Types of Networks
WAN (Wide Area Network)
Wide Area Networks are what most would consider the “Internet” as a whole. These at a larger scheme consist of ISPs routing traffic to each other and is what is responsible for connecting you to websites, cloud services and other systems. Businesses, Homes and Data Centers are given WAN IP addresses so that they may communicate with each other. These addresses are publicly accessible to the world which makes a firewall important on a network.
LAN (Local Area Network)
Local Area Networks are the collection of devices on an internal network. This would consist of things like printers, computers, servers, switches, wireless access points, cameras and other network attached devices. WLANS (Wireless Local Area Networks) are devices connected to the LAN via wireless means. VLANS are Virtual LANs that are created by a Firewall and handed out to different devices. This allows for a more restricted internal network.
Other Types of Networks
PAN (Personal Area Network) would consist of devices belonging to you a person. This would include things connected via Bluetooth. Your phone, wireless earbuds or speaker, smart watch.
CAN (Campus Area Network) is exactly as it sounds. A larger area consisting of buildings that are connected. Often campus sized.
MAN (Metropolitan Area Network) would consist of a network on a city sized scale.
Devices on a Network
Modems
Modems are the devices that bring in internet from the ISP (Internet Service Provider). This internet traffic will often be brought in by fiber optic cabling or coaxial cabling. The modem is assigned an IP address either statically or dynamically from the ISP. For almost all use cases, modems should be put into pass-through mode with a request to the ISP.
Firewalls & Routers
Firewalls (Routers) are responsible for routing internet traffic throughout the network and providing security measures as well. They often take on other tasks like providing a DHCP Server (Dynamic Host Configuration Protocol), DNS Server (Domain Name System), and VPN Server (Virtual Private Networks). Some devices can even play their own part in security systems.
Switches
Switches are devices that allow for a higher number of hosts (Computers, Servers, WAPs, etc) to connect to a network. Switches are either managed or unmanaged and feature a range of ethernet ports from 8 to 48 and more. A managed switch allows for you to view the status of different ports, as well as configure different options on a per port basis. They can be disabled, restricted to certain VLANs, and bandwidth limited. Unmanaged switches will only route traffic. Switches are also responsible for providing PoE (Power over Ethernet) to other devices on the network. This allows for devices such as IP Cameras and WAPs to be powered from the switch, freeing the need for external power.
Wireless Access Points
These devices deploy a Wi-Fi signal for client devices to connect to. Wireless access points allow for multiple SSIDs and traffic shaping of said SSIDs. This allows for guest networks to be created with no inward access to secure internal SSIDs; These systems can also include splash screens upon connection and authentication measures. The physical device is powered by PoE (Power over Ethernet) and will feature LED’s on them to denote different status’ by sight.
IP Addresses
Every device that is on a network needs an IP address to communicate with other devices. IP addresses are assigned to a device by a DHCP Server or is assigned statically on the device. An IP address conflict is when two devices on a network hold the same IP address and both devices lose connectivity. A device with a dynamically set IP address can lose its address and have it reassigned a different one. A device with a statically set IP address will hold that IP address under all circumstances.
Subnets are the result of dividing networks. The most common subnet you will see is a /24 subnet which is 255.255.255.0; This subnet allows for a pool of 256 addresses. Only 254 addresses are usable by the network, though. A network consisting of 192.168.1.0 to 192.168.1.255 would only have .1 to .254 as usable addresses. .0 will act as a network address and .255 will act as a broadcast addresses.
When setting a static IP address, you have to provide an IP Address (e.g. 192.168.1.43), a Subnet Mask (255.255.255.0) to have access to an internal network. For access to the Internet, a device must also have a Default Gateway. This address points to the firewall of the network. Most often assigned to the .1 and .254.
It is important to keep in mind that the average network of a home user is 192.168.1.x or 192.168.0.x. This means a business should be set up on a different addressing scheme to avoid conflicts when an end user is connected via a VPN (Virtual Private Network).
Common Services on a Network
DHCP Servers
A DHCP (Dynamic Host Configuration Protocol) Server is a service that dynamically hands out IP addresses to devices on an internal network. These IP addresses are handed out on a lease basis, so that if a device does not connect to a network after a predetermined time, it’s IP addresses is no longer reserved to it and it will be handed out to another newly connected device. This allows for networks to have a larger number of devices on them without having to worry about exhausting it’s IP pool. The DHCP server will hand out an IP address, the default gateway, and DNS addresses for the device to use.
DHCP Servers can have ranges of IPs that are set as reserved ranges. DHCP Servers will NOT hand out IP addresses to devices that are inside of these ranges. This allows us to set devices on a static IP without having to worry about the DHCP assigning that IP to other devices.
DNS Servers
DNS (Domain Name System) Servers are responsible for translating domain names into IP addresses. This allows for domains such as google.com to point to 172.217.4.206 and for users to reach services easier. This also allows for internal domains for businesses as well. If a network features a domain, it is important to point primary DNS to the Domain Controller and another DNS. DNS can also be filtered out by a firewall or separate device to restrict access to websites on a network. If a DNS Server goes down, you can expect connectivity issues to outside internet and internal domains.
VPN Servers
VPN (Virtual Private Networks) Servers provide outside clients to connect and route traffic via an encrypted and secure tunnel. This allows a user to have a secure connection in a public location and access network resources. VPN Servers can limit access that VPN clients have to internal networks are. VPN Connections should require authentication to connect. Clients are handed IP addresses either outside the main subnet or on the main subnet. VPNs can exist as a half or full tunnel. A full tunnel means that all traffic is routed through the VPN Server. A half tunnel only routes traffic that that is meant for devices on the VPN Server’s network.
Methods of Connection
Fiber
Fiber optic cabling, in simplified terms, transfers data via beams of light inside of a reflective cable. Fiber optic cabling features a very high uptimes, high speeds and a higher price because of it’s benefits and infrastructure. This connection method is most recommended for businesses that view it’s internet connection as extremely essential and is a good choice if budget permits. You will most often see this cable when internet is entering a building to a modem.
Coaxial
Coaxial cabling is the transfer of data over a copper core. This is a very common form of cabling leading to homes and businesses. It has a good uptime but slower over all speeds than fiber.
Ethernet
Ethernet cable is the most common cable in an internal network. This cable features an RJ-45 connector.
Wireless
Wireless connections can consist of multiple methods. When internet is entering a business via wireless, you can expect long range antennas and satellites. These connection methods can be interfered with in times of bad weather, strong winds or physical obstructions. Other methods that are commonly encountered are WiFi and Bluetooth connections.
Wi-Fi networks are often broadcast on 2.4GHz and 5GHz bands. 2.4GHz provides further coverage at a lower speed. 5GHz provides high speeds at cost of coverage.
Important Acronyms
CAN – Campus Area Network
DDNS – Dynamic Domain Name System
DHCP – Dynamic Host Configuration Protocol
DNS – Domain Name System
IP – Internet Protocol
ISP – Internet Service Provider
LAN – Local Area Network
MAN – Metropolitan Area Network
NAS – Network Attached Storage
NIC – Network Interface Card
P2P – Peer to Peer
PAN – Personal Area Network
PoE – Power over Ethernet
TCP – Transmission Control Protocol
UDP – User Datagram Protocol
VLAN – Virtual Local Area Network
VoIP – Voice over Internet Protocol
VPN – Virtual Private Network
WAN – Wide Area Network
WLAN – Wireless Local Area Network