Command Line Interface Reference Guide > The SLB Configuration Menu > /cfg/slb/real <server number> Real Server SLB Configuration
/cfg/slb/real <server number>
Real Server SLB Configuration
Use this menu to configure information about real servers that participate in a server pool for SLB or application redirection. The minimum required parameters for real server SLB configuration are:
*Real server IP address
*Real server enabled (disabled by default)
Note: When you set the ID while configuring objects such as real servers, virtual servers, or groups, ensure that you also specify at least one additional setting such as the description. Otherwise, Alteon does not treat such an object as created and removes it on apply.
 
[Real Server 1 Menu]
health - Set specific health check for this server
adv - Real Server Advanced Menu
layer7 - Layer 7 Command Menu
ids - IDS Command Menu
thrsh - thrsh Command Menu
type - Set real server type
ipver - Set IP version
rip - Set IP addr of real server
name - Set real server name
weight - Set weight for real server
maxcon - Set maximum number of connections
tmout - Set minutes inactive connection remains open
backup - Set backup real server
preempt - Enable/Disable backup preemption
inter - Set interval between health checks
retry - Set number of failed attempts to declare server DOWN
restr - Set number of successful attempts to declare server UP
overflo - Enable/Disable backup on overflow
addport - Add real port to server
remport - Remove real port from server
downbw - Set the WAN Link download bandwidth limit
upbw - Set the WAN Link upload bandwidth limit
ena - Enable real server
dis - Disable real server
shut - Shutdown real server
del - Delete real server
cur - Display current real server configuration
 
Real Server Configuration Menu Options (/cfg/slb/real) 
Command Syntax and Usage
health <health check id|inherit|NoCheck>
 
Sets a health check for this server.
Values:
*<health check id> — Sets the specified health check for the server.
*inherit — The server inherits the group health check.
*NoCheck — Removes health checks from this server.
Note: Setting a specific health check for a server overrides the group health check settings.
adv
 
Displays the Real Server Advanced menu. To view this menu, see /cfg/slb/real/adv Real Server Advanced Menu.
layer7
 
Displays the Real Server Layer 7 menu. To view this menu, see /cfg/slb/real <server number>/layer7 Real Server Layer 7 Configuration.
ids
 
Displays the Real Server IDS (Intrusion Detection System) menu. To view this menu, see /cfg/slb/real <real server ID>/ids Real Server IDS Configuration Menu.
thrsh
 
Displays the Real Server Threshold menu for setting a threshold per group for the number of concurrent connections. To view this menu, see /cfg/slb/real <real server ID>/thrsh Real Server Threshold Menu.
type
 
Sets the real server type.
Values: local, remote, wanlink.
ipver <v4 | v6>
 
Sets the IP version of the real server.
rip <real server IP address>
 
Sets the IP address of the real server. The format of the IP address depends on the IP version specified using the ipver command. When using this command, the address entered is pinged to determine if the server is up, and the administrator is warned if the server does not respond.
name <string, maximum 128 characters> |none
 
Defines an alias for each real server. This lets the network administrator quickly identify the server by a natural language keyword value.
Values: 1-128 characters
weight <real server weight (1-48)>
 
Sets the weighting value that this real server is given in the load balancing algorithms. Higher weighting values force the server to receive more connections than the other servers configured in the same real server group. A setting of 10 assigns the server roughly 10 times the number of connections as a server with a weight of 1.
Values: 1 – 48
Default: 1
avail <server weight (1-48)>
 
Displays the currently available real server for Global Server Load Balancing (GSLB), and allows the user to change to another real server for GSLB.
maxcon <max connections, 0-200000> [<mode, physical/logical]
 
Sets the maximum number of simultaneous connections that this real server can support.
No new connections are issued to this server if this limit is reached. New connections are issued again to this server once the number of current connections has decreased below the limit.
Note: If all servers in a real server group for a virtual server reach their simultaneous connection limit at the same time, client requests are sent to the backup/overflow server or backup/overflow server group. If no backup servers or server group are configured, client requests are dropped by the virtual server.
Values: 0-200,000
Default: 0 (no connection limit)
The mode command sets the maximum connections mode.
Real servers with the same IP address must be configured with the same maximum connections mode.
Values:
*physical — Real servers with the same IP address configured with the physical maximum connections mode must all have the same maxcon value.
*logical — Real servers with the same IP address configured with the logical maximum connections mode can each have a different maxcon value.
Default: physical
tmout <even number of minutes (2-32768)>
 
Specifies the length of time, in minutes, that an inactive session remains in the session table.
Every client-to-server session being load balanced is recorded in the session table. When the client ends the session, the session table entry is removed.
In certain circumstances, such as when a client application is abnormally terminated by the client’s system, TCP and UDP connections remain registered in the session table. In order to prevent table overflow, these orphaned entries must be aged out of the session table.
Default: 10
Notes
*Radware recommends that you set the timeout to a value greater than 2 minutes.
*When a service is set with a timeout value (/cfg/slb/virt/service/tmout) of 0 (default), the service uses the real server timeout value set here.
Also use this option to set the number of minutes to wait before removing orphan table entries.
This option is also used with the persistent option (see the pbind command at /cfg/slb/virt <server number> /service <virtual port or application name> Virtual Server Service Configuration). When pbind is activated, this option sets how long an idle client is allowed to remain associated with a particular server.
backup <real server ID (alphanumeric)>|none
 
Sets the real server used as the backup or overflow server for this real server.
To prevent loss of service if a particular real server fails, use this option to assign a backup real server ID. If the real server becomes inoperative, Alteon activates the backup real server until the original becomes operative again.
The backup server is also used in overflow situations. If the real server reaches its maximum connections (maxcon) limit, the backup comes online to provide additional processing power until the original server becomes desaturated.
The same backup or overflow server may be assigned to more than one real server at the same time
preempt disable|enable
 
The real server configuration to enable or disable backup preemption.
Values:
*enable — The primary server preempts the backup server when the primary server comes up.
*disable — The backup server continues to serve the traffic even when primary server comes up.
Default: enable
Note: The preempt option does not support preemption between a primary backup group and secondary backup group real servers.
For example, G1 is the primary group, G2 is the backup group, and G3 is the secondary backup group.
If G1 fails, G2 functions as backup for G1. If G2 fails, G3 functions as the backup group for G1.
If G2 becomes active, G3 will not preempt and continues to handle the connections until it is alive.
inter [1-600|inherit]
Sets the interval (in seconds) between real server health verification attempts.
Determining the health for each real server is a basic function for SLB. By default, Alteon checks the health of a real server using ICMP.
Once servers are attached to groups which, in turn, are attached to services, Alteon checks the availability of the services running on the server using the health checks configured for the group. However, it is possible to override this behavior and configure for each real server its own health checks.
This option lets you choose the time between health checks, or use the interval defined within the health check itself.
Values:
*1-600
*inherit — Takes the value from the health check that checks the server.
Default: inherit
retry [1-63|inherit]
 
Sets the number of failed health check attempts required before declaring this real server inoperative, or uses the value defined within the health check itself.
Values:
*1-63
*inherit — Takes the value from the health check that checks the server.
Default: inherit
restr [1-63|inherit]
 
Sets the number of successful health check attempts required before declaring a TCP and UDP service operational, or uses the value defined within the health check itself.
Values:
*1-63
*inherit — Takes the value from the health check that checks the server.
Default: inherit
overflo enable|disable
 
Enables or disables backup upon overflow.
addport <real server port (2–65534)>
 
Adds multiple service ports to the server.
remport <real server port (2–65534)>
 
Removes multiple service ports from the server.
remote disable|enable
 
Enables or disables remote site operation for this server. This option should be enabled when the real IP address represents a remote server (real or virtual) that Alteon accesses as part of its GSLB network. For more information, see the Alteon Command Line Interface Application Guide.
Default: disable
fasthc disable|enable
 
Enables or disables fast health checking.
Values:
*Enable — The real server goes down operationally as soon as the physical port connected to the real server goes down.
*Disable — The real server goes down only after the configured health check interval.
Default: enable
downbw
 
Sets the maximum WAN Link download bandwidth limit (in MBps).
If the WAN link download bandwidth reaches the configured limit, it marks the server as overflowed and does not forward any new session to it
This setting also used for link selection based on utilization (the least-loaded link) which is available only with ‘Server Bandwidth’ metric.
Valid range: 0-100000
Default: 0
upbw
 
Sets the maximum WAN Link upload bandwidth limit (in MBps).
If the WAN link upload bandwidth reaches the configured limit, it marks the server as overflowed and does not forward any new session to it
This setting also used for link selection based on utilization (the least-loaded link) which is available only with ‘Server Bandwidth’ metric.
Valid range: 0-100000
Default: 0
ena
 
You must perform this command to enable this real server for Layer 4 service. When enabled, the real server can process virtual server requests associated with its real server group. When using the apply and save commands, this option enables this real server for operation until explicitly disabled.
For an operations-level command to enable SLB, see /oper/slb/ena on /oper/slb Operations-Level SLB Options.
dis
 
Disables this real server from Layer 4 service. A disabled server no longer processes virtual server requests as part of the real server group to which it is assigned. This option, when the apply and save commands are used, disables this real server until it is explicitly re-enabled.
Note: This option does not perform a graceful server shutdown.
shut connection|psession
 
Specifies how to gracefully shut down a real server.
Values:
*connection — Continues sending traffic to the server belonging to active connections but denies any new connections.
*psession — Continues sending traffic to the server belonging to active connections and accepts new connections if they belong to persistent session entry. The same persistent sessions as in oper are preserved (SSLID, cookie, filter Layer 7 lookup).
del
 
Deletes this real server from the Layer 4 switching software configuration. This removes the real server from operation within its real server groups.
Note: Use this command with caution, as it will delete any configuration options that have been set for this real server. This option does not perform a graceful server shutdown.
cur
 
Displays the current configuration information for this real server.