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> Chapter 26 - Server Load Balancing > Example Weighted load balancing configuration

Example Weighted load balancing configuration

This example shows how to using firewall load balancing to load balances all traffic among 3 real servers. In the example the Internet is connected to port2 and the virtual IP address of the virtual server is 192.168.20.20. The load balancing method is weighted. The IP addresses of the real servers are 10.10.10.1, 10.10.10.2, and 10.10.10.3. The weights for the real servers are 1, 2, and 3.

This configuration does not include a health check monitor.

GUI configuration

Use the following procedures to configure this load balancing setup from the FortiGate GUI.

To add the HTTP virtual server
  1. Go to Policy & Objects > Virtual Servers.
  2. Select Create New.
  3. Add an IP virtual server that allows users on the Internet to connect to the real servers on the internal network. In this example, the FortiGate port2 interface is connected to the Internet.
Name HTTP_weghted_LB
Type IP
Interface port2
Virtual Server IP 192.168.20.20
Load Balance Method Weighted

All other virtual server settings are not required or cannot be changed.

  1. Select OK.
To add the real servers and associate them with the virtual server
  1. Go to Policy & Objects > Real Servers.
  2. Select Create New.
  3. Configure three real servers that include the virtual server All_Load _Balance. Because the Load Balancing Method is Weighted, each real server includes a weight. Servers with a greater weight receive a greater proportion of forwarded connections,

    Configuration for the first real server.
Virtual Server HTTP_weghted_LB
IP Address 10.10.10.1
Port Cannot be configured because the virtual server is an IP server.
Weight 1
Maximum Connections 0

Setting Maximum Connections to 0 means the FortiGate unit does not limit the number of connections to the real server. Since the virtual server uses First Alive load balancing you may want to limit the number of connections to each real server to limit the traffic received by each server. In this example, the Maximum Connections is initially set to 0 but can be adjusted later if the real servers are getting too much traffic.

Configuration for the second real server.

Virtual Server HTTP_weghted_LB
IP Address 10.10.10.2
Port Cannot be configured because the virtual server is an IP server.
Weight 2
Maximum Connections 0

Setting Maximum Connections to 0 means the FortiGate unit does not limit the number of connections to the real server. Since the virtual server uses First Alive load balancing you may want to limit the number of connections to each real server to limit the traffic received by each server. In this example, the Maximum Connections is initially set to 0 but can be adjusted later if the real servers are getting too much traffic.

Configuration for the third real server.

Virtual Server HTTP_weghted_LB
IP Address 10.10.10.3
Port Cannot be configured because the virtual server is an IP server.
Weight 3
Maximum Connections 0

Setting Maximum Connections to 0 means the FortiGate unit does not limit the number of connections to the real server. Since the virtual server uses First Alive load balancing you may want to limit the number of connections to each real server to limit the traffic received by each server. In this example, the Maximum Connections is initially set to 0 but can be adjusted later if the real servers are getting too much traffic.
To add the virtual server to a security policy

Add a port2 to port1 security policy that uses the virtual server so that when users on the Internet attempt to connect to the web server’s IP address, packets pass through the FortiGate unit from the wan1 interface to the dmz1 interface. The virtual IP translates the destination address of these packets from the virtual server IP address to the real server IP addresses.

  1. Go to Policy & Objects > IPv4 Policy.
  2. Select Create New.
  3. Configure the security policy:
Policy Type Firewall
Policy Subtype Address
Incoming Interface port2
Source Address all (or a more specific address)
Outgoing Interface port1
Destination Address HTTP_weghted_LB
Schedule always
Service ALL
Action ACCEPT
Enable NAT Select this option and select Use Destination Interface Address.
  1. Select other security policy options as required.
  2. Select OK.

CLI configuration

Load balancing is configured from the CLI using the config firewall vip command and by setting type to server-load-balance. The default weight is 1 and does not have to be changed for the first real server.

Use the following command to add the virtual server and the three weighted real servers.

config firewall vip

edit HTTP_weghted_LB

set type server-load-balance

set server-type ip

set extintf port2

set extip 192.168.20.20

set ldb-method weighted

config realservers

edit 1

set ip 10.10.10.1

next

edit 2

set ip 10.10.10.2

set weight 2

next

edit 3

set ip 10.10.10.3

set weight 3

end

end