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Table Of Contents

GLOSSARY

The following glossary of acronyms expands acronyms and initialisms that are used in Cisco IOS System Messages.

Numerals
	10GE	10 Gigabit Ethernet
A
	AAA	authentication, authorization, and accounting
	AAL5	ATM adaptation layer 5
	ABM	asynchronous balanced mode
	ABR	Area Border Router
	AC	alternating current
	ACE	Allegro Crypto Engine
	ACIP	ATM Cable Interface Processor
	ACK	acknowledgment
	ACL	access control list
	ACO	alarm cutoff
	ACTLU	activate logical unit
	ACTPU	activate physical unit
	ADSL	asymmetric digital subscriber line
	AFI	Address Family Identifier
	AH	Authentication Header
	AIC	Alarm Interface Controller
	AIM	Advanced Interface Module
	AIM	advanced integration module
	AIP	ATM Interface Processor
	AIS	Alarm indication
	ALC	ATM line card
	ALPS	Airline Product Set
	AMD	Advanced Micro Devices
	ANR	Automatic Network Routing
	ANSI	American National Standards Institute
	ANY-PHY	Any physical layer-data link layer
	AP	access point
	AP	authentication proxy
	API	application programming interface
	APING	APPC Ping
	APN	access point name
	APPC	Advanced Program-to-Program Communications
	APPN	Advanced Peer-to-Peer Networking
	APS	automatic protection switching
	AQD	average queue depth
	ARAP	AppleTalk Remote Access Protocol
	ARB	Adaptive Rate-Based
	ARP	Address Resolution Protocol
	ARQ	automatic repeat request
	AS	autonomous system
	ASCU	agent-set control unit
	ASIC	application-specific integrated circuit
	ASP	ATM switch processor
	ATA	Advanced Technology Attachment
	ATA	Analog Telephone Adaptor
	ATF	area to free
	ATM	Asynchronous Transfer Mode
	AToM	Any Transport over MPLS
	AURP	AppleTalk Update-Based Routing Protocol
	AutoRP	Auto-Rendezvous Point
	AVL	approved vendor list

B
	BAP	Bandwidth Allocation Protocol
	BB	broadband
	BBI	begin bracket indicator
	BCS	business critical solution
	BERT	bit error rate tester
	BFR	Bigger, Faster Router
	BFRP	big fast route processor
	BGP	Border Gateway Protocol
	BGPPA	Border Gateway Protocol Policy Accounting
	BIC	backplane interface card
	BIDI	bidirectional bus
	BIND	Berkeley Internet Name Domain
	BIP	bit interleaved parity
	BIS	Broadband Interface Shelf
	BLLI	Broadband Low Layer Information
	BMA	Buffer Management ASIC
	BOOM	10BASE-T Ethernet LAN interface card
	BOOTP	Bootstrap Protocol
	BPDU	bridge protocol data unit
	BPI	baseline privacy interface
	BPVC	Bridged Permanent Virtual Circuit
	BR	Undefined
	BRI	Basic Rate Interface
	BRF	Bridge Relay Function
	BSC	Binary Synchronous Communications
	BSS	Business Support System
	BSTUN	Block Serial Tunnel
	BTU	British thermal unit
	BUS	broadcast-and-unknown server

C
	CA	certification authority
	CAIM	Compression Advanced Interface Module
	CAM	content-addressable memory
	CAMR	Cisco Access Metro Router
	CAR	Undefined
	CAS	channel-associated signaling
	CASA	Cisco Appliance and Services Architecture
	CBAC	Context-Based Access Control
	CBC	Cell Bus Controller
	CBI	Cell Bus Interface
	CBus	CiscoBus
	CBWFQ	Class Based Weighted Fair Queueing
	CCA	Common Configuration Architecture
	CCAPI	call control API
	CCB	call control block
	CCB	configuration control block
	CCO	Cisco Connection Online
	CCW	channel command word
	CDI	Common Driver Interface
	CDL	Converged Data Link
	CDM	cable data modem
	CDP	Cisco Discovery Protocol
	CDR	clock and data recovery
	CE	certificate enrollment
	CEB	Common EMS Base
	CEBI	conditional end bracket indicator
	CEF	Cisco Express Forwarding
	CES	circuit emulation service
	CET	Cisco Encryption Technology
	CF	Checkpoint Facility
	CFI	Common Flash Interface
	CGMP	Cisco Group Management Protocol
	CGX	CryptoGraphics eXtensions
	CHAP	Challenge Handshake Authentication Protocol
	cHPI	compact Host Port Interface
	CI	connection identifier
	CICS	Customer Information Control System
	CIP	Channel Interface Processor
	CIR	committed information rate
	CIS	Card Information Services
	CIU	Communication Interface Unit
	CLAW	Common Link Access for Workstations
	CLI	command-line interface
	CLNS	Connectionless Network Service
	CLS	Cisco link services
	CLSI	Cisco link services interface
	CMCC	Cisco Mainframe Channel Connection
	CMNS	Connection Mode Network Service
	CMPC	Cisco Multipath Channel
	CMTS	cable modem termination system
	CNR	Cisco Network Registrar
	CNOS	change number of sessions
	CNS	Cisco Networking Services
	CNSP	Complete Number Sequence PDU
	COAPS	Count of APS switchovers
	codec	coder-decoder
	CoS	class of service
	CoSQ	Class of Service Queues
	COT	continuity testing
	CP	control point
	CP	coprocessor
	CPA	Channel Port Adapter
	CPE	customer premises equipment
	CPI	common part indicator
	CPI-C	common programming interface for communications
	CPK	Undefined
	CPM	Combination Port Module
	CPUIF	Undefined
	CRC	cyclic redundancy check
	CRF	Concentrator Relay Function
	CRL	certificate revocation list
	cRTP	compressed Real-Time Protocol
	CRV	call reference value
	CSA	compression service adapter
	CSAR	Cisco Cell Segmentation and Reassembly
	CSC	clock switch card
	CSG	Content Services Gateway
	CSI	called subscriber identification
	CSM	call switching mode
	CSM	call switching module
	CSNA	Cisco SNA
	CSNP	Complete Sequence Number PDU
	CSU	channel service unit
	CTC	Cisco Transport Controller
	CTL	Certificate Trust List
	CTRC	Cisco Transaction Connection
	CTS	Clear To Send
	CV	Cisco View
	CWAN	Constellation WAN
	CWTLC	Constellation Wan Toaster Line Card
	CyBus	Cisco Extended Bus

D
	DAE	data aggregrator end
	DBus	diagnostic bus
	DC	direct-connect
	DC	direct current
	DCD	data carrier detect
	DCE	data communications equipment
	dCEF	distributed Cisco Express Forwarding
	DDOS	distributed denial of service
	DDR	dial-on-demand routing
	DDSM	Digital Data Services Manager
	DECnet	Digital Equipment Corporation network
	DEMUX	demultiplexer
	DFC	dial feature card
	DFP	Dynamic Feedback Protocol
	DFRAC	Dual Framer and RAC
	DHCP	Dynamic Host Configuration Protocol
	DHCPv6	Dynamic Host Configuration Protocol, version 6
	DIB	Directory Information Base
	DIP-4	4-bit Diagonal Interleaved Parity
	DLC	data-link connection
	DLC	data-link control
	DLCI	data-link connection identifier
	dLFI	Distributed Link Fragmentation and Interleaving
	dLFIoATM	Distributed Link Fragmentation and Interleaving over ATM
	dLFIoFR	Distributed Link Fragmentation and Interleaving over Frame Relay
	DLR	designated local retransmitter
	DLSw	data-link switching
	DLU	dependent logical unit
	DLU	destination logical unit
	DLU	dynamic logical unit
	DLUR	dependent logical unit requester
	DLUS	dependent logical unit server
	DM	dense mode
	DM	disconnect mode
	DMA	direct memory access
	DMAC	destination MAC
	DML	distributed multilink
	DMLP	Distributed Multilink Point-to-Point Protocol
	DNIS	dialed number identification service
	DNS	Domain Name Server
	DNS	Domain Name Service
	DNS	Domain Name System
	DOCSIS	Data-over-Cable Service Interface Specifications
	DOI	domain of interpretation
	DoS	denial of service
	DPRAM	dual-port RAM
	DR	Designated Router
	DR	dynamic replenishment
	DRAM	dynamic RAM
	DRDA	Distributed Relational Database Architecture
	DRiP	Duplicate Ring Protocol
	DRP	Director Response Protocol
	DRQ	Direct memory access Receive Queue
	DS	dial shelf
	DSA	delayed stop accounting
	DSC	dial shelf control
	DSC	dial shelf controller
	DSCP	differentiated service code pointer
	DSI	dial shelf interconnect
	DSI	dial shelf interface
	DSIP	Dial Shelf Interconnect Protocol
	DSL	digital subscriber line
	DSLAM	digital subscriber line ATM multiplexer
	DSMP	Distributed Stream Media Processor
	DSP	digital signal processor
	DSP	Domain Specific Part
	DSP	digital signal processor
	DSPFARM	digital signal processor farm
	DSPM	digital signal processor module
	DSPRM	Digital Signal Processor Resource Manager
	DSPU	downstream physical unit
	DSR	data set ready
	DSU	data service unit
	DSU	digital service unit
	DTE	data terminal equipment
	DTP	Dynamic Trunking Protocol
	DTQ	Direct memory access Receive Queue
	DTR	data terminal ready
	DVMRP	Distance Vector Multicast Routing Protocol

E
	E1T1	E1 line or T1 line
	EADI	Extended Availability Drop and Insert
	EAIM	Encryption AIM
	EAP	Extensible Authentication Protocol
	EAPoUDP	Extensible Authentication Protocol over User Datagram Protocol
	EARL	enhanced address recognition logic
	EC	EtherChannel
	ECA	ESCON Channel Adapter
	ECC	error-correcting code
	ECC	Error-Check Code
	ECC	error checking and correction
	ECM	Extensible Call Model
	ECM	External Control Memory
	EEM	Embedded Event Manager
	EEPROM	electronically erasable programmable read-only memory
	EGP	exterior gateway protocol
	EHSA	enhanced high system availability
	EID	endpoint identifier
	EIGRP	Enhanced Interior Gateway Routing Protocol
	EIO	Elastic I/O
	ELAN	emulated LAN
	ENUM	enumeration
	ENVM	Constellation WAN Environmental Monitor
	EOBC	Ethernet Out-of-Band Channel
	EOC	embedded operations channel
	EOF	end-of-frame
	EOIR	enhanced online insertion and removal
	EoMPLS	Ethernet over MPLS
	EOU	Extensible Authentication Protocol over User Datagram Protocol
	EPM	External Packet Memory
	ESCON	Enterprise System Connection
	ESMP	Even Simpler Management Protocol
	ESP	Extended Services Processor
	ESP	Extended Services Platform
	ESW	Ethernet Switch
	ESWILP	Ethernet Switch with Inline Power
	ESYS	Undefined
	ETM	Enhanced Timing Module
	EXAR	Chip manufacturer

F
	FAQ	frequently asked question
	FB	feature board
	FBB	fast back-to-back
	FBB	from backplane buffer
	FCFS	First Come First Served
	FCIT	Fiber Channel Idle Time
	FC-PFQ	feature card per-flow queueing
	FCPA	Fibre Channel Port Adapter
	FCS	frame check sequence
	FDDI	Fiber Distributed Data Interface
	FDL	Facility Data Link
	FDM	frequency-division multiplexing
	FE	Fast Ethernet
	FEC	Fast EtherChannel
	FECPM	Fast Ethernet Combo Port Module
	FI	format indicator
	FIA	Fabric Interface ASIC
	FIB	forwarding information base
	FIFO	first-in, first-out
	FIR	Finite Impulse Response
	FM	fault monitoring
	FMSP	Fax Media Services Provider
	FPGA	field-programmable gate array
	FPI	Forwarding Path Identifier
	FQDN	fully qualified domain name
	FQPCID	fully qualified procedure correlation identifier
	FREEDM	Frame EnginE and Data link Manager
	FRMR	Frame Reject
	FRoM	FrameRelay over MPLS
	FRoMPLS	FrameRelay over MPLS
	FRR	Fast ReRoute
	FRU	field-replaceable unit
	FSIP	Fast Serial Interface Processor
	FSM	finite state machine
	FTBB	from/to backplane buffer
	FTP	File Transfer Protocol

G
	GBIC	Gigabit Interface Converter
	GC	global configuration
	GDS	general data stream
	GE	Gigabit Ethernet
	GEFC	Gigabit Ethernet/Fibre Channel
	GEIP	Gigabit Ethernet Interface Processor
	GGSN	gateway GPRS support node
	GKTMP	Gatekeeper Transaction Message Protocol
	GLBP	Gateway Load Balancing Protocol
	GLC	gigabit line card
	GP	Global Pointer
	GPRS	general packet radio service
	GRP	gigabit route processor
	GSN	GPRS support node
	GSR	Internet router
	GT95K	Undefined
	GTF	Generalized Trace Facility
	GTP	GPRS tunneling protocol
	GULF	GULF-2488 ASIC

H
	HA	High Availability
	HA	Home Agent
	HAL	Halcyon
	HAPX	Hardware Assisted Packet Classification
	HDLC	High-Level Data Link Control
	HDV	High Density Voice
	HDX	half-duplex
	HEC	header error control
	HERA	Undefined
	HGW	home gateway
	HMAC	hash message authentication codes
	HMS	Home Media Server
	HPI	Host Port Interface
	HPR	High-Performance Routing
	HQF	Hierarchical Queuing Framework
	HSA	high system availability
	HSRP	Hot Standby Router Protocol
	HSSI	High Speed Serial Interface
	HT-FPGA	Hyper Transport Field-Programmable Gate Array
	HWAF	Hardware Address Filtering
	HWIC	High-Speed WAN Interface Card
	HWICD	High-Speed WAN Interface Card, double-wide
	HWIDB	hardware interface descriptor block

I
	I2C	Inter-Integrated Circuit
	IBGP	internal BGP
	IBL	Input Buffer Logic
	IBOC	in-band bit-oriented code
	ICC	Inter Card Communication
	ICC	Interface Controller Card
	ICMP	Internet Control Message Protocol
	ICPIF	Calculated Planning Impairment Factor
	ICS	Integrated Communication System
	IDAP	Internet Data Access Presentation
	IDB	interface descriptor block
	IDPROM	Identification PROM
	IDS	Internal Data Services
	IDT	Integrated Digital Terminal
	IDU	indoor unit
	IE	information element
	IEEE	Institute of Electrical and Electronics Engineers
	IETF	Internet Engineering Task Force
	IF	intermediate frequency
	IGMP	Internet Group Management Protocol
	IGRP	Interior Gateway Routing Protocol
	IIC	Undefined
	IIF	Input interface
	IIH	IS to IS Hello PDU
	IIN	Undefined
	IKE	Internet Key Exchange
	ILMI	Integrated Local Management Interface
	ILP	inline power
	ILPM	inline power module
	IMA	inverse multiplexing over ATM
	IMSI	international mobile subscriber identity
	IOB	Undefined
	IP	Internet Protocol
	IPC	interprocess communication
	IPDC	Internet Protocol device control
	IPDLC	IP data link connection
	IPE	Inter-PRE Ethernet
	IPG	Inter Packet Gap
	IPHC	IP Header Compression
	IPM	Cisco Internetwork Performance Monitor
	IPPCP	IP Payload Compression Protocol
	IPRM	IP Router Manager
	IPS	IP Storage
	IPSec	IP Security
	IPv6	IP version 6
	IPX	Internetwork Packet eXchange
	ISA	Integrated Services Adapter
	ISAKMP	Internet Security Association and Key Management Protocol
	ISDN	Integrated Services Digital Network
	ISE	Internet Services Engine
	IS-IS	Intermediate System-to-Intermediate System
	ISL	Inter-Switch Link
	ISR	intermediate session routing
	ISRHOG	Interrupt Service Routine HOG
	ISSU	In-Service Software Upgrade
	IST	Internal Spanning Tree
	IVR	interactive voice response
	IXP	Internet Exchange Point

L
	L2	Layer 2
	L2F	Layer 2 Forwarding
	LAC	L2TP access concentrator
	LACP	Link Aggregate Control Protocol
	LAIS	SONET Line level Alarm Indication Signal
	LANCE	Local Area Network Controller Ethernet
	LANE	LAN Emulation
	LAPB	Link Access Procedure, Balanced
	LAT	local-area transport
	LC	line card
	LCATM	Label controlled ATM
	LCB	Line Control Block
	LCC	Line card Configuration Coordinator
	LCD	liquid crystal display
	LCDOS	line card operating system software
	LCI	local channel identifier
	LCN	logical channel number
	LDLC	LocalDirector link control
	LDN	local directory number
	LDP	Label Distribution Protocol
	LEC	LANE Client
	LECS	LANE Configuration Server
	LED	light-emitting diode
	LEN	low-entry networking
	LES	LANE Server
	LFD	Label Forwarding Database
	LFSID	local-form session identifier
	LIR	link incident report
	LIU	line interface unit
	LLC	logical link control
	LLC2	Logical Link Control, type 2
	LLD	low level design
	LMI	Local Management Interface
	LNM	LAN Network Manager
	LNS	L2TP network server
	LOF	Loss of Frame
	LOS	Loss of Signal
	LPD	line printer daemon
	LRC	line card redundancy controller
	LRJ	location rejection
	LRQ	location request
	LS	LightStream
	LSA	link-state advertisement
	LSD	label switching database
	LSIPC	LightStream interprocess communication
	LSP	label switch path
	LSP	link-state packet
	LSP	Link-State PDU
	LSS	LightStream switching
	LU	logical unit
	LU6.2	logical unit type 6.2
	LVC	label switched controlled virtual circuits
	LWAPP	Lightweight Access Point Protocol
	LYRA	Constellation+ Advanced Forwarding Engine Layer2

M
	MAC	Media Access Control
	MAR	Midrange Access Routers
	MARS	Multicast Address Resolution Server
	MATM	MAC Address Table Manager
	MAU	media attachment unit
	MAX	maximum
	MBE	multiple-bit error
	MBRI	Multi-BRI
	MBRI	Multiport Basic Rate Interface
	MBus	maintenance bus
	MCD	Undefined
	MCNS	Multimedia Cable Network System Partners, Ltd.
	MCOM	Microcom carrier card
	MCDMA	Multi-Channel DMA
	MCSC	Multi-Channel Serial Controller
	MD5	message digest 5
	MDB	Multicast Descriptor Block
	MDL	maintenance data link
	MDRR	Modified Deficit Round Robin
	MDS	multicast distributed switching
	MDSS	Multicast Distributed Shortcut Switching
	MDT	multicast distribution tree
	MEMD	memory device
	MFD	Multicast Fast Drop
	MFE	Multi-port Fast Ethernet
	MFI	MPLS forwarding infrastructure
	MFIB	Multicast Forwarding Information Base
	MGCP	Media Gateway Control Protocol
	MGID	Undefined
	MIB	Management Information Base
	MIB/SMT	Management Information Base/Station Management
	MIC	media interface connector
	MICA	Modem ISDN channel aggregation
	MID	Multiplex ID
	MIDB	multicast interface data block
	MII	media-independent interface
	MLD	Multicast Listener Discovery
	MLP	Multilink Point-to-Point Protocol
	MLPPP	Multilink Point-to-Point Protocol
	MLS	multilayer switching
	MLSM	multi-layer switching for multicast
	MLTG	multilink trunk group
	MMAP	memory map
	MMC	Undefined
	MMI	Modem Management Interface
	MMLS	multicast multilayer switching
	MNCNS	Multimedia Cable Network System Partners, Ltd.
	MNP4	Microcom Networking Protocol 4
	MP	Multilink Protocol
	MPC	MultiPath Channel
	MPC	Multiprotocol-over-ATM client
	MPLS	Multiprotocol Label Switching
	MPOA	Multiprotocol over ATM
	MPPE	Microsoft Point to Point Encryption
	MPS	Multiprotocol-over-ATM server
	MQC	Modular Quality of Service (QoS) command line interface (CLI)
	MRIB	Multicast Routing Information Base
	MRP	Multiservice Routing Processor
	MPT	Ministry of Posts and Telecommunications
	mroute	Multicast route
	MRW	Undefined
	MS	Management Services
	MS	mobile subscriber
	MSC	Modular Services Card
	MSDP	Multicast Source Discovery Protocol
	MSFC	Multilayer Switch Feature Card
	MSP	Media Service Provider
	MSR	Multiservice Switch Router
	MSS	maximum segment size
	MST	Multiple Spanning-Tree Protocol
	MSTOO	multiple spanning tree root
	Mtree	matings tree
	MTU	maximum transmission unit
	MURIB	Multicast Unicast Routing Information Base
	MVIP	Versatile Interface Processor
	MW	Undefined
	MWAM	Multi-Processor WAN Application Module
	Mx	Mueslix

N
	NAK	negative acknowledgment
	NAM	Network Analysis Module
	NAS	network access server
	NAT	Network Address Translation
	NBAR	network-based application recognition
	NBP	Name Binding Protocol
	NCE	network connection endpoint
	NCP	Network Control Program
	NCP	Network Control Protocol
	NEAT	E1 and T1 processor
	NFAS	Non Facility Associated Signaling
	NHDR	Network Layer Header
	NHRP	Next Hop Resolution Protocol
	NHS	Next Hop Server
	NIM	network interface module
	NIP	Nitro Interconnect Protocol
	NLP	network-layer packet
	NLSP	NetWare Link Services Protocol
	NM	network module
	NM-HD	high density network module
	NME	Network Management Ethernet
	NMI	nonmaskable interrupt
	NMP	Network Management Processor
	NMS	network management system
	NMVT	network management vector transport
	NNI	Network-to-Network Interface
	NNS	network node server
	NPE	network processing engine
	NRM	normal response mode
	NRP	Network Routing Processor
	NRP	node route processor
	NSAP	network service access point
	NSDB	Network Security Database
	NSE	network services engine
	NSF	Non-stop forwarding
	NSP	Network Switch Processor
	NSP	node switch processor
	NTP	Network Time Protocol
	NVRAM	nonvolatile RAM

O
	OAM	Operation, Administration, and Maintenance
	OBL	Output Buffer Logic
	OC	Optical Carrier
	ODU	outdoor unit
	OER	Optimized Edge Routing
	OFC	open fiber control
	OIF	Output interface
	OIR	online insertion and removal
	ONS	Optical Networking Systems
	OOBP	out-of-band port
	OOD	Online Offline Diagnostics
	OOS	out of service
	ORF	outbound route filter
	OSCP	Optical Supervisory Channel Protocol
	OSM	Optical Services Module
	OSP	Open Settlements Protocol
	OSPF	Open Shortest Path First
	OSS	Operations Support System
	OU	organizational unit

P
	PA	port adapter
	PAD	packet assembler/disassembler
	PAgP	Port Aggregation Protocol
	PAM	port adapter module card
	PAM	pulse amplitude modulation
	PAN	4-Port and (8+1) Port ESWILP HWIC
	PAP	Password Authentication Protocol
	PARAM1	Undefined
	PARAM2	Undefined
	PASCB	port adapter system control block
	PASV	passive mode FTP
	PBP	packet-by-packet
	PC	program counter
	PCA	Parallel Channel Adapter
	PCF	Packet Control Function
	PCF	Profile Configuration File
	PCI	protocol control information
	PCID	procedure correlation identifier
	PCM	pulse code modulation
	PCMCIA	Personal Computer Memory Card International Association
	PCR	peak cell rate
	PDP	policy decision point
	PDSN	Packet Data Serving Node
	PDU	protocol data unit
	PEMF	Power Entry Module and Filter
	PF	protocol filtering
	PGM	Pragmatic General Multicast
	PHAD	Physical Layer Interface Module (PLIM) header add-drop ASIC
	PHY	physical layer interface
	PIC	Peripheral Interface Controller
	PIC	point in call
	PIE	protocol information element
	PIF	Packet Input FIFO
	PIM	Protocol Independent Multicast
	PIM-SM	Undefined
	PIMv2	Protocol Independent Multicast version 2
	PIU	PCM Interface Unit
	PKCS	Public Key Cryptographic Standards
	PKI	public key infrastructure
	PLD	programmable logic device
	PLIM	Physical Layer Interface Module
	PLU	primary logical unit
	PLX	PCI to local bus bridge vendor
	PM	port management
	PMA	Packet Memory Access
	PMC	PCI Mezzanine Card
	PMON	Performance Monitor
	PNNI	Private Network-Network Interface
	PNSP	Partial Number Sequence PDUs
	POE	Power Over Ethernet
	PoS	Packet over SONET
	PoS	Packet over SONET/SDH
	POST	power-on self test
	POT1E1	Packet Over T1 E1
	POTS	plain old telephone service
	PPC	primary point code
	PPP	Point-to-Point Protocol
	PQUICC	Quad Integrated Communications Controller
	PRE	Performance Routing Engine
	PRI	Primary Rate Interface
	PROM	programmable read-only memory
	PRP	Performance Route Processor
	PSA	Packet Switching ASIC
	PSC	processor and switch card
	PSM	Protection Switch Module
	PSNP	Partial Sequence Number PDU
	PTB	Peer Transaction Bus
	PTM	Packet Transfer Mode
	PU	physical unit
	PU 2.0	Physical Unit type 2.0
	PU 2.1	Physical Unit type 2.1
	PVC	permanent virtual circuit
	PVC	permanent virtual connection
	PVDM	Packet Voice DSP Module
	PVID	Port VLAN ID
	PVP	permanent virtual path
	PVST+	Per-VLAN Spanning Tree
	PXF	Parallel eXpress Forwarding
	PXM	Processor Switching Module

Q
	QA	queue and accumulator
	QEM	QEM driver
	QLLC	Qualified Logical Link Control
	QM	QoS manager
	QMAC	Quad Token Ring Media Access Controller ASIC
	QoS	quality of service
	QSTAT	Undefined

R
	RA	registration authority
	RAC	Resource Availability Confirm
	RAC	Ring Access Controller
	RADIUS	Remote Authentication Dial-In User Service
	RARP	Reverse Address Resolution Protocol
	RAS	Registration, Admission, and Status
	RAS	remote access server
	RBCP	Router Blade Configuration Protocol
	RBD	receive buffer descriptor
	RBS	Robbed-Bit Signaling
	RCP	remote copy protocol
	RDB	relational database
	RE	Undefined
	RED	Undefined
	REQACTPU	request to activate a physical unit
	REQDACTPU	request to deactivate a physical unit
	REQ(D)ACTPU (RSP)	Route Switch Processor request to activate or deactivate a physical unit
	REXEC	remote execution
	RF	radio frequency
	RF	Redundancy frequency
	RIB	Routing Information Base
	RIM	Undefined
	RIP	Routing Information Protocol
	RISC	reduced instruction set computing
	RJE	remote job entry
	RLDRAM	Undefined
	RLM	Redundant Link Manager
	RMON	Remote Network Monitoring
	RNR	receive not ready
	ROM	read-only memory
	RP	Route Processor
	RPA	Resource Pool Allocation
	RPC	Remote Procedure Call
	RPF	Reverse Path Forwarding
	RPM	Route Processor Module
	RPM	Resource Pool Management
	RPMXF	Route Processor Module, express forwarding
	RPR	Route Processor Redundancy
	RPR+	Route Processor Redundancy plus
	RPS	Ring Parameter Server
	RR	receive ready
	RRP	Redundant Route Processor
	RS	router shelf
	RS-232	EIA/TIA-232
	RSA	Rivest, Shamir, and Adelman (a public-key cryptographic system)
	RSC	route switch controller
	RSCPB	RSC front panel push button
	RSCV	Route Selection Control Vector
	rsh	remote shell
	RSM	Route Switch Module
	RSP	Route Switch Processor
	RSPAN	Remote Switched Port Analyzer
	RSRB	remote source-route bridging
	RSRC	Resource
	RSVP	Resource Reservation Protocol
	RTAL	Receive Telecombus Aligner/Interface
	RTC	real-time console
	RTM	Real Time Monitor
	RTP	Rapid Transport Protocol
	RTP	Real-Time Transport Protocol
	RTR	response time reporter
	RTS	Request To Send
	RTT	round-trip time
	RTTMON	Round Trip Time Monitor
	RU	request/response unit
	RUDP	Reliable User Data Protocol
	Rx	Receive
	RXP	Resonate Exchange Protocol

S
	SA	security association
	SA	Source-Active
	SA	Service Assurance
	SADB	security association database
	SAF24	SAR adapter FPGA OC24
	SAFI	Subsequent Address Family Identifier
	SAP	service access point
	SAR	segmentation and reassembly
	SBE	single-bit error
	SC	Undefined
	SCB	storage control blocks
	SCB	system control board
	SCC	Signaling Connection Control
	SCCP	Signaling Connection Control Part
	SCM	Service Connection Manager
	SCP	Service Control Point
	SCP	Switch-Module Configuration Protocol
	SCP	System Control Protocol
	SCR	sustained cell rate
	SDCC	Serial Data Communication Channel
	SDEE	Security Device Event Exchange
	SDF	Signature Definition File
	SDLC	Synchronous Data Link Control
	SDLLC	Synchronous Data Logical Link Control
	SDM	Security Device Manager
	SDP	Session Description Protocol
	SDP	Shelf Discovery Protocol
	SDRAM	synchronous DRAM
	SDT	Start Data Transfer
	SEF	severely errored frames
	SERDES	Serializer-Deserializer
	SFC	switch fabric card
	SFP	Small Form Factor Pluggable
	SGBP	Stack Group Bidding Protocol
	SGCP	Simple Gateway Control Protocol
	SGSN	Serving GPRS Support Node
	SID	Service ID
	SIM	Undefined
	SIMM	single in-line memory module
	SIP	Session Initiation Protocol
	SLARP	Serial Line Address Resolution Protocol
	SLB	Server Load Balancing
	SLC	signaling link code
	SLCI	Signaling Link Code Interface
	SLIC	Subscriber Line Interface Circuit
	SLIP	Serial Line Internet Protocol
	SLU	secondary logical unit
	SM	sparse mode
	SM	state machine
	SMbus	System Management bus
	SMDS	Switched Multimegabit Data Service
	SME	Signature Micro Engine
	SMRP	Simple Multicast Routing Protocol
	SMTP	Simple Mail Transfer Protocol
	SNA	Systems Network Architecture
	SNASw	SNA Switching Services
	SNMP	Simple Network Management Protocol
	SNR	signal-to-noise ratio
	SNRM	Set Normal Response
	SO-DIMM	Small Outline Dual In-line Memory Modules
	SOF	start-of-frame
	SOP	Second-Generation Packet-over-SONET
	SP	Switch Processor
	SPA	Shared Port Adapter
	SPAN	Switched Port Analyzer
	SPD	Security Policy Database
	SPE	service processing element
	SPI	security parameter index
	SPI4	Unavailable.
	SPID	service profile identifier
	SPM	source path message
	SPMM	SIMM DSP module
	SRA	Seamless Rate Adaptation
	SRA	source routing accelerator
	SRAM	static RAM
	SRC	Switch Redundancy Controller
	SRCP	Simple Resource Coordination Protocol
	SRDB	source route relational database
	SRIC	Sculptor Input Controller
	SRIF	Sculptor Interface
	SROC	Sculptor Output Controller
	SRP	Server Redundancy Protocol
	SRP	Spatial Reuse Protocol
	SRR	Single Ring Recovery Protocol
	SSA	Serial Storage Architecture
	SSCOP	Service-Specific Connection-Oriented Protocol
	SSCP	system services control points
	SSE	silicon switching engine
	SSG	Service Selection Gateway
	SSH	Secure Shell
	SSL	Secure Socket Layer
	SSM	Single State Mode
	SSM	Source Specific Multicast
	SSO	Stateful SwitchOver
	SSP	Silicon Switch Processor
	SSP	state synchronization protocol
	SSRAM	synchronous static RAM
	SSRP	Simple Server Redundancy Protocol
	SSS	Subscriber Service Switching
	SSTP	Shared Spanning-Tree Protocol
	STP	Spanning-Tree Protocol
	STUN	serial tunnel
	SU	service unit
	SU	signaling unit
	SVC	switched virtual circuit
	SVI	switched virtual interface
	SVIP	Versatile Interface Processor 2
	SW56	switched 56K
	SWIDB	software for Interface Descriptor Block
	SYSMGT	system management

T
	TAC	Cisco Technical Assistance Center
	TACACS	Terminal Access Controller Access Control System
	TAZ-B	Undefined
	TBB	to backplane buffer
	TBI	Ten Bit Interface
	TBM	Transmit Buffer Manager
	TCA	telecommunications access method
	TCATM	Tag Control ATM
	TCAM	Ternary Content Addressable Memory
	TCB	Transmission Control Block
	TCL	Toolkit Command Language
	TCP	Transmission Control Protocol
	TDM	time-division multiplexing
	TDP	Tag Distribution Protocol
	TDR	time domain reflectometer
	TE	terminal equipment
	TE	tunnel equipment
	TE3	Undefined
	TED	Tunnel Endpoint Discovery
	TEI	terminal endpoint identifier
	TFIB	Tag Forwarding Information Base
	TFTP	Trivial File Transfer Protocol
	TG	transmission group
	TIB	Tag Information Base
	TIM	Tree Information Base
	TIC	Toaster Input Controller
	TID	Terminal Identifier
	TIFF	tagged image file format
	TLB	translation look-aside buffer
	TLV	type, length, value
	TMQ	terminal port queueing
	ToS	Type of Service
	TP	Transport Protocol
	TR	Token Ring
	TRANGE	time-range
	TSC	Tag Switch Controller
	TSCAM	Traffic Shaping Carrier Access Module
	TSI	transmitting subscriber information
	TSP	tag-switched path
	TT	Undefined
	TT2RP	Toaster-to-RP
	TTAL	Transmit Telecombus Aligner/Interface
	TTL	time to live
	TVC	tag switched controlled virtual circuit
	TVC	tag virtual circuits
	Tx	transmit

U
	UA	unnumbered acknowledgement
	UART	Universal Asynchronous Receiver/Transmitter
	UCB	University of California, Berkeley
	Ucode	Microcode
	UDF	Undefined
	UDLD	UniDirectional Link Detection
	UDP	User Datagram Protocol
	UPF	Undefined
	UPS	uninterruptible power supply
	URM	Universal Router Module
	uRPF	Unicast Reverse Path Forwarding

V
	VACL	VLAN access control list
	VAD	voice activity detection
	VBR	variable bit rate
	VBR-nRT	variable bit rate—non-real time
	VC	virtual circuit
	VCC	virtual channel connection
	VCD	virtual circuit descriptor
	VCCI	Virtual Channel Common Index
	VCHAN	virtual channel
	VCI	virtual channel identifier [ ATM only]
	VCN	virtual circuit number
	VDSL	very high bitrate digital subscriber line
	VFC	voice feature card
	VFC	VoIP feature card
	VFR	Virtual Fragment Reassembly
	VG	voice gateway
	VIC	voice interface card
	VIP	Versatile Interface Processor
	VLAN	virtual LAN
	VMAC	Virtual MAC
	VMPS	VLAN Membership Policy Server
	VMR	value, mask, result
	VNM	Voice Network Manager
	VoIP	Voice over IP
	VP	virtual path
	VPC	virtual path connection
	VPD	voice packet driver
	VPDN	Virtual Private Dialup Network
	VPI	virtual path identifier
	VPN	Virtual Private Network
	VPNv4	Virtual Private Network version 4
	VQP	VLAN Query Protocol
	VQPC	VQP client
	VRF	VPN Routing and Forwarding
	VRRP	Virtual Router Redundancy Protocol
	VSI	Virtual Switch Interface
	VSM	Voice Service Manager
	VT	virtual terminal
	VTAM	virtual telecommunications access method
	VTMS	Versatile Traffic Management and Shaping
	VTP	VLAN Trunk Protocol
	VTSP	voice telephony service provider
	VTT	voltage termination
	VWIC	Voice/WAN interface card

W
	WCCP	Web Cache Communication Protocol
	WCS	writable control store
	WDS	Wireless Domain Services
	WIC	WAN interface card
	WLM	Workload Manager
	WRED	Weighted Random Early Detection
	WWW	World Wide Web

X
	XCA	external communication adapter
	XCVR	transceiver
	XDR	eXternal Data Representation
	XID	exchange identification
	XML	eXtensible Markup Language
	XNS	Xerox Network Systems
	XOT	X.25-over-TCP
	XTagATM	extended tag ATM

Z
	ZBT	zero bus turnaround