Final answer:
To enable IPv6 routing on Cisco routers, the command 'ipv6 unicast-routing' is used in global configuration mode. This command allows the router to route IPv6 traffic properly across its interfaces.
Step-by-step explanation:
To enable IPv6 routing on Cisco routers using the IOS system, the necessary global configuration command is ipv6 unicast-routing. This command activates IPv6 forwarding on the router and allows it to make routing decisions for IPv6 traffic. Without this command, the router would treat IPv6 packets as flat data and would not route them between interfaces.
Once you enter the global configuration mode on a Cisco router, you can enable IPv6 routing with the following steps:
- Enter the command configure terminal to access global configuration mode.
- Type the command ipv6 unicast-routing and press enter.
- Exit configuration mode by typing end or using the Ctrl + Z shortcut.
After this configuration, the router is ready to route IPv6 traffic across the network, ensuring connectivity for IPv6-enabled devices and networks.