Traditional catalyst switches like Cisco Catalyst 3750 / 3560, by default do not have IPv6 routing enabled, and simply entering the " ipv6 unicast-routing " won't work! First, enable dual-stack routing by: sdm prefer dual-ipv4-and-ipv6 This should be followed by a reboot, post which enable IPv6 routing by: ipv6 unicast-routing Post which you should be able to do all the IPv6 configuration..