# Network Setup and WAN Technologies

## Introduction

As the sole IT support specialist at a small company, you have set up a network that initially consisted of a few computers in a single office. To conserve IP addresses, you used nonwritable address space for the internal IPs. You configured a router with Network Address Translation (NAT) to connect the office to the internet provided by an ISP. Additionally, you set up a local DNS server and a DHCP server for network configuration.

## Network Expansion

As the company grows, you have plenty of address space for internal IPs. Some salespeople need remote access to resources while on the road, so you configure a VPN server and enable port forwarding. This allows employees from anywhere in the world to connect to the office LAN.

## Wide Area Networks (WAN)

With the expansion of the company, a new office is opened in another city. This is where Wide Area Networks (WAN) come into play. Unlike Local Area Networks (LAN), WAN spans across multiple physical locations.

WAN technologies require contracting a link with an ISP to connect the different sites. The ISP handles the data transmission between the sites. Each site has a demarcation point where the ISP's network takes over. The area between the demarcation point and the ISP's core network is called a local loop, which could be a T carrier line or a high-speed optical connection.

From the ISP's regional office, the connection extends to the ISP's core network and the wider internet.

## Data Link Layer Protocols in WAN

WANs utilize various protocols at the data link layer to transport data between sites. These protocols differ from the commonly used Ethernet protocols found in LANs. The specific protocols used in WANs and the core internet infrastructure are beyond the scope of this course.

Expand your network and connect multiple locations with WAN technologies! 🌐💼

## WAN Protocols

### Physical versus software-based WANs

* WAN router: Hardware devices that act as intermediate systems to route data amongst the LAN member groups of a WAN (also called WAN endpoints) using a private connection. WAN routers may also be called border routers or edge routers. These routers facilitate an organization’s access to a carrier network. WAN routers have a digital modem interface for the WAN, which works at the OSI link layer, and an Ethernet interface for the LAN.
* Software-Defined WAN (SD-WAN): Software developed to address the unique needs of cloud-based WAN environments. SD-WANs can be used alone or in conjunction with a traditional WAN. SD-WANs simplify how WANs are implemented, managed, and maintained. An organization’s overall cost to operate a cloud-based SD-WAN is significantly less than the overall cost of equipping and maintaining a traditional WAN. One of the ways that SD-WANs help reduce operational costs is by replacing the need for expensive lines leased from an ISP by linking regional LANs together to build a WAN.

### WAN optimization

There are multiple techniques available to optimize network traffic and data storage on a WAN:

* Compression: Reducing file sizes to improve network traffic efficiency. There are many compression algorithms available for text, image, video, etc. The sender and the receiver will need apps that offer the same compression/decompression algorithm to encode and decode the compressed files.
* Deduplication: Prevents files from being stored multiple times within a network to avoid wasting expensive hard drive space. One copy of the file is kept in a central location. All other “copies” are actually file pointers to the single copy of the file. This saves valuable hard drive space, makes performing data backups more efficient, and reduces the amount of time needed to recover from data loss disasters.
* Protocol Optimization: Improves the efficiency of networking protocols for applications that need higher bandwidth and low latency.
* Local Caching: Storing local copies of network and internet files on a user’s computer to reduce the need to resend the same information across the network every time the file is accessed. Some WAN optimization products can cache shared files at one physical LAN location when groups of employees at the location tend to request the same set of files frequently.
* Traffic Shaping: Optimizing network performance by controlling the flow of network traffic. Three techniques are commonly used in traffic shaping:
  * Bandwidth throttling - controlling network traffic volume during peak use times.
  * Rate limiting - capping maximum data rates/speeds.
  * Use of complex algorithms - classifying and prioritizing data to give preference to more important traffic (e.g., an organization might want to prioritize private LAN-to-LAN traffic within the organization’s WAN and give a lower priority to employees accessing the public Internet).

### WAN Protocols

WAN Internet Protocols are used in conjunction with WAN routers to perform the task of distinguishing between a private LAN and the related public WAN. Several WAN protocols have been developed over the decades for this task, as well as other purposes, including:

* Packet switching: A method of data transmission. In packet switching, messagesare divided into small units called packets, which are then transmitted independently over the network. The packets can take different routes to reach their destination and are reassembled at the receiving end. This allows for more efficient and reliable transmission of data over the network.
* Frame Relay: A WAN protocol that operates at the data link layer of the OSI model. It uses virtual circuits to transmit data between network nodes. Frame Relay is known for its simplicity and efficiency, making it suitable for small to medium-sized networks.
* Asynchronous Transfer Mode (ATM): A WAN protocol that uses fixed-size cells to transmit data. ATM provides high-speed transmission and is often used for voice, video, and data services.
* MPLS (Multi-Protocol Label Switching): A protocol that uses labels to determine the path that packets should take through a network. MPLS improves the efficiency and performance of data transmission in WANs by allowing for faster routing decisions.
* Point-to-Point Protocol (PPP): A protocol used to establish a direct connection between two network nodes. PPP is often used to connect a computer to an ISP and is commonly used for dial-up and DSL connections.
* HDLC (High-Level Data Link Control): A data link layer protocol that provides a reliable and efficient way to transmit data over WANs. HDLC is widely used in point-to-point connections and is the default encapsulation method for serial links in Cisco routers.

These are just a few examples of WAN protocols. The choice of protocol depends on factors such as network requirements, available infrastructure, and the specific needs of the organization.

## Conclusion

WAN technologies play a crucial role in connecting multiple locations and enabling communication between them. WAN protocols, such as Frame Relay, ATM, MPLS, PPP, and HDLC, provide the necessary mechanisms for data transmission over wide area networks. Additionally, WAN optimization techniques, such as compression, deduplication, protocol optimization, local caching, and traffic shaping, can enhance network performance and efficiency. Whether using traditional WAN routers or software-defined WAN solutions, organizations have various options to establish and optimize their wide area networks.
