The commonly asked questions surrounding switches
Network switches are essential components in modern computer networks, enabling devices to communicate efficiently. However, not all switches are created equal. In this guide, we will answer some commonly asked questions surrounding switches and some of their protocols.
A technology that allows electrical power and data to be transmitted over a single cable. It is used for devices such as IP cameras, wireless access points, and VoIP phones.
There are three main types of PoE: PoE (IEEE 802.3af), PoE+ (IEEE 802.3at), and PoE++ (IEEE 802.3bt). The original PoE standard provides up to 15.4W of DC power, while PoE+ supports up to 30W, and PoE++ delivers up to 90W. Each standard caters to different power requirements, allowing for a broader range of devices to be powered via PoE.
When selecting the right type of switch to meet your needs, one consideration is whether to use a managed or an unmanaged switch. The key difference is in the amount of control and security you have over the settings of the switch.
Unmanaged switches are designed to just plug in and run, with no settings to configure. These are fine to use in small networks with only basic needs. Managed switches, however, are fully configurable, are customisable, and provide a range of data on performance. Those attributes make them more suitable for larger networks and networks supporting critical activities.
Layer 1 switches, often referred to as physical layer switches or unmanaged switches, are the simplest form of network switches.
These switches operate at the physical layer of the OSI (Open Systems Interconnection) model and are primarily responsible for transmitting data frames between devices. Here’s what sets them apart:
Functionality: Layer 1 switches operate at the lowest layer of the OSI model. They lack the intelligence and capabilities to inspect or understand the data they are handling. Essentially, they function like network hubs, sending data to all connected devices without any form of filtering or decision-making.
Use Cases: Layer 1 switches are typically used in small, basic networks where there is no need for advanced features like VLAN support, Quality of Service (QoS), or network segmentation. They are cost-effective and straightforward, making them suitable for home networks or simple office setups.
Scalability: These switches are limited in terms of scalability and often come with a fixed number of ports. They are not suitable for larger or more complex networks.
Layer 2 switches, also known as data link layer switches or Ethernet switches, operate at the data link layer of the OSI model. They offer more advanced features compared to Layer 1 switches:
Functionality: Layer 2 switches are capable of making decisions based on the Media Access Control (MAC) addresses of devices connected to them. They build and maintain MAC address tables, allowing them to forward data frames only to the port where the destination device resides. This reduces network congestion and improves efficiency.
Use Cases: Layer 2 switches are commonly used in local area networks (LANs) and can support features like Virtual LANs (VLANs), which enable network segmentation for better security and traffic management. They are suitable for most enterprise and small to medium-sized business networks.
Scalability: Layer 2 switches come in various port configurations and can be scaled to accommodate larger networks. However, they do not possess routing capabilities, limiting their usefulness in more complex networks.
Layer 3 switches, also known as network layer switches or multilayer switches, operate at the network layer (Layer 3) of the OSI model. They offer the highest level of functionality and intelligence among the three types of switches:
Functionality: Layer 3 switches combine the capabilities of Layer 2 switches with routing functionality. They can make routing decisions based on IP addresses, allowing them to route traffic between different IP subnets or VLANs within a network. This makes them suitable for routing between LANs or even acting as a router for smaller networks.
Use Cases: Layer 3 switches are ideal for medium to large-scale networks where inter-VLAN routing, routing between different IP subnets, and advanced network features like Access Control Lists (ACLs) and Quality of Service (QoS) are required. They are commonly found in enterprise networks and data centres.
Scalability: Layer 3 switches come with various port configurations, making them suitable for networks of different sizes. They are highly scalable and can handle complex routing requirements.
Spanning Tree Protocol (SPT) is a very useful layer2 protocol which helps build a loop free logical topology for networks, it prevents bridge loops and broadcast radiation throughout a network which could ultimately crash the network.
A virtual local area network (VLAN) is a virtualised connection that connects multiple devices and network nodes from different LANs into one logical network.
Virtual Local Area Networks (VLANs) separate an existing physical network into multiple logical networks. Thus, each VLAN creates its own broadcast domain. Communication between two VLANs can only occur through a router that is connected to both. VLANs work as though they are created using independent switches.
There are a lot of ways to connect switches. You can daisy chain them, star link them, cascade them, cluster them or stack them. In most modern networks, cascades, clusters, and stacks tend to be more prevalent.
The primary difference between half-duplex and full-duplex is their mode of communication. Full-duplex enables simultaneous two-way communication, meaning devices can send and receive data at the same time. Half-duplex permits two-way communication but not simultaneously; a device must wait for the other to finish transmitting before it can respond. In a half-duplex system, both parties can communicate with each other, but not simultaneously; the communication is one direction at a time.
Configuring switch ports involves several steps to ensure proper network connectivity and security. Here are the general steps for configuring switch ports:
1. Access the Switch: First, you need to access the switch’s management interface. This can be done via a web browser (using the switch’s IP address), a command-line interface (CLI) through SSH or Telnet, or a physical console connection.
2. Identify the Port: Determine which port you want to configure. Ports are usually labelled numerically (e.g., Gigabit Ethernet 1/0/1 or Fast Ethernet 0/1).
3. Assign VLANs: If your switch supports virtual LANs (VLANs), assign the appropriate VLAN(s) to the port. VLANs allow you to segment the network for better organisation and security.
4. Configure Speed and Duplex: Set the speed (e.g., 100 Mbps, 1 Gbps) and duplex mode (half or full) for the port. This ensures compatibility with connected devices.
5. Enable or Disable Port Security: You can enable features like MAC address filtering, limiting the number of allowed MAC addresses, or enabling sticky MAC addresses. These help prevent unauthorised devices from connecting to the port.
6. Configure Port Mode: Decide whether the port should be an access port (for connecting end devices) or a trunk port (for connecting to other switches). Trunk ports carry traffic for multiple VLANs.
7. Set Port Description: Add a description to the port for documentation purposes. This helps identify the purpose of the port.
8. Apply Quality of Service (QoS): If needed, configure QoS settings to prioritise certain types of traffic (e.g., voice or video) over others.
9. Enable or Disable Spanning Tree Protocol (STP): STP prevents loops in the network by blocking redundant paths. By default, most switches have STP enabled.
10. Save Configuration: After making changes, save the configuration to the switch’s memory so that it persists after a reboot.
The UPLINK port is a special port that is used to connect the virtual switch to a physical switch – essentially bridging the virtual switch’s simulated network to a physical network.
An SFP module is used to interconnect fibre cables to network switches and other communication devices, such as industrial Ethernet switches and media converters.
While RJ45 ports may serve sufficiently for shorter distances with lower costs, SFP ports offer superior security, reliability, and future-proofing. Both port types have their merits, and the most suitable one is contingent on your unique situation.
In summary, determining which SFP to use involves considering the distance and bandwidth requirements of your network. Single-mode SFPs are suitable for long distances and higher data rates, while multimode SFPs are more cost-effective for shorter distances and lower bandwidth needs.
An easy and quick way is to distinguish the colour of the SFP module Bale Clasp. SFP with black colour-coded Bale Clasp stands for multimode SFP, while SFP Bale Clasp in blue, yellow, red refers to single-mode SFP.
