Subject: RE: [nemo] RE: Issue 6

From: "Pascal Thubert (pthubert)" <[email-masked]>
Date: Wed, 23 Jul 2003 09:23:32 +0100

> -----Original Message-----
> From: Vijay Devarapalli [mailto:[email-masked]]
> Sent: mardi 22 juillet 2003 23:07
> To: Pascal Thubert (pthubert)
> Cc: Jongkeun Na; Kent Leung (kleung); S. Felix Wu; [email-masked]
> Subject: Re: [nemo] RE: Issue 6
> 
> "Pascal Thubert (pthubert)" wrote:
> >
> > Can't we just drop code 143 and accept the implicit whatever?
> >
> > There are at least 3 cases of implicit with different problems
> > associated:
> >
> > - static route: HA could check for a static route but it does not
> > control it. The admin may change it. Should we drop the binding
then?
> > - prefix table: source of our recent discussion on how it compares
with
> > other IGPs
> > - dynamic route: HA does not have the associated routes yet. No clue
if
> > there will eventually be one? Should we drop the binding if none
come
> > up?
> >
> > You see code 143 is tricky to use for not much added value.
Sugestion,
> > get rid of the last paragraph and if the code. In implicit mode, the
HA
> > does its best and that's it.
> 
> I disagree. it is always good to have an error message
> if something goes wrong. the MR shouldnt assume the HA
> has setup forwarding for the Mobile Network, when the
> HA actually didnt. the MR has now way of figuring out
> whats wrong, if packets from the CN to MNNs are dropped
> at the HA.

Then you do not want implicit mode at all. Because even if the HA has
some prefixes listed for that MR in its prefix table, the may not be
correct, or complete. Unless the HA lists the prefixes it knows of in
the B-Ack. Again I'm talking about the real implicit, the one with
prefix table, as opposed to static routes or IGP over MRHA.

Consequence, if you want full checking, you need implicit, plus the list
of accepted prefixes in the B-Ack if not all.

In the latter case, (IGP over MRHA) the HA can not know at B-Ack time
whether it will ever get the right routes, or whether the MR will try
anything. So the code 143 is straight infeasible.

Pascal