What Is Network Topology?
Network topology is the way a network is arranged and communicates across the network. Why is it important? There are pros and cons for different topologies, how devices can (and cannot) interconnect, and where any potential slowdowns may occur.
You need to understand the strengths and weaknesses of each as you decide how to deploy your topology to make the best decisions about which topology to deploy.
Types of Network Topologies
Admins have several options when choosing which network topology to use. The choice will depend in part on the size and scale of their organizations, their business goals, and their budget.
Star Topology
Star topology is the most common type of setup you’ll find. The network is arranged so that nodes are connected to a central hub, which acts as a server. The hub manages data transmission across the network. In other words, any piece of data sent through the network travels through the central hub before ending at its destination.
PROS:
- Convenient management from one central location
- If one node fails, the network still functions
- Devices can be added or remove without taking the network down
- Easier to identify and isolate performance issues
CONS:
- If the central hub fails, your entire network goes down
- Performance and bandwidth is limited by the central node
- Can be expensive to operate
Bus Topology
Sometimes called backbone topology or line topology, a bus topology orients devices along a single cable running from one end of the network to the other end. Data will flow along the cable as it travels to its destination.
PROS:
- Cost-effective for smaller networks
- Simple layout; all devices connected via one cable
- More nodes can be added by lengthening the line
CONS:
- The network is vulnerable to cable failures
- Each node added slows transmissions speeds
- Data can only be sent in one direction at a time
Ring Topology
In a ring topology, nodes are configured in a circular pattern. Data travels through each device as it makes its way around the ring. In a large network, repeaters may be necessary to avoid packet loss during transmission.
PROS:
- Cost-effective
- Inexpensive to install
- Easy to identify issues or performance issues
CONS:
- If one node goes down, it can take multiple nodes down with it
- All devices share bandwidth which can limit throughput
- Adding or removing nodes means downtime for the entire network
Ring topologies can be set up as single ring (half-duplex) or dual ring (full-duplex) to allow traffic to flow in both directions simultaneously.
Tree Topology
In a tree topology, a central node connects secondary hubs. These hubs have a parent-child relationship with devices. The central hub is like the tree’s trunk. Where branches connect are the secondary hubs or controlling nodes, and then connected devices are attached on the limbs.
PROS:
- Extremely flexible and scalable
- Often used word WANs to support spread-out devices
- Branches can be assessed individually for performance issues
CONS:
- If a central hub fails, nodes will become disconnected (although branches can continue to function independently)
- The structure can be difficult to manage effectively
- Uses much more cabling than other methods
Mesh Topology
In a mesh topology, nodes are interconnected. Full-mesh modes connect every device directly to every other device on the network. In a partial mesh topology, most devices connect to others. This offers multiple pathways for data delivery. Data is delivered via the shortest distance available for transmission.
PROS:
- Reliable and stable
- No single node failure can take the network offline
CONS:
- Complex degree of interconnectivity between nodes
- Labor-intensive to install
- Uses much more cabling to connect every device.
Hybrid Topology
A hybrid topology is what you’d expect from the name. It used multiple topology structures. This is more common in large enterprises. For example, each department may have one type of topology, such as a star or line topology, but the department hub then connects to a central hub.
PROS:
- Flexibility
- Can be customized to customer needs
CONS:
- Complexity increases
- Expertise in multiple topologies is needed
- May be more difficult to determine performance issues
Which Topology Is Best for Your Network?
There’s no right or wrong answer to the question of which topology is best for your network. In many cases, it comes down to comfort level and the amount of redundancy you need in your network.
The cost will also play a role. The more cable you need and the more complex the topology, the more expensive and time-consuming it will be to install and manage.
Whatever you choose, it’s important that you plan for the future. As business needs change and evolve, you’ll likely need to add, remove, or change devices. Depending on your choice, it may be easier (or harder) to scale. One of the reasons so many organizations pick star topologies is because it’s easy to make changes without significant disruption.
Mapping Your Topology
Effective network topology management requires visual mapping. No matter which topology you deploy, you’ll want an accurate map network diagram. It should include devices, interconnections, and potential bottlenecks in case of failure. It’s always better to know these things ahead of time when you have to troubleshoot. It may also be a requirement of your business for compliance regulations such as PCI-DSS for credit card transactions.
As networks become more complex – and dynamic – network topology maps become a backbone of business continuity. It provides a comprehensive view of the network. Fortunately, there are discovery and mapping tools, such as WhatsUp Gold that can auto-generate layer 2 and 3 topologies, dependencies, and discover everything connected to your network. It can literally map your entire network in minutes. When you make changes to the network, the maps are automatically updated so you always have the most current view of your network topology.
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