Memorize Flashcards
PAN > LAN > CAN > MAN > WAN
PAN (Personal Area Network): Bluetooth, USB Harddrive to laptop, Video Camera to Computer
LAN (Local Area Network): Connects components in limited distance, Ethernet or Wireless, Internal wired or wireless networks
CAN (Campus Area Network): Building-centric LANs across a University, industrial park, or business park (e.g. College Campus, Military bases)
MAN (Metropolitan Area Network): Connections scattered locations around entire city, 25 mile radius or so (e.g. City departments like police department, community college with campuses spread out)
WAN (Wide Area Network): Connects geography disparate internal networks; Consists of VPNs tunneled over interent (e.g. The internet! or a company connecting itself across country or world)
Bus, Ring, Star, Hub-and-Spoke, Full-Mesh, Partial-Mesh
(How they work, Redundancy)
Bus: Cable running through that each device taps into, old tech, form single collision domain, NO REDUNDANCY
Ring: Cable runs in a loop; data travels in one direction;
FDDI (Fiber Network) uses TWO counter-rotating rings and HAS REDUNDANCY
Token Ring has devices pass a token and take turns talking (like a Talking Stick)
Star: Most popular LAN tech, all devices connect to single point, NOT REDUNDANT if central device fails whole network fails.
Hub-and-Spoke: Similar to star but with WAN links; NOT REDUNDANT if central office fails; If Deer Park is main central office and fails, all other cities are hosed
Full-Mesh: MOST REDUNDANT; Very expensive to connect every node to every node; Number of Connections n(n-1)/2 (e.g. 5 nodes (5)(5-1)/2 = 10 connections
Partial Mesh: Like full mesh but don’t connect every node, just strategic ones giving SOME REDUNDANCY; best bang for you buck
Wireless Network Topology
Infrastructure mode vs. Ad Hoc mode
Wireless Mesh Topology
Infrastructure mode: Most comon type, requires centralized mgmt, uses a Wireless Access Point (WAP) as centralized point (like STAR topolgoy)
Ad Hoc mode: decentralized network, no routers or WAPs; P2P connections;
Wireless Mesh: interconnection of different TYPES of nodes/devices using clients, routers, gateway, and different methods of connection (wifi, microwave, satellites, etc.)
Internet of Things (IOT)
802.11 (Wi-Fi), Bluetooth, RFID, NFC, Infrared (IR), Z-Wave, Ant+
802.11 is Wi-fi and what devices can send data over
Bluetooth uses lower energy and allows things like mouse, keyboards, headphones etc. to connect to another device.
RFID uses electromagnetic fields to read data stored in embedded tags (have to be close to read data) (e.g. Badge to get into building at work)
NFC enables two devices to actually communicate back and forth within about 4cm range. (e.g. Apply Pay)
Infrared (IR): operates with line of site to transmit data (e.g. remote control for TV)
Z-Wave: HOME AUTOMATION; short range communication at lower power consumption than Wi-Fi
Ant+: SENSOR DATA; used with remote control systems (tire pressure, TV’s, lights, etc.)
OSI Model and Data Types
Away Don’t
Pizza Don’t
Sausage Don’t
Throw Some
Not People
Do Fear
Please Birthdays?
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
7,6,5 Data
4 Segments
3 Packets
2 Frames
1 Bits
OSI Layer 1 (Physical) (Bits)
How are bits represented on medium? (Copper vs. Fiber)
How cables wired and connected?
Examples?
OSI: Physical/Bits (Network Interface in TCP/IP)
Copper network: Electrical voltages are used; 0 volts is 0, and +/- 5 volts is a 1
Fiber network: Light is used; 0 is no light, 1 is light.
TIA/EIA-568-B is standard wiring for RJ-45 cables and ports
Straight thru would typically be B to B
Cross over cables would be B to A
Connections are from a physical topology perspective so bus, ring, star, etc.
Examples: Cables (ethernet, fiber optic), Radio Frequencies (Wi-FI, bluetooth), Infra Devices (hubs, WAP’s, Media Converters)
OSI Layer 2 (Data Link) (Frames)
How it works; examples?
Packages data into frames. Performs error detection/correction, uniquely identify devices with MAC addresses, Logical topology, synchronization via clocks
MAC address: 48 bits, first 24 bits is vendor code, second 24 unique to device
Examples: Network Interface Card (NIC), Bridges, Switches
OSI Layer 3 (Network) (Packets)
How data is fowarded, Route Discovery, Flow Control, Packet Reordering, Examples
Fowards traffic using a Logical Address (IPv4 or IPv6)
IP protocol wont out as routing protocol across internet
Gotcha: Sometimes “switching” is used as a nother term for routing
Data is fowarded or routed by:
Packet switching or “routing”: data dvided into packets, common, (analogy: sending mail through mailbox)
Circuit Switching: dedicated communication link established (analogy: a phone call)
Message switching: data divide into messages similar to packet swithcing, but these can be stored and fowarded
Routers use protocols like RIP, OSPF, EIGRP to maintain a routing table and understand how to foward a packet to an IP Address
Provide flow control and packet reordering capability
Examples: Routers, Multilayer swtiches, IPv4, IPv6, ICMP
OSI Layer 4 (Transport) (Segment)
Transmission Control Protocol (TCP)
vs.
User Datagram Protocol (UDP)
TCP (Segments)
Reliable: If segments are dropped, TCP detects it and resends segment.
(C)onnection-Oriented
Segment retransmission and flow control through windowing.
Segment sequencing (1, 2, 3, 4, etc.)
Acknowledge segments
UDP (Datagrams)
(U)nreliable: If a segment is dropped, sender is unaware.
Connectionless: Fire and forget!
No retransmission or windowing.
No sequencing. Can come in out of order.
No acknowledgments.
Windowing - adjust amount of data sent in each segment
Buffering
Examples: TCP, UDP, WAN Accelrators, Load Balancers, Firewalls (e.g. block TCP Port 80)
OSI Layer 5 (Session) (Data)
What is H.323 and H.264 used for?
Converstation kept seperate from others to prevent intermingling
Setup, maintain, tear down sessions.
Examples:
H.323 is for voice/video conversation (FaceTime, YouTube, Skype
Also H.264 operations the Real Time Protocol or (RTP) for streaming video/audio
OSI Layer 6 (Presentation) (Data)
What does this layer handle? What are some examples?
Think Data Formatting and Encryption.
Data Formatting formats data for proper compatibailty between devices (ASCII, GIF, JPG); ensures data is readable by receiving system
Encryption scrambles data to keep from prying eyes (e.g. TLS Transport Layer Security)
Examples:
HTML, XML, PHP, JavaScript (websites)
ASCII, EBCDIC, UNICODE (text)
GIF, JPG, TIF, SVG, PNG (images)
MPG, MOV, (videos)
TLS, SSL (security/encryption)
OSI Layer 7 (Application) (Data)
Provides application services (not the app itself like Microsoft Word, or Outlook)
So an example is for an
Email app: POP3, IMAP, SMTP.
Web app: HTTP, HTTPS
Domains Name Service (DNS)
File Transfer Protocol (FTP, FTPS)
Remote Access (TELNET, SSH)
Simple network management protocol (SNMP)
OSI vs. TCP/IP
PDNTSPA vs ATIN
Appliation, Presentation, Session are now all Application
Transport is still Transport.
Network is now Interent
Data Link and Physical are now Network Interface
TCP/IP Layer Examples
Layer 1, 2, 3, 4
Layer 1 (Network Interface): Ethernet, Token Ring, FDDI, RS-232
Layer 2 (Interent): IP, ICMP, ARP, RARP
Layer 3 (Trasnport): TCP, UDP, RTP (voice/video)
Layer 4 (Application): HTTP, Telnet, FTP, SNMP, DNS, SMTP, SSL, TLS
Ports
What range? How is the range divided?
Port Numbers can be 0 to 65,535
“Well known” or Reserved port are 0 to 1023
Ephemeral Ports are short-lived and auto selected from a predefined range are 1024 to 65,535
FTP
File Transfer Protocol
Port 20 (data channel), 21 (the connection between hosts)
Transfers files between client and server
Unsecured
Data transferred in the clear
Secure Shell SSH
SSH File Transfer Protocol SFTP
Port 22
Cryptographic network protocol for operating network services securely over an unsecured network
Remote login to computer systems by users
Port 22 for SFTP: provide file access, file transfer, and file management over any reliable data stream securely
