Understanding Network Topologies: Bus, Star, Ring, Mesh, Tree, Hybrid

Network topologies refer to the physical or logical arrangement of devices in a network. Here are some common types: *Physical Topologies:* 1. *Bus Topology*: All devices connected to a single cable (backbone). 2. *Star Topology*: Devices connected to a central hub or switch. 3. *Ring Topology*: Devices connected in a circular configuration. 4. *Mesh Topology*: Each device connected to every other device. 5. *Hybrid Topology*: Combination of two or more topologies. *Logical Topologies:* 1. *Broadcast Topology*: Data sent to all devices on the network. 2. *Point-to-Point Topology*: Direct connection between two devices. *Advantages and Disadvantages:* Each topology has its pros and cons, such as scalability, fault tolerance, and complexity. *Common Applications:* 1. *LANs (Local Area Networks)*: Star topology is commonly used. 2. *WANs (Wide Area Networks)*: Mesh topology is often used.

Did you know one Ethernet cable can deliver both power and data?That’s the magic of Power over Ethernet (PoE) a technology reshaping how businesses build smarter, scalable, and cost-effective networks. In my latest article, I break down what PoE is and why it matters more than ever in 2025.

I have implemented a VLAN segmentation and inter-VLAN routing setup using one Layer 3 switch and two Layer 2 access switches. VLAN Creation: VLAN 10 and VLAN 20 were created to logically segment the network. Devices in VLAN 10 and VLAN 20 were assigned to different ports on the Layer 2 switches. Trunk Configuration: The uplink ports between the Layer 2 switches and the Layer 3 switch were configured as 802.1Q trunk links, carrying traffic for both VLANs. Inter-VLAN Routing: On the Layer 3 switch, SVIs (Switch Virtual Interfaces) were created for VLAN 10 and VLAN 20, each assigned an IP address to serve as the default gateway for devices in the respective VLANs. IP routing was enabled on the Layer 3 switch, allowing devices in VLAN 10 and VLAN 20 to communicate with each other through Layer 3 switching. Result: Devices connected to VLAN 10 and VLAN 20, even though separated by different Layer 2 switches, can now communicate successfully via the Layer 3 switch. This design improves network segmentation, scalability, and security while still allowing controlled communication between VLANs

Hub: Works at the physical layer (Layer 1) of the OSI model. Sends data to all devices connected to it, even if only one device needs it. Causes more network collisions, leading to slower performance. Considered an older, less efficient device. Ethernet Switch: Works at the data link layer (Layer 2). Sends data only to the intended device (based on MAC address). Reduces collisions, improves speed and efficiency. Provides better performance and security compared to hubs.

The impact of minor adjustments on network optimization becomes clear when we examine what happens in the field. On the physical side, tilting an antenna by just a few degrees, shifting its azimuth, or repositioning a sector can completely reshape coverage patterns. On the parameter side, recalibrating transmit power, optimizing PCI allocations, refining neighbor lists, and adjusting handover thresholds can significantly enhance the network's performance. At Teletek, we bring both sides together. These changes may seem minor, but they yield significant results: stronger signal quality, fewer dropped calls, smoother handovers, faster data speeds, and improved performance at the cell edge. Our process is simple but precise—we study live network counters, analyze benchmark and drive test data, and run simulations before making any changes. This way, every adjustment is deliberate, and every improvement is made without disrupting service. The end result is a stronger, more reliable, and higher-capacity network that works better where it matters most: in the hands of the user.

If Episode 1 answered “What is Networking ?”, today we go one step deeper into the blueprint of all digital communication : the OSI Model The Open Systems Interconnection (OSI) Model breaks networking into 7 logical layers, each with a specific role in moving data from one device to another Here’s a quick breakdown : 1️⃣ Physical : cables, signals, Wi-Fi waves 2️⃣ Data Link : MAC addresses, Ethernet, local delivery 3️⃣ Network : IP addresses, routing across networks 4️⃣ Transport : TCP/UDP, reliable delivery, ports 5️⃣ Session : manages connections (start, maintain, end) 6️⃣ Presentation : data format, compression, encryption 7️⃣ Application : user-facing services like HTTP, DNS, email 💡 Analogy : Think of it like sending a letter Layer 1 = the road the mail truck drives on Layer 2 = the house number Layer 3 = the city map Layer 4 = registered mail vs. postcard Layer 5 = keeping the phone line open Layer 6 = translating the language Layer 7 = the actual message you write The OSI Model helps engineers troubleshoot systematically : Cable issue ? Check Layer 1 Wrong IP ? Look at Layer 3 App not working ? Go to Layer 7 #Networking #NetworkingFundamentals #BackToSchool #IT #ComputerNetworks

Layer 3 Switch: A multilayer switch can perform both switching and routing functions. It is ‘Layer 3 aware’, meaning it can operate at the network layer of the OSI model. You can assign IP addresses to its interfaces, similar to how you would with a router. Virtual interfaces can be created for each VLAN, and each can be assigned an IP address. You can also configure routes on a multilayer switch, just like a router. These switches are commonly used for inter-VLAN routing, allowing communication between different VLANs without requiring an external router. SVIs (Switch Virtual Interfaces) are virtual interfaces on a multilayer switch to which you can assign IP addresses. Each PC should be configured to use the SVI (not the router) as its gateway address. To send traffic between different subnets/VLANs, PCs send their traffic to the switch, and the switch routes the traffic between VLANs. To enable an SVI (Switch Virtual Interface) on a switch, the following conditions must be met: 1.       The VLAN must exist on the switch. 2.       The switch must have at least one access port in the VLAN in an up/up state, and/or one trunk port that allows the VLAN that is in an up/up state. 3.       The VLAN must not be shutdown (the shutdown command can disable a VLAN). 4.       The SVI must not be shutdown (SVIs are disabled by default). Syntax: Interface vlan <Vlan ID> Ip address <IP Address> <subnet mask> IP routing This command enables the layer 3 functions in the L3 switch Int gi0/0 No switchport This configures the interface as a ‘routed port’, which means it's a Layer 3 port and not a Layer 2 switchport.

The goal of this procedure is to eliminate all network meshes by changing the network topology. Usually, there are a considerable number of possible topology states. This procedure chooses one topology that minimizes network losses, considering all activated constraints and without creating isolated sub-systems. At the beginning of the procedure, all switchable elements of the considered voltage level are switched on. After that, an iterative process follows and contains the following core: 1.  Load flow calculation. 2.  Determination of the element with the lowest apparent power from the all the switchable elements and elements that are not yet worked off. 3.  The found element is switched off. 4.  If the system contains an isolated part or if any constraint is violated, the element is switched on again and is marked as worked off. The iteration continues until there is no switchable element or element that is not yet worked off. Usually, the resulting system contains no meshes. If this is not desired, one must deactivate the "Switchable" option of the elements that must not be switched off. The "Switchable" option exists only for lines and cables. If the “Prevent overloaded elements” option is activated, the procedure contains an additional check. An element is switched off only if the number of overloaded elements is not increasing. If the “Prevent limit violations of node voltages” option is activated, elements are switched off only if the number of voltage violations is not increasing. If the procedure is not able to eliminate all meshes, there may be too many constraints. The optimization problem contains the following constraints: •Maximum element loadings •Node voltage limits •Set of non-switchable elements

The goal of this procedure is to eliminate all network meshes by changing the network topology. Usually, there are a considerable number of possible topology states. This procedure chooses one topology that minimizes network losses, considering all activated constraints and without creating isolated sub-systems. At the beginning of the procedure, all switchable elements of the considered voltage level are switched on. After that, an iterative process follows and contains the following core: 1.  Load flow calculation. 2.  Determination of the element with the lowest apparent power from the all the switchable elements and elements that are not yet worked off. 3.  The found element is switched off. 4.  If the system contains an isolated part or if any constraint is violated, the element is switched on again and is marked as worked off. The iteration continues until there is no switchable element or element that is not yet worked off. Usually, the resulting system contains no meshes. If this is not desired, one must deactivate the "Switchable" option of the elements that must not be switched off. The "Switchable" option exists only for lines and cables. If the “Prevent overloaded elements” option is activated, the procedure contains an additional check. An element is switched off only if the number of overloaded elements is not increasing. If the “Prevent limit violations of node voltages” option is activated, elements are switched off only if the number of voltage violations is not increasing. If the procedure is not able to eliminate all meshes, there may be too many constraints. The optimization problem contains the following constraints: •Maximum element loadings •Node voltage limits •Set of non-switchable elements

The goal of this procedure is to eliminate all network meshes by changing the network topology. Usually, there are a considerable number of possible topology states. This procedure chooses one topology that minimizes network losses, considering all activated constraints and without creating isolated sub-systems. At the beginning of the procedure, all switchable elements of the considered voltage level are switched on. After that, an iterative process follows and contains the following core: 1.  Load flow calculation. 2.  Determination of the element with the lowest apparent power from the all the switchable elements and elements that are not yet worked off. 3.  The found element is switched off. 4.  If the system contains an isolated part or if any constraint is violated, the element is switched on again and is marked as worked off. The iteration continues until there is no switchable element or element that is not yet worked off. Usually, the resulting system contains no meshes. If this is not desired, one must deactivate the "Switchable" option of the elements that must not be switched off. The "Switchable" option exists only for lines and cables. If the “Prevent overloaded elements” option is activated, the procedure contains an additional check. An element is switched off only if the number of overloaded elements is not increasing. If the “Prevent limit violations of node voltages” option is activated, elements are switched off only if the number of voltage violations is not increasing. If the procedure is not able to eliminate all meshes, there may be too many constraints. The optimization problem contains the following constraints: •Maximum element loadings •Node voltage limits •Set of non-switchable elements