This glossary contains CCNA module 3 and CCNP module 1 terms. An Excel version can be downloaded.
| Terme | Description |
| ACL | Access Control List. Used on router, they allow to limit network traffic, to control traffic flow, to secure access, to filter access type transferred or stopped on interfaces. |
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| Adapter | Card placed in a computer to allow connection to a network. |
| Administrative distance | Administrative distance represents reliability of an information source on routing. It's a number : higher it is, less reliable is the source. |
| Answer Time | Time between the send of a message et the reception of her answer. |
| Appletalk | Protocol realized by Apple to make Macintoshes networks. |
| ARP | Address Resolution Protocol. Protocol allowing to resolve dynamically a logic address (IP) in a physical address (MAC) |
| Asymmetric switching | An asymmetric switching is used for client-server traffic needing a better bandwidth for the server. |
| ATM | Asynchronous Transfer Mode. High bandwidth technology of information transfer using multiplexing and cell switching. |
| Autonomous Switching | Method allowing routers to transfer data the most speedily as possible. This technique puts in cache routing decisions. |
| Autonomous system | Routers in a domain managed by an administrative entity. Routers exchange informations by routing protocols. |
| Backbone | The backbone is the central access point of a network. |
| Bandwidth | The bandwidth is the theoretical maximal flow of a communication channel. It's defined in bit/second (bps). |
| BGP | Border Gateway Protocol. BGP is an external routing protocol. |
| Bit | A bit is the lower quantity of informations in a computer. It's a binary number which taking 0 or 1 value. |
| Bitrate | Quantity of informations transmitted by time units. It is measured in bits per seconds (bps). |
| BPDU | Bridge Protocol Data Unit. Data structure exchanged by protocols. (ex : datagrams for IP, packets for X25...). |
| Bridge | Equipment allowing to connect networks. It allows network segmentation. |
| Broadcast | A broadcast is a diffusion of informations to hosts in the same network. (broadcast domain). |
| Buffer | Used by switches and routers, it allows to stock packets before transmition. |
| Carrier Detect | Method to allow only one station to emit at time. When a station wants to emit an information, it listens the support : if it's free, it transmits, if it's busy, it will try a new access later. |
| CBWFQ | Class Based Weighted Fair Queuing. Queuing Mechanism allowing packets to be stocked un a queue profiting of a more important priority. |
| Collision | A collision appears when many informations are emitted on the same shared media. |
| Collision domain | A collision domain corresponds to a part of a network where hosts share the access of the media. Hub can't segment domains. |
| Congestion | Congestions appear when a network is charged. It realizes a slow down of answer time and file transfers. |
| Convergence | Convergence is the speed to which all network units have the same view of the network topology. |
| CRC | Cyclic Redundancy Code. Code calculated by network units of type "Store And Forward" in frame control sequence field before transmition. |
| CSMA/CD | Carrier Sense Multiple Access with Collision Detect. Multiple access Carrier Detection method allowing to one host to emit at the time. |
| Cut-through | Switching Mod allowing latency reduction. The switch reads destination address before receiving all the frame to transmit it when it's possible. |
| Data Frame | Informations sent in one bloc by a network card. It consists in encoding data. |
| Datagram | Data unit used by a protocol in non connection mode. The sending of a datagram isn't reliable because non mechanism will verify if data are transmitted. |
| Distance vector | Routing algorithm that use routing table transmition between neighbors routers. |
| DNS | Domain Naming System. System used to translate an IP to a name on a domain. |
| DUAL | Bounded to EIGRP protocol, DUAL is an algorithm maintaining a topology up to date et creating route table. |
| Dynamic routing | Routing which automatically adjusts itself to the network where it is, without needing to know specified routes. |
| EGP | External Gateway Protocol. External routing protocol. |
| EIGRP | Enhanced IGRP. EIGRP is an improved version of IGRP. Improvements carry on convergence and effectiveness of protocol operations. |
| Encapsulation | Mechanism used in layer architecture where informations of a layer are the data of the lower layer. |
| Enterprise server | Server which carry all users of the enterprise. It offers global functions as mail or name resolving. It is placed in the main distributor. |
| Ethernet | Ethernet is communication standard on local networks at 10Mb/s, 100Mb/s or 1Gb/s. It corresponds at IEEE 802.3 norm and uses CSMA/CD technique. |
| External route | An external route allows to exchange routing informations on networks which are not on the same autonomous system. |
| Fast Switching | Method allowing routers to transmit data the most speedily as possible. This technique puts in buffer routing decisions. |
| FastForward | Cut-through switching. This method transmits a packet just after reception of its destination address. It allows to obtain a very slow latency time. |
| FDDI | Fiber Distributed Data Interface. Optical fiber network with a bandwidth at 100Mb/s. |
| FireWall | The goal of a firewall is to protect a network (or just a computer) against externals attacks. |
| Fragment free | Cut-Through Switching. The goal of this method is to filter collisions fragments before transferring. |
| Freeze | A route to a network is frozen when a router is informed that this network is moved away or broken down. |
| FTP | File Transfer Protocol. Communication protocol for files transfers. |
| Full Duplex | Communication mode allowing to transmit a packet and receiving some at the same time. |
| Generic Mask | It's a quantity of 32 bits divided in four octets. |
| GNS | Get Nearest Server. Request packet sent by a client on an IPX network to locate the nearest active server. |
| Gopher | Information searching system by keywords to navigate on Internet. |
| Horizontal interconnection | An horizontal interconnection allows to connect computers to the intermediary distributor IDF. |
| HTTP | Hypertext Transfer Protocol. Data transfer protocol on the Web. |
| HTTPS | Hypertext Transfer Protocol Secure. Secured data transfer protocol on the Web. |
| HUB | A hub is a network device which transmits packets that it receives on a port to others ports. It doesn't realize switching. |
| ICMP | Internet Control Message Protocol. Protocol allowing to control IP protocol. |
| IDF | Intermediate Distribution Facility. Facility which regroups intermediaries connections. |
| IEEE | Institute of Electrical and Electronical Engineers. American institute realizing norms in domains of electric, electronic and computers. |
| IGMP | Internet Group Management Protocol. Protocol that allows an host to join to a multicast group and quit it. |
| IGP | Interior Gateway Protocol. Protocole permettant d'échanger les informations de routage à l'intérieur d'un système autonome. |
| IGRP | Internet Gateway Routing Protocol. Internal route protocol using distance vector, developed by Cisco to replace RIP. |
| Internal route | An internal route exchange routing informations on networks which are in the same administrative structure (autonomous system). |
| IP Address | Logical Address defined on 32 bits. It is the address of a station on the network. |
| IPX | Internetwork Packet exchange. Novell NetWare network protocol. |
| LAN | Local area network. Used to connect a lot of stations in a building. |
| Latency | Also called Duration. Its is the time taken by a packet to reach its destination. |
| LDAP | Lightweight Directory Access Protocol. Simplified Protocol to access to a directory. |
| Link state | Algorithm using a complex topology basis. It allow every routers to have a global view on the network topology. |
| Mac Address | Physical address. It is unique and defined on 48 bits. It define the network material. The first half is for the manufacturer, and the last half is to identify the material. |
| MDF | Main Distribution Facility. Main room where the connection between the IDF are located. |
| Metric | Numerical value which depends on the routing protocol. It allows the router to find the best path. |
| Micro segmentation | It can be made by switch to segment workstations into VLANs. |
| MTU | Maximum Transmission Unit. Maximum size of a data unit carried by a network. (ex : 1500 octets for an Ethernet network). |
| Multicast | It allows to transmit data to multiple receivers. |
| NBMA | Non Broadcast Multi Access. Describe a network that prevents broadcast (ex : X.25) or multicast (ex : too big Ethernet network). |
| NCP | NetWare Core Protocol. Novell protocol that gives applications and client/server connections. |
| NetBEUI | NetBIOS Extended User Interface. Developed by IBM and et taken by Microsoft, NetBEUI is a communication protocol on networks. |
| NIC | Network Information Center. Coordinator of networks charged to ensure the coherence between addresses and names. |
| NNTP | News Network Transfer Protocol. |
| NTP | Network Time Protocol. Time exchange protocol very used on Internet allowing to up to date the system time from a remote server. |
| OSPF | Open Shortest Path First. Route protocol based on link state technique. |
| Packet | Data unit used by a connexionless protocol. |
| Point-to-multipoint | Link between one terminal and several ones. |
| Point-to-point | Link between two terminals. |
| POP | Post Office Protocol. Protocol allowing to reach email boxes. |
| Port | Port allowing devices to be plugged to a computer. |
| Propagation time | Time elapsed between a signal creation and its reception. |
| Reverse poison | This update is from the IGRP protocol, and prevents routing loops. It speeds the convergence. |
| RIP | Routing Information Protocol. Internal routing protocol in an autonomous system. |
| Route Maps | Continuation of criterias with associated actions. Their goals is to control redistribution, to manage routing informations and to define politics in the routing politic. |
| Route table | Table that allows routers to know where to transmit packets between their interfaces. It links an interface to the networks accessible through it. |
| Routed protocol | Protocols that allow routers to transmit data to their destination. (ex : TCP/IP) |
| Router | Third layer unit that transmits packets from a network to another. |
| Routing | Action to find a way to a host in a network. |
| Routing loop | This appears when routers transmit datagrams between themselves without giving it to the receiver. When many routers are implicated in the loop, each one transmit the datagram to the next router in the loop. The datagram will loop with no time limit. |
| Routing protocol | Protocol that allows routers to share their routing tables. |
| RTMP | Routing Table Maintenance Protocol. Route protocol defined by Apple. |
| RTP | Realtime Transport Protocol. Protocol which adds synchronization informations to IP data packets to avoid lost of data. |
| SAP | Service advertisement protocol. IPX network protocol that allows to list available network services. |
| SAP Table | Table associating IPX network services and their network address. It is kept by network devices as routers. |
| Segmentation | This means cutting big collision domains into smalls ones. It can be done by switches, routers, bridges... |
| Silicon Switching | This method allows routers to transmit data as fast as possible. Routing decision are put in a buffer. |
| SMTP | Simple Mail Transfer Protocol. Protocol allowing to transmit electronic mails. |
| Spanning tree | Part with no buckle of a network topology. |
| Split-horizon | Update which prevent routers to transmit informations on a route by the way they come. This prevents routing loops. |
| SPX | Sequenced Packet Exchange. Connection oriented 4° layer protocol. It supplements IPX in Netware network. |
| Static routing | Routing made with static entries in the route table. |
| Store and forward | Switching method with a high error checking. The packet is fully received before being transmitted. |
| Stuffing signal | Signal emitted by a Ethernet host when it detected a network collision. |
| Switch | Network unit that makes switching. It reduces collision domains. |
| Switching | Connection between two network points. It is possible to realize packets or cells switching. |
| Switching table | Table that allows a switch to determine where to distribute packets between its ports. It links a port with MAC address accessible by it. |
| Symmetric switching | Switching giving the same bandwidth on all the ports. |
| Synchronization | Way to allow two or more entities to be in phase. |
| TCP/IP | Transmission Control Protocol/Internet Protocol. Protocol allowing a reliable control of sending data. |
| Telnet | Application protocol providing a virtual terminal service allowing to take control of a remote host. |
| Tics | Time units. |
| Token Ring | Protocol defining access technique to a local network using a token turning on a ring. The host which has the token is authorized to make theirs operations on the network, others must wait its availability. |
| Topology | Physically organization of a network. |
| Transmitting time | Duration of a network packet trip, from when it left the emitter to its arriving on the receiver. |
| UDP | User Datagram Protocol. In opposite of TCP, it doesn't require an acknowledge allowing better performances but a lower reliability. |
| Unicast | Qualify a communication with only one emitter and only one receiver. |
| Vertical interconnection | A vertical interconnection allows to connect intermediaries distributor IDF to master distributor MDF. |
| Virtual network | Virtual LAN. Way to logically regroup computers of the same network. |
| VLAN | Virtual LAN. Way to logically regroup computers of the same network. |
| VLSM | Variable Length Subnetwork Mask. Optimization of IP attribution by using different subnetwork mask for a same network. |
| WAN | Wide Area Network. Physical or logical network which cover a wide zone. |
| Workgroup server | Server used by a group of users. It offers file or application sharing. It is located in the IDF. |
| X.25 | WAN Protocol. Transmition protocol by packet switching. |