Week 9 Tech Journal: Chapter 13 Notes - Zacham17/my-tech-journal GitHub Wiki

These are notes that I took on the assigned sections of Chapter 13 in the A+ Textbook for week 9. This chapter contained information about networking.

Networking Overview:

  • A network is two or more devices that have the capability to communicate with one another and share resources
  • Types of Networks Include:
    • Personal Area Network(PAN): Personal Devices that can communicate in close proximity through a wired or wireless network
    • Local Area Network(LAN): A group of devices that can share resources in a single area, such as a room, home, or building. Ethernet is the most common LAN
    • Metropolitan Area Network(MAN): Connectivity between sites within the same city. Connects multiple LANs
    • Wide Area Network(WAN): Connectivity between LANs on a large geographic scale.
    • Wireless LAN(WLAN): A wireless network that consists of an access point and some wireless devices.
    • Wireless Mesh Network(WMN): Wireless connectivity that is especially good in emergency situations because WMNs do not require traditional access points, pass data between peer radio devices, and can be used over large distances

Copper Media:

  • Copper media is used to connect network devices, and to connect devices to a network
  • Copper media comes in twisted pair and coaxial variations
  • Unshielded Twisted Pair(UTP): Commonly used in homes for telephone wiring and network devices.
  • Twisted Pair Cable: A type of cable which contains four pairs of conductors entwined around each other.
  • Shielded Twisted Pair(STP): has extra foils that provide more shielding; Mostly used in industrial settings
  • The categories of UTP cable include:
    • Cat 3
    • Cat 5
    • Cat 5e
    • Cat 6
    • Cat 6a
    • Cat 7
  • Plenum Cable: a special cable that is treated with fire retardant materials to make it less of a fire risk
  • Polyvinyl Chloride(PVC) Cable: an alternative to plenum cable that has a plastic cable insulation
  • Terminating a cable is to cut off the end, and replace the RJ-45 connector
  • The wires are grouped in colored pairs in a twisted pair cable.
  • Straight Through cable: Used to connect a computer to a switch or network wall outlet.
  • T568A and T568B are cable standards
  • Crossover Cable: Used when connecting two computers or switches together
  • Cable Strippers: are used to strip the insulation off cable
  • Crimper: is used to secure RJ-45 connector onto the cable
  • A cable tester can be used to test if a cable is working properly
  • Patch Panel: has network ports on the front of it and wiring connected to the back of it to provide network connectivity.

Ethernet Concepts:

  • Ethernet LAN is the most common type of LAN
  • Half-Duplex: Communication in one direction at a time
  • Full-Duplex: Can Transmit and Receive simultaneously
  • There are different types of Ethernet, they are:
    • 10BaseT
    • 100BaseT
    • 1000BaseT
    • 1000BaseSX
    • 1000BaseLX
    • 10GBaseSR
    • 10GBaseLX4
    • 10GBaseLR
    • 10GBaseER
    • 10GBaseT
  • Full duplex uses four wires

The OSI Model:

  • International Organization for Standardization(ISO)
  • Open Systems Interconnect(OSI)
  • OSI Model: a standard for information transfer across the network
  • It controls:
    • How different media are arranged and interconnected
    • How network devices with different languages communicate
    • How a network device contacts another network device
    • How and when data is transmitted
    • How data is sent to the correct device
    • How is is known if the network data was received properly
  • There are 7 Layers to the OSI Model
  • From top to bottom, they are:
    • Application: Provides network services
    • Presentation: Translates data from one character set to another
    • Session: Manages the communication and synchronization between network devices
    • Transport: Provides the mechanisms for how data is sent, such as reliability and error correction
    • Network: Provides path selection between two networks
    • Data Link: Encapsulates bits into frames
    • Physical: Defines how bits are transferred and received
  • Each layer performs a unique function

The TCP/IP Model:

  • Network Protocol: a data communication language.
  • Transmission Control Protocol/Internet Protocol(TCP/IP): the protocol suite used in most networks today. It consists of many protocols
  • The TCP/IP Model has four layers:
    • Application: format data specific for the purpose; equivalent to application, presentation, and session layers of OSI model. The Protocols are HTTP, Telnet, DNS, HTTPS, FTP, TFTP, TLS, SSL, POP, SNMP, IMAP, NNTP, and SMTP
    • Transport: add port numbers in the header. So the computer can identify which application sends the data. Protocols are TCP and UDP
    • Internet: IP adds a source and destination IP address.
    • Network Access: Defines how to format the data for the type of network used. MAC address is used here

More IPv4 Addressing:

  • Network Number: part of the IP address that represents which network the computer is on
  • Host Address: part of the IP address that represents the specific computer on the network
  • There are classes of IP addresses(x represents host ID):
    • Class A: 0-127.x.x.x
    • Class B: 128-191.0-255.x.x
    • Class C: 192-223.0-255.0-255.x
  • Broadcast Address: the IP address used to communicate with all devices on a particular network. This is when a 255 is in the last octet of the host address
  • Virtual Local Area Network(VLAN): a method used to create multiple networks within a switch
  • Subnet Mask: a number that a computer uses to determine which part of the IP address represents the network and which portion represents the host
  • The defaults are as such:
    • Class A: 255.0.0.0
    • Class B: 255.0.0.0
    • Class C: 255.255.255.0
  • A “/” after the subnet indicates how many consecutives 1s there are in it
  • Classless Inter-domain Routing(CIDR): a method of allocating IP addresses based on the number of host addresses needed for a particular network

Wireless Networks Overview:

  • Wireless Networks transmit data over air using either infrared or radio frequencies

Wireless Network Standards:

  • IEEE 802.11 define wireless network standards
  • Different variations are:
    • 802.11a: Speeds up to 54Mbps; incompatible with 802.11b
    • 802.11b: Operates in the 2.4000 and 2.4835 GHz radio frequency ranges with speeds up to 11Mbps
    • 802.11e: Provides standards related to quality of service
    • 802.11g: Operates in the 2.4 GHz range, with speeds up to 54 Mbps, and is backward compatible with 802.11b.
    • 802.11i: Relates to wireless network security and includes AES (Advanced Encryption Standard) for protecting data.
    • 802.11n: Operates in the 2.4 and 5 GHz ranges and is backward compatible with the older 802.11a, b, and g equipment. Speeds up to 600 Mbps using MIMO antennas. Maximum of four simultaneous data streams.
    • 802.11ac: Operates only in the 5 GHz range, which makes it backward compatible with 802.11n and 802.11a. Speeds up to 6.93 Gbps. Maximum of eight simultaneous data streams using MU-MIMO antennas.
    • 802.11ad: Also known as WiGig and works in the 60 GHz range. Speeds up to 6.76 Gbps.

Bluetooth:

  • Bluetooth is a wireless technology.
  • Bluetooth has 3 classes of devices
  • Bluetooth supports both data and voice transmissions

Wireless Network Components:

  • Access Point(AP): The central connecting point for a wireless network. Coordinates wireless access for wireless devices. Commonly connects to a wired network.
  • Wireless Bridge: A physical device or software that connects two or more networks. Could connect a wireless network to a wired network. An example of a wireless bridge is a building where all devices connect wirelessly to the bridge. The bridge connects to the wired network, which eventually connects to the Internet.
  • Wireless NIC: Integrated into a wireless device
  • Wireless Router: An AP/router device that normally has both wireless capability and a few wired Ethernet ports.
  • Router/Switch Functionality: when wireless routers have switch ports built into them

Wireless Network Design:

  • Infrastructure Mode: an AP is part of the wireless network when a device is in this mode
  • Ad Hoc Mode: Two wireless devices communicate directly with one another.
  • Service Set Identifier(SSID): 32 alphanumeric characters that are assigned to access points to differentiate between wireless networks
  • Repeater(Wireless Extender): used to extend the range of a network
  • Power Over Ethernet(PoE): A standard used by a switch when providing power through an ethernet cable
  • PoE Switch: A switch that uses PoE
  • PoE Injectors are used when a switch doesn’t support PoE
  • An AP can also be configured with a channel ID
  • Channel ID: defines what frequency the access point operates
  • 11 channels are used in the US