Symptom
When trying to configure EEM with event neighbor-discovery the command is not accepted until you specify the cdp event to monitor. Example below
9396-A(config-applet)# event neighbor-discovery interface ethernet 1/3 ?
. Sub interface separator
cdp Create a cdp event specification
9396-A(config-applet)# event neighbor-discovery interface ethernet 1/3
Max Limit for CDP EEM events reached !!
9396-A(config-applet)# event neighbor-discovery interface ethernet 1/3 cdp ?
add New CDP cache entry added
all CDP cache entry is added, deleted or updated
delete Existing CDP cache entry deleted
update CDP cache entry updated
9396-A(config-applet)# event neighbor-discovery interface ethernet 1/3 cdp add
Configuration accepted successfully
Workaround
Specify the CDP event-to-monitor.