I would like to know what is the main purpose of use the "standby" at the "inservice standby <group>" defined under the virtual server?. It's just a information ("as description") to associate the HSRP standby into this virtual server or it's have another function?.
IOS SLB "inservice standby" is used where you require stateless redundancy for vservers across 2 SLB routers or switches. Using this command makes the vserver state follow the HSRP state of the relevant interface, to prevent the situation where one router is processing routing traffic but the other router is active and listening for traffic directed to the vserver address. It is much more than a description for the HSRP group, it is the mechanism to allow redundancy to function.
