Configuring a Real Server Group

This section describes how to configure a real server group on the web UI.

Configuring a Real Server Group

Choose Policy > Server Load Balancing > Real Server Group.
Click Add in Real Server Group.

Configure the functions of a real server group.

Parameter	Description
Name	Name of a real server group.
Load Balancing Algorithm	Algorithm to implement SLB. The default algorithm is round robin. The drop-down list contains load balancing algorithms supported by the FW: Round robin Weighted round robin Least connections Weighted least connections Source IP Hash Weighted source IP Hash If real servers have different performance, use a weighted load balancing algorithm.
Health check	Protocol	Protocol for service health check. TCP: sends TCP probe packets. HTTP: sends HTTP probe packets. HTTPS: sends HTTPS probe packets. The virtual system does not support HTTPS health check. DNS: sends DNS probe packets. RADIUS: sends RADIUS probe packets. ICMP: sends ICMP probe packets. By default, this parameter is set to --NONE--, which indicates that service health check is not performed on servers.
	URL	URL can only be configured when the protocol is HTTP. Get request sent to a specific URL of the real server. If no URL is set, the home page is requested. The requested Host is the address of the real server.
	status	The status code can only be configured when the protocol is HTTP. During an HTTP probe, the FW checks the response code in the response packet sent from the real server. If the response code does not match the FW configuration, the FW considers a probe failure. The default status code is 200.
	Port	Destination port of a probe packet. By default, this parameter is set to --NONE--, which indicates that service health check is not performed on servers. The FW constructs probe packets as follows: Source IP address: IP address of the outbound interface. Destination IP address: IP address of the real server. Destination port: If port-number is set, its value is used. If the destination port is not set but the real server port is set, the real server port is used. NOTE: You configure either a health check port or a physical server port at least.
	Check interval	Interval between sending probe packets for health check. This parameter cannot be set if Health check is set to --NONE--.
	Failures	Maximum number of consecutive probe failures for service health check. This parameter cannot be set if Health check is set to --NONE--.
Source NAT	After Source NAT is enabled, the FW translates the source addresses of packets sent to a real server into addresses in the address pool or outbound interface connecting to the real server. This implementation simplifies the route configuration for packets sent from the real server to clients. Only the route to the Source NAT address pool or the FW interface is required.
Action for a Busy Real Server	When a real server is overloaded, for example, CPU usage, memory usage, or session usage reaches a certain threshold, and the number of concurrent connections reaches the maximum value, three policies can be configured to deal with the overloading situation. Reschedule: Choose a new server to establish new connections based on the load balancing algorithm. Forcibly Schedule: Ignore the overloaded server and still establish new connections on this server. Discard: Discard the packets and do not establish any connection.
Real Server List Click Add to configure the parameters of a real server. After the configuration is complete, click OK.
Real Server IP Address	IP address of a real server. Click Add to add a real server. This server participates in traffic distribution by default, that is, Enable is selected by default. If a real server needs to perform an operation, such as system software upgrade, click the IP address of this server and clear the selection of Enable to exclude this server from traffic distribution.
Port	Port number of a real server. If the port number is not specified, no port translation is performed. In this case, the real server port is the same as the port of the virtual server by default.
Description	Description of a real server.
Weight Value	Weight of a real server. This parameter can be set only when Load Balancing Algorithm is set to a weighted algorithm. NOTE: The weight sum of servers in a real server group must be equal to or less than 8192.
Weight	Percentage of the weight of a real server. This parameter is displayed only when Load Balancing Algorithm is set to a weighted algorithm. It cannot be set and is calculated by the FW.
Maximum Number of Connections	Maximum number of connections on a real server. When the number of concurrent connections on a real server reaches the maximum number of connections, the FW no longer allocates new connections to the server. At the same time, the FW sends the log FW_SLB/5/OVERLOADED to inform the administrator of the server overload. After the number of concurrent connections on the real server falls below 80% of the maximum number of connections, the FW sends the log FW_SLB/6/Normal to inform the administrator of the server restoration.
Enable	Whether a real server is enabled. If the real server is disabled, the FW does not check the health status of the real server, and no traffic is assigned to the real server.
Edit	Change the configuration of a real server.

Click OK.
Real Server Group List displays the new virtual server.

Real Server Group List

After the real server group is configured, the administrator can view the configuration of real servers and observe traffic processing by real servers in the past five minutes under the Real Server Group List.

Within the first five minutes after the real server group function is enabled, the parameters under the 5-Minute Statistics are empty; after five minutes, you can click Refresh to display the statistic values. The system automatically collects statistics on the values for the past five minutes every five minutes. You can click Refresh to view the statistics.

Parameter	Description
Name	Name of a real server.
Load Balancing Algorithm	Algorithm to implement SLB.
Health Check Type	Protocol for service health check.
Real Server IP Address	IP address and port number of a real server.
Weight Value(Weight)	Weight of a real server and the percentage of this weight.
Health Status	Health status of a real server. indicates that a server is available, and indicates that a server is unavailable.
Health Status Changes	The number of health status changes between available and unavailable.
5-Minute Statistics	Traffic	Traffic processed by a real server in the past 5 minutes.
	Traffic Percentage	Percentage of traffic processed by a real server in the past 5 minutes.
	session	Total number of sessions for a real server in the past 5 minutes.
Concurrent Sessions	Concurrent sessions of a real server group.
Edit	Change the configuration of server load balancing.