Chapter 6: Networking Fundamentals Definitions and Questions

Bus topology

- A network layout in which there is one main trunk, or backbone, that all the various computers and network devices are connected to. - uses the least amount of cabling - each computer shares the same data and address path

Straight Tip (ST) Connector

- A straight, round connector used to connect fiber-optic cabling to a network device. - most widely used fiber-optic connector - very easy to use

CAT 5e Cable

- A UTP cable commonly found in wired Ethernet networks, designed for 100 MBps-wired Ethernet networks

CAT 6 Cable

- A UTP cable type that provides more than 1 Gb/s of throughput up to 100 meters - can carry 10 Gb/s on shorter distance

Modem

- A device that allows computers to communicate over telephone lines

RJ-45 (registered jack 45)

The standard connector used with shielded twisted pair and unshielded twisted pair cabling.

Bridges

- operate in Data Link layer (Layer 2) - are used to divide network segments into multiple collision domains - isolate network traffic, preventing unwanted traffic from entering a segment when there are no recipients on that segment

Wireless personal area networks (WPANs)

- personal, short distance area wireless network for interconnecting devices centered around an individual person's work space. - Bluetooth

Web server

- refers to server software, or hardware dedicated to running said software, that can serve contents to the World Wide Web - processes incoming network requests over HTTP and several other related protocols

Broadcasting

- repeating any signal that comes in on one port and copy it to the other ports - also referred to as multiport repeaters

Layer 3 - Network Layer

- responsible for logical addressing of messages - data is organized into chinks called packets - like the traffic cop - able to judge the best network path for the data based on network conditions, priority, and other variables - manages traffic through packet switching, routing, and controlling congestion of data

Topology

-The physical and logical design of a computer network; examples include mesh, bus, ring, star and hybrid; the physical layout of the network devices and the cabling, and how all the components communicate with each other

Dedicated servers

- assigned to provide specific applications or services for the network and nothing else - specializes in only a few tasks - requires fewer resources and may translate to efficiency and can thus be considered having a beneficial impact on network performance

Star Topology

- A topology with one central node that has each computer or network device attached to the central node. - All data first goes into the central node and then is sent out to its destination. (Think of it like a bicycle wheel with spokes.)

Centralized Processing

- Processing performed in one computer or in a cluster of coupled computers in a single location.

Plenum-rated cable

- Teflon type of covering - the coating does not produce toxic gas when burned and is rated for used in ventilation plenums that carry breathable air

RJ-11 (registered jack 11)

- The standard connector used with unshielded twisted pair cabling (usually Cat 3 or Level 1) to connect analog telephones.

CAT 5 Cable

- UTP capable of 100 Mbps. Four twisted wire pairs (eight wires). - used for Ethernet

Crimper

- Used to attach a connector (for example, an RJ-45 connector) to the end of an unshielded twisted-pair (UTP) cable.

Fiber-optic cable

- a cable that transmits data at close to the speed of light along glass or plastic fibers. - supports very long lengths - immune to electromagnetic interference - laser diodes generate laser light

Full-duplex communication

- a computer can send and receive data simultaneously. - advantage over half-duplex is performance

Local Area Network (LAN)

- a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building.

Metropolitan Area Network (MAN)

- a computer network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network (WAN).

Firewall

- a hardware of software solution that serves as your network's security guard - most important device on networks that are connected to the Internet - protect your network resources from hackers - can simultaneously prevent computers on your network from accessing undesirable content on the Internet

Patch Panels

- a large hub that is rack mounted - houses multiple cable connections but possesses no network intelligence - sole purpose is to connect cables together

Vampire tap

- a metal tooth sinks into the cable, thus making the connection with the inner conductor - connected to an external transceiver that in turn has a 15-pin AUI connector to which you attach a cable that connect to the station

BNC connector

- a miniature quick connect/disconnect radio frequency connector used for coaxial cable.

Single Point of Failure (SPOF)

- a part of a system that, if it fails, will stop the entire system from working - SPOFs are undesirable in any system with a goal of high availability or reliability, be it a business practice, software application, or other industrial system.

Hub

- a small hardware device that joins multiple computers together within one local area network (LAN). - connects multiple Ethernet devices together, making them act as a single segment.

Wide Area Network (WAN)

- a telecommunications network or computer network that extends over a large geographical distance/place - multiple, disbursed LANs connected together

Media Access Control (MAC) address

- a unique identifier assigned to a network interface controller for communications at the data link layer of a network segment. - are used as a network address for most IEEE 802 network technologies, including Ethernet, Wi-Fi and Bluetooth.

Personal Area Network (PAN)

- a very small-scale network designed around one person within a very limited boundary area - networks that use Bluetooth technology

CAT 3 Cable

- able to transmit data at speeds up to 10Mbps - 8 wires

Connectivity Device

- allow communications to break the boundaries of local networks and really provide the backbone for nearly all computer networks, regardless of size

Layer 7 - Application Layer

- allows access to network services - file service, print services, and other applications operate

Layer 5 - Session Layer

- allows applications on different computer to establish, maintain, and end a session - session= one virtual conversation - enables network procedures, such as identifying passwords, logons, and network monitoring

Client Software

- allows the computer to talk to the servers and request resources from them - comes with all operation systems today

Distributed Processing

- also known as distributed computing - defined as using a network of computers to perform specific tasks with one main computer used for more complicated tasks. - an example is a peer-to-peer network.

Subscriber Connector (SC)

- also known as square connector - latched connectors, making it virtually impossible to pull out the connector without releasing its latch - work with single-mode or multimode optical fibers

Patch cable

- an electrical or optical cable used to connect one electronic or optical device to another for signal routing. - is the same on both ends

Resources

- any item that can be used on a network - printers and other peripherals - disk storage and file access - applications

Layer 2 - Data Link Layer

- arranges data into chunks called frames - in these chunks is control information indicating the beginning and end of the datastream - it makes transmission easier and more manageable and it allows for error checking within the data frames - describes the unique physical address (also known as MAC address) for each NIC

Nondedicated servers

- assigned to provide one or more network services and local access - expected to be slightly more flexible in its day-to-day use than dedicated servers - used to direct network traffic and perform administrative actions

Client-Server Resource Model

- better than peer-to-peer model for large networks - Server-based networks use one or more dedicated, centralized servers. - All administrative functions and resource sharing are performed from this point. - This makes it easier to share resources, perform backups, and support an almost unlimited number of users. -This model also offers better security.

Half-duplex communication

- between the sender and receiver, only one of them can transmit at any one time - example is a walkie-talkie

Multipurpose servers

- both a file and print server at the same time

CAT 6a Cable

- can handle 10Gbps speed, but at longer distances (up to 100 meters) than CAT-6 can

Passive hub

- connect all ports together electrically but do not have their own power source

Piconet

- consists of two or more devices occupying the same physical channel (synchronized to a common clock and hopping sequence). - It allows one master device to interconnect with up to seven active slave devices.

Coaxial cable (coax)

- contains center conductor core made of copper, which is surrounded by a plastic jacket with a braided shield over it

Layer 4 - Transport Layer

- controls the data flow and troubleshoots any problems with transmitting or receiving datagrams - takes larger messages and segments them into smaller ones and takes smaller segments and combines them into a single, larger message, depending on traffic flow

Servers

- core component of the network - provides a link to the resources necessary to perform any task - offering direction to the client computers regarding where to go to get what they need

Frames

- data is moved from one computer to the next in discrete chunks - store roughly 1500 bytes of data each

Layer 1 - Physical layer

- describes how data gets transmitted over a communication medium - defines how long each piece of data is and the translation of each into the electrical pulses or light impulses that are sent over the wires, or the radio waves that are sent through the air - decides whether data travels unidirectionally or bidirectionally across the hardware

Layer 6 - Presentation Layer

- determines the "look" or format, of the data - performs protocol conversation and manages data compression, data translation, and encryption

Local Connector (LC)

- developed by Lucent Technologies - is a mini form factor (MFF) connector - popular for use with Fibre-Channel adapters, fast storage area networks and Gigabit Ethernet adapters

Routers

- device that analyzes the contents of data packets transmitted within a network or to another network. - determine whether the source and destination are on the same network or whether data must be transferred from one network type to another, which requires encapsulating the data packet with routing protocol header information for the new network type.

Ring Topology

- devices are connected in a ring and pass information to or from each other according to their adjacent proximity in the ring structure. - This type of topology is highly efficient and handles heavier loads better than bus topology. - difficult to add computers b/c network will go down if one entity is removed

Default deny

- firewall rule set in that the only network connections that are permitted are the ones that have been explicitly allowed

Unshielded Twisted Pair (UTP)

- have two or four pairs of twisted wires going though it - has a PVC or plenum coating but no outer foil shield to protect it from interference

Shielded Twisted Pair (STP)

- have two or four pairs of twisted wires going through it - has an extra layer of braided foil shielding surrounding the wires to decrease electrical interference

Network Operating System (NOS)

- is a computer operating system system that is designed primarily to support workstation, personal computer, and, in some instances, older terminal that are connected on a local area network (LAN). - popular NOS's are Unix and Linux and Microsoft's Windows

Open Systems Interconnection (OSI) Model

- is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology.

Domains (server-based networks)

- is a subnetwork made up of a group of clients and servers under the control of one central security database.

Hybrid Topology

- is an integration of two or more different topologies to form a resultant topology which has many advantages (as well as disadvantages) of all the constituent basic topologies rather than having characteristics of one specific topology.

Switch

- is used to connect various network segments. - A network switch is a small hardware device that joins multiple computers together within one local area network (LAN).

Single-purpose server

- it is a file server only or a print server only

Wireless Access Point (WAP)

- lets users connect to your network via an 802.11 technology

Network

- links two or more computers together to communicate and share resources

RG-8 (thicknet)

- max segment distance of 500 meters - used primarily for network backbones

Cable

- medium used to transfer data physically from computer to computer

RG-58 A/U

- more often used in a conventional physical bus

Twisted-pair cable

- most popular type of cabling because of its flexibility and low cost - consists of several pairs of wire twisted around each other within an insulated jacket

Infrastructure

- networking framework in which devices communicate with each other by first going through an Access Point (AP).

Domain Controller

- server computer that responds to security authentication requests within a Windows domain. - is a concept introduced in Windows NT whereby a user may be granted access to a number of computer resources with the use of a single username and password combination.

Print servers

- servers that host printing services for users

File servers

- servers that provide files to the users on the network

Access Control List (ACL)

- set of rules that determines which traffic gets through the firewall and which traffic is blocked - typically configured to block traffic by IP address, port number, domain name, or some combo of all three

Repeater or Extender

- small, powered device that receives a signal, amplifies it, and sends it on its way - purpose is to extend the functional distance of a cable run - work at the Physical Layer (Layer 1) of the OSI model

Network Interface Card (NIC)

- special expansion card that allows the PC to talk on a network - must connect it to a cabling system that connects to other computers - prepares data, sends data, and controls the flow of data - can also receive and translate data into bytes for the CPU to understand

Coax splitter

- takes a single signal and splits it into multiple replicas of the same signal - used for cable TV - can weaken signal

Workstations (client computers)

- the computers on which the network users do their work, performing activities such as word processing, database design, graphic design, email, and other office or personal tasks

Mesh Topology

- the infrastructure nodes connect directly, dynamically and non-hierarchically to as many other nodes as possible and cooperate with one another to efficiently route data from/to clients. - each device is connected to every other device - rarely found in LANs b/c of complexity of the cabling - cables must be run from each device to every other device

For 2 computers to send and receive data, the cards must agree on several things:

- the max size of the data frames - the amount of data sent before giving confirmation - the time needed between transmissions - the amount of time to wait before sending confirmation - the speed at which data transmits

Public Side, Private Side

- the two connections a firewall must have to operate.

Polyvinyl Chloride (PVC)

- the type of plastic coating found on most network cables. Emits poisonous gasses when burned.

RG-6

- used to connect cable to cable modem - 75 ohms

Crossover cable

- used to connect computing devices together directly. - it is most often used to connect two devices of the same type, e.g. two computers (via their network interface controllers) or two switches to each other. - different on each end

RG-59

- used to connect old cable TV boxes - 75 ohms

Demilitarized Zone (DMZ)

- used to connect servers that can be considered both public and private, such as web and email servers

F-Connector (Coaxial)

- used with cable TV - the exposed end of the copper cable is pushed into the receptacle, and the connector is threaded so that it can screw into place

Active hub

- uses electronics to amplify and clean up the signal before it is broadcast to the other ports - be used to extend the length of a network

Multi-mode cable

- uses visible and infrared light - always 2 cables - used as horizontal cable - prevents light getting through the cable and shortens the distance but delivers more available bandwidth

Single-mode cable

- very thin in diamater - uses laser light - uses as backbone cabling - used in phone systems - light travels straight down the fiber and does not bounce off the cable walls

Peer-to-Peer Network (workgroups)

- when two or more PCs are connected and share resources without going through a separate server computer. - can be an Ad Hoc connection—a couple of computers connected via a Universal Serial Bus to transfer files.

Switches

- work on Layer 2 - provide centralized connectivity just like hubs - examine the Layer 2 header of the incoming packet and forward it properly tot he right port and only that port - essentially a virtual connection between sender and receiver

Ethernet over Power (EoP) adapter

- you use when you cannot run cables for a network connection and wireless is a problem -

Riser cable

Another term for vertical cable; refers to cable that goes between floors in a building. - better than PVC but less than plenum

568A wiring configuration

white/green stripe green solid white/orange stripe blue solid white/blue stripe orange solid white/brown stripe brown

568B wiring configuration

white/orange stripe orange solid white/green stripe blue solid white/blue stripe green solid white/brown stripe brown