On "dc-cs2"
router vrrp vlan 821 name dc-rtlab ip address 10.15.64.1/24 ip helper-address 129.97.15.253 tagged trk1 forbid trk2,trk3 ip ospf area 4 ip ospf passive vrrp vrid 249 owner virtual-ip-address 10.15.64.1/24 enable exit exit
On "dc-cs1"
router vrrp vlan 821 name dc-rtlab ip address 10.15.64.2/24 ip helper-address 129.97.15.253 tagged trk1 forbid trk3 ip ospf area 4 ip ospf passive vrrp vrid 249 backup virtual-ip-address 10.15.64.1/24 enable exit exit