wdisp/ping_extsrv_url is a SAP Parameter attribute which is used to control URL for ping health check requests for external servers information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
URL that the SAP Web Dispatcher uses for ping requests to external
servers. The ping requests that can be configured with these parameters
are used for the health check of the instances.
The specified request is sent periodically to each application server
(that is, to each instance). If the specified request for a server does
not respond positively within a defined time (HTTP status code 200
(OK)), this server is removed from the Web Dispatcher load balancing.
You can configure the frequency with which a request is sent to each
instance with the parameter wdisp/auto_refresh. You can configure the
time allowed for receiving the response with the parameter
wdisp/info_timeout.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.