Technical Tip: Load-balance weight and persistence rule notion

scheehan_FTNT · ‎05-04-2022

Description

This article describes Persistence rule influence Load-Balance Weight decision.

Scope

FortiADC v6.0 and later.

Solution

Assigns relative preference among members—higher values are more preferred and are assigned connections more frequently. Weight is not priority based.

Servers are dispatched requests proportional to their weight, relative to the sum of all weights.

Hence, its does not guarantee the first request to the highest weight server.

Scenario_1:

Clients: 20

Web Server: 4

Persistence Rule: No

Results:

rs_1 real_server: 2
rs_2 real_server: 4
rs_3 real_server: 6
rs_4 real_server: 8

Note.

The persistence table is evaluated before load balancing rules. If the packets received by FortiADC match an entry in the persistence session table, the packets are forwarded to the server that established the connection, and load balancing rules are not applicable.

Scenario_2:

Clients: 20

Web Server: 4

Persistence Rule: LB_PERSIS_HASH_SRC_ADDR

Results:

rs_1 real_server: 2
rs_2 real_server: 8
rs_3 real_server: 4
rs_4 real_server: 6

Conclusion:

With Persistence rule applied, traffic request were dispatch based upon influence by persistence rule method.