Computer Networks
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a collection of computer equipment that's connected with wires, optical fibers, or wireless links. The various separate devices can communicate with one another and exchange information.
Computer Networks
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latency in a network
ping
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reduces costs as a result of resource sharing
- sharing hardware/peripherals
- sharing apps
- sharing files between entowrk users
- sharing a single network connection
- sharing hardware/peripherals
- sharing apps
- sharing files between entowrk users
- sharing a single network connection
Benefits of Networks
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Hackers/Security
Viruses
Network Failure
Setup costs
Tech support & maintenance
Viruses
Network Failure
Setup costs
Tech support & maintenance
Disadvanatges of Networks
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Hacker Activities
Hacker Access
1. Directly (physically on your computer, has your password, etc.)
2. Via logical ports (not a physical port (usb, hdmi), but through email, etc.)
Trojan horses
- appear useful
- back-door; take over control
Denial of Service
Dsitributed DOS
- comes from multiple PCs
- Harder to trace
1. Directly (physically on your computer, has your password, etc.)
2. Via logical ports (not a physical port (usb, hdmi), but through email, etc.)
Trojan horses
- appear useful
- back-door; take over control
Denial of Service
Dsitributed DOS
- comes from multiple PCs
- Harder to trace
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LAN - Local Area Network
- within a small area such as a building or a campus
WAN - Wide Area Network
- covers a much larger geographic area, such as a sate, or a country
Ex. Internet - largest WAN
- within a small area such as a building or a campus
WAN - Wide Area Network
- covers a much larger geographic area, such as a sate, or a country
Ex. Internet - largest WAN
Network Classifications
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PAN - Personal Area Network
- interconnection fo your personal digital devices
MAN - metropolitan area network
- public high-speed network with range of about 50 miles; covers a town or a city
- interconnection fo your personal digital devices
MAN - metropolitan area network
- public high-speed network with range of about 50 miles; covers a town or a city
Additional Classifications
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node
any device that's connected to a network
Ex. laptops, desktops, smartphones
Ex. laptops, desktops, smartphones
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redundancy
multiple routes or paths leading to the same destination in a network
alternative way for data to be transferred
- more redundancy, the better
alternative way for data to be transferred
- more redundancy, the better
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IEEE - Institute of Electrical and Elctronic Engineers
- creates the standards
- project 802 - "local network standards"; family of standards; protocol
IEEE 802 refers to a family of IEEE standards dealing with local area networks
- creates the standards
- project 802 - "local network standards"; family of standards; protocol
IEEE 802 refers to a family of IEEE standards dealing with local area networks
LAN Standards
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protocol
standards
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Clearly defined rules/standards
- how devices communicate with one another
how data is packaged in messages for sending and recieving
Common Network Protocols
TCP - transmission control protocol
IP - internet procotol
HTTP (S) - hypertext transfer protocol
FTP - file transfer protocol
SMTP - simple mail transfer protocol
- how devices communicate with one another
how data is packaged in messages for sending and recieving
Common Network Protocols
TCP - transmission control protocol
IP - internet procotol
HTTP (S) - hypertext transfer protocol
FTP - file transfer protocol
SMTP - simple mail transfer protocol
Network Protocols
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802.3 - standard for ethernet networks
developed in the 1970s
most efficient, reliable, and fast
standard of how connected computers send data
developed in the 1970s
most efficient, reliable, and fast
standard of how connected computers send data
Ethernet Networks
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1. transmission media
- cables, radio waves
2. network adapters
- communication between "nodes" and the network
3. network naviagtion devices
- move data around network
4. software
- NOS (network operation system)
- cables, radio waves
2. network adapters
- communication between "nodes" and the network
3. network naviagtion devices
- move data around network
4. software
- NOS (network operation system)
Main Components of Networks
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Network Interface Card
NIC stands for...
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hardware device enabling communication between entowrk "nodes"
- external devices/USB
- intenral devices (expansion cards)/NIC
- external devices/USB
- intenral devices (expansion cards)/NIC
Network Adapters
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Nodes - any hardware device that is connected to a netowrk; devices may include
- router - transmits data between networks
modem - connects network to ISP (shortform of modulate-demodulate)
switch - transmits data along only 1 network
hub - common connection point for multiple devices on a network
Today most routers funcation as combinations of router and switch/hub
- router - transmits data between networks
modem - connects network to ISP (shortform of modulate-demodulate)
switch - transmits data along only 1 network
hub - common connection point for multiple devices on a network
Today most routers funcation as combinations of router and switch/hub
Network Devices
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Packet switching - data is broken into "packets" & sent over shared routes at the same time. Packets are reassembled by the receivbing computer
Circuit switching - both parties need to present at the same time
Ex. phone call, zoom call, etc.
Circuit switching - both parties need to present at the same time
Ex. phone call, zoom call, etc.
Communication
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Synchronous
- both the sender and reciever are communication in real time
Ex. zoom call
Asynchronous
- sending and receiving messages at different times...not in real time
Ex. recorded lectures, email - can be done whenever without both parties being there
- both the sender and reciever are communication in real time
Ex. zoom call
Asynchronous
- sending and receiving messages at different times...not in real time
Ex. recorded lectures, email - can be done whenever without both parties being there
Types of Communication
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"Design"
Peer-to-peer- locally controlled (every computer is equal, no one computer is a server)
Client/server - centrally controlled (probably has an administrator or IT department that controls the server/network)
Peer-to-peer- locally controlled (every computer is equal, no one computer is a server)
Client/server - centrally controlled (probably has an administrator or IT department that controls the server/network)
Network Architectures
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Peer-to-peer
- no "file server" - each PC is equal
- easy to set up
- suitable for a small number of computers
- home networking
- no "file server" - each PC is equal
- easy to set up
- suitable for a small number of computers
- home networking
Networks
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1. power line - uses home electrical wiring
2. phone line - uses conventional phoen lines
ethernet - use proctol for communcation between ndoes, costly, efficient - retransmits until the data is successfulyl sent
wireless - use radio wabves and follow IEEE stands
"Wifi" wireless fidelity
Major difference is the transmission media
2. phone line - uses conventional phoen lines
ethernet - use proctol for communcation between ndoes, costly, efficient - retransmits until the data is successfulyl sent
wireless - use radio wabves and follow IEEE stands
"Wifi" wireless fidelity
Major difference is the transmission media
Peer-to-peer netwrok types
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Cleitn/server
- has "file server"
- high capacity/speed computer
- contains the NOS
- clients make requests of the server
suitable for larger installations
the internet
- has "file server"
- high capacity/speed computer
- contains the NOS
- clients make requests of the server
suitable for larger installations
the internet
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Cloud Netwokr
avoid large capital expednitruees on hardware
scalable - available on demand
maintenance fee
efficient
scalable - available on demand
maintenance fee
efficient
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Wired Networks Topologies
The arrangement of nodes in a network is referred to as its physical topology
- star, ring, bus, mesh, tree
- star, ring, bus, mesh, tree
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Wireless Networks
Radio waves, not cablings
Wi-Fi - connect through "hotspot"
- Several IEEE standards (802.11)
Wirleess network adapte r
- transceiver (combo of TRANSmitter and reCEIVER)
device designed to connect computers or electronic devices within a network, allowing them to transmit and receive messages
Wi-Fi - connect through "hotspot"
- Several IEEE standards (802.11)
Wirleess network adapte r
- transceiver (combo of TRANSmitter and reCEIVER)
device designed to connect computers or electronic devices within a network, allowing them to transmit and receive messages
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Speed of Transmission
Bandwidth - represents the measure of computer network speed (Ex. width of a highway - the wider the highway, the more cars can pass through at one time)
latency - refers to delays incurred in processing data. low latency is desirable
rate od data transmission between nodes is measured in Gbps
(1 gigabit = 1 billion bits)
latency - refers to delays incurred in processing data. low latency is desirable
rate od data transmission between nodes is measured in Gbps
(1 gigabit = 1 billion bits)
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Firewall Network Protection (think of a wall between apartments that slow down or stop fires from spreading from one area to the next)
Software
- port protection (stops hackers from accessing virtual ports)
It's like...locking your doors and windows protects against burglars
Hardware
- Firewalls can be hardware or software
protects your network from the outside work, similalr to a firewall between rooms in a building
- port protection (stops hackers from accessing virtual ports)
It's like...locking your doors and windows protects against burglars
Hardware
- Firewalls can be hardware or software
protects your network from the outside work, similalr to a firewall between rooms in a building
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VPN - virtual private network
Protects you from hacking, may slow down browsing
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Computer Threats
Malware
- malicious software
spyware
adware
phishing - when someone fishes or baits you into giving them information
pharming - redirects searches into another destination
DOS - Denial of Service ---------------------- | Makes it so a device is left unusable
DDOS - Distributed Denial of Service -----| - A DDOS attack is a cyber-attack from multiple systems on a server, service, website, or network, flooding it with Internet traffic
ransomware
botnets/zombies - robot networks (networks that have been taken over by hackers and left useless)
worms - takes up network bandwidth; they don't steal you information but slow down the network (Not considered a virus)
trojan horses - program that appears to be useful but is actually a program that allows for a backdoor for hackers
cookies - text files that websites put on your harddrive without your knowledge; holds information that can be used for next time that same website is used)
- malicious software
spyware
adware
phishing - when someone fishes or baits you into giving them information
pharming - redirects searches into another destination
DOS - Denial of Service ---------------------- | Makes it so a device is left unusable
DDOS - Distributed Denial of Service -----| - A DDOS attack is a cyber-attack from multiple systems on a server, service, website, or network, flooding it with Internet traffic
ransomware
botnets/zombies - robot networks (networks that have been taken over by hackers and left useless)
worms - takes up network bandwidth; they don't steal you information but slow down the network (Not considered a virus)
trojan horses - program that appears to be useful but is actually a program that allows for a backdoor for hackers
cookies - text files that websites put on your harddrive without your knowledge; holds information that can be used for next time that same website is used)
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Internet & WWW
The Internet came first (before the Web)
The Internet is hardware
The World Wide Web (WWW) was invented on 1989 - 1991. The WWW is the part of the Internet and was made in Switzerland.
The Internet was invented on 1968-1970. (Wasn't known as the internet at that point). The Internet is the infrastructure.
The Internet is hardware
The World Wide Web (WWW) was invented on 1989 - 1991. The WWW is the part of the Internet and was made in Switzerland.
The Internet was invented on 1968-1970. (Wasn't known as the internet at that point). The Internet is the infrastructure.
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