3Com Switch 4800G 24-Port Configuration Manual page 909

The adjacent device performs the same operation until the NTDP topology
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collection request is sent to all the devices within specified hops.
When the NTDP topology collection request is advertised in the network, large
numbers of network devices receive the NTDP topology collection request and
send NTDP topology collection response at the same time, which may cause
congestion and the management device busyness. To avoid such case, the
following methods can be used to control the speed of the NTDP topology
collection request advertisement:
Upon receiving an NTDP topology collection request the device does not
■
forward it, instead, it waits for a period of time and then forwards the NTDP
topology collection request on the first NTDP-enabled port.
On the same device, except the first port, each NTDP-enabled port waits for a
■
period of time and then forwards the NTDP topology collection request after
the port before it sends 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 269.
Figure 269 Management/member device state change
Receives the
handshake or
management
packets
Connect
After a cluster is created and 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 it as Active.
After a cluster is created, its member devices begin to send handshake packets
■
first. The management device also sends handshake packets to the member
Active
Fails to receive
handshake
packets in three
consecutive
intervals
State holdtime exceeds
the specified value
Cluster Management Overview
Disconnect state
is recovered
Disconnect
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