Cisco 500 series Administration Manual page 69

Stack Management
Stack Topology
Cisco 500 Series Stackable Managed Switch Administration Guide
Stack in Ring Topology
A ring topology is more reliable than a chain topology. The failure of one link in a
ring does not affect the function of the stack, whereas the failure of one link in a
chain connection causes the stack to be split.
Topology Discovery
A stack is established by a process called topology discovery. This process is
triggered by a change in the up/down status of a stack port.
The process is triggered in the following cases:
• Changing the stack topology from a ring to a chain
• Merging two stacks into a single stack
• Splitting the stack
• Inserting other slave units to the stack, for instance because the units were
previously disconnected from the stack due to a failure. This can happen in
a chain topology if a unit in the middle of the stack fails.
During topology discovery, each unit in a stack exchanges packets, which contain
topology information. After the topology discovery process is completed, each
unit contains the stack mapping information table of all units in the stack.
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