You understand now how similar the two protocols are, but still they are not exactly the same. There are many differences as presented in the following list, but the good news for you as a CCNA candidate is that most of the differences are outside the scope of this book and your CCNA exams: //////////////
The Type 3 LSA name. **
The OSPFv3 neighbors do not have to have their IPv6 addresses in the same IPv6 subnet, while OSPFv2 neighbors must have their IP addresses in the same subnet to form neighbor relationships.**
There are some new LSA types used by OSPFv3 only and not by OSPFv2, but these are beyond scope as we mentioned.**
The details inside LSA types 1, 2, and 3 are also different for OSPFv3 and OSPFv2 but these are again outside scope here.**
So, as you can see there are more similarities than differences and the few differences that exist are also out of scope for your CCNA exams. So you can reuse most of your OSPFv2 concepts for OSPFv3. ////
In the next section, we will cover OSPFv3 verification and troubleshooting with associated concepts. ////
OSPFv3 Verification and Troubleshooting ////
The OSPFv3 show commands used for verification and troubleshooting are also very similar to OSPFv2 commands mostly the ip keyword getting replaced by ipv6. When the OSPFv3 process first comes up on a router, the IOS reads the OSPFv3 configuration and then enables OSPFv3 on interfaces. So, we will start our OSPF verification and troubleshooting by examining OSPFv3 interfaces. If the interfaces look good, you can move on to OSPFv3 neighbors, and then to the OSPFv3 topology database, and finally to OSPFv3 routes added to the IPv6 routing table. ///
For verification and troubleshooting examples, we will use the OSPFv3 multi-area topology presented and configured earlier in this chapter. ///
OSPFv3 Interfaces ////
The ip ospf process-id area area-id command is used in interface configuration mode to make OSPFv3 run on an interface. You can quickly scan the output of show running-config to identify the OSPFv3 interfaces as well as the area number for each. ///
You can be much more effective at verification and troubleshooting by using the respective show commands than trying to read the configuration. And that’s not the only reason to favor specific show commands over the show running-config command. Many simlet questions on the CCNA exams do not even let you into the enable mode of the router, so you just cannot use the show running-config command to see the configuration. So, if you think your good configuration skills alone can help you verify and troubleshoot OSPFv3 for CCNA, think again. ////
There are three show commands that can provide you useful information about interfaces enabled for OSPFv3: ///
show ipv6 protocols **
show ipv6 ospf interface brief **
show ipv6 ospf interface **
All three commands list the interfaces, both non-passive and passive, on which OSPFv3 has been enabled, but with different level of details. In our case, there is no passive interface, but you can make any interface passive by using the passive-interface command in interface configuration mode.