Subject: RE: [nemo] RE: draft-ietf-nemo-home-network-models-05

From: "Pascal Thubert \(pthubert\)" <[email-masked]>
Date: Tue, 14 Feb 2006 16:42:31 +0100

>
>> Note that NEMO does not require autoconf operations; and last that I
>>  know, a Cisco router will not auto-configure an address on a prefix
>>  that is shorter than 64.
>
>You seem to imply that a router _will_ auto-configure an address from
an
>RA with prefix /64.  YEs?  A "router" fixed or mobile shouldn't
>statelessly auto-configure an IPv6 address at all, be it prefix /64 or
>shorter, no?
>
[Pascal] Alex, the Mobile Router needs to auto-configure an address on
its egress interface as it roams... 

Pascal

---

From: Alexandru Petrescu <[email-masked]>
Date: Tue, 14 Feb 2006 17:32:01 +0100

Pascal Thubert \(pthubert\) wrote:
> 
>> 
>>> Note that NEMO does not require autoconf operations; and last 
>>> that I know, a Cisco router will not auto-configure an address on
>>>  a prefix that is shorter than 64.
>> 
>> You seem to imply that a router _will_ auto-configure an address 
>> from an RA with prefix /64.  YEs?  A "router" fixed or mobile 
>> shouldn't statelessly auto-configure an IPv6 address at all, be it 
>> prefix /64 or shorter, no?
>> 
> [Pascal] Alex, the Mobile Router needs to auto-configure an address 
> on its egress interface as it roams...

Right... I meant so too... my remark was not necessary in this context.

What stays clear to me about the aggregated mode is the following.

The aggregated mode is something not supported by RFC3963 because 
RFC3963 works when the Home Address is derived from the prefix on the 
home link.

draft-ietf-nemo-home-network-models-xx.txt:
"it makes sense for a Mobile Router to register using a Home Address
  from one of its own MNPs."

No, it makes no sense.

Otherwise I agree with you.

Alex

---

From: Thierry Ernst <[email-masked]>
Date: Wed, 15 Feb 2006 12:12:22 +0900

> RFC3963 works when the Home Address is derived from the prefix on the 

According to me, this is not so clear. RFC 3963 is a result of merging
several ideas, including the idea from Ryuji that the MR's HoA can be
taken from the MNP. This said, I don't have the technical deepth that
you have to evaluate if RFC 3963 allow it ort not. 

So, I cced Ryuji regarding this point.

>   from one of its own MNPs."

Well, to Alex it may not make sense. But it makes some sense for other
authors of RFC 3963.

> Otherwise I agree with you.

Thierry.

---

From: Ryuji Wakikawa <[email-masked]>
Date: Thu, 16 Feb 2006 01:56:07 +0900

Hi Alex and Thierry

Please check the RFC3964 section3
We said
    "A Mobile Router has a unique Home Address through which it is
    reachable when it is registered with its Home Agent.  The Home
    Address is configured from a prefix aggregated and advertised by its
    Home Agent.  The prefix could be either the prefix advertised on the
    home link or the prefix delegated to the Mobile Router. "

Some advantages using HoA derived from MNP.
The operators do not suffer from matching HoA from the home link and  
assigned MNP.
We can save a prefix/64 for just assigning HoA to MRs.

regards,
ryuji

---

From: Alexandru Petrescu <[email-masked]>
Date: Thu, 16 Feb 2006 17:37:51 +0100

Ryuji Wakikawa wrote:
> Hi Alex and Thierry
> 
> Please check the RFC3964 section3 We said "A Mobile Router has a
> unique Home Address through which it is reachable when it is
> registered with its Home Agent.  The Home Address is configured from
> a prefix aggregated and advertised by its Home Agent.  The prefix
> could be either the prefix advertised on the home link or the prefix
> delegated to the Mobile Router. "

Hi Ryuji, there can be no implementation that derives the HoA from MNP
and simultaneously is defended by proxy ND by HA.  Is there any?

> Some advantages using HoA derived from MNP. The operators do not
> suffer from matching HoA from the home link and assigned MNP. We can
> save a prefix/64 for just assigning HoA to MRs.

I'm not sure I understand how the matching hurts the operators.

I don't think addresses or prefixes are saved, can you explain?

Alex

---

From: Ryuji Wakikawa <[email-masked]>
Date: Mon, 20 Feb 2006 04:11:15 +0900

Alex

> and simultaneously is defended by proxy ND by HA.  Is there any?

I don't know how you can conclude like this..

SHISA can generate HoA from MNP.
MR can return home in some configuration.
When MR returns home, HA does not remove network route of MNP pointed  
to MR.
Thus, without proxy ND, MR can return home.

> I don't think addresses or prefixes are saved, can you explain?

You need /64 or shorter prefix to assign HoA.

regards,
ryuji

---

From: Alexandru Petrescu <[email-masked]>
Date: Mon, 20 Feb 2006 18:07:15 +0100

Ryuji Wakikawa wrote:
 >>> Hi Alex and Thierry Please check the RFC3964 section3 We said "A
 >>>  Mobile Router has a unique Home Address through which it is 
reachable when it is registered with its Home Agent.  The Home Address 
is configured from a prefix aggregated and advertised by
 >>>  its Home Agent.  The prefix could be either the prefix
 >>> advertised on the home link or the prefix delegated to the Mobile
 >>> Router. "
 >>>
 >>
 >> Hi Ryuji, there can be no implementation that derives the HoA from
 >>  MNP and simultaneously is defended by proxy ND by HA.  Is there any?
 >
 > SHISA can generate HoA from MNP. MR can return home in some 
configuration. When MR returns home, HA does not remove network route
 >  of MNP pointed to MR. Thus, without proxy ND, MR can return home.

Mobile IPv6 and NEMO require HA to do proxy ND for the Home Address.  If
some HA does not do proxy ND for the Home Address then it's a little bit
incomplete.

That's why I was saying that one can't implement a Mobile IPv6/NEMO HA
doing proxy ND for a Home Address derived from the MNP.

 > You need /64 or shorter prefix to assign HoA.

You need a /64 prefix for all the MRs and MHs (and maybe some LFNs too)
present on the home link.  It is at least needed to put something in the
RAs the HA sends on its home link (otherwise MR can't realize it is back
home).

draft-xx:
 > To properly identify the Home Network, the MR must expect a shorter 
prefix than that of the Mobile Network from which the Home Address was 
formed.

This is not implementable.

Most prefix match in routing is a "longest-match".  A shorter prefix
can't be really matched  unless a precise bound is specified, but then
it's an "exact match".

I.e. if a MR in "aggregated mode" attaches to a network whose first two
bits match its Home Address, but all the other (3rd up to 63rd) bits
don't match, will falsely believe it is at home.

Alex