D-Link DES-3228PA Installation Guide - Page 69

Managing Stacking Understanding the Stack Topology Understanding the Stack Topology The DES-3228PA provides the following of stacking topologies: • Ring Topology • Chain Topology Ring Topology A stacked Ring topology is where all devices in the stack are connected to each other forming a circle. Each stacked device accepts data and sends it to the device to which it is physically connected. The packet continues through the stack until it reaches the destination port. The system automatically discovers the optimal path on which to send traffic. Figure 29: Stacking Ring Topology Most difficulties incurred in Ring topologies occur when a device in the ring becomes non-functional, or a link is severed. In a stack, the system automatically switches to a Stacking Failover topology without any system downtime. An SNMP message is automatically generated, but no stack management action is required. However, the stacking link or stacking member must be repaired to ensure the stacking integrity. After the stacking issues are resolved, the device can be reconnected to the stack without interruption, and the Ring topology is restored. Chain Topology In a chain topology, there are two units that have only one neighbor. Every unit has an uplink neighbor and a downlink neighbor. The chain topology is less robust than the ring topology. A failure in the chain results in a topology change to the stack. The location of the failure determines the severity of this topology change. The chain topology also acts as a fail-safe for the ring topology. When the ring topology fails, the stack automatically reverts to the chain topology. Stacking Failover Topology If a failure occurs in the stacking topology, the stack reverts to Stacking Failover Topology. In the Stacking Failover topology, devices operate in a chain formation. The Stacking Master determines where the packets are sent. Each unit is connected to two neighboring devices, except for the top and bottom units. Page 66