Health-Check Commands. Extreme Networks Px Series, Px 1
Extreme Networks Px Px1 application switch provides a powerful platform for managing network traffic and load balancing. It offers features such as health checks, server grouping, virtual services, and more. This command reference guide provides detailed information on all the commands available in the ExtremeWarePx software, making it an essential resource for administrators managing these switches.
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6
Health-Check Commands
This chapter describes commands for conÞguring health checks.
Types of Health Checks
The application switch supports the following types of health checks:
¥ ICMP Ping ÑUses ICMP Òecho requestÓ to ensures that the host is reachable. In general, this does not provide any information about application health, but provides the simplest check.
¥ TCP Open ÑOpens a connection to a speciÞed TCP/IP port. Optionally, the application switch can compare the response sent upon open to a preconÞgured string to further ensure that the application responded correctly.
¥ HTTP Ñ Sends an actual HTTP request to the server, typically a GET request. Optionally, the application switch can compare the returned page to a preconÞgured string to further ensure that the application responded correctly.
You conÞgure the type of health check for each server group. The same type of health check is performed on all servers in a given server group. The server itself always performs ping health checks.
If you conÞgure TCP-open or HTTP checks, those checks will be performed as well.
If health checks are enabled, and you do not speciÞcally conÞgured the type of health check for a particular server group, that group uses ping health checks by default.
Health Check Properties
The application switch maintains values for four properties that control the health-check procedure:
Property interval retry-interval fail-after restore-after
Meaning
Time interval between successful configured health checks
Time interval between rechecks after a failed health check
Number of consecutive failed health checks after which a server is removed from service
Number of consecutive successful health checks after which a server is returned to service
Global
Default Value
30 seconds
10 seconds
2
2
ExtremeWarePx1 1.2 Command Reference Guide 201
Health-Check Commands
You can change the global default values for these properties. In addition, you conÞgure these properties for each server group. The same property values are used for all servers in a given server group.
If health checks are enabled, and you do not speciÞcally conÞgure a particular property for a particular server group, that group uses the propertyÕs global default value.
If you change the global default value for any property, the new global default will be used by any server group that did not speciÞcally conÞgure that particular.
If the CPU is swamped by too many health checks or other tasks, the interval and retry-interval times may be stretched. By design, health checks are randomized. The average interval between two consecutive health checks is interval ; however, any individual check is performed using a minor randomized interval of interval plus or minus 50%. The actual interval between any particular pair of consecutive health checks may be as short as interval / 2 or as long as interval * 3 / 2
.
Health Check Procedure
The health check procedure:
1 As soon as the system comes up or a server is enabled, a health check is performed on the server. If it passes, the server goes into service immediately; if not, it remains out of service.
2 As long as the server is in service, the health check is repeated every interval seconds. If the server passes a health check, it remains in service; if it fails, it is removed from service.
3 If the server fails a health check, it is rechecked after retry-interval
seconds.
Ñ If a recheck fails, the recheck is repeated after retry-interval seconds. After fail-after consecutive failures, the server is removed from service.
Ñ If a recheck succeeds, the recheck is repeated after retry-interval
seconds. After restore-after consecutive successes, the server is put into service.
ARP Checks
In addition to the health check described in the preceding sections, an additional check is performed automatically for servers on the same network as the application switchÕs system IP. In this situation, the switch sends periodically sends ARP requests to each server in its network. The switch uses information in the ARP response when it sends trafÞc to servers on the local network
The global property arp-interval controls the frequency with which ARP checks are performed. This property is initially set to 5 minutes; that is, an ARP signal is send to a server in the same network as the system IP every 5 minutesÑin addition to any ping, TCP open, or HTTP health check that is conÞgured for the sever.
You can change the value of the arp-interval property with the
configure health-check arp-interval
command.
202 ExtremeWarePx1 1.2 Command Reference Guide
configure health-check arp-interval
configure health-check arp-interval
configure health-check arp-interval <minutes>
Description
Sets the global arp-interval property.
Syntax Description minutes The number of minutes between ARP checks for servers in the same network as the application switch system IP; a number between 1 and 1000, inclusive.
Default
Initially, the value for the arp-interval property is 5 minutes.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command changes the arp-interval property to 10 minutes.
configure health-check arp-interval 10
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 203
Health-Check Commands
configure health-check fail-after
configure health-check fail-after <number>
Description
ConÞgures the global default value for the fail-after
property.
Syntax Description number The global default value for the number of consecutive failed health checks after which a server is removed from service.
Default
Initially, the global default value for the fail-after
property is 2.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command changes the global default value for the fail-after property to 3.
configure health-check fail-after 3
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
204 ExtremeWarePx1 1.2 Command Reference Guide
configure health-check interval
configure health-check interval
configure health-check interval <seconds>
Description
ConÞgures the global default value for the interval
property.
Syntax Description seconds The global default value for the time interval between successful health checks; a number between 2 and 255, inclusive.
Default
Initially, the global default value for the interval
property is 30 seconds.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command changes the global default value for the interval property to 45 seconds.
configure health-check interval 45
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 205
Health-Check Commands
configure health-check restore-after
configure health-check restore-after <number>
Description
ConÞgures the global default value for the restore-after
property.
Syntax Description number The global default value for the number of consecutive successful health checks after which a server is returned to service
Default
Initially, the global default value for the restore-after
property is 2.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command changes the global default value for the restore-after property to 3.
configure health-check restore-after 3
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
206 ExtremeWarePx1 1.2 Command Reference Guide
configure health-check retry-interval
configure health-check retry-interval
configure health-check retry-interval <seconds>
Description
ConÞgures the global default value for the retry-interval
property.
Syntax Description seconds The global default value for the time interval between rechecks after a failed health check.
Default
Initially, the global default value for the retry-interval
property is 10 seconds.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command changes the global default value for the retry-interval property to 15 seconds.
configure health-check retry-interval 15
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 207
Health-Check Commands
configure server slow-start initial-connections
configure server slow-start initial-connections <number>
Description
Sets the global initial maximum number of connections to a server.
Syntax Description number The initial maximum number of connections to a server; a number between 1 and 100, inclusive.
Default
The initial maximum defaults to 5 connections.
Usage Guidelines
You must have administrator privileges to issue this command.
The number of connections over time for a particular server are calculated from an initial maximum number of connections, and an interval. When a server is brought up, connections are limited to the initial maximum number. After the number of seconds conÞgured for the interval, the maximum number of connections allowed is doubled.
command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command sets the global initial maximum number of connections to 10.
configure server slow-start initial-connections 10
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
208 ExtremeWarePx1 1.2 Command Reference Guide
configure server slow-start interval
configure server slow-start interval
configure server slow-start interval <seconds>
Description
Sets the global interval used to adjust the limit for server connections.
Syntax Description seconds The global interval between server connections.
Default
The interval defaults to 5 seconds.
Usage Guidelines
You must have administrator privileges to issue this command.
The number of connections over time for a particular server are calculated from an initial maximum number of connections, and an interval. When a server is brought up, connections are limited to the initial maximum number. After the number of seconds conÞgured for the interval, the maximum number of connections allowed is doubled.
This command sets the global interval. You can set the initial maximum number of connections with the
configure server slow-start initial-connections
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command sets the global interval to 3 seconds.
configure server slow-start interval 3
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 209
Health-Check Commands
configure server-group health-check fail-after
configure server-group name <name string> health-check fail-after <number>
Description
ConÞgures the fail-after
property for the speciÞed server group.
Syntax Description name string number
The name of the server group for which to configure the property.
The number of consecutive failed health checks after which a server in the specified group is removed from service.
Default
If this command is not issued, the global default value for the fail-after property is used.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command sets the fail-after
property to 3 for the server group named srvgroup1
.
configure server-group name "srvgroup1" health-check fail-after 3
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
210 ExtremeWarePx1 1.2 Command Reference Guide
configure server-group health-check http
configure server-group health-check http
configure server-group name <name string> health-check http
{object <object string> {return <return string>}}
Description
ConÞgures HTTP health checks for the speciÞed server group.
Syntax Description name string object string return string
Name of the server group for which to configure the health-check type.
Name of the object to be retrieved.
String to match in the returned page.
Default
If no health-check type is conÞgured for a server group, that group uses ping health checks by default.
Usage Guidelines
You must have administrator privileges to issue this command.
The object
parameter speciÞes the name of the object to be retrieved by an HTTP GET request. You may also use the return
parameter to specify a string to match in the returned page. When the health check is performed on a server:
1 A connection is opened to the port conÞgured for the server. The health check fails if the connection cannot be opened.
2 If the object
parameter was speciÞed, that the health check requests the speciÞed object. The health check fails if no object is returned.
3 If the return parameter was speciÞed, the health check examines the Þrst 1000 bytes of returned text to see if it contains the speciÞed return string; the health check passes if the return string is found.
If the return
parameter was not speciÞed, the HTTP response codes are checked. Acceptable HTTP response codes are 200-299 and 401.
If you omit the object
parameter, when the health check is performed on a server:
1 A connection is opened to the port conÞgured for the server. The health check fails if the connection cannot be opened.
2 The health check sends an HTTP ÒheadÓ request (HEAD / HTTP/1.0\r\n\r\n) to the server. The
HTTP response codes are checked. Acceptable HTTP response codes are 200-299 and 401.
All data requests use HTTP 1.0.
You must use the
command to commit the conÞguration changes made by this command.
ExtremeWarePx1 1.2 Command Reference Guide 211
Health-Check Commands
Example
The following command conÞgures the server group named sg1
to use HTTP GET health checks that request the object index.html
: configure server-group name "sg1" health-check http object index.html
The following command conÞgures the server group named sg1 to use HTTP GET health checks that request the object index.html
and check for the string "Welcome" : configure server-group name "sg1" health-check object index.html return "Welcome"
The following command conÞgures the server group named extr to use HTTP GET health checks that do a Òhead /Ó on the server: configure server-group name "extr" health-check http
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
212 ExtremeWarePx1 1.2 Command Reference Guide
configure server-group health-check interval
configure server-group health-check interval
configure server-group name <name string> health-check interval <seconds>
Description
ConÞgures the interval
property for the speciÞed server group.
Syntax Description name string seconds
The name of the server group for which to configure the property.
The time interval between successful health checks for servers in the specified group.
Default
If this command is not issued, the global default value for the interval property is used.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command sets the interval
property to 45 seconds for the server group named srvgroup1
.
configure server-group name "srvgroup1" health-check interval 45
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 213
Health-Check Commands
configure server-group health-check ping
configure server-group name <name string> health-check ping
Description
ConÞgures ping health checks for the speciÞed server group.
Syntax Description name string Name of the server group for which to configure the health-check type.
Default
If no health-check type is conÞgured for a server group, that group uses ping health checks by default.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command conÞgures the server group named sg1 to use ping health checks.
configure server-group name "sg1" health-check ping
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
214 ExtremeWarePx1 1.2 Command Reference Guide
configure server-group health-check restore-after
configure server-group health-check restore-after
configure server-group name <name string> health-check restore-after <number>
Description
ConÞgures the restore-after
property for the speciÞed server group.
Syntax Description name string number
The name of the server group for which to configure the property.
The number of consecutive successful health checks after which a server in the specified group is returned to service.
Default
If this command is not issued, the global default value for the restore-after property is used.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command sets the restore-after
property to 3 for the server group named srvgroup1
.
configure server-group name "srvgroup1" health-check restore -after 3
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 215
Health-Check Commands
configure server-group health-check retry-interval
configure server-group name <name string> health-check retry-interval <seconds>
Description
ConÞgures the retry-interval
property for the speciÞed server group.
Syntax Description name string seconds
The name of the server group for which to configure the property.
The time interval between rechecks after a failed health check for servers in the specified group.
Default
If this command is not issued, the global default value for the retry-interval property is used.
Usage Guidelines
You must have administrator privileges to issue this command.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command sets the retry-interval
property to 15 seconds for the server group named srvgroup1
.
configure server-group name "srvgroup1" health-check retry-interval 15
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
216 ExtremeWarePx1 1.2 Command Reference Guide
configure server-group health-check tcp-open
configure server-group health-check tcp-open
configure server-group name <name string> health-check tcp-open return <return string>
Description
ConÞgures TCP open health checks for the speciÞed server group.
Syntax Description name string return string
Name of the server group for which to configure the health-check type.
String to be compared to the response.
Default
If no health-check type is conÞgured for a server group, that group uses ping health checks by default.
Usage Guidelines
You must have administrator privileges to issue this command.
When a TCP open health check is performed on a server:
1 A connection is opened to the port conÞgured for the server. The health check fails if the connection cannot be opened.
2 If the return parameter was speciÞed, the health check compares the response returned by the open operation to the speciÞed return string. The health check fails if the return string does not match the response.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command conÞgures the server group named sg1
to use TCP open health checks: configure server-group name "sg1" health-check tcp-open
The following command conÞgures the server group named sg1 to use TCP open health checks, that check for the return string "HELLO" : configure server-group name "sg1" health-check tcp-open return "HELLO"
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 217
Health-Check Commands
disable health-check
disable health-check
Description
Disables the health-check facility.
Syntax Description
This command has no parameters or options.
Default
The health-check facility is enabled by default.
Usage Guidelines
You must have administrator privileges to issue this command.
When health-check facility is disabled, no health checks are performed.
To disable health checks for a particular server group without disabling the entire health-check facility,
issue the disable health-check server-group-name
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command disables the health-check facility.
disable health-check
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
218 ExtremeWarePx1 1.2 Command Reference Guide
disable health-check server-group-name
disable health-check server-group-name
disable health-check server-group-name <name string>
Description
Disables health checks for a speciÞed server group.
Syntax Description name string The name of the server group for which health checks are to be disabled.
Default
Health checks are enabled for all server groups by default.
Usage Guidelines
You must have administrator privileges to issue this command.
If you want to disable the entire health-check facility, use the disable health-check
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command disables health checks for the server group named svrgroup1 .
disable health-check server-group-name "srvgroup1"
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 219
Health-Check Commands
disable server
disable server
[(index <index number>) |
(ipaddress <IP address> {port <port number>})]
Description
Disables a server, forcing the server to be down.
Syntax Description index number
IP address port number
The unique index number of the server to be disabled.
The IP address of the server(s) to be disabled. The IP address plus the port number uniquely identify a server.
The port number of the server to be disabled. The port number plus the IP address uniquely identify a server.
Default
All servers are enabled by default.
Usage Guidelines
You must have administrator privileges to issue this command.
You can identify a server to be disabled either by its index number or by its IP address and port number. If you specify only the IP address, this command disables all servers with that IP address (and any port number).
Disabling a server forces it to be down (for example, for maintenance). While the server is disabled, it is not used by the Px-series application switch. A disabled server is indicated as Òforced downÓ (FDOWN) in the output from the
You must use the
command to commit the conÞguration changes made by this command.
Example
This example disables all servers with IP address 5.5.5.5:
* station2:16 # disable server ip 5.5.5.5
* station2:17 # show health server-group name sg20000
Healthcheck is currently enabled default interval 30 sec timeout 5 sec retry interval 10 sec arp interval 5 min default fail after 2, restore after 2
12600/12823 ping rx/tx
16451/16622 DNS query rx/tx
5 DOWN 94 UP 4 *UP 2 *DOWN 4 FDOWN flags: E - check Enabled, D - check Disabled, R - mac is resolved ra - restore after, fa - fail after, left - secs till next check index IP
5.5.5.5
port proto
ICMP state
FDOWN check
IDLE left
24 run
-1 ra
2
20000 5.5.5.5
90 ICMP FDOWN IDLE 18 0 2 fa
2
2 ups flg
0 E
0 E
220 ExtremeWarePx1 1.2 Command Reference Guide
disable server
20001
20002
5.5.5.5
5.5.5.5
91
92
ICMP
ICMP
FDOWN
FDOWN
IDLE
IDLE
14
15
0
0
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
2
2
2
2
0
0
E
E
ExtremeWarePx1 1.2 Command Reference Guide 221
Health-Check Commands
disable server slow-start
disable server slow-start
Description
Disables server slow start.
Syntax Description
This command has no parameters or options.
Default
Slow start is enabled by default.
Usage Guidelines
You must have administrator privileges to issue this command.
In order not to overload a server that has just come up, server slow start restricts the number of connections that the server can process. Slow start is performed when health checks bring a server back online, or when a server is enabled, if health checking is disabled for that server's server group.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command disables server slow start.
disable server slow-start
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
222 ExtremeWarePx1 1.2 Command Reference Guide
enable health-check
enable health-check
enable health-check
Description
Enables the health-check facility.
Syntax Description
This command has no parameters or options.
Default
The health-check facility is enabled by default.
Usage Guidelines
You must have administrator privileges to issue this command.
When the health-check facility is enabled, health checks are performed on every server group except
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command enables the health-check facility.
enable health-check
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 223
Health-Check Commands
enable health-check server-group-name
enable health-check server-group-name <name string>
Description
Enables health checks for a speciÞed server group.
Syntax Description name string The name of the server group for which health checks are to be enabled.
Default
Health checks are enabled for all server groups by default.
Usage Guidelines
You must have administrator privileges to issue this command.
Health checks are performed only if the health-check facility itself is enabled. This facility is enabled by default. It can be disabled with the
command and re-enabled with the enable health-check
command.
You use this command to re-enable health checks for a server group after disabling them with the
disable health-check server-group-name
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command enables health checks for the server group named svrgroup1 .
enable health-check server-group-name "srvgroup1"
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
224 ExtremeWarePx1 1.2 Command Reference Guide
enable server
enable server
enable server
[(index <index number>) |
(ipaddress <IP address> {port <port number>})]
Description
Re-enables a server that has been disabled.
Syntax Description index number
IP address port number
The unique index number of the server to be enabled.
The IP address of the server(s) to be enabled. The IP address plus the port number uniquely identify a server.
The port number of the server to be enabled. The port number plus the IP address uniquely identify a server.
Default
All servers are enabled by default.
Usage Guidelines
You must have administrator privileges to issue this command.
You can identify a server to be enabled either by its index number or by its IP address and port number.
If you specify only the IP address, this command enables all disabled servers with that IP address (and any port number).
Enabling a server brings the server back into normal use by the Px-series application switch.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command enables the server with index number 1: enable server index 1
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
ExtremeWarePx1 1.2 Command Reference Guide 225
Health-Check Commands
enable server slow-start
enable server slow-start
Description
Enables server slow start.
Syntax Description
This command has no parameters or options.
Default
Slow start is enabled by default.
Usage Guidelines
You must have administrator privileges to issue this command.
In order not to overload a server that has just come up, server slow start restricts the number of connections that the server can process. Slow start is performed when health checks bring a server back online, or when a server is enabled, if health checking is disabled for that server's server group.
You must use the
command to commit the conÞguration changes made by this command.
Example
The following command enables server slow start.
enable server slow-start
History
This command was available in ExtremeWarePx 1.1.
Platform Availability
This command is available on the Px-series application switch.
226 ExtremeWarePx1 1.2 Command Reference Guide

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Key features
- Health Checks
- Server Grouping
- Virtual Services
- Load Balancing
- Traffic Management