# network switch

> computer networking device that uses packet switching to forward data; one main component of the Internet infrastructure and of each computer network

**Wikidata**: [Q4503](https://www.wikidata.org/wiki/Q4503)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Network_switch)  
**Source**: https://4ort.xyz/entity/network-switch

## Summary
A **network switch** is a computer networking device that uses **packet switching** to forward data efficiently within a network. It is a core component of both the **Internet infrastructure** and local computer networks, enabling devices to communicate by directing data packets to their correct destinations.

## Key Facts
- **Function**: Uses **packet switching** to forward data between devices in a network.
- **Classification**: A type of **networking hardware**, alongside routers and hubs.
- **OSI Model Layers**: Primarily operates at the **data link layer (Layer 2)**, though some (like **Layer 3 switches**) also function at the **network layer (Layer 3)**.
- **Subtypes**:
  - **Layer 2 switch**: Operates at the data link layer.
  - **Layer 3 switch**: Supports routing functions (network layer).
  - **Multilayer switch**: Provides functionality beyond the data link layer.
  - **Modular switch**: Allows field-replaceable components.
- **Related Devices**:
  - **Network bridge**: Combines smaller networks into a larger one.
  - **Ethernet hub**: Less efficient than a switch (broadcasts data to all ports).
- **Common Brands/Models**:
  - **Cisco Catalyst** (e.g., Catalyst 6500, Cisco 9200L-48T-4X).
  - **Cisco CBS series** (e.g., CBS250-8T-E-2G, CBS250-16T-2G).
- **Aliases**: Also called a **switching hub, bridging hub, MAC bridge, or Ethernet switch**.
- **Industry Use**: Critical in **LAN switching**, **GSM network switching subsystems**, and **Frame Relay networks**.

## FAQs
### Q: What is the difference between a network switch and an Ethernet hub?
A: A **network switch** intelligently forwards data only to the intended device, improving efficiency and security. An **Ethernet hub** broadcasts data to all connected devices, leading to congestion and slower performance.

### Q: What layers of the OSI model do network switches operate on?
A: Most switches operate at the **data link layer (Layer 2)**, but **Layer 3 switches** can also perform routing functions at the **network layer (Layer 3)**.

### Q: What are some common types of network switches?
A: Common types include **Layer 2 switches**, **Layer 3 switches**, **multilayer switches**, **modular switches** (with replaceable parts), and **Frame Relay switches** for specific protocols.

### Q: How does a network switch improve network performance?
A: By using **packet switching**, it reduces collisions and unnecessary traffic, directing data only to the correct port rather than broadcasting it to all devices.

### Q: What are some well-known network switch brands?
A: **Cisco** is a major manufacturer, with models like the **Catalyst 6500**, **Cisco 9200L**, and **CBS250 series** widely used in enterprise and data center environments.

## Why It Matters
Network switches are fundamental to modern **computer networking**, enabling efficient, secure, and high-speed data transmission. Unlike older hubs, switches **reduce network congestion** by intelligently routing data only to the intended recipient, which is critical for **scalability** in both small offices and large data centers. They form the backbone of **local area networks (LANs)** and are essential in **Internet infrastructure**, ensuring that data packets travel quickly and reliably. Without switches, networks would be slower, less secure, and prone to bottlenecks, making them indispensable in today’s digital world—from home setups to global telecommunications.

## Notable For
- **Efficiency**: Uses **packet switching** to minimize unnecessary data transmission, unlike hubs.
- **Scalability**: Supports **VLANs (Virtual LANs)** and **trunk ports** for complex network segmentation.
- **Versatility**: Available in multiple forms, including **Layer 2**, **Layer 3**, and **modular switches** for different use cases.
- **Enterprise Adoption**: Brands like **Cisco Catalyst** dominate data centers and corporate networks.
- **GSM & Telecommunications**: Integral to **network switching subsystems** in mobile communications (e.g., GSM).

## Body
### **Core Functionality**
- A **network switch** connects devices (computers, servers, printers) within a **local area network (LAN)**.
- Operates using **MAC addresses** to forward **Ethernet frames** to the correct destination port.
- Unlike a **hub**, it does not broadcast data to all ports, reducing **collisions** and improving **bandwidth efficiency**.

### **Types of Network Switches**
- **Layer 2 Switch**:
  - Operates at the **data link layer (OSI Layer 2)**.
  - Uses **MAC addresses** for forwarding decisions.
  - Common in basic LAN setups.
- **Layer 3 Switch**:
  - Functions at both **Layer 2** and **Layer 3 (network layer)**.
  - Can perform **static routing** and **inter-VLAN routing**.
  - Used in larger networks requiring routing capabilities.
- **Multilayer Switch**:
  - Provides functionality **above the data link layer**, sometimes up to **Layer 4 (transport layer)**.
  - Supports advanced features like **QoS (Quality of Service)**.
- **Modular Switch**:
  - Allows **field-replaceable units** (e.g., line cards, power supplies).
  - Example: **Cisco Catalyst 6500** (used in enterprise environments).
- **Frame Relay Switch**:
  - Specialized for **Frame Relay** protocol, used in wide-area networks (WANs).

### **Key Components**
- **System Board**: Core processing unit.
- **Electrical Receptacle**: Power input.
- **Housing**: Physical enclosure.
- **Ports**: Typically **Ethernet ports** (RJ-45) or **fiber optic (SFP)** for high-speed connections.
- **Trunk Ports**: Used to carry **multiple VLANs** between switches.

### **Related Technologies**
- **Network Bridge**: Combines two networks into one; switches can perform bridging functions.
- **Ethernet Hub**: Obsolete predecessor; broadcasts data to all ports.
- **Small Form-Factor Pluggable (SFP) Transceiver**: Used in switches for **fiber optic or copper networking**.

### **Industry & Military Use**
- **MilDef Group** (Sweden) supplies **ruggedized network switches** for military applications.
- **GSM Networks**: Switches are part of the **network switching subsystem** in mobile telecommunications.

### **Common Models & Manufacturers**
- **Cisco**:
  - **Catalyst 6500**: Modular switch for large enterprises.
  - **9200L-48T-4X**: Fixed-configuration switch with 48 ports.
  - **CBS250 Series**: Small business switches (e.g., CBS250-8T-E-2G).
- **Netgear**: Consumer-grade switches (e.g., **5-port Gigabit Switch**).

## Schema Markup
```json
{
  "@context": "https://schema.org",
  "@type": "Thing",
  "name": "Network switch",
  "description": "A computer networking device that uses packet switching to forward data; a main component of the Internet infrastructure and computer networks.",
  "url": "https://en.wikipedia.org/wiki/Network_switch",
  "sameAs": [
    "https://www.wikidata.org/wiki/Q184617",
    "https://en.wikipedia.org/wiki/Network_switch"
  ],
  "additionalType": "https://www.wikidata.org/wiki/Q184592" // Networking hardware
}

## References

1. Freebase Data Dumps. 2013
2. Quora
3. KBpedia
4. [OpenAlex](https://docs.openalex.org/download-snapshot/snapshot-data-format)