Mobile IPv6

Mobile IPv6 is a cleaner, improved version of Mobile IPv4.

Three big changes:

1. No Foreign Agent needed
2. Route optimization (fixes triangle routing!)
3. Built-in security

Change 1: No Foreign Agent

In MIPv4, the Foreign Agent helped you get a Care-of Address.

In MIPv6, your phone does this itself. Why?

• IPv6 has auto-configuration built in
• Your phone can generate its own Care-of Address automatically
• Modern phones are powerful enough to handle decapsulation

One less entity to worry about.

Change 2: Route Optimization

Remember the triangle problem? Packets always detoured through Home Agent.

MIPv6 fixes this.

How It Works

1. First packet still goes through Home Agent (CN doesn’t know where you are)
2. Home Agent tells CN: “Hey, the mobile node is actually at this Care-of Address”
3. Now CN sends directly to you

Triangle routing only happens once. After that, packets go direct.

Change 3: Built-in Security

MIPv4 had security bolted on as an afterthought.

MIPv6 uses IPsec by default for all signaling:

• Binding Updates are authenticated
• Registration messages are encrypted
• No one can hijack your Home Address

The Full Process

1. You move to a new network
2. Auto-configure a Care-of Address (no Foreign Agent needed)
3. Send Binding Update to Home Agent: “I’m at this new address”
4. Home Agent forwards first packets to you
5. Route optimization: Home Agent tells CN your real location
6. CN sends directly to you from now on

MIPv4 vs MIPv6

MIPv6 = MIPv4 minus the Foreign Agent, plus route optimization.