Subject: [mobile-ip] Low Latency MIPv4 Handoffs: PreReg Tunnels

From: Jonathan Wood <[email-masked]>
Date: Fri, 2 Nov 2001 13:23:22 -0800 (PST)

Tunnel use and management needs to be better defined. Tunnels are
usually point-to-point, and so need to be explicitly set up
by both endpoints. Hosts will generally not decapsulate anything
sent to them if they do not have a tunnel set up with the
corresponding host.

For PreReg, this means that FAs will need to explicitly set up
tunnels with neighboring FAs. Are these tunnels created dynamically
or just once when each FA starts up? How are they managed and
configured?

Once up, exactly what is sent through the tunnel? It looks like
agent advertisements and solicitations from the MN are. Is there
anything else?

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From: "Karim El-Malki (ERA)" <[email-masked]>
Date: Mon, 5 Nov 2001 20:04:08 +0100

> sent to them if they do not have a tunnel set up with the

The minimal requirement is that FAs have a manually configured
list of neighbouring FAs (i.e. FAs to which MNs could hand-off to).
The FA routers which get an encapsulated agent advertisement
from one of the FA neighbours would decapsulate and deliver the packet.
As long as there is some pre-configured security between the routers,
as required in the draft, it should not be a problem to enable the
tunneling.

> or just once when each FA starts up? How are they managed and

If the implementation requires a tunnel configuration then, assuming
manual configuration as above, a tunnel would be configured for each
entry in the list of neighbouring FAs. This depends on the implementation
and is only needed for target triggers.

> agent advertisements and solicitations from the MN are. Is there

It's only nFA agent advertisements that go through the tunnel when
there's a target-trigger. I'm assuming that the MN solicitation
directly to nFA is out.

/Karim

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From: Jonathan Wood <[email-masked]>
Date: Mon, 5 Nov 2001 17:53:45 -0800 (PST)

> and is only needed for target triggers.

OK, so the tunnels are static, and are configured by some
mechanism out of the scope of the draft. Calling this out in
the draft might help implementors.

> there's a target-trigger. I'm assuming that the MN solicitation

I should have written "agent advertisements and registration replies
to the MN." The latter, however, now seems to be an open issue,
as discussed in a seperate email.

Jonathan