Mobile Inter-networking with IPv6 : Concepts, Principles and Practices

8

Return Routability

We can’t solve problems by using the same kind of thinking we used when we created them.    –Albert Einstein

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In this chapter, we describe the Return Routability protocol and the function and protocol operations of the Mobility Header messages used with it. Return Routability refers to the method for establishing that the mobile node is able to receive packets delivered to the IPv6 addresses that it claims to own. This is just about all that can be expected from a protocol like Mobile IPv6 that is modeled as running at the network layer; if Bob and Alice could converse using the Internet’s (optimal) routing in spite of mobility, then the mobility protocol has served a very basic need. If packets are routed correctly, then the protocol is considered to be "working" at that level. If the mobile device can receive data at the IPv6 addresses it claims, then routing is working. For scenarios where Return Routability is considered to be too expensive, or where even higher confidence in the security of the Binding Update process is required, a static key configuration process has been devised, as described in Section 8.8.

There is no provision for verifying that the mobile node truly does "own" the IPv6 addresses. In fact, the Internet as such itself does not have an "address ownership" mechanism. This means, for instance, that a device could usurp the use of an ...