
|
Link layers
|
Reference on CRC page.
|
CRT
|
Cathode Ray Tube
|
Television set, Computer Monitor
|
Cathode ray tube
|
CSMA/CA
|
Carrier sense multiple access / collision avoidance
|
Wireless
|
IEEE Std 802.11 Downloads
|
CSMA/CD
|
Carrier sense multiple access / collision detection
|
Physical layer
|
IEEE Std 802.3TM-2002
|
CSU/DSU
|
Channel service unit / data service unit
|
Telecom
|
Telecom Glossary
|
CMOS
|
Complementary metal-oxide semiconductor
|
Utility
|
CMOS
|
DAM
|
Database activity monitoring
|
Security
|
Database activity monitoring
|
DAM
|
Digital asset management
|
Internet Layer
|
Digital asset management
|
DCE
|
Data communications equipment
|
Telecom
|
Telecom Glossary
|
DEC (obs.)
|
Digital Equipment Corporation
|
Organization
|
Digital Equipment Corporation formally Purchased by Compaq in 1998. Merged with Hewlett-Packard 2002.
|
DES
|
Data Encryption Standard (obs. See AES)
|
Security
|
Federal Information Processing Standard (FIPS) FIPS-46-3
|
DHCP
|
Dynamic Host Configuration Protocol
|
Application layer, Internet Layer
|
RFC 2131 and others
|
DIMM
|
Dual In-line Memory Module
|
Hardware
|
DIMM
|
DNS
|
Domain Name System
|
Application layer
|
Over 30 RFCs here.
|
DRAM
|
Dynamic random-access memory
|
Hardware
|
Dynamic random-access memory
|
DSL
|
Digital subscriber line
|
Telecom
|
Telecom Glossary
|
DSLAM
|
Digital subscriber line access multiplexer
|
Telecom
|
Telecom Glossary (proposed)
|
DTE
|
Data Terminal Equipment
|
Telecom
|
Telecom Glossary
|
DMI
|
Desktop Management Interface
|
Utility
|
Desktop Management Interface
|
EHA
|
Ethernet Hardware Address (MAC address)
|
Link layer
|
IEEE Std 802 IEEE OUI Assignments
|
EIA
|
Electronics Industry Alliance
|
Organization
|
EIA
|
EIGRP
|
Enhanced Interior Gateway Routing Protocol
|
Internet Layer
|
Cisco Doc ID: 16406
|
EMAC
|
Ethernet Media Access Control
|
Link Layer
|
|
EOF
|
End Of Frame (HDLC, etc.)
|
Link layer
|
HDLC framing
|
ESS
|
Extended service set (Wi-Fi group)
|
Wireless
|
IEEE Std 802.11-2007
|
FCC
|
Federal Communications Commission (US)
|
Organization
|
US FCC
|
FCS
|
Frame check sequence (Ethernet)
|
Link layer
|
Ethernet Frame IEEE Std 802.3
|
FDDI
|
Fiber Distributed Data Interface
|
Link layer
|
American National Standards Institute X3T9.5 (now X3T12), ISO/IEC 9314-x
|
FTP
|
File Transfer Protocol
|
Application layer
|
RFC 959 and others
|
GBIC
|
Gigabit interface converter
|
Hardware
|
Seagate Specification
|
gbps
|
Gigabit per second
|
Physical layer
|
Gigabit per second
|
GEPOF
|
Gigabit Ethernet (over) Plastic Optical Fiber
|
Physical layer
|
IEEE P802.3bv
|
GMAC
|
Gigabit Ethernet Media Access Control
|
Link Layer
|
|
HDLC
|
High-level Data Link Control
|
Link layer
|
ISO 13239
|
HTTP
|
HyperText Transfer Protocol
|
Application layer
|
W3C Change History for HTTP
|
HTTPS
|
HyperText Transfer Protocol Secure
|
Transport and other layers
|
SSL 3.0 Specification
|
IaaS
|
Infrastructure as a service
|
Cloud Services
|
IaaS Microsoft Docs
|
IANA
|
Internet Assigned Number Authority
|
Organization
|
IANA
|
ICaaS
|
Integration Capability as a Service
|
Organization
|
ICaaS
|
ICMP
|
Internet Control Message Protocol
|
Internet Layer
|
RFC 792
|
IDF
|
Intermediate distribution frame
|
Physical layer
|
Structured cabling or Telecom Glossary
|
IDS
|
Intrusion Detection System
|
Security
|
Wikipedia
|
IEEE
|
Institute for Electrical and Electronic Engineers
|
Organization
|
IEEE
|
IETF
|
Internet Engineering Task Force
|
Organization
|
IETF
|
IMAP
|
Internet Message Access Protocol
|
Application layer
|
RFC 3501
|
IP
|
Internet Protocol
|
Internet Layer
|
RFC 791 RFC 1606
|
IPS
|
Intrusion prevention system
|
Security
|
"NIST - Guide to Intrusion Detection and Prevention Systems (IDPS)". 2007-02. Retrieved 2010-08-24.
|
IS-IS
|
Intermediate System to Intermediate System (routing protocol)
|
Internet Layer
|
ISO/IEC 10589:2002
|
ISDN
|
Integrated Services Digital Network
|
Telecom
|
IEC Area 716-xx
|
ISP
|
Internet service provider
|
Telecom
|
Telecom Glossary
|
ITU-T
|
International Telecommunication Union
|
Organization
|
http://www.itu.int
|
kbps
|
Kilobit per second
|
Physical layer
|
Kilobit per second
|
LACP
|
Link Aggregation Control Protocol
|
Data link layer
|
|
LAN
|
Local area network
|
Link and other layers
|
Telecom Glossary
|
LAPB
|
Link Access Procedure, Balanced (x.25)
|
Telecom
|
ITU-T Recommendation X.222
|
LAPF
|
Link-access procedure for Frame Relay
|
Telecom
|
RFC 1490
|
LLC
|
Logical link control
|
Link layer
|
Telecom Glossary
|
MAC
|
Media access control
|
Link layer
|
IEEE Std 802.3 and 802.11, for example
|
MAM
|
Media access management (related to Digital asset management)
|
Internet layer
|
Wikipedia
|
MAN
|
Metropolitan area network
|
Telecom
|
Telecom Glossary
|
Mbps
|
Megabits per second
|
Physical layer
|
Megabit_per_second
|
MC
|
Multiple choice
|
IT Professional Certification
|
About certification exams
|
MDF
|
Main distribution frame
|
Physical layer
|
Glossary See also Structured cabling
|
MIB
|
Management information base (SNMP)
|
Application layer
|
RFC 3418
|
MII
|
Media-independent Interface
|
Link layer
|
|
MoCA
|
Multimedia over Coax Alliance
|
Organization
|
Multimedia over Coax Alliance
|
MPLS
|
Multiprotocol Label Switching
|
network technology
|
|
MTU
|
Maximum Transmission Unit
|
Multiple layers
|
|
NAC
|
Network access control
|
Link and other layers
|
IEEE 802.1x
|
NAS
|
Network-attached storage
|
Hardware / Storage
|
Computer data storage
|
NAT
|
Network Address Translation
|
Internet Layer
|
Cisco Internet Protocol Journal: A look Inside Network Address Translators
|
NBMA
|
Non-Broadcast Multiple Access (e.g. Frame Relay ATM)
|
Telecom
|
See ATM, Frame Relay and X.25, for examples.
|
NIC
|
Network Interface Card
|
Physical layer
|
Telecom Glossary
|
NRZ
|
Non-return-to-zero
|
Physical layer
|
Federal Standard 1037C
|
NRZI
|
Non-return to zero inverted
|
Physical layer
|
Federal Standard 1037C
|
NVRAM
|
Non-volatile RAM
|
Hardware
|
Sample vendor data here
|
OSI
|
Open System Interconnect (joint ISO and ITU standard)
|
Organization
|
ISO/IEC 9594-5:2005 Open Systems Interconnection Protocol Specifications
|
OSPF
|
Open Shortest Path First (routing protocol)
|
Internet Layer
|
RFC 2238
|
OUI
|
Organization Unique Identifier
|
Link and other layers
|
IEEE OUI Assignments
|
PAP
|
Password authentication protocol
|
Security
|
RFC 1334
|
PAT
|
Port address translation
|
Internet Layer
|
RFC 1918
|
PaaS
|
Platform as a service
|
Cloud Computing/Service
|
Platform as a service
|
PC
|
Personal computer (host)
|
Hardware
|
|
PIM
|
Personal information manager
|
Software category
|
|
PCM
|
Pulse-code modulation
|
Physical layer
|
ITU-T G.711
|
PDU
|
Protocol data unit (such as segment, packet, frame, etc.)
|
Multiple layers
|
Fed Std 1037C
|
POP3
|
Post Office Protocol, version 3
|
Application layer
|
RFC 1939
|
POP
|
Point of presence
|
Telecom
|
Telecom Glossary
|
POST
|
Power-on self test
|
Hardware
|
Cisco Catalyst 2800 User Guide, for example
|
POTS
|
Plain old telephone service
|
Telecom
|
Telecom Glossary
|
PPP
|
Point-to-point Protocol
|
Telecom
|
RFC 1661
|
PPTP
|
Point-to-Point Tunneling Protocol
|
Telecom
|
RFC 2637
|
PTT
|
Public Telephone and Telegraph
|
Telecom
|
Telecom Glossary or Free Dictionary
|
PVST
|
Per-VLAN Spanning Tree
|
Link layer
|
Cisco's introduction to Spanning Tree Protocol
|
RADIUS
|
Remote Authentication Dial-In User Service
|
Security
|
RFC 2865
|
RAM
|
Random Access Memory
|
Physical layer
|
Telecom Glossary
|
RARP
|
Reverse ARP
|
Link layer
|
RFC 903
|
RIMM
|
Rambus In-line Memory Module
|
Hardware
|
Wikipedia
|
RFC
|
Request for Comments
|
Multiple layers
|
IETF's RFC Index
|
RIP
|
Routing Information Protocol
|
Internet Layer
|
RFC 2453, for RIP version 2
|
RLL
|
Run-Length Limited
|
Physical layer
|
RLL is used in a wide range of encodings.
|
ROM
|
Read-Only Memory
|
Hardware
|
Telecom Glossary
|
RSTP
|
Rapid Spanning Tree Protocol
|
Link layer
|
IEEE 802.1w - Rapid Reconfiguration of Spanning Tree
|
RTP
|
Real-time Transport Protocol
|
Application layer
|
RFC 3550
|
SaaS
|
Software as a service
|
Cloud Computing/Service
|
Software as a service Microsoft Docs
|
SDLC
|
Synchronous Data Link Control
|
Link layer
|
Cisco Technology Handbook: SDLC and Derivatives
|
SDN
|
Software-defined networking
|
Architecture
|
Software-defined networking
|
SFD
|
Start-of-frame delimiter (Ethernet, HDLC, etc.)
|
Link layer
|
IEEE 802.3 (Ethernet), or RFC 2687 (HDLC), for examples
|
SFP
|
Small form-factor pluggable
|
Hardware
|
Seagate Specification
|
S-HTTP
|
Secure HTTP (rarely used)
|
Transport and other layers
|
RFC 2660 See also https
|
SLARP
|
Serial Line ARP (Address Resolution Protocol)
|
Link and other layers
|
Archived Cisco Serial Line Encapsulation extension
|
SLIP
|
Serial Line Internet Protocol (obs.)
|
Telecom
|
RFC 1055
|
SIMM
|
Single In-line Memory Module
|
Hardware
|
Wikipedia
|
SMTP
|
Simple Mail Transfer Protocol
|
Application layer
|
RFC 5321
|
SNA
|
Systems Network Architecture (IBM)
|
Multiple layers
|
SNA Protocol Suite
|
SNAP
|
SubNet Access Protocol
|
Link layer
|
IEEE 802 Overview and Architecture
|
SNMP
|
Simple Network Management Protocol
|
Application layer
|
RFC 1155, RFC 3410 thru RFC 3418 and others
|
SOF
|
Start of frame
|
Link layer
|
IEEE 802.3 (Ethernet), or RFC 2687 (HDLC), for examples
|
SRAM
|
Static random access memory
|
Hardware
|
PC Guide's Definition
|
SSH
|
Secure shell
|
Application layer
|
RFC 4252
|
SSID
|
Service set identifier (Wi-Fi)
|
Wireless
|
IEEE 802.11
|
STP
|
Spanning Tree Protocol
|
Link layer
|
Cisco's Introduction to Spanning Tree Protocol
|
SYN (TCP)
|
Synchronization
|
Link and other layers
|
RFC 793 and many others
|
TCP/IP
|
Transmission Control Protocol/Internet Protocol
|
Transport layer
|
RFC 793 and many others
|
TDM
|
Time-division multiplexing
|
Physical layer
|
Fed Std 1037C
|
TFTP
|
Trivial File Transfer Protocol
|
Application layer
|
RFC 1350
|
TIA
|
Telecommunications Industry Alliance
|
Organization
|
Telecommunications Industry Association
|
TOFU
|
Trust On First Use
|
Security
|
Improving SSH-style Host Authentication with Multi-Path Probing
|
UDP
|
User Datagram Protocol
|
Transport layer
|
RFC 768
|
URL
|
Uniform Resource Locator
|
Web address
|
URL spec (1994)
|
USB
|
Universal Serial Bus
|
Physical and other layers
|
USB 3.0 Specification
|
UTP
|
Unshielded twisted pair
|
Physical
|
Many versions are defined by TIA, such as: TIA-568-B
|
VC
|
Virtual circuit
|
Transport and other layers
|
Telecom Glossary
|
VLAN
|
Virtual local area network
|
Link layer
|
IEEE 802.1Q
|
VLSM
|
Variable-length subnet masking
|
Architecture
|
RFC 1518 RFC 1519
|
VM
|
Virtual machine
|
virtualization/emulation
|
Virtual machine
|
VPN
|
Virtual private network
|
Application layer
|
Virtual Private Network Consortium
|
W3C
|
World Wide Web Consortium
|
Organization
|
W3C
|
WAN
|
Wide-area network
|
Telecom
|
Telecom Glossary
|
WEP
|
Wired Equivalent Privacy
|
Wireless
|
IEEE 802.11
|
Wi-Fi
|
An implementation of IEEE wireless communication standard 802.11
|
Wireless
|
Wi-Fi Alliance
|
WLC
|
Wireless LAN Controller
|
Wireless
|
Cisco
|
WPA
|
Wi-Fi Protected Access
|
Security
|
IEEE 802.11i
|
www
|
World Wide Web
|
Architecture
|
W3C Consortium
|