Enabling IPv6 on Cisco Routers.
By default, IPv6 traffic-forwarding is disabled on a Cisco router. It must be activated between interfaces by using the global configuration command – ipv6 unicast-routing. The global configuration command must be used in both Stateful (DHCPv6) and Stateless autoconfiguration.
There are two basic steps used to activate IPv6 on a Cisco router:
i. First, you must activate IPv6 traffic-forwarding on the router, and
ii. then you must configure each interface that requires IPv6.
Command syntax for enabling IPv6 on Cisco routers:
When a network router interface is configured with an ipv6 address, a link-local address will be configured automatically for the interface.
You must specify the entire 128-bit IPv6 address or specify to use the 64-bit prefix by using the eui-64 option.
IPv6 Address Configuration Example
From the above IPv6 address configuration example, router1 is shown connected to an IPv6 WAN to router2 with a subnet prefix address of 2001:db8:3c4d:2::/64.
We used the following commands:
R1(config)#ipv6 unicast-routing ( configure the router to activate IPv6 routing and configure the router fa0/1 interface).
The EUI-64 option is used to create the 64-bit MAC address.
The MAC address of the Ethernet Fa0/1 interface is 0260.3d47.1720.
Using the show ipv6 interface fa0/1 command, the MAC address is displayed as part of the IPv6 address with the Hex characters FFFE (16 bits) added in the middle, which expands the 48-bit MAC address to create the IPv6 64-bit link-local address.
R1#show ipv6 interface fa0/1
Fa0/1 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::260:3dFF:FE47:1720
Global unicast addresses:
2001:DB8:C18:1:260:3EFF:FE47:1720, subnet is 2001:DB8:C18:1::/64
Joined group addresses:
MTU is 1500 bytes
How IPv6 address is formed.