TP-Link JetStream T2700G-28TQ User Manual page 50

Stack Introduction
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1. Stack Elements
1) Stack Role
Each device in the stack system is called stack member. Each stack member processes
services packets and plays a role which is either master or slave in the stack system. The
differences between master and slave are described as below:
Master: Indicates the device is responsible for managing the entire stack system.
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Slave: Indicates the device provides backup for the master. If the master fails, the stack
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will elect a new master from the remaining slaves to succeed the previous master.
2) Stack Event
Stack event indicates the global events which might happen during stack operation process,
with two options:
Merge: It occurs when two independent stacks merge into one stack because of stack link
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establishment, as shown in the following figure:
When stack merge occurs, the previous masters compete to be the new master. The stack
members of the defeated stack will join the winner stack as a slave to form a new stack.
Master will assign Unit Number to the newly joined members and compare their
configuration files. The members with different configurations files with the master will
download the configuration files of the master and re-configure.
Split: It occurs when stack splits into two or more stacks because of stack link failures, as
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shown in the following figure:
After stack partition occurs, each newly established stack elects their own new master and
use the MAC address of the master as its stack MAC address. However, stack partition
probably brings about routing and forwarding problems on the network since the
partitioned stacks keep operating with the previous IP address by default, which results in
same IP address being reused in the same LAN.
2. Operation Procedure
Stack management involves these four stages: Connecting the stack members, Topology
collection, Master election, and Stack management and maintenance.
Figure 5-4 Stack Merge
Figure 5-5 Stack Split
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