IPv6Global Config

ipv6 unicast-routing

Enables IPv6 unicast routing on a Cisco router, allowing it to forward IPv6 packets and participate in IPv6 routing protocols.

Syntax·Global Config

ipv6 unicast-routing

When to Use This Command

Enable IPv6 routing on a router that will serve as a gateway for IPv6-enabled VLANs.
Configure a router to participate in OSPFv3 or EIGRP for IPv6 in a dual-stack network.
Prepare a router to forward IPv6 traffic between subnets in a small-to-medium enterprise network.
Enable IPv6 on a router that will be used for IPv6-only testing or lab environments.

Command Examples

Enable IPv6 unicast routing globally

Router(config)# ipv6 unicast-routing

Router(config)#

No output is displayed upon successful execution. The command simply enables IPv6 routing globally. Use 'show ipv6 interface brief' to verify that interfaces are now IPv6-capable.

Verify IPv6 routing is enabled

Router# show ipv6 interface brief

GigabitEthernet0/0    [up/up]
    FE80::1
    2001:DB8:1::1
GigabitEthernet0/1    [up/up]
    FE80::2
    2001:DB8:2::1

The output shows each interface with its link-local (FE80::) and global unicast (2001:DB8::) IPv6 addresses. The [up/up] indicates the interface is operational and IPv6 is enabled.

Understanding the Output

The command 'ipv6 unicast-routing' produces no direct output. Its effect is seen in subsequent show commands. Use 'show ipv6 interface brief' to see which interfaces have IPv6 enabled and their addresses. The first column is the interface name, followed by status in brackets (line protocol/interface status). Then each IPv6 address is listed on a separate line. Link-local addresses start with FE80, global unicast addresses are typically assigned from a prefix like 2001:DB8::/32 for documentation. If an interface does not appear, IPv6 is not enabled on it. Good status is 'up/up'; anything else indicates a problem. Also use 'show ipv6 route' to see the IPv6 routing table, which will be empty until routes are added via static or dynamic routing.

CCNA Exam Tips

CCNA exam tip: 'ipv6 unicast-routing' is required before you can configure any IPv6 routing protocol (OSPFv3, EIGRP for IPv6) or static routes.

CCNA exam tip: Without this command, a router will not forward IPv6 packets even if interfaces have IPv6 addresses configured.

CCNA exam tip: The command is global configuration mode only; it cannot be applied per interface.

CCNA exam tip: Remember that 'ipv6 unicast-routing' is the IPv6 equivalent of 'ip routing' for IPv4.

Common Mistakes

Mistake 1: Forgetting to enable 'ipv6 unicast-routing' before configuring OSPFv3 or EIGRP for IPv6, causing the routing process to fail to start.

Mistake 2: Assuming that assigning an IPv6 address to an interface automatically enables IPv6 routing; the global command is still required.

Mistake 3: Typing 'ipv6 routing' instead of 'ipv6 unicast-routing'; the correct command is 'ipv6 unicast-routing'.

Related Commands

ipv6 enable

Enables IPv6 processing on an interface, allowing the interface to forward IPv6 traffic and participate in IPv6 routing protocols.

ipv6 route [prefix/len] [next-hop]

Configures a static IPv6 route in the global routing table, specifying the destination prefix and next-hop address or exit interface.

show ipv6 interface brief

Displays a summary of IPv6 interface status and addresses, useful for quickly verifying IPv6 configuration and interface operational state.

show ipv6 route

Displays the IPv6 routing table on a Cisco router, showing all known IPv6 routes and their next-hop information for troubleshooting and verification of IPv6 routing.

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