network axamples: Local and Wide Area Networks A system that transmits any combination of voice, video or data between users. network operating system a.k.a NOS Also known as the NOS, software that operates connectivity between client a server computers. network interface card a.k.a. NIC Hardware device used to connect computers to a network. workstation Also known as 'clients' A computer on a Network where users perform a variety of tasks such as word processing, e-mailing or web browsing. In a LAN, these computers connect to a Server. Server A type of computer in a LAN that has functions such as data storage, authentication and processing data. logical addresses Software based, easily changed identifiers that are members of a common hiherarchial group. flat network This type of network has all its nodes under a single network space. segments Groups or nodes per network address that are part of a larger network. segments Router switches and bridges can be used to separate these parts of a network. logical names User friendly names the identify a network resource. connectionless Communications with little overhead, individual packets contain information about the sender and receiver. If some data is not received, the process must start over. connection oriented For data integrity issues. Two nodes establish virtual paths to transmit data through. flow control The rules established by two nodes that define how much information whill be sent withing a time interval, how they will signal for data flow to stop and resume (to keep the slower computer for being overwhelmed) and how to acknowledge successful receipt of data. buffering A method by which a receiving node allocates storage area to hold transmission data when data is arriving faster than the node can process it. cyclic redundancy check An error checking method by which the receiving computer performs a set of calculations, agreed upon by the sender and receiver, then compares the calculations with data placed inside a packet. The output determines whether the packet was received successfully or if an error condition occured. Local Area Network A network with physical constraints. Typically occupies a single structure such as a bank, office or other department. Wide Area Network A type of network that interconnects otherwise isolated Local Area Networks. internet The largest and most common Wide Arean Network campus area network a.k.a. CAN A network located in a business park, multi-building school or business complex. metropolitan area network a.k.a. MAN A network that is a type of WAN, geographically defined to an area such as a city. repeater Devices on a LAN that amplify the electrical signals and helps overcome distance limitations. hub A device that connects computers on a LAN. This type of device broadcasts the signals it receives to all computers connected to it. bridge This device is used to connect two network segments together and can interconnect different tupes of media, such as 10BT, 100BT and Fiber. It also keeps track of MAC addresses and send data directly to the intended segment. switch A type of Hub or Bridge that keeps a table of MAC addresses and directs data to the specific use. This avoids having to broadcast data to all clients and reduces network congestion. full duplex A mode in which ports can send or receive data simultaneously. half duplex A mode in which pors can either send or receive data, not both at the same time. router An internetworking device that is aware of all other devices on the network. They make forward and drop decisions by examining network addresses. broadcast storm A situation in which a broadcast is repeatedly passed between repeaters, bridges or switches until the network is overloaded or incapacitated. router This device do not pass broadcasts and can effectively prevent broadcast storms. media access control a.k.a. MAC address An address on a network interface card (NIC) that is unique and assigned to them by the manufacturer. router Which of these devices can apply to a LAN or a WAN: Repeater, Hub, Bridge, Switch, Router? node Any device connected to a network such as printers, computers, routers, etc. protocol Defines how communication will take place. An agreed upon standard for communicating. network address Also known as a Logical Address. A unique identifier for any node on a network. dynamic address A network address assigned by and administered by a central server. static address A scheme where a unique address in manually configured for a node on the network. Ensures that a device on a network is always found at the same address. internetwork operating system Also known as IOS A software program found on Cisco routers used to manage, control or monitor it's performance. open systems interconnect a.k.a The OSI A standard that defines how communications between various hardware and software devices takes place. Designed to meet interoperability standards between diverse systems. physical address An address that's hardware encoded to a network device to identify it on the network. logical address Unique addresses that are software based and can be easily changed on any device. flow control A function of the Transport layer, it ensures that routed protocols Layer 3 protocols that a router uses to route traffic across a network from the network addresses these protocols provide. i.e. IPX, IP & Appletalk. routing protocols Protocols that are tasked with route determination. They keep track of of the status of available routes. hop count A measure of each internetworking device that a packet muss pass through to get to its destination. metric A statistical value that determines the performance or availability of a particular hop or path. static routing Types of routing protocols that require a network administrator to manually enter routes on a routing device. Devices with this configuration do not update each other and do not accomodate changes in network topology. dynamic routing These types of routing protocols that build and maintain their own routing tables by sharing information with neighboring networking devices. distance vector protocols Protocols that use a hop count to determine the best route for traffic. distance vecor protocols These protocols consider routes with more than 16 hop counts unreachable. routing information protocol A distance vector protocol that uses hop count as its only metric. Does not support VLSM and is limited to 16 hops. flapping routes Network routes that are going up and down and cause repeated changes to a routing table. triggered updates Occurs when there is a change in the metric of a known route. split horizontal/poison reverse Amethod used to prevent one router from sending information it received back from another router back to its original sender. RIP v2.0 An updated version of RIP that supports VLSM and 128 bit secure authentication. interior gateway routing protocol An advanced distance vector routing protocol that has an upper limit hop count of 255 hops. interior gateway routing protocol Although this is a distance vector routing protocol, it uses latency, reliability and link capacity to determine the best route. It can also load balance over unequal links. link state protocols These protocols build routing tables based on link status (active or inactive) and makes routing decisions based on a virtual network diagram it keeps. As links go up and down, notifications are sent to adjoining routers. open shortest path first A link state protocol that supports VLSM and determines routes by the shortest path as well as link state. cost A calculation used to determine the best route based on bandwidth. aras Logical groups of OSPF routers configured to share link state information. enhanced igrp A link state protocol that supports VLSM, supernetting, load balancing over unequal paths, link state router updating (no periodic updates) and uses 'hello' packets to determine the presence of neighboring routers.