We covered the following topics in this blog: Key Features, WAN Technologies and Architecture, WAN Terminology and Components, Encapsulation and Protocols, and advantages of Wide Area Network WAN. WAN Topologies, LAN vs WAN, and Virtual Private Networks (VPNs) in WANs.
Wide Area Network (WAN)
An essential component of contemporary business networking is a wide area network, or WAN. A network that connects several local area networks (LANs) across towns, nations, or continents is known as a wide area network (WAN). It is frequently constructed utilizing leased telecommunication lines, public networks, or satellite links to facilitate communication and data sharing between geographically separated locations, such as a company’s branch offices. The biggest WAN is the Internet.
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Important Features of a WAN
Geographic Scope: Wide area networks (WANs) link locations that are usually separated by cities, nations, or even continents.
Ownership and Business Model: The WAN infrastructure is usually leased from a service provider (SP), which is a significant difference from a LAN, which is normally owned by the organization. WANs employ a business model where the consumer (enterprise or person) must lease the service from a provider, generally a telephone company (telco) or cable company.
OSI Layers: WAN technologies mainly provide the Data-Link (Layer 2) protocols and Physical (Layer 1) standards needed for long-distance communication. Routers are essential WAN devices that forward IP packets over WAN lines while operating at Layer 3 (Network Layer).
Purpose: WANs serve the purpose of facilitating communication and data sharing between individuals and organization at regional or branch offices as well as providing access to corporate networks for travelling personnel, which makes them essential for corporate contexts. WANs support file transfers, email, and the WWW and offer full-time remote resources linked to local services.
Connectivity: A variety of technologies and media, such as satellite connections, optical fibre transmission, radio wave transmission, and circuit-switched telephone lines, are used to establish wide area networks (WANs).
Data Transfer: Small units known as data packets are used to transfer data across a wide area network (WAN).
Routers: Located at the edge of the LAN, routers are crucial networking equipment that link it to the WAN network of the service provider. They route data packets to their destination by selecting the ideal path.
WAN Technologies and Architecture
The Open Systems Interconnection (OSI) model, which defines and standardizes telecommunication by visualizing network function across seven layers, serves as the conceptual foundation for WAN architectures. The Physical (Layer 1) and Data-Link (Layer 2) standards are typically defined by WAN technologies.
WANs are often constructed and run using the following connectivity techniques and technologies:
Software-Defined WAN (SD-WAN): This cutting-edge method uses virtualization and application-level controls to streamline WAN designs. By intelligently routing traffic over several connections (such as broadband internet, MPLS, or LTE) via a centralized controller, SD-WAN frequently replaces expensive leased lines with less expensive network links. In addition to increasing efficiency, SD-WAN is skilled at handling demanding, high-bandwidth applications like video and voice.
Leased Lines: These are private, dedicated network connections that connect two LAN endpoints. They are frequently hired from a network provider. They provide fixed, guaranteed bandwidth.
Packet Switching: This method separates a message into packets of a size defined by the outgoing link, which may follow different routes and are collected and reassembled at the destination. Technologies that make use of this include X.25 and Frame Relay.
Multiprotocol Label Switching (MPLS): By directing data traffic using short path labels rather than complicated IP addresses, Multiprotocol Label Switching (MPLS) is a network routing optimisation approach that frequently creates a cohesive, effective network over existing infrastructure.
Virtual Private Networks (VPNs) and tunneling: Tunneling allows data packets to travel over the public internet safely by encapsulating them within other packets. VPNs, or encrypted tunnels, offer safe connections between networks and are essential for safeguarding private information sent over wide area networks.
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Other widely used WAN access methods consist of:
Ethernet WANs (Carrier Ethernet/Metro Ethernet): WANs that use Ethernet links as the access link between the client and the SP’s network are known as Ethernet WANs (Carrier Ethernet/Metro Ethernet). For long-distance connections, fibre Ethernet protocols are frequently used. Logically, Ethernet WANs can operate as a LAN switch (E-LAN/VPLS) that connects several sites in a full mesh or as a single point-to-point connection (E-Line/VPWS).
Broadband: Usually depending on pre-existing infrastructure such as copper phone lines or CATV cabling, DSL, cable, and fibre Internet connection are consumer-focused technologies frequently utilized by enterprises for Internet access.
Wireless WANs (WWAN): Wireless WANs (WWAN) include satellite internet (VSAT), which is usually utilized in rural areas, and cellular service (3G/4G/5G/LTE), which can connect users and remote sites where other WAN connection is unavailable. Large areas are typically covered by WWANs (Cities and Beyond).
WAN Terminology and Components
The path from the customer premises to the service provider network involves specific equipment and points of responsibility.
| Term | Description |
|---|---|
| CPE (Customer Premises Equipment) | Equipment (like a router, modem, or CSU/DSU) typically owned by the subscriber and located on the customer’s site. |
| DTE (Data Terminal Equipment) | The user’s device that sends and receives data, typically the customer’s router. |
| DCE (Data Circuit-Terminating Equipment) | The device that provides the interface between the DTE and the WAN service provider’s facility, converting user data into an acceptable form for the WAN. The DCE often provides the necessary clocking for synchronous serial lines. |
| CSU/DSU (Channel Service Unit/Data Service Unit) | A DCE device used to connect DTE (like routers) to a digital circuit (like a T1/T3 line). |
| Demarcation Point (Demarc) | The precise physical point where the service provider’s responsibility for wiring and maintenance ends and the customer’s (CPE) responsibility begins. |
| Local Loop | The cabling (often copper) that extends from the demarc into the WAN service provider’s Central Office (CO). |
| POP (Point of Presence) | The access point of the provider’s services (Internet, private WAN, or cloud resources). The CO is sometimes referred to as a POP. |
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Encapsulation and Protocols
Layer 2 protocols are necessary for WAN links in order to encapsulate traffic for long-distance transmission. High-Level Data Link Control (HDLC) is the standard encapsulation for serial ports on a Cisco router.
WANs frequently employ the following Layer 2 encapsulation and tunneling protocols:
- HDLC: A dedicated point-to-point serial line WAN encapsulation protocol. The HDLC implementation used by Cisco is proprietary.
- PPP (Point-to-Point Protocol): An open-standard WAN protocol that provides dynamic IP assignment and data link configuration control. It negotiates basic line interoperability using LCP (Link Control Protocol).
- Point-to-Point Protocol over Ethernet, or PPPoE, is a popular protocol that encapsulates PPP into an Ethernet frame and is used with DSL and WiMax services.
- Frame Relay: A packet-switched technique that uses HDLC encapsulation to manage many virtual circuits and is more efficient than X.25.
- A WAN technique called MPLS (Multiprotocol Label Switching) is used to establish an IP-based service in which the provider routes traffic according to an MPLS label. It blends packet and circuit switching.
Advantages of wide area network WAN and Disadvantages
WAN Topologies
The physical configuration of the network connections is described by WAN topologies. The three primary categories are:
Star or Hub-and-Spoke: A single central hub (router) gives distant networks access to a core router in a star or hub-and-spoke configuration. Although some Ethernet services, such as E-Tree, are hub-and-spoke in nature, remote sites are unable to connect directly with one another. Connecting an ISP to its clients often uses this design. One point of failure could be the central router.
Complete Mesh: All of the devices in the set are directly connected to each other via a virtual circuit or connection. Although it is the most expensive and difficult to implement, this offers the highest redundancy.
Partially Meshed: This design is the best balanced because not every device is connected to every other router, providing better redundancy and performance than hub-and-spoke.
Virtual Private Networks (VPNs) in WANs
In contemporary WANs, a Virtual Private Network (VPN) is crucial because it enables safe communication between private networks across a public network, usually the Internet.
- Function: VPNs use Internet-routed virtual connections known as VPN tunnels. They provide privacy and data integrity services by encrypting packets and authenticating endpoints.
- Comparison to WAN: A VPN secures access to remote resources by making the remote host appear to be local on the remote network, whereas a standard WAN connects distant LANs and treats them as remote networks.
- Technologies: DMVPN (Dynamic Multipoint VPN), GRE (Generic Routing Encapsulation) for tunnelling, and IPsec (working at Layer 3) are common VPN implementations. VPN technology is frequently used for WAN connectivity in small office/home office (SOHO) networks.
LAN vs WAN
| Feature | Wide Area Network (WAN) | Local Area Network (LAN) |
|---|---|---|
| Geographical Area | Covers large distances (cities, countries, continents). | Confined to a small area (single building, home, or office). |
| Connectivity | A network of networks, connecting multiple LANs. | A single network connecting local devices. |
| Speed/Performance | Generally slower data transfer rate and higher latency due to large distances. | Typically faster with higher bandwidth and lower latency. |
| Cost & Complexity | More expensive and complex to design, install, and manage. | Less expensive and easier to set up and manage. |
| Ownership | Often leased from service providers (mix of public and private). | Usually owned and managed by the organization or individual. |
Consider an organization’s internal IT infrastructure to understand the distinction between a WAN and a LAN. Fast, local communication is made possible by the LAN, which functions similarly to the wiring and network switch on one floor of an office building. Similar to long-haul fibre optic cables and leased lines that link a local office (LAN) to another branch office in a different nation, the WAN depends on outside service providers to span the enormous geographic distance.
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