What Does Network Topology Mean?
Network topology refers to the physical or logical layout of a network. It defines the way different nodes are placed and interconnected with each other. Alternately, network topology may describe how the data is transferred between these nodes.
There are two types of network topologies: physical and logical. Physical topology emphasizes the physical layout of the connected devices and nodes, while the logical topology focuses on the pattern of data transfer between network nodes.
Techopedia Explains Network Topology
The physical and logical network topologies of a network do not necessarily have to be identical. However, both physical and network topologies can be categorized into five basic models:
- Bus Topology: All the devices/nodes are connected sequentially to the same backbone or transmission line. This is a simple, low-cost topology, but its single point of failure presents a risk.
- Star Topology: All the nodes in the network are connected to a central device like a hub or switch via cables. Failure of individual nodes or cables does not necessarily create downtime in the network but the failure of a central device can. This topology is the most preferred and popular model.
- Ring Topology: All network devices are connected sequentially to a backbone as in bus topology except that the backbone ends at the starting node, forming a ring. Ring topology shares many of bus topology's disadvantages so its use is limited to networks that demand high throughput.
- Tree Topology: A root node is connected to two or more sub-level nodes, which themselves are connected hierarchically to sub-level nodes. Physically, the tree topology is similar to bus and star topologies; the network backbone may have a bus topology, while the low-level nodes connect using star topology.
- Mesh Topology: The topology in each node is directly connected to some or all the other nodes present in the network. This redundancy makes the network highly fault-tolerant but the escalated costs may limit this topology to highly critical networks.
Network Topologies and the Physical Network
The earlier physical networks of computing at the end of the 20th century used these methods above to create these topologies explicitly. It’s fairly simple to envision the individual workstations being connected through Ethernet, or later through Wi-Fi, in a ring, star, tree, or bus setup, or any of the other topologies mentioned. However, figuring out the best topology involves a detailed look at the goals and objectives and other setup factors for a given network.
Topologies and the Virtual Network
As the cloud became a place to keep data, run networks and deliver end-user services, the concept of virtualization took over the world of modern computing.
In a virtualized network, those traditional physical pieces of hardware are to an extent replaced by logical partitioned resources often called “virtual machines” that parcel out CPU and memory accordingly. With that in mind, the traditional network topologies might still be used, but they’re more logical than they are a way to characterize hardware setups. In other words, the logical topologies are built “on top of” the physical topologies that connect hardware.
In this type of modern network, the mesh topology, or a vibrant tree topology, would perhaps be more applicable and more popular. Where specific network destinations receive addresses and are dealt with as though they are individual nodes of the network, they're more likely to be connected to many other nodes than they would have been in the early days when that required individual physical linking.
In addition, new best practices have evolved: for physical topologies, that includes assessing the capability of systems to offer features like high bandwidth, large bisection capacities, and a greater number of alternative data paths. In the world of logical topologies, experts have begun to talk about “topology switching” as a means of dynamic customization for VLANs and other network setups.
Network Topology and Opacity
In the most modern systems, networks have become so complex that traditional topologies now apply in different ways. One of these phenomena is the use of opaque systems to foil hackers or outside cyberattacks. Some experts are now suggesting that by shielding the IP addresses and isolating different parts of the network into segments, companies can practice better cybersecurity hygiene. All of that continues to change how network topologies are used.