Category Archives: ipv6

How do NAT64 and DNS64 work?

As part of improving IPv6 content on this blog, I have chosen to write about how we can integrate these slightly distinct technologies DNS64 and NAT64. On this post, I will try to show how a native IPv6 client can access an IPv4 resource. In my opinion it isn’t really difficult but needs some focus as what is done with these two techniques is slightly different than what we have done with DNS and NAT so far and you must read every paragraph here not to miss anything. First I will explain the concepts and show the configuration. If you are familiar with the concepts, you can skip to the configuration step. For DNS64 BIND software is used and vSRX for NAT64.

We have the following topology and the question we ask here is that we have a client PC which has only an IPv6 address 2015:1000::2/64 and this client device doesn’t know anything about IPv4 world. How can it reach a web server e.g www.cnn.com having an IPv4-only address of 185.31.17.73? By the way, at the time of this writing www.cnn.com doesn’t have any IPv6 address. Let’s see how we will let our client PC access this resource.

DNS64-NAT64-vSRX-juniper-topology

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ARP, GARP and IPv6 neighbor discovery

I would like to focus more on IPv6 on the upcoming posts and I think the best topic to start IPv6 is the discovery phase but before delving into IPv6, I need to write about how address resolution works in IPv4 world. I did read couple of RFCs as well so you may find something that you didn’t know before. I also touch on GARP and share my test results. Let’s start with the outline about what we will see on this post.

  • How does ARP work?
  • What is GARP and under what conditions we send this packet?
  • How does IPv6 neighbor discovery work?
  • We will use the following topology on these tests

    lab1020-arp-garp-ipv6-nd-topology
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