Chapter 1: Overview

Ethernet Switching Basics

MAC Address Table

Duplex Mode

An Ethernet switch interconnects network devices, such as workstations, printers, routers, and other Ethernet switches, so that they can communicate with each other by sending and receiving Ethernet frames.

Every hardware device on your network has a unique MAC address. This address is assigned to the device by the device’s manufacturer. For example, when you install a Network Interface Card (NIC) in a computer so that you can connect it to the network, the NIC already has a MAC address assigned to it by its manufacturer.

The MAC address table in the AT-GS900/8POE Gigabit Ethernet switch can store up to 8K MAC addresses. The switch uses the table to store the MAC addresses of the network end nodes connected to the ports, along with the port number on which each address was learned.

A switch learns the MAC addresses of the end nodes by examining the source address of each packet received on a port. It adds the address and port on which the packet was received to the MAC table if the address had not already been entered in the table. The result is a table that contains all the MAC addresses of the devices that are connected to the switch’s ports, and the port number where each address was learned.

When the switch receives a packet, it also examines the destination address and, by referring to its MAC address table, determines the port on which the destination end node is connected. It then forwards the packet to the appropriate port and on to the end node. This increases network bandwidth by limiting each frame to the appropriate port when the intended end node is located, freeing the other switch ports for receiving and transmitting data.

If the switch receives a packet with a destination address that is not in the MAC address table, it floods the packet to all the ports on the switch. If the ports have been grouped into virtual LANs, the switch floods the packet only to those ports which belong to the same VLAN as the port on which the packet was received. This prevents packets from being forwarded into inappropriate LAN segments, decreasing network security. When the destination end node responds, the switch adds its MAC address and port number to the table.

If the switch receives a packet with a destination address that is on the same port on which the packet was received, it discards the packet without forwarding it on to any port. Since both the source end node and the destination end node for the packet are located on the same port on the switch, there is no reason for the switch to forward the packet.

Duplex mode refers to how an end node receives and transmits data. If an

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Allied Telesis GS900/8POE manual Ethernet Switching Basics, MAC Address Table Duplex Mode
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GS900/8POE specifications

The Allied Telesis GS900/8POE is a versatile and robust switch designed for small to medium-sized enterprises that require reliable network performance combined with power over Ethernet (PoE) capabilities. As part of the GS900 series, this switch offers a range of features, technologies, and characteristics that cater to modern networking demands.

One of the main features of the GS900/8POE is its eight 10/100/1000BASE-T Ethernet ports, which enable seamless connectivity for a variety of devices. Each port is equipped with Power over Ethernet capabilities, allowing the switch to deliver up to 15.4 watts of power per port. This is particularly beneficial for powering devices such as IP cameras, wireless access points, and VoIP phones without the need for additional power sources, minimizing installation costs and clutter.

The GS900/8POE also supports advanced Layer 2 switching capabilities, including VLAN (Virtual Local Area Network) support, which enhances network segmentation and security. By allowing administrators to create isolated networks within a larger network, VLANs reduce broadcast traffic and improve overall performance. Additionally, the switch supports Quality of Service (QoS) features, ensuring that time-sensitive applications, such as video streaming and voice communications, receive priority over less critical data.

Another noteworthy characteristic of the GS900/8POE is its fanless design, which makes it ideal for environments where noise levels need to be kept to a minimum. This design approach not only enhances the aesthetics of the deployment area but also increases reliability by reducing moving parts that could potentially fail.

Security is also a significant focus in the GS900/8POE's design, with features like MAC address filtering and DHCP snooping to protect against unauthorized access and potential network attacks. These safeguards ensure that network administrators can maintain control over connected devices and mitigate risks associated with security breaches.

In summary, the Allied Telesis GS900/8POE switch is a feature-rich solution that meets the demands of modern networks. Its PoE capabilities, advanced Layer 2 features, fanless operation, and robust security measures make it an excellent choice for businesses looking to expand their network infrastructure while keeping operational efficiency and reliability at the forefront. Whether used in a small office setting or for branch locations, the GS900/8POE provides a compelling balance of performance and functionality.
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