Networking Overview

• Networks are everywhere from roads and highways, a network of friends or family, or even a network of cellphones to connect to other devices.
• A network by computer definition are two or more devices that have the capability to communicate with one another to share a multitude of resources
• Computer networks are divided into major categories including:
• Personal area networks (PAN) for close proximity devices such as bluetooth
• Local area networks (LAN) for sharing in the range of a home or building
• Metropolitan area network (MAN) for sharing within the same city
• Wide area network (WAN) for a connection between two LANs across the globe
• Wireless LAN (WLAN) that uses an access point and devices extremely close by like laptops
• Wireless WAN (WWAN) for a wireless connectivity across the world using a mix of technology
• Wireless mesh network (WMN) which are great for emergency situations since they require no normal access point and can be used across large distances

Copper Media

• Copper media is common cabling for connection to a network
• Copper media can come in to major types: Coaxial and Twisted Pair
• Twisted pair cables can be either shielded or unshielded
• Unshielded can be used for purposes such as telephone wires
• Shielded can be used for more duty heavy purposes such as outside hazards and industrial settings
• Unshielded comes in different versions known as categories or Cat for short
• These categories include:
• Cat 3 used in telephone systems
• Cat 5 which is easily outclassed by a Cat 5e
• Cat 5e (enhanced) used in 10, 100, and 1000 BaseT networks and is a very efficient ethernet cable for all sorts of devices
• Cat 6’s overall contains better ethernet than a 5e but the cable is overall bigger
• Cat 6a supports frequencies up to 500 MHz compared to the Cat 6’s 250 MHz limit
• Cat 7 is backwards compatible to Cat 5e and 6, supports 10GBaseT Ethernet and a frequency of up to 600 MHz

Ethernet concepts

• A LAN is the most common type of network category
• Ethernet issues can include a full and a half duplex transmission, slowdown, or bandwidth increase
• Ethernet was originally designed for half duplex but because of collisions it can be used to its fullest potential
• Full duplex is used today as it can simultaneously send and receive for a much quicker performance

The OSI Model

• The International Organization for Standardization (ISO) created a communication model known as the Open Systems Interconnect (OSI).
• The OSI model is a standard for information transfer across a network
• Using a set guideline, the model is able to perform task while providing a strong structure to see where the rules fit
• The OSI model is broken down into 7 layers from top to bottom
• Application
• Presentation
• Session
• Transport
• Network
• Data Link
• Physical
• Each layer except physical, provides for the layer above it in order to run
• Each layer adds information to the data that is being sent through a network

The TCP/IP Model

• A Transmission Control Protocol/Internet Protocol (TCP/IP) is a protocol used today and is required in order to connect to the internet
• The TCP/IP protocol consist of a large variety of protocols within it and describes how information flows through the computer

More IPv4 Addressing

• An IP address is broken into two major parts: the network number and the host number.
• The network number is the portion of an IP address that represents which network the computer is on.
• All computers on the same network have the same network number
• The host address is the specific computer on the network.
• The amount of bits on a network number and host numbers depends on IP class

Wireless Networks Overview

• Wireless networks are networks that transmit data over air/radio frequencies
• Wireless networks operate in layer 1 and 2 of the OSI model
• Good for environments that aren't build for cabling

Wireless Network Standards

• The following are standards for wireless networks
• 802.11a are after 802.11b and is not compatible with it
• 802.11b operates in a 2,4835 GHz radio frequency
• 802.11e provides a standard to the 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 form of wireless technology using PAN.
• Well used in external devices such as keyboards and earbuds
• Bluetooth support data and voice transmission
• Short in range making it useful in small areas or with devices close by

Wireless Network Design

• The easiest way to describe an access point is to think of it as a network hub, but instead of connecting wired devices and sharing bandwidth, the AP connects wireless devices that share bandwidth
• It's common for home networks to use integrated services routers that can allow wireless and wired connectivity
• access points can also be wired to or connect wirelessly to another AP, have a wired or wireless connection to a wireless repeater or connect to a wired network
• Corporate APs are powered through ethernet cables that can go from the mounted AP to a switch, which provides the power through the Ethernet cable using a standard called Power over Ethernet
• On Top of an SSID, an access point can be configured with a number known as a channel ID which defines what frequency the access points can operate
• access point must not overlap a channel ID