Troubleshooting IPv6 OSPFv3 Neighbor Adjacencies

This topic is to discuss the following lesson:

https://networklessons.com/ipv6/troubleshooting-ipv6-ospfv3-neighbor-adjacencies/

I found something really cool. I dont see it mentioned here so I will bring it up as it may help others especially if they are testing.

when you use the “Show ipv6 ospf” command it gives some important information.

  1. if your expecting an Area to be shown such as Area 0, Area 1, ect… it will show all the areas that the router sees. This is important as you can check your areas, and if one is missing BAM! Your well on your way to finding your issue and to eliminating other non issues. Obviously this is important tool in the use of this command.

  2. The one I figured out on my own lol… When you use the command “Show Ipv6 ospf” command it will also tell you the number of interfaces in the areas… We could also use the trouble shooting technique of scanning the configuration and that is a really helpful tool but if you can narrow it down for an area your looking at such as OSPF or EIGRP well that is going to save a lot of time especially if the router config is a monster. I found out by playing with the commands and then drilling into each one and analyzing them that loop back addresses are counted as interfaces!

For example, say you have three interfaces on a router in Area 1. you could go through the running config and get mentally dulled trying to check the entire config. Or you could run that command and check and see if you have three interfaces in that area.

If they do then you know you configured OSPF on them and its one less thing you have to worry about and you can find out fast.

You could then pair that with the “show ipv6 ospf interface” command which you can cross reference to your topology to double check if you need.

My main technique for prepping for the Tshoot test is ping. I read the question then apply two techniques in unison.

  1. Top Down approach until I cannot go any further.
  2. Bottom up approach until I cannot go any further.
  3. I write down the device that I cannot reach for example if working IPV6 I would work from DWS1 towards R1 and from R1 I would work towards DWS1. Doing this I can get the issue narrowed down to two devices. (remember Cisco gives us the typologies for the test so we can study them)
  4. I was previously checking configs then with a few commands and using the technique of “spotting the difference”. This works and you will find the issue if you understand all the routing and switching protocols from CCNP. (check out this web page if your not familiar with the techniques: https://networklessons.com/cisco/ccnp-tshoot/troubleshoot-networks/ )

This was slow though and as I am reviewing and getting better and better with the protocols I started combing with more understanding and less “spotting the difference” using it more of a reminder when stuck than anything.

  1. Now I have started to transition past this as I was not happy with it and now I am starting to break every down and starting to use more and more of the different show commands making sure to try and memorize the commands as well in case the question mark does not work on the test. I am noticing its more exciting using these commands and as I get familiar its also faster. I can knock my time down to a quarter or eighth of the time that it takes using the spot the difference and search show run.

Anyway I have a lot more to learn and go but I got really excited about seeing a couple things in regards to OSPFv3 so figured I would share in case it helps others!

I have found alot more information in regards to just OSPFv3 but I think I have to leave something to the imagination as a big part of learning is also exploring and that helps to cement things into your memory. I have about six commands specific to OSPv6 that I wrote down and started using. A few of the commands show similar things.

Also I use simulators, Tons of GNS3 Labs that I build off the typologies and lesson from this website. They say lab…lab… lab… well with the Tshoot I think that is where its really going to pay off tons of live actual experience trouble shooting and building and tearing down labs.

Hey Brian

Thanks so much for sharing these experiences with us! They can be very helpful, especially for those that are preparing for the same exam as you are!

Keep at it!

Laz

Hello team,

There’s a tiny typo at the beginning of the lesson. In the sentense below “OSPFv3 for IPv4” means OSPFv2:

Thanks

Thank you Boris, just fixed this.

Rene