3Com 4210G Series Configuration Manual page 1077

then forwards the NTDP topology collection request after its prior port forwards the NTDP
topology collection request.
Cluster management maintenance
1) Adding a candidate device to a cluster
You should specify the management device before creating a cluster. The management device
discovers and defines a candidate device through NDP and NTDP protocols. The candidate device
can be automatically or manually added to the cluster.
After the candidate device is added to the cluster, it can obtain the member number assigned by the
management device and the private IP address used for cluster management.
2) Communication within a cluster
In a cluster the management device communicates with its member devices by sending handshake
packets to maintain connection between them. The management/member device state change is
shown in Figure 26-3.
Figure 26-3 Management/member device state change
Connect
State holdtime exceeds
the specified value
After a cluster is created, a candidate device is added to the cluster and becomes a member
device, the management device saves the state information of its member device and identifies it
as Active. And the member device also saves its state information and identifies itself as Active.
After a cluster is created, its management device and member devices begin to send handshake
packets. Upon receiving the handshake packets from the other side, the management device or a
member device simply remains its state as Active, without sending a response.
If the management device does not receive the handshake packets from a member device in an
interval three times of the interval to send handshake packets, it changes the status of the
member device from Active to Connect. Likewise, if a member device fails to receive the
handshake packets from the management device in an interval three times of the interval to send
handshake packets, the status of itself will also be changed from Active to Connect.
If this management device, in information holdtime, receives the handshake or management
packets from its member device which is in Connect state, it changes the state of its member
device to Active; otherwise, it changes the state of its member device to Disconnect, in which case
the management device considers its member device disconnected. If this member device, which
is in Connect state, receives handshake or management packets from the management device in
information holdtime, it changes its state to Active; otherwise, it changes its state to Disconnect.
If the communication between the management device and a member device is recovered, the
Active
Disconnect
26-4