Internet Protocol Transport Control Protocol User Datagram Protocol File Transfer Protocol Secure File Transfer Protocol Trivial File Transfer Protocol Simple Mail Transfer Protocol Hypertext Transfer Protocol Hypertext Transfer Protocol Secure IPTCPUDPFTPSFTPTFTPSMTPHTTPHTTPS
Post Office Protocol Internet Message Access Protocol Secure Shell Internet Control Message Protocol Address Resolution Protocol Reverse Address Resolution Protocol Internet Group Management Protocol POPIMAPSSHICMPARPRARPIGMP
Circuit switchingUses physical path for transmission of data. A physical connection is established between source and destination & then data are sent .Packet switching Data are broken into small parts called packets. Numbered packets may take any shortest route for transmission. virtual connection is made between source and destination.
DTE (Data Terminal Equipment) - Digital device that generates, transmits and receives messages. - Terminal to show the movement of messages in and out of the terminal. - Server and the hosts maintain data and give information to Terminals.Example: ATMs (Automatic Teller Machines)
DCEData Communications Equipment. The DCE provides a physical connection to the network, forwards traffic, and provides a clocking signal used to synchronize data transmission between DCE and DTE devices. DTE.
Twisted pair cable - Up to 7 categories of twisted pair but Category 3 and 5 twisted pairs are mostly used. - Category 3 has 2 individually insulated wires twisted together . - Category 5 is same as 3 with more number of twist per cm. More the number of twists the better the communication medium . -Leads to less cross talk and better signal transmission over longer distances.
Can infrared be used for transmission? - The infrared waves - used for short range communication in networking (up to 45 km). - Wireless communication - no physical medium is required to connect the transmitter and receiver . - Works on line of sight system. - No government license is needed till now for this communication.
Satellite and cable medium- Delay in satellite during its transmission - 3 micro seconds per km.- Delay in cable wire is 5 microseconds per km.- Satellite is broadcast media placed in the geo stationary orbit around the earth.- Satellite - wireless communication- Cable - wired communication. On security grounds cable is better than a satellite.
10Base210-Mbps baseband Ethernet specification using 50-ohm thin coaxial cable. 10Base2,which is part of the IEEE 802.3 specification, has a distance limit of 606.8 feet (185 meters) per segment.10Base5, 10BaseF, 10BaseFB, 10BaseFL, 10BaseFP, 10BaseT, 100BaseT, 100BaseTX, 100BaseX,
2G mobile networkSecond generation mobile network. Refers generically to a category of mobile wireless networks and services that implement digital technology. GSM is an example of a 2G mobile network standard.2G+, 3G, 4G
802.xA set of IEEE standards for the definition of LAN protocols.802.1, 802.2, 802.3, 802.5, 802.11
AAAauthentication, authorization, and accountingAARPAppleTalk Address Resolution Protocol. A protocol in the AppleTalk protocol stackthat maps a data-link address to a network address.
ABR1. available bit rate. QoS class defined by the ATM Forum for ATM networks. Used for connections that do not require timing relationships between source and destination. CBR, UBR, and VBR.2. area border router. Router located on the border of one or more OSPF areas that connects those areas to the backbone network.
access listA list kept by routers to control access to or from the router for a number of services. (to prevent packets with a certain IP address from leaving a particular interface on the router).Acknowledgment (ACK)Notification sent from one network device to another to acknowledge that some eventoccurred (for example, the receipt of a message). NAK.
Address mappingAllows different protocols to interoperate by translating addresses from one format to another. when routing IP over X.25, the IP addresses must be mapped to the X.25 addresses so that the IP packets can be transmitted by the X.25 network.
Address resolutionFor resolving differences between computer addressing schemes. Address resolution usually specifies a method for mapping network layer addresses to data link layer addresses.
ADSLAsymmetric Digital Subscriber Line. One of four DSL technologies. Downstream rates from 1.5 to 9 Mbps. Upstream bandwidth ranges from 16 to 640 kbps. ADSL work at distances up to 18,000 feet (5,488 meters) over a single copper twisted pair. HDSL, SDSL,VDSL.
ANSIAmerican National Standards Institute. A voluntary organization composed ofcorporate, government, and other members that coordinates standards-relatedactivities, approves U.S. national standards, and develops positions for the UnitedStates in international standards organizations
Application LayerLayer 7 of the OSI reference model. Provides services to application processes (e-mail, file transfer, ..) that are outside the OSI model. Identifies and establishes the availability of intended communication partners, synchronizes cooperating applications, and establishes an agreement on the procedures for error recovery and the control of data integrity.
ARPAddress Resolution Protocol. Internet protocol used to map an IP address to a MACaddress.RARP, Proxy ARP
ARPANETAdvanced Research Projects Agency Network. ARPANET was developed in the 1970s by BBN and funded by ARPA (and later DARPA). It eventually evolved into the Internet.
ASCIIAmerican Standard Code for Information Interchange. 8-bit code for characterrepresentation.
ATMAsynchronous Transfer Mode. International standard for cell relay in which multiple service types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells. Takes advantage of high-speed transmission media, such as SONET.
authenticationIn security, the verification of the identity of a person or a process.authorizationThe method for remote access control.
BER1. bit error rate. Ratio of received bits that contain errors.2. basic encoding rules. Rules for encoding data units described in the ISO ASN.1standard. (SNMP)
BGPBorder Gateway Protocol. Inter-domain routing protocol that replaces EGP. BGP exchanges reachability information with other BGP systems. BGP4, EGPbit rateSpeed at which bits are transmitted, usually expressed in bits per second.
BOOTPBootstrap Protocol. Used by a network node to determine the IP address of its Ethernet interfaces to affect network booting.Border GatewayA router that communicates with routers in other autonomous systems.
BridgeDevice that connects and passes packets between two network segments that use thesame communications protocol. Bridges operate at the data link layer (Layer 2) of the OSI reference model. In general, a bridge filters, forwards, or floods an incomingframe based on the MAC address of that frame.
BroadcastData packet that are sent to all nodes on a network. Broadcasts are identified by abroadcast address. Broadcast AddressA special address reserved for sending a message to all stations. Generally, a broadcast address is a MAC destination address of all ones.
Broadcast DomainSet of all devices that receive broadcast frames originating from any device within the set. Broadcast domains typically are bounded by routers because routers do not forward broadcast frames.
Broadcast StormAn undesirable network event in which many broadcasts are sent simultaneously across all network segments. A broadcast storm uses substantial network bandwidth causing network time-outs.BrouterConcatenation of “bridge” and “router.” Used to refer to devices that perform both bridging and routing functions.
Bus topologyLinear LAN architecture in which transmissions from network stations propagate thelength of the medium and are received by all other stations. Ring topology, star topology, tree topology.
CATVcable television. A communication system where multiple channels of programmingmaterial are transmitted to homes using broadband coaxial cable. Formerly calledCommunity Antenna Television.
CBRconstant bit rate. QoS class defined by the ATM Forum for ATM networks. CBR is used for connections that depend on precise clocking to ensure undistorted delivery.ABR, UBR, VBR.
CDMAcode division multiple access. A method of dividing a radio spectrum to be shared bymultiple users through the assignment of unique codes. CDMA implements spreadspectrum transmission.CDPCisco Discovery Protocol
CHAPChallenge Handshake Authentication Protocol. Security feature supported on linesusing PPP encapsulation that prevents unauthorized access. PAP.
CIDRclassless interdomain routing. Allows routers to group routes together to reduce the quantity ofrouting information carried by the core routers. With CIDR, several IP networks appear to networks outside the group as a single, larger entity.
Coaxial CableCable consisting of a hollow outer cylindrical conductor that surrounds a single innerwire conductor. Two types of coaxial cable currently are used in LANs: 50-ohm cable,which is used for digital signaling, and 75-ohm cable, which is used for analogsignaling and high-speed digital signaling.
CollisionIn Ethernet, the result of two nodes transmitting simultaneously. The frames fromeach device impact and are damaged when they meet on the physical media.Collision DomainIn Ethernet, the network area within which frames that have collided are propagated.Repeaters and hubs propagate collisions; LAN switches, bridges, and routers do not.
CongestionTraffic in excess of network capacity.Congestion AvoidanceMechanism by which a network controls the traffic entering the network to minimize delays. To use resources most efficiently, lower-priority traffic is discarded at the edge of the network if conditions indicate that it cannot be delivered.
CSMA/CDcarrier sense multiple access collision detect. Devices ready to transmit data first check the channel for a carrier. If no carrier issensed for a specific period of time, a device can transmit. If two devices transmit atonce, a collision occurs and is detected by all colliding devices.CSMA/CA
data-link layerLayer 2 of the OSI reference model. Responsible for physical addressing, network topology, line discipline, error notification, ordered delivery of frames, and flow control. IEEE divided this layer into two sublayers: the MAC sublayer and the LLC sublayer.
default routeRouting table entry that is used to direct frames for which a next hop is not explicitly listed in the routing table.ip route 0.0.0.0 0.0.0.0 next hop IP/exit interface
DHCPDynamic Host Configuration Protocol. Provides a mechanism for allocating IPaddresses dynamically so that addresses can be reused when hosts no longer needthem.
Digital SignatureValue computed with a cryptographic algorithm and appended to a data object in such a way that any recipient of the data can use the signature to verify the data’s origin and integrity.
DLCIdata-link connection identifier. Value that specifies a PVC or an SVC in a FrameRelay network. In the basic Frame Relay specification, DLCIs are locally significant.
DNSDomain Name System. System used on the Internet for translating names of networknodes into addresses.
DQDBDistributed Queue Dual Bus. Data-link layer communication protocol, specified inthe IEEE 802.6 standard, designed for use in MANs.
DTEdata terminal equipment. Device at the user end of a user-network interface. DTE connects to a data network through a DCE device (for example, a modem) uses clocking signals generated by the DCE. DCE.