Acronym
Meaning
Primary
Applicability
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
Organization
Institute
API
Application Programming
Interface
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
Organization
has been replaced by ITU-T
ITU-T
CHAP
Challenge-Handshake
Authentication Protocol
(PPP)
Security, telecom
RFC 1994
CIDR
Classless Inter-Domain
Routing
Architecture
RFC 1518 RFC 1519
ANSI
Software
CIR
Committed Information Rate
Telecom
(Frame Relay)
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
Cyclical redundancy check
Link and other layers 24 References here.
CRC-16-CCITT
Cyclical redundancy check
(X.25, HDLC)
Link layers
CSMA/CA
Carrier sense multiple access
Wireless
/ collision avoidance
IEEE Std 802.11 Downloads
CSMA/CD
Carrier sense multiple access
Physical layer
/ collision detection
IEEE Std 802.3TM-2002
CSU/DSU
Channel service unit / data
service unit
Telecom
Telecom Glossary
CMOS
Comp metal-oxide
semiconductor
Utillity
Wikipedia
DCE
Data communications
equipment
Telecom
-Telecom Glossary
DEC (obs.)
Digital Equipment
Corporation
Organization
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 Application layer,
Protocol
Internet Layer
Reference on CRC page.
RFC 2131 and others
DNS
Domain Name System
Application layer
Over 30 RFCs here.
DRAM
Dynamic random-access
memory
Hardware
DSL
Digital Subscriber Line
Telecom
Telecom Glossary
DSLAM
Digital Subscriber Line
Access Multiplexor
Telecom
Telecom Glossary (proposed)
DTE
Data Terminal Equipment
Telecom
Telecom Glossary
DMI
Desktop Management
Interface
Utillity
Wikipedia
EHA
Ethernet Hardware Address
Link layer
(MAC address)
IEEE Std 802 IEEE OUI Assignments
EIA
Electronics Industry Alliance Organization
EIA
EIGRP
Enhanced Interior Gateway
Routing Protocol
Internet Layer
Cisco Doc ID: 16406
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
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 Transport and other
Secure
layers
SSL 3.0 Specification
IANA
Internet Assigned Number
Authority
Organization
IANA
ICMP
Internet Control Message
Protocol
Internet Layer
RFC 792
IDF
Intermediate distribution
frame
Physical layer
Structured cabling or Telecom
Glossary
IDS
Intrusion Detection
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
"NIST - Guide to Intrusion
Detection and Prevention Systems
(IDPS)". 2007-02. Retrieved 201008-24.
IPS
Intrusion prevention system Security
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
Telecommunications 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
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
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
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
Sample vendor data here
Link and other layers IEEE 802.1x
Hardware
OSI
Open System Interconnect
Organization
(joint ISO and ITU standard)
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
PC
Personal computer (host)
Hardware
PIM
Personal information
manager
Software category
PIM
Privileged Identity
Management
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
Application layer
3
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 DialSecurity
In User Service
RFC 2865
RAM
Random Access Memory
Physical layer
Telecom Glossary
RARP
Reverse ARP
Link layer
RFC 903
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
RCP
Royal College of Physicians
RFC 69
Gibson layer
SDLC
Synchronous Data Link
Control
Link layer
Cisco Technology Handbook: SDLC
and Derivatives
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
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
Telecom
(obs.)
RFC 1055
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
Seagate Specification
IEEE 802.11
Cisco's Introduction to Spanning
Tree Protocol
STP
Spanning Tree Protocol
Link layer
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
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
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
IEEE 802.11 (Wi-Fi Alliance)
Wireless
Wi-Fi Alliance
WPA
Wi-Fi Protected Access
Security
IEEE 802.11i
www
World Wide Web
Architecture
W3C Consortium