Subject: [mobile-ip] Reverse tunneling issues

From: George Tsirtsis <[email-masked]>
Date: Thu, 28 Mar 2002 07:33:00 -0500

There is a general problem with reverse tunneling and packet loss, which
applies to MIPv4 and I think MIPv6 also. Draft-oneill-mip-revtun-ho-00.txt
exposed the problem that we faced while trying to implement reverse
tunneling in MIPv4.

It boils down to the fact that there is no "smooth" handoff equivalent when
the MN operates in reverse tunneling mode. The above draft talks about how
packets can be lost during handoff and lists a number of different ways of
solving the problem from simple configuration changes in the HA, to possible
extensions to Mobile IP signaling.

As I said, the above work has been done in the context of MIPv4 but similar
issues may apply to MIPv6, I am still trying to determine this...

Is the WG interested in working on this issue? Has anyone else faced or
thought of similar problems with packet loss in reverse tunneling?

I would appreciate your feedback/thoughts.

Ragards
George

---

From: "Hesham Soliman (ERA)" <[email-masked]>
Date: Thu, 28 Mar 2002 13:46:39 +0100

George,

Haven't read the draft, but do the problems
disappear with triangular routing? 
Or would you still have the same problem for inbound
traffic?

Another question, for MIPv4, is it more due to the fact
that reverse tunnelling is done by the FA? Because 
this doesn't exist in v6.

Sorry I don't mean to hammer you with questions but
I'm just curious about the main reasons. 

Hesham

  > -----Original Message-----
  > From: George Tsirtsis [mailto:[email-masked]]
  > Sent: Thursday, March 28, 2002 1:33 PM
  > To: [email-masked]'
  > Cc: [email-masked]'; [email-masked]'
  > Subject: [mobile-ip] Reverse tunneling issues
  > 
  >

---

From: George Tsirtsis <[email-masked]>
Date: Thu, 28 Mar 2002 13:00:52 -0500

inline

-----Original Message-----
From: James Kempf [mailto:[email-masked]]
Sent: Thursday, March 28, 2002 5:35 PM
To: [email-masked]
Cc: [email-masked]; [email-masked]
Subject: Re: [mobile-ip] Reverse tunneling issues

George,

>
> GT> Inbound traffic is ok because of PFANE in MIPv4 and BU to oldAR in
MIPv6
> so, yes this is only when you do reverse tunneling. Actually the
packet loss
> is mostly at the HA side. For example if the HA has a reverse tunnel
entry
> from CoAx it can accept packets coming from that CoA. If now the MN
moves,
> it will send a new reverse registration for CoAy. If this reaches the
HA
> while packets from the oldCoAx are still on their way to the HA, these
> packets will thrown on the floor (because the HA replaces old binding
with
> new one).

I think with FMIPv6 you can defer the BU to the HA until the traffic
slows down.

GT> And what will that do? and when will the traffic slow down? I guess I do
not understand what you are saying.

Also, what about registering CoAy as an alt-CoA initially?

GT> From what I understand about alt-COAs they do replace your bindings,
don't they? so you still have the problem.

> And there is a bit more loss if the CoAy registration is
> immediately followed by data packets because of difference between
fast and
> slow paths in the HA...

I'm not sure I understand this, maybe I need to read Alan's draft.

GT> It may be a good idea...

George