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移动 IP
IP 地址既编码主机的身份，也编码其所在位置，因此当设备在网络间移动时，这种对应关系就会断裂，除非架构将标识符与定位符分离。移动 IP 保留一个永久的归属地址作为长期标识符，而归属网络上的归属代理通过代替移动节点应答地址解析查询来截获分组，并将其隧道传输至该节点从当前外地网络注册的转交地址；经由归属网络的绕行构成三角路由，路由优化通过绑定更新将转交地址直接告知通信对端来消除该三角，这些绑定更新会被缓存并设置超时以防过期；整个方案依赖于认证，因为任何能够注册转交地址的人都可能劫持流量。
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Which message does an abandoned foreign agent send to tell a correspondent to stop using an out-of-date cached binding?