3Com 4210 PWR Configuration Manual page 325

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On the management device, you need to enable the cluster function and
configure cluster parameters. On the member/candidate devices, however, you
only need to enable the cluster function so that they can be managed by the
management device.
Cluster maintenance
1 Adding a candidate device to a cluster
To create a cluster, you need to determine the device to operate as the
management device first. The management device discovers and determines
candidate devices through NDP and NTDP, and adds them to the cluster. You can
also add candidate devices to a cluster manually.
After a candidate device is added to a cluster, the management device assigns a
member number and a private IP address (used for cluster management) to it.
2 Communications within a cluster
In a cluster, the management device maintains the connections to the member
devices through handshake packets. Figure 101 illustrates the state machine of
the connection between the management device and a member device.
Figure 101 State machine of the connection between the management device and a
member device
Receives the
handshake or
management
packets
Connect
After a cluster is created and a candidate device is added to the cluster as a
■
member device, both the management device and the member device store
the state information of the member device and mark the member device as
Active.
The management device and the member devices exchange handshake
■
packets periodically. Note that the handshake packets exchanged keep the
states of the member devices to be Active and are not responded.
If the management device does not receive a handshake packet from a
■
member device after a period three times of the interval to send handshake
packets, it changes the state of the member device from Active to Connect.
Likewise, if a member device fails to receive a handshake packet from the
management device after a period three times of the interval to send
handshake packets, the state of the member device will also be changed from
Active to Connect.
If the management device receives a handshake packet or management packet
■
from a member device that is in Connect state within the information
holdtime, it changes the state of the member device to Active; otherwise, it
changes the state of the member device (in Connect state) to Disconnect, in
Active
Fails to receive
handshake
packets in three
consecutive
intervals
State holdtime exceeds
the specified value
Cluster Overview
Disconnect state
is recovered
Disconnect
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