Subject: Re: [nemo] Rechartering: FMIPv6 for NEMO

From: Syam Madanapalli <[email-masked]>
Date: Thu, 10 Nov 2005 20:12:04 +0530

Hi,

I see there is at least one scenario where the current FMIPv6
may not be sufficient for session continuity for the nodes in the
Mobile Network when the MR is moving from Home Network.

When MR is moving from Home Network it is required to
establish a tunnel from PAR to NAR for the Mobile Network
Prefixes along with the MR's pCoA (i.e. MR's HoA).

Also we can think of optimization here as PAR and Nemo HA
may be on the same link and even may be on the same box,
so we can eliminate the tunnel between PAR and MR, and
establish the tunnel between Nemo HA and MR. This optimization
may require further analysis to check for other impacts.

The other scenario is where we may need updates to FMIPv6 is
when MR delegates any prefixes on a Foreign Network and moves
to another Foreign Network before the expiry of the prefixes
delegated on the previous link.

I think the problems in applying the FMIPv6 to NEMO are simple
And can be easily fixed, so it is good idea to include this in the
charter for known problems. I am writing a draft on this, I will let
you know when I done with it.

Thanks,
Syam

> Dear all,
>
> Shouldn't we take a look at how FMIPv6 should work for NEMO Basic
> Support ? Isn't there any other protocol we need to fx ?
>
> Thierry

---

From: Chan-Wah NG <[email-masked]>
Date: Fri, 11 Nov 2005 01:24:04 +0800

Hello Syam,

True, as I'd mentioned in my previous response to Thierry, when the MR
is a nAR or pAR, the FMIP gets very inefficient, which might defeat the
purpose of having FMIP at all.

However, conceiviably, that will be countered when a RO mechnaism is in
place.  I don't know whether we need various different optimization
schemes for each protocol that will run together with NEMO-BS, or simply
develop a general NEMO-RO solution.

/rgds
/cwng

---

From: Syam Madanapalli <[email-masked]>
Date: Thu, 10 Nov 2005 23:54:35 +0530

Hello Wah-Wah,

> purpose of having FMIP at all.

The scenario I mentioned is about FMIPv6 Client implementation on MR.
If PAR and NAR support on MRs is inefficient then one can choose not to
do that.

- Syam

---

From: Chan-Wah NG <[email-masked]>
Date: Fri, 11 Nov 2005 02:48:47 +0800

> If PAR and NAR support on MRs is inefficient then one can choose not to

Opps, sorry. Still have not receovered from the change of time-zone, I
guess :)  Anyway, see comments in-line.

> > > may require further analysis to check for other impacts.

Is this any different from a MIPv6 mobile host leaving its home network?
I can't believe FMIP has not considered it.  Anycase, should one send
FBU to the router on its own home link when a BU is sufficient?  Make no
sense to do that.

> > > delegated on the previous link.

Maybe, if we do have a mechanism for prefix delegation from foreign
network.

Even assuming we do have one, I don't see any problem here.  It is an
implementation consideration.  Implemented correctly, it will work
without any need for any changes for FMIP:

(a) When MR is at pAR, it has CoA=MR.pCoA.  In addition, it obtains
prefix P from the foreign network. 

(b) pAR, should now know that packets sent to P should be routed to
MR.pCoA

(c) When MR moves to nAR, its send FBU to pAR, setting up a binding
between MR.nCoA and MR.pCoA

(d) When pAR receives a packet addressed to P, it routes the packet to
MR.pCoA (just like (b)).  To route packet to MR.pCoA, the next hop
interface is the tunnel to MR.nCoA.  So, packets sent to prefix P is
correctly forwarded to MR.nCoA.

/rgds
/cwng

---

From: Syam Madanapalli <[email-masked]>
Date: Fri, 11 Nov 2005 00:37:36 +0530

Hi,

"Every problem in computer science can be solved by adding a level of
indirection."
-Kaufman

I see your point.
What if the routing entry expires and does not know where to send.
And as you said it depends the implementation look up. Some may
look for P:: finds MR is the next hop, looks for Neigbhor cahce, may not
present and gives up.

Tunnel look up may depends for /128 bit addresses and may be a good
idea to explicity associate a prefix to the tunnel like in NEMO Basic
Support.

Thanks,
Syam

---

From: Chan-Wah NG <[email-masked]>
Date: Fri, 11 Nov 2005 03:33:13 +0800

> "Every problem in computer science can be solved by adding a level of
:).  Sometimes adding a level of indirection IS THE solution.

> look for P:: finds MR is the next hop, looks for Neigbhor cahce, may not

The foriegn network is delegating prefix to the MR.  It is the
responsibility of the foreign network to ensure the AR's routing table
entry continues to be valid for as long as the prefix is delegated.
Thus, unlikely for there to be a case where the routing entry has
expired before the delegated prefix is expired.

> idea to explicity associate a prefix to the tunnel like in NEMO Basic

Of-course, I am just uncertain whether it is worth the effort to expand
a protocol for this, especially when correctly implemented, the original
mechanism works.

Having said that, it might a good idea to wait until there is a clear
prefix delegation mehcniam available at the foreign network.  Because,
in that case, the FMIP would most likely need to to be expanded anyway
to to support the transfer of prefix from pAR to nAR, or to pre-delegate
new prefix at nAR.  HI and HIACK would most likely be needed to change
as well.

/rgds
/cwng

-- 
Chan-Wah NG <[email-masked]>
Panasonic Singapore Labs

---

From: Alexandru Petrescu <[email-masked]>
Date: Mon, 14 Nov 2005 17:47:38 +0100

Syam Madanapalli wrote:
> Hi,
> 
> I see there is at least one scenario where the current FMIPv6 may not
>  be sufficient for session continuity for the nodes in the Mobile 
> Network when the MR is moving from Home Network.
> 
> When MR is moving from Home Network it is required to establish a 
> tunnel from PAR to NAR for the Mobile Network Prefixes along with the
>  MR's pCoA (i.e. MR's HoA).

Is it "required"?  It is sufficient for the PAR to establish a tunnel
from PAR to NAR about the MR's pCoA and MR's nCoA, no need to establish
a tunnel for each LFN's address (and not any address from that MNP), right?

Because packets from HA to LFN are encapsulated to MR's CoA (not to
LFN's address), so it is sufficient for PAR and NAR to deal with that
MR's CoA and packets do arrive fast at LFN's HoA.

> Also we can think of optimization here as PAR and Nemo HA may be on 
> the same link and even may be on the same box, so we can eliminate 
> the tunnel between PAR and MR, and establish the tunnel between Nemo
>  HA and MR. This optimization may require further analysis to check 
> for other impacts.

If the NEMO HA is co-located with a PAR then it means that only one
handover can happen fast: between home and the next AR; all the other
handovers (between various ARs) will not benefit from this enhancement,
right?

> The other scenario is where we may need updates to FMIPv6 is when MR
>  delegates any prefixes on a Foreign Network and moves to another 
> Foreign Network before the expiry of the prefixes delegated on the 
> previous link.

MR wouldn't delegate any prefix to the Foreign Network.  Do you mean
that the Foreign Network delegates prefixes to MR?

> I think the problems in applying the FMIPv6 to NEMO are simple And 
> can be easily fixed, so it is good idea to include this in the 

Would it be possible to clarify a little bit more here before making it
into a draft?

Alex

---

From: Syam Madanapalli <[email-masked]>
Date: Wed, 16 Nov 2005 10:05:31 +0530

Hi Alex,

> MR's CoA and packets do arrive fast at LFN's HoA.

The scenario I was talking about is when MR is moving from Home Network
(HN) to Foreign Network (FN).

Even in this scenario, if implemented correctly i.e. PAR looks up the routing
for the packet destined to an LFN, finds that next-hop is MR, and then it must
find that any packet destined to MR needs to be tunneled to MR's NCoA,
then there is no problem in applying FMIP.
I

> handovers (between various ARs) will not benefit from this enhancement,

That's right. Also if HA and AR are the same link we can apply this
but one may loose some packets that might have already arrived at AR.
I think in most cases, the movement between HN and FN happens frequently
than FN to FN.

> that the Foreign Network delegates prefixes to MR?

Yes

Thanks,
Syam