Settings | Guidelines |
Configured HA Mode | • Standalone • Active-passive |
Group Name | Name to identify the HA cluster if you have more than one. This setting is optional, and does not affect HA function. The maximum length is 35 characters. |
Device Priority | Number indicating priority of the member node when electing the cluster primary node. This setting is optional. The smaller the number, the higher the priority. The valid range is 0 to 9. The default is 5. Note: By default, unless you enable Override, uptime is more important than this setting. Tip: On a standby device, this setting can be reconfigured using the CLI command execute ha manage <serial-number_str> <priority_int>. |
Override | Enable to make Device Priority a more important factor than uptime when selecting the primary node. |
Group ID | Number that identifies the HA cluster. Nodes with the same group ID join the cluster. If you have more than one HA cluster on the same network, each cluster must have a different group ID. The group ID is used in the virtual MAC address that is sent in broadcast ARP messages. The valid range is 0 to 63. The default is 0. |
Detection Interval | Number of 100-millisecond intervals at which heartbeat packets are sent. This is also the interval at which a node expects to receive heartbeat packets. This part of the configuration is pushed from the primary node to member nodes. The valid range is 1 to 20 (that is, between 100 and 2,000 milliseconds). The default is 2. Note: Although this setting is pushed from the primary node to member nodes, you should initially configure all nodes with the same Detection Interval to prevent inadvertent failover from occurring before the initial synchronization. |
Heartbeat Lost Threshold | Number of times a node retries the heartbeat and waits to receive HA heartbeat packets from the other nodes before concluding the other node is down. This part of the configuration is pushed from the primary node to member nodes. Normally, you do not need to change this setting. Exceptions include: • Increase the failure detection threshold if a failure is detected when none has actually occurred. For example, in an active-passive deployment, if the primary node is very busy during peak traffic times, it might not respond to heartbeat packets in time, and a standby node might assume that the primary node has failed. • Decrease the failure detection threshold or detection interval if administrators and HTTP clients have to wait too long before being able to connect through the primary node, resulting in noticeable down time. The valid range is from 1 to 60. The default is 6. Note: Although this setting is pushed from the primary node to member nodes, you should initially configure all nodes with the same Heartbeat Lost Threshold to prevent inadvertent failover from occurring before the initial synchronization. |
ARP Packet Numbers | Number of times that the cluster member broadcasts extra ARP packets when it takes on the primary role. (Even though a new NIC has not actually been connected to the network, the member does this to notify the network that a new physical port has become associated with the IP address and virtual MAC of the HA cluster.) This is sometimes called “using gratuitous ARP packets to train the network,” and can occur when the primary node is starting up, or during a failover. Also configure ARP Packet Interval. Normally, you do not need to change this setting. Exceptions include: • Increase the number of times the primary node sends gratuitous ARP packets if an active-passive cluster takes a long time to fail over or to train the network. Sending more gratuitous ARP packets may help the failover to happen faster. • Decrease the number of times the primary node sends gratuitous ARP packets if the cluster has a large number of VLAN interfaces and virtual domains. Because gratuitous ARP packets are broadcast, sending them might generate a large amount of network traffic. As long as the active-passive cluster fails over successfully, you can reduce the number of times gratuitous ARP packets are sent to reduce the amount of traffic produced by a failover. The valid range is 1 to 16. The default is 5. |
ARP Packet Interval | Number of seconds to wait between each broadcast of ARP packets. Normally, you do not need to change this setting. Exceptions include: • Decrease the interval if an active-passive cluster takes a long time to fail over or to train the network. Sending ARP packets more frequently may help the failover to happen faster. • Increase the interval if the cluster has a large number of VLAN interfaces and virtual domains. Because gratuitous ARP packets are broadcast, sending them might generate a large amount of network traffic. As long as the active-passive cluster fails over successfully, you can increase the interval between when gratuitous ARP packets are sent to reduce the rate of traffic produced by a failover. The valid range is from 1 to 20. The default is 6 seconds. |
Monitor | Mark the checkboxes for the network interface to be used for port monitoring and heartbeat packets. The standard practice is to use mgmt2 for the port monitoring and heartbeat packets. Use the same port number for all cluster members. For example, if you select mgmt2 on the primary node, select mgmt2 as the heartbeat interface on the other member nodes. |
CLI commands: config system ha set mode <standalone | active-passive> set group-name <group_name_str> set priority <priority_int> set override <enable | disable> set group-id <group_id_integer> set hb-interval <hb_interval_int> set hb-lost-threshold <hb_lost_thresh_int> set hbdev <mgmt1 | mgmt2> set arps <arps_int> set arps-interval <arps_interval_int> end |