IPv6 Routing

Most of the routing protocols we’ve already discussed have been upgraded for use in IPv6 networks. Also, many of the functions and configurations that we’ve already learned will be used in almost the same way as they’re used now. Of course, static routing in IPv6 is still an option.

RIPng

The primary features of RIPng (next generation) are the same as they were with RIPv2. It is still a distance-vector protocol, has a max hop count of 15, and uses split horizon, poison reverse, and other loop avoidance mechanisms, but it now uses UDP port 521. It still uses multicast to send its updates too, but in IPv6, it uses FF02::9 for the transport address. This is actually kind of cool since in RIPv2, the multicast address was 224.0.0.9, so the address still has a 9 at the end in the new IPv6 multicast range.

Probably one of the biggest changes with all of the IPv6 routing protocols is the fact that you configure or enable the advertisement of a network from interface configuration mode instead of with a network command in router configuration mode. Here are the charms to enable RIPng:

Router#conf t
Router(config)#ipv6 router rip ?
WORD User selected string identifying this process

Router(config)#ipv6 router rip test
Router(config-rtr)#exi
Router(config)#
Router(config)#int fa 0/0
Router(config-if)#
Router(config-if)#ipv6 rip test enable
Router(config-if)#

As you see, now we can have multiple RIPng processes running. When you confiure them, you need to specify the identifyer for the process, so when you configuring the interfaces, you must choose the routing process in which that interface is part of.

EIGRPv6

EIGRPv6 works much the same as its IPv4 predecessor does-most of the features that EIGRP provided before EIGRPv6 will still be available. EIGRPv6 is still an advanced distance-vector protocol that has some link-state features. The neighbor discovery process using hellos still happens, and it still provides reliable communication with reliable transport protocol that gives us loop-free fast convergence using the Diffusing Update Algorithm (DUAL). Hello packets and updates are sent using multicast transmission, and as with RIPng, EIGRPv6’s multicast address stayed almost the same. In IPv4 it was 224.0.0.10; in IPv6, it’s FF02::A (A = 10 in hexadecimal notation).

The use of the network command is gone, and the network and interface to be advertised must be enabled from interface configuration mode. But you still have to use the router configuration mode to enable the routing protocol in EIGRPv6 because the routing process must be literally turned on like an interface with the no shutdowncommand.

Router(config)#ipv6 router eigrp 20
Router(config-rtr)#no shu
Router(config-rtr)#exi
Router(config)#
Router(config)#int fa 0/0
Router(config-if)#
Router(config-if)#ipv6 eigrp 20
Router(config-if)#

The number 20 in the configuration is the Autonomous Systes, as in IPv4.

OSPFv3

The foundation of OSPF remains the same-it is still a link-state routing protocol that divides an entire internetwork or autonomous system into areas, making a hierarchy. In version 3, you assign the RID, area ID, and link-state ID, which are all still 32-bit values but are not found using the IP address anymore because an IPv6 address is 128 bits. Changes regarding how these values are assigned, along with the removal of the IP address information from OSPF packet headers, makes the new version of OSPF capable of being routed over almost any Network layer protocol.

Adjacencies and next-hop attributes now use link-local addresses, and OSPFv3 still uses multicast traffic to send its updates and acknowledgments, with the addresses FF02::5 for OSPF routers and FF02::6 for OSPF-designated routers. These new addresses are the replacements for 224.0.0.5 and 224.0.0.6, respectively.

Router(config)#ipv6 router ospf ?
<1-65535> Process ID

Router(config)#ipv6 router ospf 1 ?

Router(config)#ipv6 router ospf 1
Router(config-rtr)#router-id 10.10.10.10
Router(config-rtr)#exi
Router(config)#
Router(config)#int fa 0/0
Router(config-if)#
Router(config-if)#ipv6 ospf 1 area 10.10.10.10

Actually, you can use only the last command. The OSPF process will be created automaticaly. You need to execute the first few commands only if you want to customize the settings of the OSPF routing process.

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