Karteikarten
Chapter 6 Networking
Karten in diesem Stapel (43)
- 1Why Use a LAN?Information sharing
Resource sharing - 2what are advantages of LAN in terms of softwarePurchase software on a per seat basis
Install software on a server for all to use
No need to have a copy on every computer on the LAN
Reduces cost
Simplifies maintenance and upgrades - 3what is LAN MeteringUsed to control the number of copies of software used on a LAN
Available for many software packages
Keeps track of the users
Prohibits using more copies of the package than the licensed number - 4what is a Dedicated server networkA server is permanently assigned a specific task
Most popular network type
90+% of all LANs - 5what is a Peer-to-peer networkNo dedicated servers used
All computers act as both clients and servers
Cheaper than dedicated, but less capability - 6Dedicated Server Networks requireone or more dedicated computers
- 7what are the characteristics of a dedicated serverPermanently assigned a specific task
Enable users to share files, printers, etc.,
May form a powerful enterprise network replacing mainframes
May form a server farm
Also requires a special communication software to enable communications with client computers - 8what are the Types of Dedicated ServersWeb servers, e-mail servers, database servers
File servers
Print servers - 9File serversAllows many users to share the same files on a common disk drive
- 10name the advantages adn disadvantages of of a Peer-to-Peer NetworksMore appropriate for small networksAdvantage:
Lower cost
No dedicated server, generally the most expensive network component
Disadvantage:
Generally slower than dedicated server networks
Each computer may be in use as a client and a server at the same time
Difficult to manage - 11name the characteristics of Network Interface Cards (NICs)Also called network cards and network adapters
Contains physical and data link layer protocols
Mostly built into motherboards today
Can be plugged into the USB port - 12in terms of Network Interface Cards, physical and data link layer protocols characteristics areIncludes a unique data link layer address (called a MAC address), placed in them by their manufacturer
Includes a socket allowing computers to be connected to the network
Organizes data into frames and then sends them out on the network - 13Network Circuits are usedto connect a computer physically to the network
- 14what are the Types of cables in network circuitsUntwisted wire pairs (UTP) – leading LAN cable type
Shielded twisted pair (STP)
Optical fiber – high capacity, being used more and more in LANs - 15what are functions of Hubs & SwitchesAct as junction boxes, linking cables from several computers on a network
Usually sold with 4, 8, 16 or 24 ports
May allow connection of more than one kind of cabling, such as UTP and coax.
Repeat (reconstruct and strengthen) incoming signals
Important since all signals become weaker with distance
Extends the maximum LAN segment distance - 16what are Access PointsAPs are used instead of hubs/switches in a wireless environment
Act as a repeater
They must be able to hear all computers on a WLAN - 17what is Power over Ethernet (POE)Used to supply power to some APs
No external power is needed
Power flows over unused Cat5 wires - 18what are the characteristics of Omni directional antennasTransmit in all directions simultaneously
Used on most WLANs
Dipole antenna (rubber duck)
Transmits in all direction (vertical, horizontal, up, down) - 19what are the characteristics of Directional antennasProject signal only in one direction
Focused area; stronger signal; farther ranges
Most often used on inside of an exterior wall
To reduce the security issue
A potential problem with WLANs
Antennas can be made from Pringles, etc. cans and are called “Cantennas” (www.cantenna.com) - 20Network Operating Systems is software thatthat controls the LAN
- 21Directory ServiceProvide information about resources on the LAN
- 22Network ProfilesIndicate the resources available in the network and authorized users
- 23NOS Server SoftwareEnables servers to operate
Replaces the normal OS on the server - 24NOS Server Software performs which functionsdata link, network, and application layer functions
basically all network functions - 25when the NOS Server Software Replaces the normal OS on the server it -Optimized to provide better performance and faster response time (for its limited number of operations)
- 26NOS Client SoftwareProvides data link and network layer functions
Interacts with application software and computer’s own operating system
Included in most OS packages such as Windows XP, Vista, 7, 8
Allows client to view and access available network resources - 27NOS Directory ServiceProvides information about resources on the LAN
- 28Network ProfilesKept by servers
Specify resources available for use by other computers
Include data files, printers, etc.
Configured when the LAN is established, and updated - 29User profilesOne profile for each user, used for security reasons
Describe what each user on a LAN has access to
Includes access codes assigned to devices and users
Only the user with a correct code can use a specific device - 30Wired EthernetUsed by almost all LANs today
Originally developed by a consortium of Digital Equipment Corp., Intel and Xerox
Standardized as IEEE 802.3 - 31what are the Types of EthernetShared Ethernet
Uses hubs
Switched Ethernet
Uses switches - 32what is Basic geometric layout of the networkThe way computers on the network are interconnected
- 33what is Logical TopologyHow the network works conceptually
Like a logical data flow diagram (DFD) or
Like a logical entity relation diagram (ERD) - 34what is Physical TopologyHow the network is physically installed
Like physical DFD or physical ERD - 35Shared Ethernet’s Logical TopologyViewed logically as a bus topology
All messages from any computer flow onto the central cable (bus)
A computer receive messages from all other computers, whether the message is intended for it or not
When a frame is received by a computer, the first task is to read the frame’s destination address to see if the message is meant for it or not - 36Switched Ethernet TopologyUses workgroup switches
Logical and physical topology of the network becomes a star topology via switch
Switch reads destination address of the frame and only sends it to the corresponding port - 37workgroup switchesDesigned to support a small set of computers (16 to 24) in one LAN
Looks similar to a hub, but very different inside
Designed to support a group of point-to-point circuits
No sharing of circuits - 38Forwarding TablesSimilar to routing tables
Lists the Ethernet address of computers connected to each port
When a frame is received, the switch reads its Layer 2 data link layer destination address and sends the frame out of the corresponding port in its forwarding table. - 39Switch OperationSwitch starts by working like a simple hub
With an empty forwarding table
It gradually fills its forwarding table by learning about the nodes
Reads the source MAC address of the incoming frame and records it to the corresponding port number
Reads the destination MAC address. If not in the Table then it broadcasts the frame to all ports
Waits for the destination computers to respond, and repeats the first step - 40Media Access Control (MAC) with Shared Ethernet uses which protocolUses a contention-based protocol called CSMA/CD
- 41what is Carrier Sense (CS):A computer listens to the bus to determine if another computer is transmitting before sending anything
Transmit when no other computer is transmitting - 42what is Multiple Access (MA):All computers have access to the network medium
- 43what is Collision Detect (CD):Declared when any signal other than its own detected
If a collision is detected
To avoid a collision, both wait a random amount of time and then resend message
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- Karteikarten am Chapter 6 Networking, erstellt von warrenj3000 am 11/11/2013.
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