Network topology optimization to minimize losses

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

✍️1. Bus Topology All devices share a single backbone cable. Simple and cost-effective, but failure of backbone stops the whole network. ✍️2. Star Topology All devices connect to a central hub or switch. Easy to manage and troubleshoot. If the central device fails, the network goes down. ✍️3. Ring Topology Devices are connected in a closed loop (ring). Data travels in one direction around the ring. Failure of one device can disrupt the whole network. ✍️4. Mesh Topology Every device connects directly to every other device. High reliability, no single point of failure. Requires many cables, very expensive. ✍️5. Tree Topology Combination of Star and Bus topologies, in a hierarchical structure. Suitable for large organizations. Scalable, but backbone failure affects the entire network. ✍️6. Hybrid Topology Combination of two or more topologies (e.g., Star + Ring). Flexible and reliable. Complex to design and implement

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.

Here’s a structured list of OSPF troubleshooting steps you can follow when OSPF is not forming adjacency or routes are missing: --- 🔎 OSPF Troubleshooting Steps 1. Check OSPF Process Status Verify OSPF is enabled: show ip ospf Ensure the OSPF process is running on the router. 2. Verify OSPF Neighbor Relationship Use: show ip ospf neighbor Confirm neighbors are in Full/2-Way state. If stuck in Init/ExStart/Exchange/Loading, there may be mismatched settings. 3. Check Interface Configuration Use: show ip ospf interface Verify correct OSPF network type (broadcast, point-to-point, NBMA). Ensure interface is up/up. 4. Match OSPF Parameters Area ID must match on both ends. Hello/Dead intervals must be identical. Authentication settings (if configured) must match. MTU mismatch can prevent adjacency. 5. Check Network Statements Ensure correct networks are advertised: show running-config | section ospf Verify the network command includes correct interfaces. 6. Verify OSPF Router ID Use: show ip ospf Each router must have a unique Router ID. 7. Check LSDB (Link-State Database) Use: show ip ospf database Confirm LSAs are received from neighbors. 8. Routing Table Verification Use: show ip route ospf Ensure OSPF routes are installed in the routing table. 9. Check Passive Interfaces Make sure no required interfaces are accidentally set as passive.

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.

(RSTP) Rapid Spanning Tree Protocol explained. It is a network protocol defined in the IEEE 802.1w standard, designed to prevent loops in Ethernet networks that use redundant paths. Here’s a breakdown: ·       Background: In switched networks, redundant links are often used to provide fault tolerance. However, these can cause switching loops, leading to broadcast storms and MAC table instability. To solve this, the original Spanning Tree Protocol (STP) (IEEE 802.1D) was introduced. ·       RSTP (Rapid STP): An enhancement of STP that provides much faster convergence (the time it takes the network to reconfigure itself after a topology change). o  STP can take 30–50 seconds to converge. o  RSTP reduces this to a few seconds. ·       How RSTP Works: o  Builds a loop-free logical topology by blocking some redundant paths. o  If the active path fails, a backup path is quickly activated. o  Uses new port roles (e.g., Alternate, Backup) and states (e.g., Discarding, Learning, Forwarding) to speed things up. ·       Port Roles in RSTP: o  Root Port (RP): The port with the best path to the root bridge. o  Designated Port (DP): The forwarding port for a network segment. o  Alternate Port: A backup for a root port. o  Backup Port: A backup for a designated port. ·       Advantages of RSTP over STP: o  Much faster convergence. o  Backward compatible with STP. o  Better utilization of links through rapid transitions. In short: RSTP = a faster, more efficient version of STP for keeping Ethernet networks loop-free.

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.

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

Part 2 of the "Undisciplined Interconnect the Silent Killer" post Fortunately, there are clean solutions. I'm a big fan of going back to the basics. The ring topology and the line topology are well understood interconnect structures. They are easy to reason about and have low overhead. From a fitter standpoint, they are easy to place and route. If you're pipelining your interconnect to meet timing in your design already, then you've already paid the latency cost that is a commonly cited downside for these topologies. By absorbing the spaghetti of data busses connecting your major modules into one of these simple structures, you save area, reduce power, have more predictable timing, and drop compile time. Some people advocate to generalize immediately to a full mesh NoC. In my experience (your mileage may vary), it's better to keep things simple when possible. Plan it out! If a ring or line or similar topology does the job, try that first. At the end of the day, less complexity means fewer bugs and faster time-to-market. The takeaway: If you are experiencing QoR or compile time issues with system integration, sanity check if the tools report bad routing congestion. If yes, and you have a complex web of busses between your modules, then look at where your I/Os are, plan out a line or ring topology to clear up as much of the mess as you believe reasonably capturable. Then win with faster time-to-market than your less disciplined competitors who drowning from system integration woes.