1-7Figure 1-3 State machine of the connection between the management device and a member deviceReceives thehandshake ormanagementpacketsFails to receivehandshakepackets in threeconsecutiveintervalsState holdtime exceedsthe specified valueDisconnect stateis recoveredActiveConnect Disconnectz After a cluster is created and a candidate device is added to the cluster as a member device, boththe management device and the member device store the state information of the member deviceand mark the member device as Active.z The management device and the member devices exchange handshake packets periodically. Notethat the handshake packets exchanged keep the states of the member devices to be Active andare not responded.z If the management device does not receive a handshake packet from a member device after aperiod three times of the interval to send handshake packets, it changes the state of the memberdevice from Active to Connect. Likewise, if a member device fails to receive a handshake packetfrom 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.z If the management device receives a handshake packet or management packet from a memberdevice that is in Connect state within the information holdtime, it changes the state of the memberdevice to Active; otherwise, it changes the state of the member device (in Connect state) toDisconnect, in which case the management device considers the member device disconnected.Likewise, if this member device, which is in Connect state, receives a handshake packet ormanagement packet from the management device within the information holdtime, it changes itsstate to Active; otherwise, it changes its state to Disconnect.z If the connection between the management device and a member device in Disconnect state isrecovered, the member device will be added to the cluster again. After that, the state of themember device will turn to Active both locally and on the management device.Besides, handshake packets are also used by member devices to inform the management device oftopology changes.Additionally, on the management device, you can configure the FTP server, TFTP server, logging hostand SNMP host to be shared by the whole cluster. When a member device in the cluster communicateswith an external server, the member device first transmits data to the management device, which thenforwards the data to the external server. The management device is the default shared FTP/TFTPserver for the cluster; it serves as the shared FTP/TFTP server when no shared FTP/TFTP server isconfigured for the cluster.Management VLANManagement VLAN limits the range of cluster management. Through management VLAN configuration,the following functions can be implemented:
