Subject: Re: [MOBILE-IP] IPv6 handover document

From: "Hesham Soliman (EPA)" <[email-masked]>
Date: Fri, 18 Aug 2000 03:29:04 +1000

Hi Mohamed,

        * If we want to handle the case of fast handoff, we  should  get
some type of assistant from L2. If we want to go through this path ,  we
should specify the following types of handoff:

        1- Mobile Node assisted handoff.

           The MN by some means will detect that it has moved to a new
foreign environment, and it will send a router solicitation

           to acquire a router advertisement from the router(s) in the new
foreign sub-network. Their are two cases of sending
   router solicitation to the routers resides at the new foreign
sub-network.

           a- The MN may have connections to the new and old   foreign
sub-network.
       In this case the MN can send the router solicitation  directly to the
new foreign sub-network  and receive the router advertisement.

   b- The MN is not allowed to have multiple connections and it only have a
connection to the current sub-network. In this case

               we could send a tunneled router solicitation to the new
foreign sub-network using the current established link.
       The router advertisement should be tunneled back to the mobile node.

        => Agree 100 %

        -----Original Message-----
From: Linfeng Yang [ mailto:[email-masked] <mailto:[email-masked]> ]
Sent: Thursday, August 17, 2000 5:07 AM
To: [email-masked]
Subject: Re: [MOBILE-IP] IPv6 handover document

        > =>Yes I think that is important, but also just as important is to
> separate fast, smooth and seamless handoffs from each other. I believe
> the basic MIPv6 already provides smooth handoffs (as far as routing goes).

        Here is my understanding about the different between fast, smooth
and
seamless handoff. Please correct me if I am wrong.

        I feel smooth handoff and seamless handoff are the same, they
describe the
handoff in the way what we want it achieve, i.e., minimized packet loss.
In basic MIPv6 smooth or seamless handoff is achieved through establishing
forwarding from a previous care-of address.

        Fast handoff on the other hand describe how we can achieve it. Fast
is
compared with basic MIPv6 in the sense that it will overcome the router
advertisement interval limit. Here I schemed one way of Fast handoff, I
call it Link Layer Assisted Fast Handoff.

        When MN is on idle movement, there is no need to perform fast
handoff,
since there is no packet loss issue.

        So MN will start fast handoff process when it is in active movement.

MN will constantly measure signal strength of message received from
current router, if it is lower than some threshold value (t1), MN will
then send a router solicitation message in hope of receiving a router
advertisement. In this way, MN can overcome the Router Advertisement
interval limit, thus speed up handoff process. MN may then receive
more than one Solicited Router Advertisement from neighboring routers.
After compare the signal strength of current router (sc) with the one
received earliest from new router (sn), MN can then decide to perform a
Handoff or not. If (sn + t2) >= sc, MN will perform handoff, otherwise
MN will send another Router Solicitation.  t2 is used to prevent
unnecessary handoff in the "ping pong" like movement within the overlap
of two router domain. After handoff new router becomes current default
router or MN, MN will then measure its signal strength from this router.

        We can see this is only local handoff, if accompanied with
establishing
forwarding from a previous care-of address, it can achieve even better
smoothness.

        Regards,

        Linfeng Yang
                Helsinki University of Technology
                Telecommunications Software and Multimedia Laboratory
                P.O.Box 9700, 02015 HUT, Finland
                Phone: +358 9 451 5250           Fax: +358 9 451 5351

---

From: Linfeng Yang <[email-masked]>
Date: Thu, 17 Aug 2000 20:48:34 +0300

Hi all,

I have to back to "work", even it is about 8:45 pm local time :-)

On Fri, 18 Aug 2000, Hesham Soliman (EPA) wrote: (Sorry, I deleted most of
the lines to keep the mail short.)

>         => Agree 100 %

I agree too. Still I feel, if we want fine tune handoff performance, we
need L2's assist. We should not isolate ourselves inside L3. We needn't go
deep to L2, but we need the interface from L2.

Linfeng Yang