How A Cluster Works - 3Com 5500-EI PWR Install Manual

Role
Member device
Candidate
device
Figure 1-2 illustrates the state machine of cluster role.
Figure 1-2 State machine of cluster role
A candidate device becomes a management device when you create a cluster on it. Note that a
cluster must have one (and only one) management device. On becoming a management device,
the device collects network topology information and tries to discover and determine candidate
devices, which can then be added to the cluster through configurations.
A candidate device becomes a member device after being added to a cluster.
A member device becomes a candidate device after it is removed from the cluster.
A management device becomes a candidate device only after the cluster is removed.
After you create a cluster on a Switch 5500-EI switch, the switch collects the network topology
information periodically and adds the candidate switches it finds to the cluster. The interval for a
management device to collect network topology information is determined by the NTDP timer. If you do
not want the candidate switches to be added to a cluster automatically, you can set the topology
collection interval to 0 by using the ntdp timer command. In this case, the switch does not collect
network topology information periodically.

How a Cluster Works

HGMPv2 consists of the following three protocols:
Configuration
Normally, a
member device is
not assigned an
external IP
address
Normally, a
candidate device
Candidate device refers to the devices that do not belong to
is not assigned an
any clusters but are cluster-capable.
external IP
address
Function
Members of a cluster
Discovers the information about its neighbors, processes
the commands forwarded by the management device,
and reports log. The member devices of a luster are
under the management of the management device.
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