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Solving the Network Location Problem with LISP Part 2

Hey Bro, Do you even LISP?

So in the last article, we discussed a bit of why a solution like LISP ( Locator/Identifier Separation Protocol) is required. To summarize, there aren’t enough IPv4 addresses to go around and there are too many IPv6 addresses to let them ‘roam’ using traditional routing methods. Available in IOS (15.1X+) and NX-OS with standards currently being developed within the IETF LISP Working Group, LISP provides a promising solution to mapping IP nodes to locations on the Internet.



If you read the last article, by now some of you are saying, “John, the devices that roam, such as mobile phones, can simply acquire new addresses on the most local network. Why do we need LISP?” It is true this is how we do it now, and it works reasonably well for most users and applications. While it would be nice to seamlessly stream as we move from one network to another, that is more of a luxury feature than a necessity.

The Case for LISP

Let’s forget about mobile devices for just a moment and consider virtual machines and cloud computing. Virtual machines (VM) themselves are increasingly mobile. If I want to do maintenance on some bare metal, I can migrate that VM to another node but if my IP address is going to change, this adds a series of complications in updating services and applications such as DNS (Domain Name Service), to point at the correct address. These name to address mappings can be cached causing significant delays between a desired move and an actualized result when the cache finally expires. Read More »

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Why You’ll Want LISP Routing – Part 2

So, lets dig into LISP Routing a little more.  If you have not done so, I would recommend you read my first post, since I am not going to review the concepts here. In this post, I am going to break things down into three steps: 1) how packets are forwarded (i.e. the data plane operation), 2) how mapping information is propagated (i.e. control plane operation), and 3) how we internetwork with non-LISP locations.

For starters, lets head into the weeds and take a look at the LISP header format.  In the last post, I mentioned there is some flexibility in how handles IP addressing.  The two examples below show a couple of scenarios: pure IPv4 and a IPv4/IPv6 hybrid:


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