1-3Figure 1-2 State machine of cluster rolez A candidate device becomes a management device when you create a cluster on it. Note that acluster 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 candidatedevices, which can then be added to the cluster through configurations.z A candidate device becomes a member device after being added to a cluster.z A member device becomes a candidate device after it is removed from the cluster.z A management device becomes a candidate device only after the cluster is removed.After you create a cluster on a Switch 4210, the switch collects the network topology informationperiodically and adds the candidate switches it finds to the cluster. The interval for a managementdevice to collect network topology information is determined by the NTDP timer. If you do not want thecandidate switches to be added to a cluster automatically, you can set the topology collection interval to0 by using the ntdp timer command. In this case, the switch does not collect network topologyinformation periodically.How a Cluster WorksHGMPv2 consists of the following three protocols:z Neighbor discovery protocol (NDP)z Neighbor topology discovery protocol (NTDP)z ClusterA cluster configures and manages the devices in it through the above three protocols.Cluster management involves topology information collection and the establishment/maintenance of acluster. Topology information collection and cluster establishment/maintenance are independent fromeach other. The former, as described below, starts before a cluster is established.z All devices use NDP to collect the information about their neighbors, including software version,host name, MAC address, and port name.z The management device uses NTDP to collect the information about the devices within specifichops and the topology information about the devices. It also determines the candidate devicesaccording to the information collected.
