Switches

Definition

Switches are networking devices that connect multiple devices on a computer network, allowing them to communicate with each other by forwarding data packets to their intended destinations. They operate at the data link layer of the OSI model, making decisions about where to send network traffic based on the destination addresses in the incoming frames.

5 Must Know Facts For Your Next Test

1. Switches use the destination MAC address in the Ethernet frame to determine where to forward the data, unlike routers which use the destination IP address.
2. Switches maintain a MAC address table that maps MAC addresses to the specific ports on the switch where the devices are connected.
3. Switches operate in a full-duplex mode, allowing for simultaneous bidirectional communication between connected devices, improving network performance.
4. Switches can segment a network into multiple collision domains, reducing the impact of collisions and improving overall network efficiency.
5. Switches support features like VLANs (Virtual Local Area Networks) and port mirroring, which enable advanced network management and troubleshooting capabilities.

Review Questions

• Explain the role of switches in a computer network and how they differ from routers.
  • Switches play a crucial role in connecting devices on a computer network by forwarding data packets to their intended destinations. They operate at the data link layer, making forwarding decisions based on the destination MAC addresses in the incoming Ethernet frames. This is in contrast to routers, which operate at the network layer and use destination IP addresses to route data between different networks. Switches help to segment a network into smaller collision domains, improve network performance, and enable advanced features like VLANs for network management.
• Describe how switches maintain and use their MAC address table to make forwarding decisions.
  • Switches maintain a MAC address table that maps the MAC addresses of connected devices to the specific ports on the switch where they are connected. When a frame arrives at a switch port, the switch examines the destination MAC address and looks it up in the MAC address table. If the destination MAC address is found, the switch forwards the frame out of the appropriate port. If the destination MAC address is not in the table, the switch will flood the frame out of all ports, except the one it was received on, to ensure the frame reaches its intended destination. Over time, the switch learns the MAC addresses and their associated ports, building an accurate MAC address table to make more efficient forwarding decisions.
• Analyze the benefits of using switches in a computer network and how they contribute to improved network performance and efficiency.
  • Switches offer several key benefits that contribute to improved network performance and efficiency. By operating at the data link layer and making forwarding decisions based on MAC addresses, switches can segment a network into smaller collision domains, reducing the impact of collisions and improving overall network throughput. Switches also support full-duplex communication, enabling simultaneous bidirectional data transfer between connected devices, further enhancing network performance. Additionally, switches can implement features like VLANs, which allow for logical segmentation of the network, and port mirroring, which enables advanced network monitoring and troubleshooting. These capabilities make switches an essential component in modern computer networks, facilitating efficient data transfer, improved network utilization, and enhanced network management and visibility.

Related terms

Router: A router is a networking device that connects multiple networks and forwards data packets between them, operating at the network layer of the OSI model.

Ethernet:

Ethernet is a widely used technology for local area networks (LANs) that defines the physical and data link layer protocols for interconnecting devices.

MAC Address: A MAC (Media Access Control) address is a unique identifier assigned to each network interface card (NIC) on a device, which is used by switches to make forwarding decisions.