I came up with the answer to your question. It takes some work, but it's
there. Review draft-ietf-mobileip-ipv6-12.txt
One the router advertisements (sections 4.1, 5.6, 5.7, etc), the routers
tell you whether they are willing to be a home agent and/or a foreign
agent. If no neighboring system is willing to be your home agent but there
is a foreign agent, you are roaming. If there is someone willing to be a
home agent but you cannot authenticate with him, your previous home agent
remains your home agent, and you are roaming. If someone advertises that he
will be your home agent and you can authenticate with him, you are at home.
The one thing that bothered me as I read this was an implicit assumption,
perhaps on my part and perhaps on the author's part, that the device has to
somehow come in contact with its home agent as a neighboring device once in
a while. I can think of a number of scenarios in which this may not be true
- imagine a case where you have a telephone mailed to you on the road
because the old one broke. You certainly want to be able to tell the new
phone the old phone's information and have it stick. Or imagine a device
which is permanently roaming - it never actually is at home. You would want
to configure a home agent address somehow. I trust that in these cases the
protocol is not required.
At 09:37 AM 10/12/00 +0900, SungJin Lee wrote:
>I got confisued while i was reading MIPv6 standards and
>have a couple of question with cases like following. The
>It is assumed that the MIPv6 node use stateless autoconfiguration.
>Let me know if i lost some in MIPv6 and IPv6 RFC.
>
>Q.1 A MIPv6 node moved to foreign link. The MIPv6 node restarts
> the system there and receives router advertisements with
> foreign network prefix.
>
> How do the MIPv6 node detect if it is located in foreign link ?
> isn't it could be normal autoconfiguration as in the home llink ?
>
>Q.2 A MIPv6 node located in it's home link. The node got an IP address
> with stateless autoconfiguration. At a time the router changed
> the home link
> prefix and multicast the router advertisement with new prefix.
> After the home link prefix ifetime expired or before the life time
> expired, it received router advertisement with new prefix.
>
> Why doesn't the IPv6 node think it's located in foreign link when it
> received ? isn't it possible the IPv6 node to think it's moved to
> a foreign
> link and start MIPv6 process ?
>
>
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