Subject: [Pana] comments on issue 108

From: Yoshihiro Ohba <[email-masked]>
Date: Tue, 27 Jul 2004 17:10:58 -0400

On Issue108: Session migration from one interface to another:

It is not a rare case that a device with multiple interfaces switches
from one interface to another.  This case actually frequently happens
to me.  I use a note PC that has a wired Ethernet interface and a
Wi-Fi interface.  While I am working in my office in a building, I
connect to a subnet from the wired Ethernet interface because wired
Ethernet is physically more stable than Wi-Fi.  When I have a meeting
in a nearby conference room in the same building, I remove the
Ethernet cable from the PC, bring the PC to the conference room and
connect to the same subnet through the Wi-Fi interface (there is no
wired Ethernet facility in the conference room).

For simplicity, let me assume MAC address is used as device-id.  There
are three ways for how to deal with this case in PANA (the same
discussion applies to the case where IP address is used as device id):

Method A: Start PANA from scratch when interface switching occurs.  Of
course PANA already supports this method.  However, this requires EAP
authentication when interface switching occurs.

Method B: Utilize PANA mobility optimization when interface switching
occurs.  The PaC performs PANA mobility optimization but with changing
the MAC address, i.e., PANA mobility optimization is performed by
using the MAC address assigned to the interface used after the
interface switching.  The current PANA specification does not prohibit
(and does not explicitly support) this method.

Method C: Use PANA-Update-Request/Answer exchange to update the device
identifier.  This is not supported in the current PANA specification.
This is more optimized but there might be some security issue since
this does not change the AAA-Key after the MAC address change.

The issues would be:

- Whether we should explicitly mention Method B in the current
specification or not.  My opinion is having some explicit text on
interface switching might be useful.

- Whether PANA should support Method C.  My opinion is PANA should not
support Method C unless we are sure there is no security issue in
Method C.

Regards,

Yoshihiro Ohba

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