IPv6 Routing

IPv6 is not enabled by default on Cisco routers. To enable IPv6 routing, the command is Router(config)#ipv6 unicast-routing.

After IPv6 is enabled, addresses are assigned to interfaces much like version 4:

Router(config-if)#ipv6 address prefix/prefix-length

To make this less abstract, a more complete example that shows an IPv6 implementation is shown in Example 8-1.


Static Routing

Static routing with IPv6 works exactly like it does with version 4. Aside from understanding the address format, there are no differences. Static routes are not currently on the BSCI test. The syntax for the IPv6 static route command is shown below, and Example 8-2 is supplied so that the command may be viewed in context as it might be applied.

Router(config)# ipv6 route ipv6-prefix/prefix-length {ipv6-address | interface-type interface-number [ipv6-address]} [administrativedistance] [administrative-multicast-distance | unicast | multicast] [tag tag]


RIPng for IPv6

RIPng is the IPv6 of RIP and is defined in RFC 2080. Like RIPv2 for IPv4, RIPng is a distance vector routing protocol that uses a hop count for its metric and has a maximum hop count of 15. RIPng also uses periodic multicast updates—every 30 seconds—to advertise routes. The multicast address is FF02::9.

RIPng is not on the BSCI exam at present, but it is presented here for completeness and to round out your appreciation for IPv6 routing and to prepare the reader for trial implementations of IPv6.

There are two important differences between the old RIP and the nextgeneration RIP. First, RIPng supports multiple concurrent processes, each identified by a process number (this is similar to OSPFv2). Second, RIPng is initialized in global configuration mode and then
enabled on specific interfaces.

Example 8-3 shows the syntax used to apply RIPng to a configuration. Notice that the syntax is very similar to traditional RIP.


Like RIP for IPv4, troubleshoot RIPng by looking at the routing table (show ipv6 route), by reviewing the routing protocols (show ipv6 protocols), and by watching routing updates propagated between routers (debug ipv6 rip).


EIGRP
EIGRP has been expanded to support IPv6, although you’ll need to verify that a specific version of IOS is capable of doing this. EIGRP for IPv6 is based on the IPv4 version. EIGRP is still an advanced distance vector routing protocol that uses a complex metric. EIGRP still has a reliable update mechanism and uses DUAL to retain fall-back paths. Like EIGRP in IPv4, it sends multicast hellos every five seconds (but the multicast address is now FF02::A). EIGRP is enabled as described in the following:

Router(config)#ipv6 router eigrp as
Router(config-rtr)#router-id ipv4-address|ipv6-address
Router(config-rtr)#interface type number
Router(config-if)#ipv6 eigrp as

Like EIGRP for IPv4, troubleshoot by looking at the routing table (show ipv6 route), by reviewing the routing protocols (show ipv6 protocols), and by monitoring neighbors (show ipv6 eigrp neighbors). Example 8-4 shows the configuration for IPv6 EIGRP. Notice that the
routing protocol must be enabled under each interface.