14 Backbone Networks, MANs, and WANs
Chapter Objectives
- Outline the purpose of backbone networks.
- Summarize the features of a metropolitan area network (MAN).
- Summarize the features of a wide area network (WAN).
- Describe the different types of WAN connections, including leased lines, broadband, and wireless.
- Differentiate between a private and public WAN and use cases for each.
- Compare and contrast a software-defined wide area network (SD-WAN) with traditional WAN technologies such as MPLS.
- Describe the features and benefits of a SDN in cost, performance, reliability, and efficiency.
- Discuss best practices for troubleshooting common WAN scenarios.
Backbone Networks
We ended the last chapter with virtual local area networks, or VLANs. As you recall, a VLAN groups devices together logically on one or more LANs so that the LANs can communicate as if they are on the same physical network, regardless of their physical location. VLANs are used to improve network performance, security, and scalability by allowing network administrators to group hosts together based on their resource needs, traffic characteristics, or other criteria.
A backbone network interconnects lower-speed distribution channels or clusters of dispersed user devices, connecting multiple networks together, and allowing them to communicate and exchange information over its high-capacity connectivity infrastructure.
While VLANs and backbone networks are both used to connect multiple networks together, they serve different purposes. A backbone network provides for the exchange of information between different LANs or subnetworks. Backbone networks can tie together diverse networks in the same building, in different buildings in a campus environment, or over wide areas.
Types of backbone networks include distributed backbones and collapsed backbones. A distributed backbone is a backbone network that consists of a number of connectivity devices connected to a series of central connectivity devices, such as hubs, switches, or routers, in a hierarchy. The routing and switching functions are decentralized at each location. In the case of a collapsed backbone, each location features a link back to a central location to be connected to the collapsed backbone. The collapsed backbone can be a cluster or a single switch or router. The topology and architecture of a collapsed backbone is a star or a rooted tree.
Backbone networks are used to link LANs together and to link other backbone networks to WANs. They are designed to provide high-speed connectivity and to ensure that data is transmitted efficiently and reliably across the network. The choice of backbone architecture depends on the specific needs of the organization, the size of the network, and the types of applications that will be running on the network. Backbone networks are operated by large telecommunications companies, internet service providers, and other organizations, and provide the high-speed data links that enable data to be transmitted quickly and efficiently between different parts of the internet.
Backbone architectures often include the following components.
Metropolitan Area Networks (MANs)
- Moderate to high data rates
- High-speed connectivity through optical fibers
- High reliability because the low network error rates
- Several connection technologies to provide connectivity
- Centralized management of network resources to monitor and manage the network
A MAN can be closely related to smart city concepts in several different ways. It may be a large number of privately owned or telecommunication provider interconnects between organizations, or it may be a public or free Wi-Fi system provided to residents of a city. As technology continues to advance and more devices become interconnected, the use of metropolitan area networks will continue to increase.
- Leased lines: A dedicated and secure leased line connects two LANs or end nodes in a point-to-point WAN environment. Old school broadband networks using dial-up technology are a historic example of point-to-point WAN. Modern enterprises also use this type of WAN to enable secure and customized network performance between two locations.
- Broadband: Broadband connections use a shared medium to connect multiple devices to the internet. Broadband connections can be either wired or wireless and can be used to connect devices over a wide area.
- Wireless: Wireless WAN connections use radio towers for communication and are often used to connect devices in remote locations. Wireless WAN connections can be made up of multiple LAN and MAN networks.
- Virtual Private Network (VPN): A VPN is a secure connection that allows users to access a WAN from a remote location. VPNs are often used by businesses to allow employees to work from home or other remote locations.
- Satellite: Satellite WAN connections use satellites to connect devices over a wide area. Satellite WAN connections are often used in remote locations where other types of WAN connections are not available.
Each type of WAN connection has its own advantages and disadvantages, and the choice of WAN connection will depend on the specific needs of the organization.
Private and Public WANs
A private WAN is a network that is owned and operated by a single organization, while a public WAN is a network that is owned and operated by a third-party service provider. Private WANs are often used by large organizations that need to connect multiple locations together. For example, a company with offices in different cities or countries might use a private WAN to connect all of its offices together. Private WANs can also be used to provide secure and reliable connectivity between different parts of an organization. For example, a hospital might use a private WAN to connect all of its departments together, allowing doctors and nurses to access patient records and other important information from any location within the hospital. Private WANs might be used to provide high-speed connectivity between an organization with different locations. For example, a financial institution might use a private WAN to connect all of its branches together, allowing customers to access their accounts from any location.
A public WAN is often used by small and medium-sized businesses that need to connect to the internet. For example, a small business might use a public WAN to connect its computers to the internet, allowing employees to access email and other online services. Public WANs can also be used to provide connectivity to remote locations. For example, a company might use a public WAN to connect its headquarters to a remote factory or warehouse. Finally, public WANs might also be used to provide backup connectivity in case of a network outage. For example, a company might use a public WAN as a backup to its private WAN, allowing employees to continue working even if the private WAN goes down.
MPLS to SD-WANs
Multiprotocol label switching (MPLS) is a protocol used in traditional networking to move data packets to a destination as quickly and efficiently as possible. MPLS routes traffic using “labels” that it assigns to a packet and controls the forwarding WAN path based on the shortest available label to improve application performance. MPLS is known for its reliability and performance where data travels along predetermined paths. MPLS as a routing method to connect to the WAN is becoming just one option as organizations adopt SD-WANs, particularly as some of their infrastructure is moved to the cloud.
Software-defined wide area networks (SD-WANs) use a a virtualized architecture that takes a software-defined approach to managing WANs. SD-WAN supports any combination of connections, whereas MPLS needs static, dedicated architecture. SD-WAN is a carrier-independent connectivity that provides improved bandwidth availability and WAN redundancy in the event of a network outage. Because SD-WAN is a software-defined approach, rather than a hardware-based one, SD-WAN does not require specialized routers. One advantage of this is that SD-WAN can help enterprises reduce operational costs.
With SD-WAN, organizations can leverage any combination of transport services, including MPLS, LTE, and broadband. SD-WAN assures consistent application performance and resiliency, automates traffic routing, and improves network security, using a centralized control function to steer traffic securely and intelligently across the WAN and directly to trusted SaaS and IaaS providers. SD-WAN architecture is designed to fully support applications hosted in on-premises data centers, public or private clouds, and SaaS services.
An important aspect of software-defined networking (SDN) is that the control plane is decoupled from the data plane, which allows administrators to centralize and automate network management. This makes networks more efficient and flexible. Some of the essential features and benefits of SDN include:
- Centralized control: With SDN, network administrators can control and configure all network resources from a single central location rather than managing individual devices and their configurations separately. This makes implementing changes, updates, and policies easier across the entire network.
- Scalability: SDN separates the control plane from the data plane, which makes it easier to scale networks up or down as needed without requiring significant reconfigurations.
- Improved security: By centralizing control and automating security policies, SDN can help administrators more quickly detect and prevent security threats, such as network intrusions and data breaches.
- WAN SDN: This type of SDN architecture is used to improve the performance and reliability of wide-area networks (WANs) and can connect different locations and devices across long distances.
- Cloud SDN: This type of SDN architecture is used to improve the performance and security of cloud-based applications and services.
Troubleshooting WANs
Network administrators encounter common issues when working with WANs.
Latency: Latency is the time it takes for data to travel from one point to another on a network. High latency can cause slow network performance and poor user experience. Optimizing network settings, upgrading hardware, or using a content delivery network (CDN) may help resolve these issues.
Bandwidth congestion: Bandwidth congestion occurs when there is too much traffic on a network, causing slow performance and dropped connections. Upgrading their hardware, optimizing network settings, and/or using Quality of Service (QoS) tools to prioritize traffic may improve bandwidth.
Poor connectivity: Connectivity issues can occur when there is a problem with the physical connection between devices on a network. Solutions often involve checking cables and connectors, resetting devices, or using diagnostic tools such as ping or traceroute.
Security breaches: Security issues such as unauthorized access or data breaches can occur on WANs just as with any other network design. Common mitigation strategies include improved firewall configurations and VPNs.
Hardware failures: Hardware failures such as router or switch failures can cause WAN outages. Auditing and replacing faulty hardware and/or using redundant hardware can help ensure high availability.
Discussion
1. Do you have concerns about the control of technology companies and/or governments over Internet access and data? How might the telecommunications and networking fields impact this control?
- B. Fung, “US lawmakers unveil a plan to give all Americans a right to online privacy | CNN Business,” CNN. Accessed: Apr. 09, 2024. [Online]. Available: https://www.cnn.com/2024/04/08/tech/online-privacy-bill/index.html.
2. Will software-defined wide area networks (SD-WANs) be able to replace traditional WANs? Why or why not?
- What is the Difference Between SD-WAN and MPLS?,” Palo Alto Networks. Accessed: Apr. 09, 2024. [Online]. Available: https://www.paloaltonetworks.com/cyberpedia/sd-wan-vs-mpls.
3. What is SASE? Do we need SD-WANs to run SASE? Why or why not?
- “SD-WAN vs. SASE: What’s the Difference?,” Palo Alto Networks. Accessed: Apr. 09, 2024. [Online]. Available: https://www.paloaltonetworks.com/cyberpedia/sd-wan-vs-sase.
4. How will the Internet, the most massive backbone network of our time, be available to all? Meaning, what will be needed in terms of infrastructure and human resources, in your opinion?
