3Com 4210 PWR - Page 322

320 CHAPTER 30: CLUSTER
Figure 100 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.
n
After you create a cluster on a Switch 4210, 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 Switch Clusteringv2 consists of the following three protocols:
■ Neighbor discovery protocol (NDP)
■ Neighbor topology discovery protocol (NTDP)
■ Cluster
A cluster configures and manages the devices in it through the above three
protocols.
Cluster management involves topology information collection and the
establishment/maintenance of a cluster. Topology information collection and
cluster establishment/maintenance are independent from each other. The former,
as described below, starts before a cluster is established.
Candidate device
Member device
Management device
D
e
s
ig
n
a
t
e
d
a
s
a
m
a
n
a
g
e
m
e
n
t
d
e
vic
e
R
e
m
o
v
e
f
r
o
m
a
c
l
u
s
t
e
r
A
d
d
e
d
t
o
a
c
l
u
s
t
e
r
R
e
mo
v
e
f
r
o
m
a
c
l
u
s
t
e
r