Hi Nitin, The switch itself doesn't know. It only knows what mac address is connected to it. Hsrp uses gratuitous arp to rewrite the existing mac address in the arp table with the mac address of the standby router (which is about to become the active router).
Hope that helps, Andres On 25/01/2011 4:19 PM, "Nitin Kumar" <[email protected]> wrote: Dear All, I have slight confusion on working of HSRP for redundant gateway. I have two access-switch/stack connected to both HSRP active and standby routers. All access switches are sending traffic to HSRP active gateway. But if for some reason HSRP state changes on Active gateway and standby becomes active... How does Access switches know when HSRP gateway has changed from active to standby and they need to send traffic over other link. Regards Nitin _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
