Size a load balancer pair from connection arrival rate and hold time, and check the state table against the per-node limit.
A connection table holds one entry per live flow, and the number of live flows is the arrival rate multiplied by how long each one lasts. In active/standby only one node carries the load, so the surviving node must fit the entire table on its own. Load balancers are almost never limited by bandwidth — they run out of connection-table entries first, and an active/active cluster sized at 80% cannot survive losing a node.
Load Balancer Capacity
concurrent connections = new connections per second × average hold time (Erlang-style concurrency); utilisation = concurrent ÷ per-node table limit.
concurrent connections = new connections per second × average hold time (Erlang-style concurrency); utilisation = concurrent ÷ per-node table limit. A connection table holds one entry per live flow, and the number of live flows is the arrival rate multiplied by how long each one lasts. In active/standby only one node carries the load, so the surviving node must fit the entire table on its own.
Load balancers are almost never limited by bandwidth — they run out of connection-table entries first, and an active/active cluster sized at 80% cannot survive losing a node.
This calculator takes 6 inputs: New connections per second, Average connection hold time, Load balancer nodes in the cluster, Active/standby (only one node carries traffic), Connection table limit per node, Aggregate throughput. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.