Administration: Stack Management
Stack Topology
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4 120
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Stack in Ring Topology (550 family)
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 might 
cause 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 following are examples of events that trigger this process:
• 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  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 of all units in the stack.