Subject: RE: [Seamoby] Examples of CAR discovery

From: "Hesham Soliman (ERA)" <[email-masked]>
Date: Tue, 2 Apr 2002 17:55:38 +0200

> > => Do you have some proof that this assertion will
  > > hold in all cases? I mean the 100 ms time limit.
  > > I'm curious because I haven't seen anything published
  > > on that and I'd like to know under what assumptions
  > > this statement would hold.
  > 
  > Of course it does not hold in all cases.  But it does
  > hold in some cases of interest (e.g., 802.11), and we ought
  > to be making the protocol work for those cases.
  > 
  > I don't know what kind of assumptions you would want
  > to hear.  One easy assumption is, "the handover can
  > occur in under 100ms" -- but somehow I expect you
  > were asking for more...

=> Yes, I meant the assumptions related to 
movement detection. It seems that (in the absence
of Fast Handovers) we would need to crank up
the RA rate on all links to satisfy this time
limit. I don't know how network administrators
would like that. I don't think it would be a problem
for a small sized RA though (without all the options), 
the big RAs can be sent when the options are timing out.

Regs,
Hesham

_______________________________________________
Seamoby mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/seamoby

---

From: "Charles E. Perkins" <[email-masked]>
Date: Tue, 02 Apr 2002 08:19:20 -0800

Hello Hesham,

> the big RAs can be sent when the options are timing out.

I would not like to see the CAR discovery protocol depend
upon information within a periodic Router Advertisement.
I would like to see that it should be possible to initiate
CARDiscovery based on other signaling within the access
network -- perhaps not even IP-based signaling, but instead
something else which would initiate the handover process.

Stuff in the Router Advertisement could indeed supply
information to the mobile node.  That could be solicited,
and based on some sort of layer-two trigger within the mobile
node.  The CAR discovery could be done "long" before the
layer-2 trigger occurred (even as much as 100ms!).  Once
the trigger occurs, things have to happen fast, and it
would be nice if we had some candidates lined up.  If you
favor a periodic RA solution, that's fine with me too as
long as it isn't the only way that CARD can be used.

>> to be making the protocol work for those cases.

Actually, we ought to make the protocol "work" in _all_ cases.
Some cases might allow faster operation of the protocol, or
for it to be more useful.  But, just as with context transfer,
I would like to suggest that any such movement should not
_require_ CAR discovery -- only that it work faster and better
when it's available.  A mobile node should be able to attach
at a new access router with no context transfer, no CARD, and
in fact no context at all.  Everything could be built up
from scratch, at the cost of additional latency and loss of
performance.

One might not deploy some context transfers or CAR discovery
for carrier-pigeon layer-2s, but the protocol ought to still
work at least to the extent of not crashing the mobile nodes.

Regards,
Charlie P.

---

From: "Charles E. Perkins" <[email-masked]>
Date: Tue, 02 Apr 2002 08:19:20 -0800

Hello Hesham,

Regards,
Charlie P.