Week #9 - Highyeena/Tech-Journal GitHub Wiki

Networking

Network Types

  • Personal Area Network (PAN) = personal devices that communicate in close proximity (wired or unwired). Ex. Bluetooth speakers connected to a phone
  • Local Area Network (LAN) = group of devices that share resources in a small area (such as a room/building). Ex. Ethernet; networked classroom
  • Metropolitan Area Network (MAN) = Connects between different sites in a city (connects multiple LANs). Ex. Connected college campuses
  • Wide Area Network (WAN) = Connects LANs on a large scale. Ex. company buildings being connected in two remote locations
  • Wireless LAN (WLAN) = wireless network with an access point and devices that connect to it.
  • Wireless WAN (WWAN) = Wireless connection on a large scale (uses a mix of technology like cellular)
  • Wireless Mesh Network (WMN) = passes data between peer radio devices and can be used over long distances (used in emergency situations)

Network Topologies

  • Network Topology = How a network is wired

  • Ethernet = common type of LAN; Every device is connected to a central device (Switches > Hubs)

  • Hubs can cause collisions as two devices try to place data onto the network at the same time (causes a delay in sending data for a period of time; switches don't have this problem)

  • Managed Switch = Has an IP address assigned. Can be configured, modified, and monitored through a corporate network.

  • Unmanaged Switch = connects devices to form a network. Used in home or small business's wired networks.

OSI Model

  • Each layer uses the layer below it and provides a function to the layer above it (cannot use a layer without using the ones below it first)
  1. Application (Data) = Provides Network Services to software applications on the network (Firewalls operate here)
  2. Presentation (Data) = Translates data from one character set to another
  3. Session (Data) = Manages the communication and synchronization between network devices
  4. Transport (Segments) = Provides the mechanisms for how data is sent (Ex. error correction)
  5. Network (Packets) = Provides path selection between two networks. (Routers are at this layer and send data toward the destination network)
  6. Data Link (Frames) = Encapsulates bits into frames. Provides error control (MAC addresses operate here)
  7. Physical (bits) = Defines how bits are transferred and received. Defines the network media, connectors, and voltage levels

TCP/IP Model

  • TCP/IP Model is the most common network protocol and is required to access the internet
  1. Application (Data) = TCP/IP-based protocol; equivalent to layers 7-5 on the OSI Model (Ex. HTTP, DNS, HTTPS)
  2. Transport (Segment) = add port numbers in the header so the computer can identify which application sends the data. Returning Data contains port numbers to determine which window the data will go into
  3. Internet (Packet) = adds a source and destination IP address to identify the source and destination network devices
  4. Network Access (Frame/Bits) = Defines how to format the data for the type of network used (Ex. If Ethernet is used, uses an Ethernet header)

Network Addressing

  • Network adapters have two types of addresses: MAC address and IP address

  • MAC address = 46 bit number burned into a chip (represented by a hexadecimal). First 24 bits represent the manufacturer

  • IP address (IPv4) = most common on LANs. 32-bit number that is entered into a NIC's config parameters. Used when multiple networks are connected + accessing the internet

  • IP address (IPv6) = used by corporate devices or ISPs. 128 bit length. Computers have both an IPv4 and IPv6 address assigned.

  • IPv4 addresses are grouped in 5 classes: A, B, C, D, E

  • Class A, B, C are used by network devices
  • Class D addresses are used for multicasting (sending data to a group of devices)
  • Class E addresses are used for experimentation

Network Troubleshooting

  • "ping" command = used to check connectivity around the network

  • First sign of network issues = unavailable resources (such as internet or local resources in a company network)

  • "ipconfig" command = used to see both wired and wireless NICs (can be used if a network device does not get an IP address properly from a server)

  • "tracert" command = displays the path a packet takes through the network (identifies faults in a larger network + shows network latency)

  • "nslookup" command (for DNS servers) = displays domain names and their associated IP addresses

  • "net" command = used to manage the entire network (displays other options for use with net)