Navigate to Placement tab to specify the high availabilty and virtual service details.
You can specify the following details:
High Availability Mode: Select the high availability mode for all the virtual services using this service engine group. You can select one of the following options:
Active/Standby: Select this Legacy HA, Active/ Standby mode to mimic a legacy appliance load balancer for easy migration to Avi Load Balancer Controller. Only two Service Engines may be created. For every virtual service active on one, there is a standby on the other, configured and ready to take over in the event of a failure of the active SE. There is no Service Engine scale out in this HA mode.
Health Monitoring on Standby Service Engine(s) to enable active health monitoring from the standby SE for all placed virtual services.
Distribute Load to use both the active and standby Service Engines for virtual service placement in the legacy active standby HA mode.
Auto-redistribute Load to make failback automatic so that virtual services that are migrated back to the SE that replaces the failed SE.
Active/Active: Select this Elastic HA (Active/Active) mode to permit up to N active SEs to deliver virtual services, with the capacity equivalent of M SEs within the group ready to absorb SE(s) failure(s).
In Elastic HA (Active/ Active), under VS Placement across Service Engines, select the mod: required.
Compact for Avi Load Balancer to spin up and fill up the minimum number of SEs. It tries to place virtual services on SEs which are already running.
Distributed (default), for Avi Load Balancer to maximize the virtual service performance by avoiding placements on existing SEs. Instead, it places virtual services on newly spun-up SEs, up to the maximum number of Service Engines.
N+M (Buffer): Select this Elastic HA N + M (Buffer) mode to distribute virtual services across a minimum of two SEs.
In Elastic HA (N+M Buffer), under VS Placement across Service Engines, select the mod: required.
Compact (default), for Avi Load Balancer to spin up and fill up the minimum number of SEs. It tries to place virtual services on SEs which are already running.
Distributed (default), for Avi Load Balancer to maximize the virtual service performance by avoiding placements on existing SEs. Instead, it places virtual services on newly spun-up SEs, up to the maximum number of Service Engines.
Number of Service Engines: The system displays the maximum number of Service Engines in this group. However, this varies based on the HA mode selected. If you select Active/Active or N + M (buffer) mode, you can amend the default value. You can define the maximum number of Service Engines that can be created within an SE group. This number, combined with the virtual services per SE setting, dictates the maximum number of virtual services that can be created within an SE group. If this limit is reached, new virtual services may not be deployed. The status will be grey indicating un-deployed status. This setting can be useful to prevent Avi Load Balancer from consuming too many virtual machines.
Buffer Service Engine: The system displays the excess Service Engine capacity provisioned for HA failover. However, this varies based on the HA mode selected. If you select Active/Active or N + M (buffer) mode, you can amend the default value.
This is the excess capacity provisioned for HA failover. In elastic HA N+M mode, this is capacity is expressed as M, an integer number of buffer service engines. It actually translates into a count of potential virtual service placements. To calculate that count, Avi Load Balancermultiplies M by the maximum number of virtual services per SE. For example, if one requests two buffer SEs, (M=2) and the max_VS_per_SE is 5, the count is 10. If max SEs/group is not reached, Avi Load Balancer will spin up additional SEs to maintain the ability to perform 10 placements.
Override Management Network: Similar to the vCenter cloud modal, once you select the management network and the network is already discovered, Enable DHCP and Enable IPv6 Auto Configuration fields will be selected. You cannot amend these two fields.
If these options are not enabled, then you will have to configure default gateways.
You can choose to configure either the IPv4 default gateway or just the IPv6 default gateway or both.
Enable Service Engine Self-Election: Select this box to enable SEs to elect a primary amongst themselves in the absence of a connectivity to a Controller. This ensures Service Engine high availability in handling client traffic even in headless mode.
Enable CPU socket Affinity: Select this box to allocate all the CPU cores for the Service Engine virtual machines on the same socket of a multi-socket CPU. Appropriate physical resources need to be present in the ESX Host. If not, then SE creation will fail and manual intervention will be required.
Enable CPU socket Affinity is applicable only for vCenter environments.
Enable Dedicated dispatcher CPU: Select this box to dedicate the core that handles packet receive or transmit from the network to the dispatching function. This option is particularly helpful in case of a group whose SEs have three or more vCPUs. You cannot use it for TCP/ IP and SSL functions.
Virtual Services per Service Engine: Specify the maximum number of vittual services (from 1 to 1000) that can be placed on a single Service Engine.
If you select Active/Standby option in High Availability mode, the following fields are enabled:
Enable Health Monitoring on Standby SE(s): Select this box to enable active health monitoring from the standby SE for all placed virtual services.
Enable Distribute Load: Select this box to use both the active and standby Service Engines for virtuals ervice placement in the legacy active standby HA mode.
Enable Auto-redistribute Load: Select this box to re-distrubute the load automatically. Redistribution of virtual services from the takeover SE to the replacement SE can cause momentory traffic loss. If the auto-distribute load option is left in its default off state, any desired rebalancing requires calls to REST API.
If you select Active/Active or N + M (Buffer) option in High Availability mode, the following fields are enabled:
Virtual Service Placement Across Service Engines: Select either Compact or Distributed options. In Compact palcement, virtual services are placed on existing SEs unitl max_vs_per_se limit is reached. In Distributed placement. Virtual services are placed on new SEs unitl max_se_limit is reached. Once this limit is reached, virtual services are placed on SEs with least load.
Scale per Virtual Service: Specify the minimum and maximum number of active Service Engines for the virtual service. A pair of integers determine the minimum and number of active SEs onto which a single virtual service may be placed. With native SE scaling, the greatest value that can be entered as a maximum is 4, with BGP-based SE scaling, the limit is much higher, governed by the ECMP support on the upstream router.
