1. HSRP TUNING When a Switch fails and charge is taken by standby Switch, in our case Switch B takes over to Switch A, Switch B will remain Active or Primary router even if Switch A comes online. Even with the priority higher priority Switch A fails to get back its position as Active Router. Switch A will only gains its position as Active Router if Switch B fails. This is not a good practice, so to solve this we setup preemption. Preemption makes sure that the router with higher priority is always selected as Active Router. Preemption Configuration: Switch A(config)# int vlan 50  Switch A(config-if)# standby 10 preempt  Switch A(config-if)# standby 10 preempt delay reload 180  To make Switch / Router to wait 180 sec after reboot and preempt.

2. HSRP TUNING Interface Tracking: If the Switch’s interface facing the wan fails it subtracts its priority so that the standby Switch takes over and become Active Switch. It is set with preempt enabled. Reason to setup Interface Tracking: Working Internal links will fail to tell if Wan of Active Switch is failed and Failover will not work. Configuration: Make sure preemption is enabled. Switch A(config)# int vlan 50  Switch A(config-if)# standby 10 track fastEthernet 0/0 70  0/0 wan link, 70 is decrement of priority, 10 is shared group.

3. HSRP TUNING TIMER: To change default timer for HSRP: Switch A(config)# standby 10 timers msec 200 msec 800  The above says timer for shared group 10 to be changed to 200 milisec for Hello packets and consider switch dead after 800 milisecs. The only disadvantage to change the timer could be bandwidth issue and or heavy processing. Thanks, Hyp3ri0n www.itpings.com

4. HSRP Virtual IP Address & Virtual Mac Address: In Virtual Mac Address e.g 0000.0C07.AC0A First 6 are vendor ID, 07AC is HSRP ID and 0A is Group 10 (HEX) It is generated on both Switches, so when the Active Switch fails the IP becomes available on Standby Switch. Clients don’t need to change any Gateway settings on their devices. Hello Messages are sent every 3 sec, Gateway is assumed Dead if no response is received in 10 secs. However we can tune the timers for fast processing.