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44 Cards in this Set
- Front
- Back
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Max twisted pair cable length |
100m |
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Crossover cable |
Computer to computer or switch to switch connections |
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Straight-through cable |
Switch to computer, router to switch (basically device to different device) |
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Shielded Twisted Pair |
Cable is shielded Reduces electrical noise within cable and from outside = better signal quality More expensive and difficult to install |
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Unshielded Twisted Pair |
Cheaper and easier to install than Shielded Twisted Pair but signal is more vulnerable to interference and thus signal quality may be lower |
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Single mode fibre optic |
Uses a single laser to transmit data Requires a very straight path Expensive High performance Long distance (10km+) |
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Multi mode fibre optic |
Uses LEDs to transmit multiple signals at the same time Cheaper Lower performance Shorter distance than single mode (4km half duplex 2km full duplex) |
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Optical Time-domain Reflectometer |
Used for estimating: the fibre's length overall attenuation locate faults (such as breaks) loss of power due to tapping in to the fibre |
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IPv4 |
4 byte addresses |
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Class A IP |
1 - 127 1st byte = net ID |
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Class B IP |
128 - 191 1st 2 bytes = net ID |
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Class C IP |
192 - 223 1st 3 bytes = net ID |
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Class D IP |
224 - 239 1st byte = net ID |
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Class E IP |
240 - 254 1st byte = net ID |
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Router |
Connects networks Each network must have different net ID Port of router that connects to a network has an IP address in that network Decides best path for forwarding data packets on a network |
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Switch |
Connects devices together to form a network |
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Public IP address |
Assigned by IPAA (Internet Assigned Number Authority) Also assigned by ISPs (in consultation with IPAA) |
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Private IP addresses |
Hidden behind proxy servers/home routers (Network Address Translation) |
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Bus topology |
All devices connect to one line Cheap and easy to install Speed/distance limitations Security issues Difficult to troubleshoot Unuseable for large networks |
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Ring topology |
Each device connects to a device on either side of it Cheap and easy to install Speed/distance limitations Difficult to change network and perform maintenance Whole network goes down if one device breaks Inefficient |
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Star topology |
Easy to upgrade & troubleshoot Ideal for large networks Simple Expensive for long distances |
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Mesh topology |
Many connections so no traffic issues Robost Fault tolerant Difficult cabling Complex installation Expensive |
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Tree topology |
Best possible solution for large network (WAN) Point-to-point communication possible Best topology for branched out network Not suitable for small networks as wastes resources Highly dependant on backbone device (root) Difficult to configure once network gets to certain size |
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Serial transmission |
Data transmitted one bit at a time Slow |
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Parallel transmission |
Several bits of data transmitted at a time |
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Internet Layering Architecture |
Application - software outside the operating system Transport - software inside the operating system Internet - only IP address used Network interface - physical address (MAC) used |
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Switches |
Dedicated bandwidth per port Can begin forwarding packets before they are fully received Internally maintains tables of port and node addresses Managed (configurable) or unmanaged |
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Switch functions |
To learn To filter To forward |
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Physical frame (MAC frame) |
Header area - contains MAC addresses (source and destination), control information and sometimes frame size information Data area - contains data being transmitted |
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Datagram |
Header area - contains IP addresses (source and destination), Time to Live and parameters for limited quality of service |
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Encapsulation |
Datagram is inserted in to physical frame and is removed by the router of the destination network |
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Routing Semantics |
Unicast - deliver a message to a specified node in the network (one to one) Broadcast - deliver a message to all nodes in the network (one to many) Multicast - deliver a message to a group of nodes which are receivers (one to many) |
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Connection oriented communication |
Call set-up
Data delivery Error check and acknowledgement Call termination e.g. phone call e.g. TCP/IP |
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Connectionless communication |
Data delivery by transmitting individual packets Constantly broadcasts - doesn't check if data received by recipient e.g. TV broadcast e.g. UDP |
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Quality of Service |
Expectation from a network to meet certain criteria, most commonly: delay jitter (variation in delay) Throughput (volume of error free data received per second) |
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Audio and video data |
Time sensitive Requires network which can provide QoS Retransmission of data due to error may cause timing and synch problems Under 150ms delay not noticeable 150 - 400ms acceptable but not ideal 400ms+ can seriously hinder interactivity in voice conversation |
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Heirachical Network Model |
Core layer switches - high speed backbone, connects to the internet Distribution layer switches - manage traffice between core and access layers, perform routing functions between VLANS Access layer switches - interface with end devices such as PCs, printers (can also be routers, switches, access points etc) |
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Ethernet |
Most popular network technology Based on star topology Collisions can occur No priority Not very efficient at high load Cheap and easy to install Easy to expand Uses twisted pair/fibre optic/wireless |
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Wireless |
Range normally between 60m - 90m Signal overlapping Multiple channels (different frequencies) Up to 600mbps (current standard) 2.4ghz or 5ghz on current standard Uses access points |
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MAC address |
6 byte physical address that is unique to each device Used by every device that connects to a LAN (issued when device is made) |
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Protocols |
Provide format/structure for messages Provide process by which networking devices share information about pathways to other networks Provide how and when error and system messages are passed between devices Provide the setting up and termination of data transfer sessions |
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The Internet Model |
Application - represents data to the user plus encoding and dialog control Transport - supports communication between diverse devices across diverse networks Internet - determines the best path through the network Network access - controls the hardware devices and media that make up the network |
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Transport Protocols |
Operate in the Transport layer and use protocol port numbers which are 16 bits long TCP/IP - connection based (error checking, re-sends data if it contains an error) UDP - connectionless |
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Web Server protocols |
Uses 4 protocols: HTTP TCP IP Ethernet |
