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Re: shim6 control packets coming from unkown locators




El 18/10/2007, a las 19:38, Alvaro Vives Martinez escribió:


While Mobile-IP is outside of the scope of the SHIM6 WG (above from the
"do no harm" level) here are some considerations.

I think it is possible to use SHIM6 in a mobility context without
allowing update messages from unknown locators. My take is that any
complete IP mobility solution needs some form of rendez-vous point, such
as a home agent or set of home agents. That is necessary in order to
allow initial contact and also to allow for simultaneous movement of two
communicating peers. Once the MNs have such a fixpoint (or set of
fixpoints) then it is trivial to have the update messages be sent with a source locator that is already known to the peer; if all locators have changed at once there is still the home locator which the MN can use by
tunneling the update message via its home agent(s).

Have you considered such an approach in your work?

Yes, in fact, actual work seems to go in that direction but following this path we reach an almost-MIPv6 solution. The SHIM6 only approach had some advantages over MIPv6 if it does not use the rendez-vous point. A balance
among them seems to be the key.


I guess that the point is that you cannot use SHIM6 as a mobility solution if you don't also use some form of anchor point (Home Agent in MIP, RVS in HIP), since those are needed for simoultaneous movement and for receiving incoming communications. So once you have this anchor point, you can use it also to send the UPDATE messages. The only difference would be that in case of a failure on the HA, ongoing communication would fail, as oposed to the case where you can send the UPDATEs directly where the communication would survive.

So, the benefit achieved with supporting UPDATE mesages from unknown locator would be this enhanced fault tolerance for this particular case.

(Of course, there may be other benefits as the ones pointed out by Jari but in other scnarios not related to mobility)

Regards, marcelo


Best regards,
Alvaro Vives
Consulintel



    Erik






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