Subject: [nemo] questions about nemo basic support

From: Hiroyuki Ohnishi <[email-masked]>
Date: Tue, 18 Jan 2005 22:07:06 +0900

hi all,

I have some questions about NEMO basic support.

-In the case that MR receives BA with Status=0 and Rbit=off in response
for de-registarion, should the MR think the de-registration as failure
one?

-In section 8.5, it says "A Mobile Router MUST implement all
requirements for IPv6 Mobile Nodes as described in Section 8.5 of [1].".
 Do MRs support MPS/MPA?  If so, in which situation do MRs use MPS/MPA?

-The draft defines two mode explicit mode and implicit mode.
 Is there any case in which MRs use these two modes selectively?
 In which situation do MRs use this function? roaming situation?

Best regard,

-- 
Hiroyuki Ohnishi <[email-masked]>

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From: Alexandru Petrescu <[email-masked]>
Date: Tue, 18 Jan 2005 19:55:30 +0100

Hiroyuki Ohnishi wrote:

> -In the case that MR receives BA with Status=0 and Rbit=off in 
> response for de-registarion, should the MR think the de-registration 
> as failure one?

I think it should only think that the MR's Home Address was correctly
de-registered and assume nothing about the MNP being or not being
de-registered.

> requirements for IPv6 Mobile Nodes as described in Section 8.5 of 
> [1].". Do MRs support MPS/MPA?  If so, in which situation do MRs use 
> MPS/MPA?

Yes, in theory MR MUST support MPS/MPA just like MH would do.  The above
phrase is more saying that a MR implementation is largely derived from
an existing MH implementation that does RFC3775.

MR may use MPS/MPA in situations where a home link get renumbered.  Just
like MH uses the same MPS/MPA to learn when things at home change and it
does not have an opportunity to come home.  In theory this may induce a
change in the Home Address too (stateless autoconf), but I'm not sure
it's mentioned in RFC3775.

I think TJ may have a better explanation of why and when MPS/MPA are used.

> -The draft defines two mode explicit mode and implicit mode. Is there
>  any case in which MRs use these two modes selectively?

Using the two modes "selectively"?  Yes, it should use only one of them.

Implicit mode is more appropriate when a routing protocol is used too.
That is needed if there are many MRs, the home network is large and the
moving network is large too.

Explicit mode is more appropriate when all routing is done with Mobile IP.

> In which situation do MRs use this function? roaming situation?

MR can use either implicit or explicit mode for any roaming situation.

Am I addressing your questions ok?

Alex

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From: Vijay Devarapalli <[email-masked]>
Date: Tue, 18 Jan 2005 11:33:26 -0800

> for de-registarion, should the MR think the de-registration as failure

its a weird case. did the earlier successful BAs have the
R bit set?

if the earlier successful BA had the R bit set, then it
means the HA supports Mobile Routers. in this case, if the
binding cache for MR's HoA is removed, all the associated
routes for MNPs are also removed. so it is a successful
registration.

from section 6.7

    In addition, the Home Agent removes the bi-directional tunnel and
    stops forwarding packets to the Mobile Network.  The Home Agent
    should keep all necessary information to clean up whichever routes it
    installed, whether they come from an implicit or explicit source.

    In Explicit mode, the Home Agent MUST ignore any Mobile Network
    Prefix Options present in the de-registration Binding Update.

its a bug in the HA implementation if the HA set the R bit
in the earlier BAs and not in the de-registration BA.

if the earlier BA did not have the R bit set, then the HA
does not support Mobile Routes at all. so there is no issue.

Vijay