12128796
Description
Flashcards by Tim Bowater, updated more than 1 year ago
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Created by Tim Bowater
about 6 years ago
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| Question | Answer |
| Network Topologies | • A Network topology defines the physical connections of the host in a computer network • Network topology is the arrangement of the various elements (links, nodes, etc.) of a communication network |
| Network Topologies | o Bus (basically in line, this is the old style coax ethernet. Like Christmas tree lights, if one goes down, they all go down.) o Ring (Ring is basically things connected in a ring fashion, but can have a device in the centre that all the devices are connecting to) |
| Network Topologies | o Star (Devices connecting to a hub or switch in the shape of a star) o Mesh (Mesh is basically everything connected to everything else, no central device) o Tree |
| Star Topology | Most common topology - Low cost and ease of installation. Each computer is individually wired to a central connecting device (hub, switch or SOHO router with twisted-pair cabling |
| MESH Topology | Every computer connects to every other computer; no central connecting device is needed. |
| Ring Topology | In a LAN Environment, each computer is connected to the network using a closed loop. Used by a Token Ring and Fibre Distributed Data Interface (FDDI) |
| Token Ring | A Token Ring network sends data logically in a ring fashion, meaning that a token goes to each computer, one at a time, and continues on in cycles. Physically Token Ring computers are connected in a star fashion. |
| Token Ring | Namely, all computers in a Token Ring network are connected to a central connecting device known as a Multistation Access Unit (MAU or MSAU). Basically, the computers can talk (send data) when they receive the token, if they need to. If they send data, it will get passed around with the token until it reaches the right device. |
| Ethernet | Ethernet is the de facto standard and is the most widely-installed local area network technology. o 802.3u or Fast Ethernet that runs at 100 Mbps. o 802.3ab or Gigabit Ethernet. |
| Frames | Computers on Ethernet networks communicate via frames. A frame is a sequence of bits containing a detectable beginning and end of a packet in the stream of bits A frame is a data packet residing on Layer 2 of the OSI model |
| Centralized Computing | Computing is done at a central location using terminals that are attached to this main system. " Mainframes are a powerful computer and the rest of the devices connected to the computer are known as terminals (or dumb terminals). " Each terminal consisted solely of a keyboard and display with no processing power. |
| Client/Server Model | The client/server model is an architecture that distributes applications between servers and client computers. Server: System that provides services such as Window Server 2008 R2 Client: Device that requests services such as Windows 7 |
| Peer-to-Peer Networking | Peer-to-Peer networking distributes applications or workloads between computers. Peers are both service providers and service requestors. E.g. File sharing but not P2P |
| Distributed Computing | Distributive computing includes both client-server and peer-to-peer networks. Every device or workstation has its own processing power |
| Remote Desktop Services and Remote Sessions | Centralized computing has made a comeback of sorts. Remote Desktop Services and remote sessions to computers are based off of the centralized computing model. Thin-client computers do not have a hard drive and store an operating system to RAM, to be loaded up every time the device is turned on. |
| Remote Desktop Services and Remote Sessions | All other applications and data are stored centrally, this system is a blend of centralized and distributive computing. |
| Servers | More powerful computers that provide centralized services: o File (file sharing) o Print o Database o Network controller o Messaging/Email o Web |
| P2P | Peer-to-peer or P2P has recently taking on additional meaning. " P2P can also refer to file sharing networks. " Examples of file sharing networks. o Napster o Gnutella o G2 |
| Standards | Standards are sets of rules that ensure hardware and software released from different companies work together |
| Open Systems Interconnection (OSI) | The Open Systems Interconnection (OSI) reference model is used to define how data communication occurs between devices The model is divided into 7 layers, each layer providing services to the layers above and below |
| Application Layer | Enables users and applications to access network services FTP, HTTP, POP3, SMTP GATEWAY |
| Presentation Layer | Translates data into a common format Commpression, Encryption |
| Session Layer | Establishes a communication session between devices Logon/Logoff |
| Transportation Layer | Manages message fragmentation and reassembly TCP/UDP |
| Network Layer | Manages data routing and creating sub networks IP, ICMP, ARP, RIP Routers |
| Data Link Layer | Provides error-free transfer of data frames 802.3, 803.5 NICs, Switches, Bridges, WAPs |
| Physical Layer | Physical network media and signal methods 100BASE-T, 1000BASE-X Hubs, Patch Panels, RJ45, Jacks |
| OSI Model Layers | Sending the file deconstructs into the appropriate layer and it is reconstructed into the appropriate layer as it is received. |
| OSI Model Layers | The data itself, your actual chunk of data is being modified, manipulated, broken apart, tagged and built in a way when it gets to the physical layer those bits can be sent across and then successfully reassembled up the stack on the other side |
| Layer 1-Physical Layer | Defines the physical and electrical medium for data transfer Physical layer components: cables, jacks, patch panels, punch blocks, hubs and MAUs. Physical layer concepts: topologies, analog versus digital/encoding, bit synchronization, baseband versus broadband, multiplexing, and serial data transfer. Unit of measurements: Bits |
| Ethernet Standards | LAN standards providing a communication method for high speed data exchange among devices Defined Physical and Data Link Layer " 100BASE-T o 100 for 100 Mbps o BASE for baseband o T for twisted-pair cabling |
| Layer 2-Data link | Establishes, maintains, and decides how transfer is accomplished over the physical layer and ensures error-free transmission over the physical layer. Physical addresses (the hexadecimal address that is burned into the ROM of the NIC), known as the MAC address uniquely identify each hardware device work at the Data Link Layer. Data Link Layer components: network interface cards and bridges. Unit of Measurement: frames. |
| Media Access Control Address | Network adapters on an Ethernet network have unique Media Access Control (MAC) address. MAC addresses are unique identifiers assigned to network adapters by the manufacturer. MAC address is six octets in length written in hexadecimal |
| Layer 2 Switches | Layer 2 switches are hardware-based and use the MAC address of each host computer´s network adapter when deciding where to direct data frames Ports on the switch are mapped to the specific MAC address of the device attached. |
| Virtual LAN (VLAN) | Layer 2 Switching can also allow for virtual LAN (VLAN) to be implemented. A VLAN is implemented to segment and organize the network, to reduce collisions, boost performance. IEEE 802.1Q is the standard that supports VLANs. A tag is added to the data frame to identify the VLAN |
| Layer 3-Network | Controls the operations of routing and switching information to different networks. Translates logical addresses or names to physical addresses. Internet Protocol (IP) is a Network Layer protocol. Devices that work at the network layer are routers and IP switches. Network Layer components: IP addresses, subnets. Unit of measurement: packets. |
| Layer 3-Switches | Switches can also reside on the network layer. A layer 3 switch determines paths for data using logical addressing (IP addresses) instead of physical addressing (MAC addresses for a layer 2 switch). Layer 3 switches forward packets, whereas layer 2 switches forward frames |
| Layer 4-Transport Layer | This layer ensures messages are delivered error-free, in sequence and with no losses or duplications. Protocols that work at this layer segment messages, ensure correct reassembly at the receiving end, perform message acknowledgement and message traffic control. |
| Layer 4-Transport Layer | The Transport Layer contains both connection-oriented and connectionless protocols. Unit of measurement used: segments or messages. |
| Connection Oriented Communications | Require both devices involved in the communication to establish an end to-end logical connection before data can be sent. These communications are considered reliable network services. Packets not received by the destination device can be resent by the sender. |
| Connectionless Communications | End-to-end connection is not necessary before data is sent. Every packet that is sent has the destination address in the header. Sufficient to move independent packets, such as in streaming media. Datagram delivery is not guaranteed and lost packets cannot be resent. E.g. watching a video online |
| Connection-based Protocols | The Transport Layer Contains both connection-oriented and connectionless protocols. Transmission Control Protocol (TCP) provides a connection-based, reliable, byte-stream service to programs. User Datagram Protocol (UDP) provides a connectionless, unreliable transport service. |
| Ports | Ports are a Layer 4 protocol that a computer uses for data transmission. Ports act as logical communications endpoint for a specific program on computers for delivery of data sent. |
| Ports | There are a total of 65,536 ports, numbering between 0 and 65,535. Ports are defined by the Internet Assigned Numbers Authority or IANA and Divided into categories. |
| TCP | TCP transport is used for logging on, file and print sharing, replication of information between domain controllers, transfer of browse lists, and other common functions. TCP can only be used for one-to-one communications. |
| UDP | UDP is often used for one-to-many communications, using broadcast or multicast IP datagrams. |
| Layer 5 - Session Layer | The Session Layer managers session establishment, maintenance and termination between network devices. Example: when you log on and log off. This layer controls the name and address database for the OS. NetBIOS (Network Basic Input Output System) is a protocol that works at this layer. |
| Layer 6 Presentation | This layer translates the data format from sender to receiver in the various OSes that may be used. Presentation Layer concepts include: character code conversion, data compression, and data encryption. Redirectors work on this layer, such as mapped network drives that enable a computer to access file shares on a remote computer. |
| Layer 7 Application Layer | Serves as the window for users and application processes to access network services. This layer is where message creation begins. End-user protocols such as FTP, SMTP, Telnet, and RAS(Remote Access Service) work at this layer. |
| Layer 7 Application Layer | This layer is not the application itself, but the protocols that are initiated by this layer. This isn`t an application e.g. Not a mail program, this layer hooks into the application. |
| TCP Model Application Layer | Defines TCP/IP application protocols HTTP, Telnet, FTP, SMNP, DNS |
| Transport Layer | Provides communication session management TCP, UDP, RTP |
| Internet Layer | Packages and routes data IP, ICMP, ARP, RARP |
| Network Interface | Details how data is physically sent through the network Ethernet, Token Ring, Frame Relay |
| TCP/IP | TCP/IP is the protocol used for internet communication |
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