Duplex Mode Store Forward | Allied Telesis AT-GS950/48 instruction

Allied Telesis AT-GS950/48 manual Duplex Mode Store Forward

Chapter 1: Overview

Duplex Mode

Store and

Forward

Back Pressure and Flow Control

Duplex mode refers to how an end node receives and transmits data. If an end node can receive or transmit data, but not both simultaneously, it is operating in what is referred to as half-duplex mode. If an end node can both receive and transmit data simultaneously, the end node is operating in full-duplex mode. Naturally, an end node capable of operating in full- duplex can handle data much faster than an end node that can only operate in half-duplex mode.

The twisted pair ports on the AT-GS950/48 Gigabit Ethernet Smart switch can operate in either half-or full-duplex mode. They are IEEE 802.3u- compliant and you can set them to Auto-Negotiation.

For Auto-Negotiation to operate properly on a switch, the end nodes connected to the switch should also use Auto-Negotiation. If an end node does not have this feature and has a fixed duplex mode of full-duplex, the result is a duplex mode mismatch between the end node and a switch port. A port on the Fast Ethernet switch connected to an end node with a fixed duplex mode of full-duplex operates at only half-duplex. This results in the end node using full-duplex and the switch port using half-duplex. This can produce network performance problems. If you encounter this situation, you must configure the port on the end node to use Auto- Negotiation or, if it lacks that feature, to half-duplex.

The switch uses store and forward as the method for receiving and transmitting frames. When a Ethernet frame is received on a switch port, the switch does not retransmit the frame out the destination port until it has received the entire frame and stored the frame in a port buffer. It then examines the frame to determine if it is a valid frame. Invalid frames, such as fragments or runts, are discarded by the switch. This ensures that only valid frames are transmitted out the switch ports and that damaged frames are not propagated on your network.

To maintain the orderly movement of data between the end nodes, an Ethernet switch may periodically need to signal an end node to stop sending data. This can occur under several circumstances. For example, if two end nodes are operating at different speeds, the switch, while transferring data between the end nodes, might need to instruct the faster end node to stop transmitting data to allow the slower end node to catch up. An example of this would be when a server operating at 100 Mbps is sending data to a workstation operating at only 10 Mbps.

How a switch signals an end node to stop transmitting data differs depending on the speed and duplex mode of the end node and switch port. A twisted pair port operating at 100 Mbps and half-duplex mode stops an end node from transmitting data by forcing a collision. A collision on an Ethernet network occurs when two end nodes attempt to transmit data using the same data link at the same time. A collision causes end nodes to stop sending data. When the switch needs to stop a 100 Mbps, half-duplex end node from transmitting data, it forces a collision on the

AT-GS950/48 specifications

The Allied Telesis AT-GS950/48 is a robust and high-performance managed Gigabit Ethernet switch designed to meet the demands of modern networks. Ideal for small to medium-sized businesses and enterprise environments, this switch delivers flexible, reliable, and high-speed connectivity while ensuring ease of management.

One of the standout features of the AT-GS950/48 is its offering of 48 Gigabit Ethernet ports, allowing for extensive connectivity options. These ports support auto-negotiation and can automatically detect the highest speed supported by connected devices, ensuring optimal performance. The inclusion of 4 additional SFP (Small Form-factor Pluggable) ports enhances the flexibility of the network design. These SFP ports enable fiber connections, making it easy to extend the network over longer distances or connect to different types of media.

The switch supports advanced Layer 2 features, including VLAN (Virtual Local Area Network) support, which allows network administrators to segment network traffic for enhanced security and performance. The AT-GS950/48 also incorporates features such as Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP) that prevent loops in the network and promote redundancy, ensuring uninterrupted service even in complex networking environments.

Additionally, the AT-GS950/48 supports Power over Ethernet (PoE), which enables the switch to deliver power to connected devices such as IP cameras, VoIP phones, and wireless access points through the Ethernet cable, reducing the need for additional power sources. This PoE capability allows for easier installation and flexibility in deploying network devices.

Allied Telesis places a strong emphasis on security, and the AT-GS950/48 reflects this commitment with features like IEEE 802.1X authentication, which secures network access by allowing only authorized users to connect. The switch also provides access control lists (ACLs) to enhance security by filtering traffic based on various criteria.

With built-in web-based management, the AT-GS950/48 enables administrators to easily configure, manage, and monitor the switch through an intuitive interface. It also supports SNMP (Simple Network Management Protocol) for integration into existing network management systems.

In summary, the Allied Telesis AT-GS950/48 combines high port density, advanced networking features, power delivery capabilities, and robust security measures, making it an excellent choice for organizations looking to build a resilient and efficient network infrastructure.