industrial ethernet switch

Good afternoon, my network engineer friends,

Whether you’re setting up a small home network or constructing a complex data center for a business, switches play a crucial role. But what exactly is a switch? How does it work? And what types are there? These questions might not be immediately clear for newcomers to the field.

Today, we’ll delve into the ins and outs of switches, from basic concepts to advanced applications, providing you with the most comprehensive guide available. We’ll cover everything from the fundamental concepts of switches to their working processes, different types of switches, from LAN switches to WAN switches, fixed-port to modular designs, and the distinctions between managed and unmanaged switches.

Additionally, we’ll discuss the versatility of switches in real-world applications, including their roles in different network scales and how to choose the right switch for your needs. This in-depth explanation will leave you with a clear understanding of switches. Read on!

1 Concept of Switches

A switch, often referred to as a “switch,” is a network device used for forwarding electrical (or optical) signals. It provides a dedicated electrical signal path between any two network nodes connected to the switch. The most common type of switch is the Ethernet switch. Other common types include telephone voice switches and fiber switches.

For example, in a university dormitory, a single Telecom broadband cable is shared by six students, each with their own broadband account. How can one cable be split into six for internet access? This is where a switch comes in, providing numerous ports for cable connections, enabling a star topology.

Explanation: Network cables transmit electrical signals, while fiber optics transmit optical signals. Switches have both RJ45 ports for cables and SC ports for fiber connections. PCs connected to the switch can communicate with each other, forming a local area network (LAN).

01 Working Process

When a port successfully connects, the switch maps the MAC address to the port, forming a MAC table. Subsequently, data packets destined for that MAC address are forwarded only through the corresponding port.

Explanation: After a terminal device connects to a switch port, its physical/hardware address (MAC address) is mapped to the port and recorded in the MAC table. Data packets contain MAC address information, and the switch forwards packets based on the address in the packet.

02 Functions of Switches

• Learning: Maps the MAC address of connected devices to the port and stores it in the MAC table. Switches “learn” MAC addresses and store them in an internal address table, establishing a temporary exchange path between the sender and receiver for data frames to reach their destination directly.
• Forwarding/Filtering: Forwards packets to the corresponding port based on the MAC address, filtering out packets not destined for other ports. When the destination address of a data frame is in the MAC address table, it is forwarded to the port connected to the destination node (broadcast/multicast frames are sent to all ports).
• Eliminating Loops: When a switch includes a redundant loop, the Spanning Tree Protocol prevents loop formation while allowing backup paths.

03 Management Methods

Switches typically have two management methods:

1. Console Cable (Configuration Cable): Connects one end to the serial port of a PC and the other to the console port of the switch. Use terminal emulation software like CRT or HyperTerminal for management. Engineers often connect their PCs to switches for configuration.
2. Web Management: Log in to the switch’s web interface for management. Connect the switch and PC with an Ethernet cable, set them to the same network, and access the management address (usually 192.168.1.1) in a browser. Web management is simpler but not all settings can be configured this way; sometimes command input is necessary.

2 Switch Switching Modes

The method by which a switch forwards data from one port to another is called the switching mode.

01 Store and Forward:

• Characteristics: The switch stores the data packet in a buffer, performs CRC (Cyclic Redundancy Check), and discards packets with CRC errors. If the packet is intact, the switch queries the address mapping table to forward it to the appropriate port.
• Advantages: No defective packets are forwarded, reducing unnecessary data transmission.
• Disadvantages: Slower forwarding rate than cut-through mode.
• Suitable Environments: Suitable for networks with average or poor link quality, as data packet processing introduces latency related to frame size.

02 Cut-Through:

• Characteristics: The switch reads only the first 6 bytes of the data frame (destination address) and forwards the packet to the corresponding port. Cut-through mode minimizes latency as the packet starts forwarding immediately after the destination address is read.
• Advantages: Fast forwarding rate, reduced latency, and improved overall throughput.
• Disadvantages: Introduces many junk communication packets to the entire network.
• Suitable Environments: Suitable for networks with good link quality and few error packets, with latency independent of frame size.

03 Fragment-Free:

• Characteristics: A hybrid solution between store-and-forward and cut-through modes. It checks if the packet length is at least 64 bytes; if less, it discards the packet; if 64 bytes or more, it forwards the packet.
• Advantages: Faster data processing than store-and-forward mode.
• Disadvantages: Slower than cut-through mode.
• Suitable Environments: General communication links.

3 Types of Switches

01 WAN Switches and LAN Switches:

• Broadly, network switches are classified into WAN switches and LAN switches.
• WAN switches are primarily used in telecommunications, providing a communication infrastructure. LAN switches connect terminal devices like PCs and network printers in local networks.

02 Enterprise-Grade, Department-Grade, and Workgroup Switches:

• Based on scale, switches can be categorized as enterprise-grade, department-grade, and workgroup switches.
• Enterprise-grade switches are typically rack-mounted, while department-grade switches can be either rack-mounted or fixed-configuration. Workgroup switches are fixed-configuration with simpler functions.
• In terms of application scale, enterprise-grade switches support over 500 information points, department-grade switches support up to 300 points, and workgroup switches support up to 100 points.

03 Unmanaged Switches:

• Provide multiple access ports, plug-and-play, suitable for monitoring network access or aggregation.

04 Light-Managed Switches:

• Support iVMS-4200 client management, enabling network topology management, QoS, and port management. Managed via Hikvision Cloud Management App for port status, topology viewing, and port restarts.

05 Fully-Managed Switches:

• Support web and command-line management, offering comprehensive management options.
• Different models have varying functionalities, including:
  • Red Port Assurance: Ensures video from critical areas (e.g., entrances, hazardous material storage) is prioritized, preventing frame loss and stuttering.
  • Combo Ports: Dual-purpose ports that can be used as electrical or optical connections for data transmission.
  • Extended Distance: Extends transmission distance up to 300 meters with Hikvision cameras using Cat5e or Cat6 cables.
  • PoE: Supports Power over Ethernet (PoE) for powering PoE devices.
  • Stable Power Supply: Supports 8-core power supply.
  • High Protection: Ensures robust network protection.

4 How to Choose a Switch

Although switches have many names, they are commonly categorized by network structure, focusing on access layer, aggregation layer, and core layer switches. Let’s analyze how to choose these types of switches.

01 Access Layer Switch Characteristics:

• Addresses adjacent user access needs, enabling shared address access within the same LAN.
• In large networks, access layer switches also manage user authentication and IP identification.
• Selection Suggestions: Focus on cost-effectiveness, as access layer switches require multiple ports and low costs.

02 Aggregation Layer Switch Characteristics:

• Aggregates multiple access layer switches, enabling policy-based connections and VLAN routing.
• Selection Suggestions: Must have higher performance than access layer switches to handle data upload and download.
• Note: If the core layer switch has enough ports and performance, aggregation layer switches can be omitted, directly connecting core and access layer switches.

03 Core Layer Switch Characteristics:

• Requires high reliability, efficiency, manageability, and low latency.
• Selection Suggestions: Focus on throughput and bandwidth, choosing switches with gigabit or higher speeds.

05 Switch Interface Types

• RJ-45 (Twisted Pair): The most common interface type, used in 10Base-T, 100Base-TX, and 1000Base-TX networks.
• Fiber Optic: Used in 100Base-FX, 1000Base-FX networks, with SC interfaces common in LAN switches.
• AUI (Attachment Unit Interface): Used for thick coaxial cable connections, now rare.
• BNC (Bayonet Nut Connector): Used for thin coaxial cable connections, also rare.
• Console: Used for switch configuration, with RJ-45 or serial console ports.
• FDDI (Fiber Distributed Data Interface): Used in early 100Mbps networks, now obsolete.

06 Switch Connection Methods

• Cascading: Multiple switches connected in various ways, forming bus, tree, or star structures.
• Redundancy: Spanning Tree Protocol (StandBy) and Port Trunking for load balancing.
• Stacking: Multiple switches combined for higher port density, with stacking units acting as a single switch.

07 POE Switch vs. Regular Switch

• POE Switch: Supports power delivery over Ethernet, reducing the need for power cables and enhancing safety.
• Power Calculation: Example with Hikvision POE switch, considering 802.3at and 802.3af terminals.

08 Switch Architecture Evolution (Mainly Rack-Mounted)

• Shared Bus: Oldest data exchange method, limited by backplane bus bandwidth, now obsolete.
• Ring Switch: Improved bus switch, still limited, now obsolete.
• Shared Memory: Uses high-speed RAM for input data storage, core engine for high-performance connections, prone to latency.
• Crossbar + Shared Memory: Combines Crossbar and shared memory for higher performance, common in modern core switches.
• Distributed Crossbar (CLOS): Separates control and forwarding planes, improving reliability and performance.

09 Main Control Board, Switching Network Board, Interface Board, Backplane

• Backplane: Connects control, switching, interface boards, fans, and power supplies, varies by manufacturer.
• Main Control Board: Manages and controls the system, handles protocols, monitors components.
• Switching Network Board: Handles cross-board data forwarding, uses high-performance ASIC chips.
• Interface Board: Provides external physical interfaces, processes data reception and transmission.

By understanding these concepts, you’ll be well-equipped to choose and manage switches effectively in various network environments.