Computer Networks · free preview
Mobile IP
An IP address encodes both who a host is and where it sits, so a device that moves between networks breaks the correspondence unless the architecture separates identifier from locator, mobile IP keeps a permanent home address as the long-lived identifier while a home agent on the home network intercepts packets by answering address resolution queries in the mobile's place and tunnels them to the care-of address the node registered from its current foreign network, the detour through home traces a triangle that route optimization straightens by telling correspondents the care-of address directly through binding updates cached and timed out against staleness, and the whole scheme depends on authentication, since anyone who can register a care-of address can steal a flow.
1. Identifier and Locator
Identifier and Locator
2. The Home Agent's Trick
The Home Agent's Trick
3. Straightening the Triangle
Straightening the Triangle
4. Handoffs and the Newer Protocol
Handoffs and the Newer Protocol
5. The broken call
A phone moves from a wireless network to a cellular network in the middle of a voice call and acquires a new address. Without mobility support, what happens to the call?
6. Identifier versus locator
What two roles does an IP address normally combine, and how does mobile IP separate them?
7. The interception
How does the home agent capture packets addressed to a mobile node that is away?
8. The triangle
A correspondent and a mobile node sit in the same building, yet their packets cross the country twice. What is the triangle routing problem?
9. The binding cache
How does a correspondent learn to send directly to a roaming node's current location?
10. The security hole
Why must mobile IP registrations and binding updates be authenticated?
11. The permanent name
What is the mobile node's unchanging address, drawn from its home network's prefix and used by correspondents, called?
12. The impersonation
Which technique lets the home agent intercept packets for an absent node by answering link-layer address queries in its place?
13. The tunnel's end
The home agent tunnels intercepted packets to which address, which names the mobile node's current point of attachment?
14. The stale entry
Which message does an abandoned foreign agent send to tell a correspondent to stop using an out-of-date cached binding?
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