This material is simplified for quick technical reference and includes legacy formats. Confirm implementation details against current product or standards documentation.

Multimedia terminology and descriptions
Multimedia Term	Description
Aspect Ratio	The ratio between the width and height of an image or display. Common examples include 4:3 for older television formats and 16:9 for modern widescreen video.
Bidirectional (B) Frame	One of the three picture types in MPEG compression. B frames are coded in relation to previous or subsequent I or P frames. B frames do not serve as a reference for other frames
Data Rate	The speed of the data stored on a type of media, usually expressed in bits per second or bytes per second.
Data Transfer Rate	The transfer rate of the storage media itself. VCD transfer rate is 1.2MB.
Downmix	The process of converting a multi-channel audio track to two- or one-channel track.
Dolby Digital	Also known as AC-3. A high-quality, bandwidth-efficient perceptual audio coding system originally developed by Dolby Laboratories for multi-channel digital sound in the cinema. It can be used in broadcast, cable, film, and recorded media in both professional and consumer applications. Dolby Digital is one of the main audio formats used in DVD.
Dolby Surround	The consumer version of the original analog Dolby multi-channel film sound format.
Drop Frame Time Code	A mode of operation when playing back NTSC video. In NTSC, the actual frame rate is roughly 29.97 fps. When the time code indicates 1 hour of film, 1 hour, 3 seconds, and 18 frames worth of actual time has elapsed, or a discrepancy of 108 frames. Some encoders resolve the time code discrepancy by dropping two frame numbers every minute, on the minute, except the tenth minutes.
DTS (Digital Theater Sound)	An audio encoding technology developed for theaters. DTS was developed to compete with Dolby Digital and is an additional audio format for DVD.
GOP (Group of Pictures)	A GOP is a single MPEG video random access unit.
Intra (I) Frame	A key reference frame in the MPEG compression algorithm. I Frames are one of the three types of frames used in MPEG compression. They contain all the data needed to represent an entire frame, hence are referred to as key reference frames.
Linear PCM	A non-compressed digital audio format. The DVD specification allows for 16 to 24 bit Linear PCM audio sampled at 48 or 96 kHz.
MP3	MP3 is the MPEG audio layer 3 standard. Layer 3 is one of three coding schemes (layer 1, 2, and 3) for the compression of audio signals defined by the MPEG committee. Layer 3 uses perceptual audio coding and psychoacoustic compression to remove the redundant parts of a sound signal. It also adds an MDCT (Modified Discrete Cosine Transform) that implements a filter bank, increasing the frequency resolution 18 times higher than that of MPEG audio layer 2.
MPEG-1	ISO/IEC standard designed for low bandwidth of compressed digital video and audio. VCD uses this format with resolution of 352x288@25fps (PAL) or 352x240@29.97fps (NTSC).
MPEG-2	ISO/IEC standard designed for transmission of high bandwidth compressed digital video and audio such as that used by broadcast television. DVD uses this format with resolution of 720x576@25fps (PAL) or 720x480@29.97fps (NTSC).
MPEG-4	ISO 14496 is an ISO/IEC standard developed by MPEG (Moving Picture Experts Group). Although defined as one standard, MPEG-4 is actually a set of compression/decompression formats and streaming technologies that address the need for distributing rich interactive media over narrow and broadband networks.
MPEG Audio	Multi-channel digital audio defined by the MPEG specification. MPEG-1 Layer 2 is compressed using perceptual coding. It has a sample rate of 32, 44.1, and 48 kHz at 16 bits and can contain mono or stereo streams. MPEG-1 Layer 3 supports variable sample rate. MPEG-2 audio is an extension of MPEG-1 audio. It supports low bit rates and up to 7.1 audio channels.
Multiplexing	Combining two or more data streams together into a single stream.
Predicted (P) Frame	Frames used in MPEG compression which are coded in relation to the nearest previous I or P frame. P frames serve as a prediction reference for B frames and future P frames.
SDDS (Sony Dynamic Digital Sound)	An audio encoding technology developed by Sony for multi-channel audio in cinemas and theaters. SDDS was developed to compete with Dolby Digital and is an optional audio format for DVD.
S-Video	A video signal that carries separate luminance and chrominance signals.
SMPTE EBU Time Code	A time-code system used to identify individual video frames and support editing and synchronisation. SMPTE stands for Society of Motion Picture and Television Engineers.

Reference 02

Networking terminology

41 entries

Definitions for common network components, protocols, models, connections and topologies.

Reference note

These descriptions are intended as an introductory reference. Some technologies are historical or deployment-specific, so verify details before using them in a live environment.

Networking terminology and descriptions
Networking Term	Description
Amplifier	A network component, also known as a repeater. Amplifiers increase the power of a signal when it is lost due to attenuation. They allow signals to cover greater distances in a LAN environment.
Application Layer	The seventh layer in the OSI model. The Application layer defines program-to-program communication, or how applications access network services. Services defined by the Application layer include file transfer, job transfer, and terminal emulation.
ATM	Broad bandwidth (155 Mb). ATM can be implemented either as a backbone solution or as an entire network solution. In the backbone scenario, ATM is used to connect departments, floors, or any part of the organization that is distant from the main server center. In the network scenario, ATM is used as the entire LAN, WAN, or MAN. LAN Emulation (LANE) is used in these types of networks to give an Ethernet feel to the network. This emulation is easier to implement than IP emulation over ATM and is much more popular.
Bandwidth	The amount of data that can be transmitted in a fixed amount of time. For digital devices, the bandwidth is usually expressed in bits per second or bytes per second. For analog devices, the bandwidth is expressed in cycles per second, or Hertz (Hz).
Bridge	A network component that connects two LANs, thus extending the range of the network. Bridges check data and forward them across LANs.
Broadband	A single wire or network pipe that has sufficient bandwidth to carry large amounts of data simultaneously.
Broadcast	When data is sent simultaneously to all stations on a network.
Brouter	A network component that serves as both a Bridge and a Router.
Buffer	Space allocated on a system's Random Access Memory (RAM) where data is stored temporarily until it is transferred to another part of the system.
Bus Topology	A LAN network structure in which all stations (nodes) are connected to the same cable. Data is transmitted up and down this single cable.
Cable Modem	A modem that connects home networking systems (computer + TV) to cable TV networks, bypassing traditional phone networks. Cable TV networks use a coaxial cable or HFC infrastructure.
Circuit Switching	A communication technology in which a dedicated channel (circuit) is established for the duration of a transmission.
Collisions	In an Ethernet network, every host connected to the network can transmit at any time. This may result in two hosts transmitting at the same time. If a collision between packets is sensed by both hosts, their NICs (Network Interface Cards) perform a Back Off - a transmission time-out. Since the length of the back-off is randomly determined, in most cases when the time-out has elapsed both NICs will be able to re-transmit without interfering with each other. There is always a chance that another host will try to send a packet, causing the back-off procedure to start again.
Coaxial Cable	Copper cable that consists of a central wire surrounded by insulation and then a grounded shield of braided wire. Coaxial wire is widely used by the cable television industries. It is less prone to interference than regular wire cables. Most older Ethernet networks also use coaxial cable.
Connectionless vs Connection-oriented Protocols	A connectionless protocol sends individual messages without first establishing a session and may not provide delivery or ordering guarantees. A connection-oriented protocol establishes logical communication state and can provide sequencing, acknowledgement and recovery mechanisms; this does not necessarily mean every packet follows one fixed network path.
Dial-Up Access	When computer devices hook up to a network via modem and public phone system on a pay-per-time basis. Usually, dial-up connections offer limited bandwidths. The alternative is a leased line that offers continuous access at a constant bandwidth to a network.
DSL (Digital Subscriber Line)	A family of technologies that transmits digital data over copper telephone lines. Common variants include ADSL (Asymmetric Digital Subscriber Line) and SDSL (Symmetric Digital Subscriber Line), often used for the access connection between a provider and a home or office.
E1/T1	In the United States, a T1 service is a framed communication protocol that delivers a two-way connection at 1.544 Mbits/s each way. In many other countries, the equivalent of T1 is a service called E1 - a two-way connection at 2.048 Mbit/s.
FDDI (Fiber Distributed Data Interface)	A set of ANSI protocols for sending digital data over fiber optic cable. FDDI networks are token-passing networks. They support data rates of up to 100 Mbps. FDDI networks usually serve as backbones for wide-area networks. FDDI-2 is an extension of FDDI that supports the transmission of voice and video too.
FTP (File Transfer Protocol)	A protocol that defines the transfer of files over the Internet.
Hub	A networking component that enables the common connection of devices to a network. Hubs are usually used to connect nodes in local area networks. Active hubs can regenerate data over the network, whereas passive hubs only transfer information.
Jitter	Variation in packet delay over time, sometimes called packet delay variation. Jitter is especially important for real-time traffic such as voice and video, where inconsistent arrival timing can affect playback quality.
IP (Internet Protocol)	The protocol that defines how packets are addressed and delivered across interconnected networks. An IP packet header contains addressing and control information used for datagram delivery. IP is part of the TCP/IP protocol suite.
IP Multicast	A method of sending one IP datagram to a multicast group identified by a group destination address. Hosts join the group to receive its traffic; they do not share the same normal unicast host address.
Local Area Networks (LAN)	A network that covers a small geographical area.
Latency	The amount of time it takes a packet to travel from source to destination. Together, latency and bandwidth define the speed and capacity of a network.
Leased Line	A permanent connection to a network that guarantees constant bandwidth and network access. Leased lines cost a fixed monthly fee.
Modem	A network interface device that allows computers to send and receive data over telephone lines.
Quality of Service (QoS)	Techniques for classifying and managing network traffic according to performance objectives such as bandwidth, delay, delay variation and loss. QoS can prioritise or differentiate traffic, but an end-to-end guarantee depends on the design and policies of every network domain involved.
Packet Switching	A networking technology in which messages are divided into packets before they are sent. Each packet is transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message. Packet switching is more efficient and robust for data that can withstand some delays in transmission, such as e-mail messages and Web pages.
Router	A networking device that connects different types of networks. Routers know how to direct data between networks that use different architectures and protocols.
RTP (Real-Time Transport Protocol)	An Internet protocol that defines the transmission of real-time data, for example, audio and video. RTP provides mechanisms for the sending (server) and receiving applications to support streaming data. RTP usually runs on top of the UDP protocol.
Star Topology	A local-area network (LAN) in which all nodes (stations) are connected to a central device.
Streaming	A technique for transferring data so that it is received as a continuous real-time stream.
TCP (Transmission Control Protocol)	One of the main Internet transport protocols. TCP establishes a connection and provides applications with a reliable, in-order byte stream, using acknowledgements and retransmission to recover from loss while the connection remains viable.
TCP/IP	A set of protocols designed by the US Department of Defense for transferring data between networks.
UDP (User Datagram Protocol)	A connectionless Internet transport protocol that lets applications exchange datagrams with minimal protocol overhead. UDP does not itself guarantee delivery, duplicate protection or ordering and is used for unicast, multicast and broadcast applications.
Virtual Private Network (VPN)	A network dedicated to a specific user or group of users that is part of a public network. For example, there are a number of systems that enable users to create dedicated networks using the Internet as the backbone for transporting data.
VLANs (Virtual Local Area Networks)	Logical Layer 2 network segments that separate broadcast domains on shared switching infrastructure. VLANs help organise and isolate traffic independently of the devices' physical locations.
WAP (Wireless Application Protocol)	A protocol that defines delivery and access of information to wireless devices.
Wide Area Network (WAN)	A network that covers large geographical areas by connecting many local area networks together.

Reference 03

TCP/UDP port reference

256 entries

A general list of service names historically or commonly associated with selected port numbers. TCP and UDP can use the same number differently.

Security and accuracy note

Do not open or block ports based on this page alone. Verify current assignments, application requirements and your organisation's firewall policy before making changes. Consult the IANA Service Name and Transport Protocol Port Number Registry for the current official registry.

General TCP and UDP port reference
Port Number	Service
1	tcpmux
5	rje
7	echo
9	discard
11	systat
13	daytime
15	netstat
17	qotd
18	send/rwp
19	chargen
20	ftp-data
21	ftp
22	ssh, pcAnywhere
23	Telnet
25	SMTP
27	ETRN
29	msg-icp
31	msg-auth
33	dsp
37	time
38	RAP
39	rlp
42	nameserv, WINS
43	whois, nickname
49	TACACS, Login Host Protocol
50	RMCP, re-mail-ck
53	DNS
57	MTP
59	NFILE
63	whois++
66	sql*net
67	bootps
68	bootpd/dhcp
69	Trivial File Transfer Protocol (tftp)
70	Gopher
79	finger
80	www-http
88	Kerberos, WWW
95	supdup
96	DIXIE
98	linuxconf
101	HOSTNAME
102	ISO, X.400, ITOT
105	cso
106	poppassd
109	POP2
110	POP3
111	Sun RPC Portmapper
113	identd/auth
115	sftp
117	uucp
119	NNTP
120	CFDP
123	NTP
124	SecureID
129	PWDGEN
133	statsrv
135	loc-srv/epmap
137	netbios-ns
138	netbios-dgm (UDP)
139	NetBIOS
143	IMAP
144	NewS
152	BFTP
153	SGMP
161	SNMP
175	vmnet
177	XDMCP
178	NextStep Window Server
179	BGP
180	SLmail admin
199	smux
210	Z39.50
218	MPP
220	IMAP3
259	ESRO
264	FW1_topo
311	Apple WebAdmin
350	MATIP type A
351	MATIP type B
363	RSVP tunnel
366	ODMR (On-Demand Mail Relay)
387	AURP (AppleTalk Update-Based Routing Protocol)
389	LDAP
407	Timbuktu
434	Mobile IP
443	ssl/https
444	snpp, Simple Network Paging Protocol
445	SMB
458	QuickTime TV/Conferencing
468	Photuris
500	ISAKMP, pluto
512	biff, rexec
513	who, rlogin
514	syslog, rsh
515	lp, lpr, line printer
517	talk
520	RIP (Routing Information Protocol)
521	RIPng
522	ULS
531	IRC
543	KLogin, AppleShare over IP
545	QuickTime
548	AFP
554	Real Time Streaming Protocol
555	phAse Zero
563	NNTP over SSL
575	VEMMI
581	Bundle Discovery Protocol
593	MS-RPC
608	SIFT/UFT
626	Apple ASIA
631	IPP (Internet Printing Protocol)
635	mountd
636	sldap
642	EMSD
648	RRP (NSI Registry Registrar Protocol)
655	tinc
660	Apple MacOS Server Admin
666	Doom
674	ACAP
687	AppleShare IP Registry
700	buddyphone
705	AgentX for SNMP
901	swat, realsecure
993	s-imap
995	s-pop
1062	Veracity
1080	SOCKS
1085	WebObjects
1227	DNS2Go
1243	SubSeven
1338	Millennium Worm
1352	Lotus Notes
1381	Apple Network License Manager
1417	Timbuktu
1418	Timbuktu
1419	Timbuktu
1433	Microsoft SQL Server
1434	Microsoft SQL Monitor
1494	Citrix ICA Protocol
1503	T.120
1521	Oracle SQL
1525	prospero
1526	prospero
1527	tlisrv
1604	Citrix ICA, MS Terminal Server
1645	RADIUS Authentication
1646	RADIUS Accounting
1680	Carbon Copy
1701	L2TP/LSF
1717	Convoy
1720	H.323/Q.931
1723	PPTP control port
1755	Windows Media .asf
1758	TFTP multicast
1812	RADIUS server
1813	RADIUS accounting
1818	ETFTP
1973	DLSw DCAP/DRAP
1985	HSRP
1999	Cisco AUTH
2001	glimpse
2049	NFS
2064	distributed.net
2065	DLSw
2066	DLSw
2106	MZAP
2140	DeepThroat
2301	Compaq Insight Management Web Agents
2327	Netscape Conference
2336	Apple UG Control
2427	MGCP gateway
2504	WLBS
2535	MADCAP
2543	sip
2592	netrek
2628	DICT
2727	MGCP call agent
2998	ISS Real Secure Console Service Port
3000	Firstclass
3031	Apple AgentVU
3128	squid
3130	ICP
3150	DeepThroat
3264	ccmail
3283	Apple NetAssitant
3288	COPS
3305	ODETTE
3306	mySQL
3389	RDP Protocol (Terminal Server)
3521	netrek
4000	icq, command-n-conquer
4321	rwhois
4333	mSQL
4827	HTCP
5004	RTP
5005	RTP
5010	Yahoo! Messenger
5060	SIP
5190	AIM
5423	Apple VirtualUser
5500	securid
5501	securidprop
5631	PCAnywhere data
5632	PCAnywhere
5800	VNC
5801	VNC
5900	VNC
5901	VNC
6000	X Windows
6112	BattleNet
6502	Netscape Conference
6667	IRC
6670	VocalTec Internet Phone, DeepThroat
6699	napster
6776	Sub7
6970	RTP
7007	MSBD, Windows Media encoder
7070	RealServer/QuickTime
7648	CU-SeeMe
7649	CU-SeeMe
7778	Unreal
8010	WinGate 2.1
8080	HTTP
8181	HTTP
8383	IMail WWW
8530	WSUS
8875	napster
8888	napster
10008	cheese worm
11371	PGP 5 Keyserver
13223	PowWow
13224	PowWow
14237	Palm
14238	Palm
18888	LiquidAudio
21157	Activision
23213	PowWow
23214	PowWow
23456	EvilFTP
26000	Quake
27001	QuakeWorld
27010	Half-Life
27015	Half-Life
27960	QuakeIII
30029	AOL Admin
31337	Back Orifice
32773	rpc.ttdbserverd
32776	rpc.spray
32777	rpc.walld
32779	rpc.cmsd
38036	timestep
40193	Novell
41524	arcserve discovery
45000	Cisco NetRanger postofficed

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