If you have multiple Ethernet switches that need to be connected over long distances, fiber is obviously a preferred choice. Moreover, when it comes to bandwidth, no currently available technology is better than single-mode fiber. It can provide significantly higher bandwidth and carry more data than traditional copper cables, which allows for faster data transmission and supports high-speed networking applications in telecommunications, data centers, financial institutions, and government departments.
In addition, fiber cables can transmit data over several kilometers without signal degradation, making them ideal for connecting switches in large campus networks and between different buildings. As they do not emit electromagnetic signals, they’re difficult to tap and secure against eavesdropping. Most importantly, any upgrades and advancements in networking technology can be easily accommodated by existing fiber infrastructure, offering scalability for future network expansions. In this article, we’ll explain how to connect multiple Ethernet switches using fiber optic cables and the equipment required for this to work.
Star Topology vs. Daisy Chain Topology
Network topology refers to the way in which the links and nodes of a network are arranged in relation to each other. Simply put, it defines how network devices are connected. Network topologies have a direct effect on how a network functions, and choosing the right topology can help increase network performance, data transfer rates, and energy efficiency. Among all, star and daisy chain topologies are most frequently used in network configurations.
What is Star Topology?
In a star topology, all the devices are connected to a central hub or switch, which acts like a data traffic controller that manages and directs the flow of data between devices. Each device has a dedicated P2P connection to the server, and they can only communicate with each other indirectly through the central hub. It’s high-performing as no data collisions will occur. If one device wants to send data to another device, it needs to send the data to the central switch first, and then the switch will transmit that info to the designated device. In the star topology, the overall bandwidth is shared among all devices, which may lead to congestion and reduced performance if a large number of devices are transmitting large amounts of data at the same time. But by using fiber optic cables, such problems can be settled properly since they can handle large amounts of data with no hassle.
Advantages of Star Topology
1. Scalability: New devices can be added to the network without affecting the existing ones.
2. Easy to troubleshoot: In case of any issues, it’s easier to identify the problem, which makes troubleshooting and maintenance much simpler compared to other topologies.
3. High performance: Data traffic can be distributed evenly across the network.
4. Security: Each device has a dedicated link to the central hub, making it easier to implement security measures and protect the network from unauthorized access.
5. Reliability: If one device fails, it does not affect the functionality of other devices.
Disadvantages of Star Topology
1. Dependency on central hub: If the hub fails, the entire network may become unavailable.
2. Cost: Require more cabling, which can be more expensive to install and maintain.
3. Complexity: Setting up and managing a star topology can be more complex in cases where a large number of devices need to be connected.
What is Daisy Chain Topology?
Daisy chain topology refers to a network configuration where multiple devices or nodes are connected in a linear sequence. In a daisy chain network, data is transmitted sequentially from one device to another, which creates a chain-like structure where each device only has two connections – one to the previous device and one to the next device. For no more than three Ethernet switches, a daisy chain is preferred because there is no loop. However, it suffers from switch failure due to a lack of redundancy. If one device fails or is disconnected, it can disrupt the entire network. The daisy chain topology is commonly used in scenarios where there is a need for a simple, linear connection, such as in certain types of industrial control systems or audio/video setups.
Advantages of Dasiy Chain Topology
1. Ease of use: It’s simple to set up and maintain, as there are no complex routing protocols needed to be configured. Each device only needs to be connected to the neighboring devices.
2. Reduced latency: Since data passes through devices in a sequential manner, the latency is relatively low compared to other complex network topologies.
3. Fewer cables: The daisy chain topologies are cost-effective to implement as they require minimal cabling and network equipment.
Disadvantages of Dasiy Chain Topology
1. Limited bandwidth: Suffer from decreased bandwidth as data has to pass through multiple devices before reaching the desired device, resulting in slower data transmission speeds.
2. Single point of failure: If one device/cable fails, it can disrupt the entire network as data transmission is dependent on the functioning of each device in the chain.
3. Difficult fault isolation: In case of a network issue or failure, it can be challenging to identify the specific device causing the problem as the data passes through multiple devices.
4. Lack of network redundancy: Do not provide built-in redundancy or alternate transmission paths, making the network vulnerable to disruptions in case of a device failure
In conclusion, to reduce network downtime and reserve optimum efficiency, the star topology is clearly a superior choice over the daisy chain. It’s more reliable and fault-tolerant. It allows for more efficient use of bandwidth and can support higher speeds. In addition, it’s more scalable and can accommodate more devices without sacrificing performance.
What Devices Do You Need to Connect Multiple Ethernet Switches?
Setting up a network requires careful planning and commitment. To avoid potential downfalls and make sure the network you establish today would satisfy your requirements several years down the road, it’s essential that you choose the right equipment for the job.
1. 4-Strand Pre-terminated Fiber Optic Cable
To connect multiple Ethernet switches, the best way is to use a multi-strand fiber cable. The 4-strand pre-terminated fiber optic cable consists of four individual strands or fibers of glass or plastic fibers enclosed in a protective sheath. These fibers come with connectors already attached to both ends, which eliminates the need for field terminations. They’re 100% tested in the factory and undeniably of high quality and accuracy. Each fiber strand has a 125μm thick cladding around a 9μm fiber core. It has very low propagation loss and just no dispersion since only one spread of the light beam (laser) is allowed to pass through, which greatly reduces the attenuation rate. What’s more, this fiber optic cable is terminated with LC connectors, a standard type of ceramic ferrule connector that is nearly half the size of the SC connector and can be easily terminated with any adhesive.
Why do you need pre-terminated fiber optic cables?
One of the biggest benefits of using 4-strand pre-terminated fiber optic cables is time and cost savings. Since the connectors are already attached, there is no need for on-site termination, which can be time-consuming and requires specialized tools, which reduces installation time and minimizes labor costs. Secondly, pre-terminated fiber cables are ready to use out of the box. They can be quickly and easily connected to network devices, saving installation time. Moreover, they are factory tested to ensure proper alignment and low insertion loss, reducing the chance of signal degradation or interruption. Last not but least, the risk of installation errors is minimized since the connectors are factory-terminated and tested for accuracy.
In brief, the 4-strand pre-terminated fiber optic cables provide convenience, reliability, and efficiency in network installations, making them a preferred choice in high-density network applications, SMB and campus networks, CATV, Internet and telephone applications, etc.
2. BiDi SFP Module
BiDi SFP modules, also known as BiDirectional Small Form-factor Pluggable modules, are optical transceivers used in fiber optic networks. These modules are capable of transmitting and receiving data over a single strand of fiber cable, enabling bidirectional communication. This is extremely useful in situations where limited fiber strands are available or where new fiber installations are costly or challenging. The BiDi SFP modules provide network flexibility as they can be used in existing single-mode fiber infrastructure. This allows organizations to leverage their existing fiber optic cables without the need for major overhauls or investments. support high-speed data transfer rates, making them suitable for applications that require fast and reliable communication.
3. Fiber Ethernet Switch or Media Converter
In the star topology, all devices need to be connected to the central hub, which means the core switch must have corresponding SFP ports that allow you to establish a dedicated fiber link for each sub-switch. But if your Ethernet switches do not have an SFP interface, then you’ll also need a fiber media converter for the integration of fiber optic and copper cabling within a network. The fiber media converter receives data signals from one media type, converts them into signals that can be transmitted over another media type, and then sends the signals to the destination. The media converter presents a cost-effective way to upgrade the existing wiring configurations with minimal influence on the legacy devices but with a substantial increase in network speeds. By converting signals to fiber optics, media converters also enables the extension of network connections beyond the 100-meter limitation of Ethernet cables.
4. LC-LC Coupler
The LC-LC coupler is a device used to connect two fiber optic cables that are terminated with LC connectors. This coupler is designed to provide low insertion loss, high return loss, and excellent repeatability. It’s widely used in high-speed data transmission applications because of its high accuracy, reliability, and stable performance. Additionally, LC-LC couplers are easy to install and maintain, helping to reduce downtime and maintenance costs.
Note: It is important to keep in mind that fiber optic cables have specific maximum distances for signal transmission, depending on the type of fiber being used. For instance, the typical transmission speed and distance limits for multi-mode fiber optic cables are 1Gbps for 550m and 100Mbps for up to 2km. Extending cables beyond these maximum distances may result in signal degradation or loss.
How to Connect Multiple Ethernet Switches Using Single Fiber?
Scenario A: Core Switch with More Than One SFP Port
a. Power off all the switches to prevent any potential damage or data loss;
b. Insert four BiDi SFP modules into the core switch, and connect each connector (A/B/C/D) of the 4-strand pre-terminated fiber optic cable to the corresponding SFP module;
c. Insert an SFP module on each Ethernet switch (A/B/C/D);
d. Connect the other end of the fiber optic cable to the corresponding Ethernet switch: strand A to switch A, strand B to switch B, strand C to switch C, etc.
e. Once all connections are complete, power on the switches and verify the connectivity and link status on each switch. Check for any errors or inconsistencies in the communication.
In cases where the distance between switches exceeds the total cable length, you can use the LC-LC coupler to connect two fiber optic cables together. For example, insert the connector of strand D into one side of the LC-LC coupler until it clicks or locks into place. Repeat the same step and connect another fiber optic cable to the LC coupler. Then, connect the second cable to the SFP module on switch D.
Scenario B: Core Switch with No SFP Port
a. Connect an Ethernet cable into one of the RJ45 ports on the core switch and connect the other end of the cable to the Ethernet port on the media converter;
b. Insert a BiDi SFP module into the media converter, repeat the same steps to set up another 3 fiber media converters, and power them up;
d. Connect each strand of the pre-terminated fiber cable to the corresponding SFP module;
f. Insert an SFP module on each Ethernet switch (A/B/C/D);
g. Connect the other end of the fiber optic cable to the corresponding Ethernet switch: strand A to switch A, strand B to switch B, strand C to switch C, etc.
