What Is WAN? LAN vs. WAN - Huawei (2024)

LAN vs. WAN

LAN and WAN are two different types of computer networks.

A LAN, also called an intranet, is typically a small-scale computer network that covers a limited geographical area, such as a home, a small store, or a floor of an office building.

A WAN, also called an external network, is a large-scale computer network that connects multiple LANs or other networks across tens to thousands of kilometers. One of the most famous WANs is the Internet.

LAN vs. WAN

A LAN is typically used in a local area and connected to a WAN through a central location, which is called a gateway. Many types of devices that can function as gateways. Home devices are mainly routers, and enterprise devices are switches (with Layer 3 routing functions), routers, and firewalls.

Devices on a LAN can connect and transmit data in wired mode, wireless mode, or both. For example, on a home network, you can use the Wi-Fi function of a laptop to access a router and watch Internet videos. When playing online games, most people connect their desktop computers to routers through network cables to ensure smooth gaming.

Home LAN

A WAN connects to multiple LANs in wired and wireless modes. For example, on a cross-region enterprise network, branch sites in different regions access the enterprise WAN through private lines provided by carriers. Some sites also access a 5G wireless network as the bypass line to ensure stable service running. WANs enable users to connect to enterprise offices, data centers, and cloud networks across multiple locations.

Enterprise WAN

WAN Examples

When it comes to providing an example of a WAN, many people think of the Internet, and even equate a WAN with the Internet. As a super-large network consisting of private, public, academic, commercial, and government networks around the world, the Internet has become the largest and most diversified WAN in the world. However, a WAN is not only the Internet, but is also widely used on campuses, and in public services, enterprises, and carrier fields. WANs are typically classified into self-built and leased WANs based on application requirements and scenarios.

1. Self-built WAN: Organizations requiring self-built WANs must have strong network construction, configuration, and O&M capabilities. Self-built WANs are fully independent and controllable. Typical examples include backbone networks constructed by carriers, education networks for higher education institutions, and internal networks of state-owned enterprises.
2. Leased WAN: Organizations require only secure and stable WANs and do not focus on the implementation of the underlying network. In this case, most organizations lease private lines provided by carriers to build their own WANs. Typical examples of this include service networks of large chain stores, banks, and securities enterprises. With the further development of the Internet, more and more organizations are renting cheaper Internet services to build their own WANs. Typical examples include the office networks of small startup companies and service networks of companies with significant cloud-based services and data.

WAN Technologies and Protocols

WANs can be implemented through wired or wireless technologies.

The following technologies and protocols are used on WANs:

• Packet switching: Packet switching is a data transmission technology that groups data into packets for transmission. Each packet carries control information such as source and destination addresses. During transmission, different paths are selected for packets based on the network congestion. Before the receiver receives all the packets, the original data cannot be reconstructed, leading to network delays and unreliable transmission. However, due to its simple design and high resource utilization, this technology forms the basis of data communication for global computer networks and is still widely used on the Internet.
• ATM: ATM is an old cell switching technology and protocol that can transmit voice, video, and data. It has the advantages of high transmission rates and low delay. However, due to complex design and high costs, ATM networks have been gradually replaced by IP networks as gigabit networks have become more popular.
• Frame relay (FR): FR is a technology and protocol that transmits data between LAN or WAN endpoints. It encapsulates data into frames for transmission over a shared FR network. For users, an FR network transmits data with other users through a channel that changes frequently and is invisible to users. With the emergence of technologies such as cable/DSL modem (commonly known as broadband modem), MPLS, and VPN, FR is becoming obsolete.
• Packet over SONET/SDH (POS): Synchronous optical network (SONET) and synchronous digital hierarchy (SDH) are high-speed communication protocol supporting the digital transmission of voice, data, and video signals over optical networks. POS defines the communication mode of point-to-point links when optical fibers and SONET (or SDH) are used.
• Point-to-Point Protocol (PPP): PPP is a data link protocol that creates a direct connection between two network nodes through dial-up or leased lines for data transmission. PPP over Ethernet (PPPoE) is the most widely used broadband access mode in homes. PPP runs on the Ethernet to complete user access authentication and is used by Internet service providers (ISPs) to provide Internet services for users. PPP over ATM (PPPoA) is similar but runs on an ATM network.
• Multi-Protocol Label Switching (MPLS): MPLS is a widely used WAN technology that improves the speed and efficiency of network data transmission. MPLS adds a predefined label to each data packet transmitted on the network. Compared with traditional methods that determine the next node based on network addresses, MPLS uses labels to guide packets along a predefined path, achieving faster data transmission. It works between the link layer and network layer in the protocol stack. Therefore, it can carry various types of traffic, including IP data packets, ATM traffic, FR traffic, SONET traffic, and Ethernet traffic.
• Transmission Control Protocol/Internet Protocol (TCP/IP): This technology consists of TCP and IP, which together form the basis of the Internet. It is a key protocol that defines end-to-end communication by specifying how data is encapsulated, addressed, transmitted, routed, and received.
• Overlay network: An overlay network is a computer network built on top of another network. However, with the advent of the intelligent cloud-network era, the performance of the Internet has improved, making it possible to build high-quality WANs over the Internet. Overlay VPN-based Ethernet VPN (EVPN), virtual extensible local area network (VXLAN), and Network Virtualization using Generic Routing Encapsulation (NVGRE) technologies offer outstanding advantages in service provisioning agility, networking flexibility, and interoperability, becoming the mainstream technologies for next-generation enterprise WANs.
• 4G/5G/LTE: In addition to wired WANs, wireless WANs are developing rapidly. Currently, most mainstream solutions use mobile telecommunications cellular technologies such as fourth-generation (4G), fifth-generation (5G), and long-term evolution (LTE) to transmit data, allowing users to access the Internet from anywhere within a service range.

Advantages and Disadvantages of WAN

• Advantages
  1. Wide connection range: A WAN can connect multiple users across a large geographical area to implement communication and resource transmission.
  2. Centralized resources: A WAN enables centralized resource storage and centralized server deployment, regardless of physical distance, facilitating subsequent access and management.
  3. High scalability: A WAN allows the access of new users and branches as required without network reconstruction.
• Disadvantages
  1. High costs: Although WANs are highly scalable, enterprise-level private lines need to be added, which requires high costs in private line leasing, network configuration, and O&M.
  2. Complex network: Currently, most WANs are private line networks or public networks provided by carriers. These networks involve complex protocols and technologies and need to be designed and managed by professionals.
  3. Security risks: WANs are prone to data leakage and information loss, especially when the Internet is used as an enterprise WAN.

WAN Optimization and SD-WAN

As more enterprises access cloud services, data centers, and mobile office through WAN links, traffic increases sharply. However, private lines are expensive, and Internet links are unreliable. Given this, WAN optimization technologies need to be introduced to reduce enterprise bandwidth costs and optimize application access experience.

Currently, mainstream WAN optimization technologies include:

• Adaptive forward error correction (A-FEC)
• Multi-fed and selective receiving
• Load balancing
• WAN data redundancy elimination

Although WAN optimization solves some WAN pain points, reduces network bandwidth costs, and improves user experience in key applications, enterprises want more from WANs. With the help of software-defined networking (SDN) concepts and overlay network technologies, software-defined wide area network (SD-WAN) emerges.

Huawei SD-WAN

To meet enterprises' WAN requirements, Huawei SD-WAN offers four core values:

1. Strong interconnection: Flexible networking builds multi-cloud and multi-network on-demand interconnection. SD-WAN can utilize hybrid link resources and flexibly use hybrid links such as optical fibers, DSL links, and LTE links to quickly provision networks and reduce link costs. In addition, SD-WAN provides various networking models, such as hub-spoke networking, full-mesh networking, hierarchical networking, and infrastructure as a service (IaaS)/software as a service (SaaS) access, to adapt to different enterprise services.
2. Optimal experience: Application-based traffic steering and optimization ensure key application experience. SD-WAN provides functions such as application identification, intelligent traffic steering, and WAN optimization to ensure user experience of key enterprise applications.
3. High performance: High-performance devices at branch sites build a new forwarding engine. The processing capabilities of devices extend from packet forwarding at Layer 1 to Layer 3 to application-centered full-service processing at Layer 3 to Layer 7, supporting the normal running of enterprise services.
4. Easy O&M: Service-driven simplified branch network O&M. Inheriting the design idea of SDN centralized management and control, SD-WAN provides network-wide centralized monitoring and visualization and obtains information such as the network-wide topology, inter-site link status, traffic statistics, and key device alarm logs in real time. SD-WAN uses zero touch provisioning (ZTP) to implement fast provisioning of branches. This plug-and-play deployment mode significantly lowers technical barriers, eliminating the need for professional network engineers to deploy services onsite and therefore saving labor costs.