Configuring IPv6 Routing

To support multiple IPv6 networks and allow devices to communicate between those networks, you need to tell the routers how to reach remote IPv6 networks. You can do so through static routes, IPv6 routing protocols, and default routes. For the router to route any customer’s IPv6 traffic, you need to enable unicast routing for IPv6 from global configuration mode. If you fail to do this, the router can send and receive its own packets, but it will not forward packets for others, even if it has the routes in its IPv6 routing table.

IPv6 can use the new and improved flavors of these dynamic routing protocols with their versions that support IPv6:

RIP, called RIP next generation (RIPng)

OSPFv3

EIGRP for IPv6

One difference with the interior gateway routing protocols for IPv6 is that none of them support network statements. To include interfaces of the routing process, you use interface commands. For EIGRP, you also need to issue the no shutdown command in EIGRP router configuration mode. Example 12-3 shows the enabling of unicast routing and the configuring of IPv6 routing protocols.

Example 12-3 Enabling IPv6 Routing and Routing Protocols

Click here to view code image

! Enables IPv6 routing of other devices' packets
R1(config)#
ipv6 unicast-routing

! Enabling all 3 IGPs on interface Fa0/1
! Note: that in a production network, we would only need 1 routing protocol
! on a given interface.   If we did have multiple identical learned routes
! the Administrative Distance (same as in IPv4) would determine which
! routing protocols would be the "best" and be placed in the routing table.
R1(config)# int fa 0/1

! Enabling RIPng on the interface
! Simply create a new "name" for the process.  I called this one "MYRIP"
! Use the same name on all the interfaces on the local router where you
! want RIPng to be used on that same router.
R1(config-if)# ipv6 rip MYRIP enable

! Enabling OSPFv3 on the interface
! Syntax is the keywords ipv6 ospf, followed by the process ID (The process ID is
! locally assigned and can be a positive integer from 1 to 65535), then the
! area information
R1(config-if)# ipv6 ospf 1 area 0

! Enabling IPv6 EIGRP on the interface
R1(config-if)# ipv6 eigrp 1
R1(config-if)# exit

! Bringing the EIGRP routing process out of its default shutdown state
! Note: This is done in global (not interface) configuration mode.
! This is not needed for RIPng or OSPFv3
R1(config)# ipv6 router eigrp 1
R1(config-rtr)# no shutdown

! Verify which routing protocols are running
R1# show ipv6 protocol
IPv6 Routing Protocol is "connected"
IPv6 Routing Protocol is "rip MYRIP"
  Interfaces:
    FastEthernet0/1
  Redistribution:
    None
IPv6 Routing Protocol is "ospf 1"
  Interfaces (Area 0):
    FastEthernet0/1
  Redistribution:
    None
IPv6 Routing Protocol is "eigrp 1"
  EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
  EIGRP maximum hopcount 100
  EIGRP maximum metric variance 1
  Interfaces:
    FastEthernet0/1
  Redistribution:
    None
  Maximum path: 16
  Distance: internal 90 external 170

The command show ipv6 route outputs the IPv6 routes the router knows how to reach, including the ones learned through dynamic routing protocols.