Mesh Versus Hierarchical Mesh Topologies

Network designers often recommend a mesh topology to meet availability requirements. In a full-mesh topology, every router or switch is connected to every other router or switch. A full-mesh network provides complete redundancy, and offers good performance because there is just a single-link delay between any two sites. A partial-mesh network has fewer connections. To reach another router or switch in a partial-mesh network might require traversing intermediate links, as shown in Figure 5-3.

Figure 5-3. A Partial-Mesh Topology (Left) and a Full-Mesh

Topology (Right)

Partial And Full Mesh Topology

NOTE

In a full-mesh topology, every router or switch is connected to every other router or switch. The number of links in a full-mesh topology is as follows:

N is the number of routers or switches. (Divide the result by two to avoid counting Router X to Router Y and Router Y to Router X as two different links.)

Although mesh networks feature good reliability, they have many disadvantages if they are not designed carefully. Mesh networks can be expensive to deploy and maintain. (A full-mesh network is especially expensive.) Mesh networks can also be hard to optimize, troubleshoot, and upgrade, unless they are designed using a simple, hierarchical model. In a nonhierarchical mesh topology, internetworking devices are not optimized for specific functions. Containing network problems is difficult because of the lack of modularity. Network upgrades are problematic because it is difficult to upgrade just one part of a network.

Mesh networks have scalability limits for groups of routers that broadcast routing updates or service advertisements. As the number of router CPU adjacencies increases, the amount of bandwidth and CPU resources devoted to processing updates increases.

A good rule of thumb is that you should keep broadcast traffic at less than 20 percent of the traffic on each link. This rule limits the number of adjacent routers that can exchange routing tables and service advertisements. This limitation is not a problem, however, if you follow guidelines for simple, hierarchical design. A hierarchical design, by its very nature, limits the number of router adjacencies.

With routing protocols, such as OSPF and EIGRP, the problem is not with the broadcast/multicast traffic and CPU resources used for day-to-day routing. The problem is the amount of work and bandwidth required to reestablish routing after an outage. Be careful not to let your network grow into a complicated mesh just because it's still working. There will probably be an outage someday and then you may learn the hard way the downfalls associated with a complex mesh of routers.

Figure 5-4 shows a classic hierarchical and redundant enterprise design. The design uses a partial-mesh hierarchy rather than a full mesh. The figure shows an enterprise routed network, but the topology could be used for a switched campus network also.

For small and medium-sized companies, the hierarchical model is often implemented as a hub-and-spoke topology with little or no meshing. Corporate headquarters or a data center form the hub. Links to remote offices and telecommuters' homes form the spokes as shown in Figure 5-5.

Figure 5-5. A Hub-and-Spoke Hierarchical Topology for a

Medium-Sized Business

Figure 5-4. A Partial-Mesh Hierarchical Design

Figure 5-4. A Partial-Mesh Hierarchical Design

Hub And Spoke Pmo
Branch Offices (Access Layer)-
Partial Mesh Network Topology

Continue reading here: The Core Layer

Was this article helpful?

+8 -1

Readers' Questions

  • Tesfay
    Which network topology provides the highest security and reliability?
    9 months ago
  • There is no definitive answer to which network topology provides the highest security and reliability, as it can vary depending on the specific requirements and circumstances of a network. However, some network topologies that are generally considered to provide higher security and reliability include:
    1. Mesh Topology: In a mesh topology, each device is connected to every other device, creating multiple paths for data transmission. This redundancy can ensure high reliability as communication can be maintained even if one or more connections fail. Additionally, the lack of a central point of failure makes it more secure against disruptions.
    2. Ring Topology: In a ring topology, devices are connected in a circular manner, where data flows in only one direction. This topology offers reliability as any failure in the ring can be automatically bypassed by data traveling in the opposite direction. It also provides security as communication is limited to devices connected directly in the ring.
    3. Star Topology: In a star topology, all devices are connected to a central hub or switch, and data flows directly from the source device to the hub and then to the destination device. It offers reliability as an issue with one device or connection does not affect the functionality of other devices. From a security perspective, it centralizes control and allows for easier monitoring and management of network traffic.
    4. Hybrid Topology: This is a combination of different topologies, such as star-ring or star-mesh. By incorporating multiple topologies, hybrid networks can provide both redundancy and centralized management, enhancing both security and reliability.Ultimately, the choice of the most suitable topology depends on the specific network requirements, including the number of devices, bandwidth needs, budget constraints, and the importance of security and reliability.
    • rahel
      Which of the following network topology is most expensive to implement and maintain?
      12 months ago
    • The most expensive network topology to implement and maintain is the mesh topology. Mesh topologies require more network devices and switching equipment than other topologies, which can increase the cost of implementation and maintenance significantly.
      • d smallburrow
        Are designing mesh networks deploy civil?
        1 year ago
      • networking The design of mesh networks for civil networking is a complex process that involves a number of different steps. The following is a brief overview of the steps involved in designing a mesh network for civil networking: 1.Create a topology – The first step in designing a mesh network is creating a topology that shows the various nodes and their connections. This will help identify how best to route traffic between different nodes. 2.Choose an appropriate protocol – Choose an appropriate communication protocol or technology, such as Wi-Fi or cellular network, to be used for the network. 3.Determine node placement – Decide where to place the nodes in order to ensure the most efficient routing of traffic, while also considering environmental factors. 4.Choose routing algorithms – Select the most appropriate routing algorithms to ensure the most efficient flow of traffic between the nodes. 5.Test and optimize – Test the network and make any necessary adjustments in order to optimize the performance of the network. 6.Deploy and monitor – Deploy the network and monitor the performance of the network over time, making any needed adjustments to optimize the network performance.
        • Melba
          Are mesh networks deploy during civil?
          1 year ago
        • unrest? Mesh networks can be invaluable tools to civilians during civil unrest, allowing them to communicate, access information, find resources, and coordinate with each other without relying on centralized networks for which access may be blocked by oppressive regimes. Mesh networks can be deployed in a number of ways, ranging from Wi-Fi mesh networks using consumer-grade devices, to low-cost "ad-hoc" mesh networks using homemade radios and antenna systems. In some cases, mesh networks have even been constructed using small, solar-powered machines to provide a reliable connection in areas with limited access to electricity.
          • moro
            Are designing mesh to deploy civil?
            1 year ago
          • engineering When designing a mesh for civil engineering, there are several considerations to keep in mind. The mesh should be easy to install, durable and able to withstand the elements. Steel, aluminum, and other high-grade metals are typically used for civil engineering meshes due to their strength and longevity. The mesh should also fit the structure and be accessible for inspections and maintenance. It is also important to ensure that the mesh is designed to meet the specific needs of the project. This can include the size, shape, and gauge of the mesh, as well as the spacing of the openings, and the locking and tensioning systems. Any mesh for civil engineering must also be designed to meet safety standards, such as those set out by OSHA. In many cases, a fall prevention system, such as a guardrail, may be required. Finally, it is important to consider the cost of the mesh and whether it fits within the project budget. Working with a local supplier may help to reduce costs and ensure a quality product.
            • DUENNA
              What is the benefit of mesh topology?
              1 year ago
            • The main benefit of a mesh topology is its reliability, since each node is connected to multiple other nodes. This allows for networks to keep running even in the event of a node failure, since there are multiple paths for traffic to travel from one node to another. Additionally, it is resistant to outside interference, since there are many paths for data to be transferred. Mesh topologies also offer better scalability, since new nodes can be easily added to the network.
              • marcello
                Are designing mesh networks to deploy?
                1 year ago
                1. Choose a network topology: Mesh networks are relatively flexible in terms of network topology, and can use star, ring, tree, or hybrid topologies.
                2. Select the nodes: Mesh networks can be composed of individual nodes, such as routers, access points, and switches. It is important to consider the number and type of nodes needed to form a reliable and efficient network, as well as the node’s ability to support the desired traffic.
                3. Select the hardware: Mesh networks require hardware to support their operations, such as routers, switches, access points, and network adapters, as well as cables, connectors, and other equipment.
                4. Implement the network: Once the networks nodes and hardware are chosen, the network must be implemented, tested, and optimized for the best performance. This will involve configuring the nodes, setting up the switch or access point, and linking all the nodes together.
                5. Monitor the mesh network: To ensure the mesh network is operating properly, regular monitoring and maintenance should be performed. This includes checking for any changes or performance issues and addressing them as necessary.
                • AZIZA
                  Can switch be used in mesh topology?
                  1 year ago
                • Yes, switch can be used in a mesh topology. Switches can be used to interconnect the nodes in a mesh topology, allowing messages to be forwarded to their intended destination.
                  • Eliisa
                    What are the disadvantages of a mesh network?
                    1 year ago
                    1. Expensive to set up: Mesh networks require multiple devices to create the network, which can be expensive and time consuming to set up.
                    2. Difficult to manage: Managing a mesh network is not as easy as managing a traditional router-based network. It requires an understanding of networking concepts and there are multiple devices to keep track of.
                    3. Limited range: Mesh networks have limited range since each node must be in close proximity to each other. This means that each node must be placed in an optimal location to maximize the network coverage.
                    4. Vulnerable to interference: Mesh networks rely on wireless connections and thus, can be more susceptible to interference from other wireless networks and devices.
                    • christine mehler
                      Are designing mesh networks to during?
                      1 year ago
                    • Mesh networks are used to help connect various devices in a decentralized manner. They allow for greater scalability, faster connectivity, and improved network reliability. Mesh networks are often used to provide internet access to rural and remote areas or to create reliable, secure communication networks for organizations. They can also be used to create resilient infrastructure networks for utilities such as water, gas, and electricity. Additionally, mesh networks can be used to build public transportation networks or in smart cities to control and monitor various elements such as traffic and environmental conditions.
                      • pervinca sackville
                        How to differ from hierarchical and mesh topologies?
                        1 year ago
                      • Hierarchical topology is a network topology in which network nodes are arranged in a hierarchy or tree-like structure. It is a centralized network architecture that consists of multiple levels of switches or nodes, each of which is responsible for forwarding data to the next level. Mesh topology is a network topology in which each node connects to every other node in the network. In a mesh network, every node has a unique path to every other node in the network, making it resilient to node failure. Unlike a hierarchical topology, a mesh topology does not have a single point of failure, but instead relies on the redundancy of the connections between the nodes to provide a reliable pathway for data.
                        • dirk
                          What are the dfference between mesh and hierarchial network topology?
                          1 year ago
                        • Mesh Network Topology: A mesh network topology is a type of network in which each node is connected to every other node in the network. This topology can be very reliable, as every node has an alternate path to any other node in the network. The downside to this topology is that it can be very complex to configure and maintain. Hierarchical Network Topology: A hierarchical network topology is a type of network in which nodes are arranged in a hierarchical structure. This type of network allows for easy scalability and growth as additional nodes can easily be added to the existing hierarchy. This topology also allows for easier troubleshooting and maintenance as the hierarchical structure allows for quick identification of problems. However, this type of topology can also be more prone to single points of failure as a single node failure can cause the entire system to go down.
                          • Nick
                            What is mesh topology?
                            1 year ago
                          • Mesh topology is a network topology in which each node is connected directly to every other node in the network. It is a type of network topology in which each device is connected to every other device, forming a network in the shape of a mesh. This topology offers several advantages such as greater reliability and increased redundancy. It also offers higher performance than a traditional wired network.
                            • Zewdi
                              What does a partial mesh look like?
                              1 year ago
                            • A partial mesh is a type of network topology in which some of the nodes (or devices) are connected only to some of the other nodes. This means that not all nodes are interconnected, only the ones that are necessary for sharing data. This type of network topology is most often used in smaller networks, such as those in a single building or home, because it can reduce the amount of hardware and wiring required.