Switches, as one of the core devices in networks, play a crucial role in achieving efficient data transmission and network management. However, to fully leverage the capabilities of switches, network engineers not only need to master their basic operations but also must deeply understand the various types of interfaces they offer. It’s likely that anyone who has worked with switches has performed their first operation by locating the switch interfaces. Although the Console interface is the one many people first encounter because it provides direct access to the switch’s command-line interface, there are many other types of interfaces that need to be well-known in practical work. These interfaces not only support different communication protocols but also cater to diverse network needs, from simple LAN connections to complex fiber communication systems. Today, we’ll discuss these interfaces beyond the Console interface, which are perfect for beginners.

100 Mbit/s 8-port industrial switch

1 Switch Interface Basics

01 Overview of Switch Interfaces

A switch is a network device used in LANs that connects different devices through multiple physical ports and intelligently forwards data packets to their destinations.

The interfaces on a switch are the foundation for these connections and data forwarding. Each interface has specific design purposes and technical specifications to adapt to different network environments and communication needs.

02 Introduction to Console Interface

Although this article focuses on other interfaces, we briefly introduce the Console interface to better understand the others.

The Console interface is usually an RJ-45 serial port that connects to a computer or terminal device via a dedicated control cable, allowing network administrators to interact directly with the switch, perform initial configurations, troubleshoot, and other advanced management tasks. The Console interface provides the most basic operational access to the switch, making it an essential tool for device configuration and debugging.

2 RJ-45 Interface

This interface is the most common network device interface, commonly known as the “crystal head,” with the professional term being the RJ-45 connector. It belongs to the twisted-pair Ethernet interface type.

It is widely used in LANs to connect computers, servers, printers, and other network devices. It uses an 8-core plug and socket design, supports twisted-pair cables (UTP or STP), and is one of the most popular network connection methods today.

01 Technical Specifications

• Supports transmission rates of 10/100/1000 Mbps, accommodating different network speed requirements.
• Can use straight-through or crossover cables to connect different types of devices.
• Adaptive capabilities allow the interface to automatically adjust speed and duplex mode based on the connection’s other end.

02 Configuration

• Use network configuration tools or CLI commands to configure the interface speed (10/100/1000 Mbps) and duplex mode (half-duplex/full-duplex).
• Set VLAN tags to ensure data frames are correctly forwarded to the designated virtual LAN.
• Configure port security to limit the number of MAC addresses connected to the port, enhancing security.

03 Usage

• Ensure the correct cable type (such as CAT5e or CAT6) is used to match the required transmission speed. Regularly check cable connections for tightness to avoid loose connections causing network interruptions.

3 SC Fiber Interface

The SC fiber interface is a widely used fiber connector, particularly suitable for applications requiring long-distance, high-speed data transmission. SC interfaces are popular due to their durability and ease of plugging and unplugging, often used within data centers or for communication between buildings.

SC fiber interfaces are mainly used in LAN switch environments, providing this interface on some high-performance gigabit switches and routers. They look similar to RJ-45 interfaces but are flatter, with the obvious difference being the internal contacts. If there are eight thin copper contacts, it’s an RJ-45 interface; if it’s a single copper rod, it’s an SC fiber interface.

01 Technical Specifications

• Supports single-mode or multi-mode fiber, with the former suitable for long-distance transmission and the latter for short-distance high-bandwidth needs.
• Data transmission rates can reach gigabit or higher.
• Provides high-bandwidth, low-latency connections through fiber cables, ideal for applications like video streaming and large data transfers.

02 Configuration

• Choose the appropriate SFP/SFP+ module for insertion into the corresponding port.
• Set the interface’s working mode (single-mode or multi-mode) based on actual needs.
• Configure the fiber interface’s transmission rate (such as 1 Gbps or 10 Gbps).

03 Usage

• Use dedicated cleaning tools to regularly clean fiber connectors to prevent dust from affecting data transmission quality. Ensure the physical path of the fiber line is secure, avoiding excessive bending or pressure.

4 AUI Interface

The AUI (Attachment Unit Interface) interface is an early standard used to connect thick coaxial cables (Coaxial Cable).

Although it’s generally not used today, it still exists in some older network architectures. The AUI interface is typically used to connect network devices to thick coaxial cables to provide reliable connections over larger network ranges.

01 Technical Specifications

• Supports a transmission rate of 10 Mbps.
• Uses 50-ohm thick coaxial cables with a maximum transmission distance of 500 meters.
• Can connect AUI interfaces to other types of interfaces using AUI-to-RJ-45 or AUI-to-BNC adapters.

02 Configuration

• Since AUI interfaces are mainly used in older network devices, configuration is relatively simple, mainly ensuring correct connections.
• If using AUI-to-RJ-45 or BNC adapters, confirm adapter compatibility.

03 Usage

• Maintain the connection of thick coaxial cables to ensure stable signal transmission. For older systems still using AUI interfaces, consider gradually upgrading to more modern network technologies.

5 FDDI Interface

The FDDI (Fiber Distributed Data Interface) interface is a technology used to implement high-speed ring network topologies.

FDDI was initially designed to support high-speed data transmission, particularly suitable for large network environments requiring high bandwidth and fault tolerance. It uses fiber as the transmission medium, providing higher reliability and security.

01 Technical Specifications

• Supports a dual-ring structure, with one ring as a backup that automatically switches when the main ring fails.
• Transmission rates can reach 100 Mbps, and higher bandwidth can be achieved through multi-layer stacking.
• Uses SC or ST type fiber connectors.

02 Configuration

• Set up the FDDI interface’s dual-ring structure to ensure the main and backup rings operate normally.
• Configure the interface’s transmission rate and fault recovery mechanisms.

03 Usage

• Monitor network performance to ensure the ring works properly, promptly detecting and handling faults. For networks using FDDI, consider whether there is a need for upgrading.