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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 down-
time. 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 topol-
ogy 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.
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Managing Stacking
Understanding the Stack Topology
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