Minor issue with MN advertisement sequence number handling

Section "2.4.4. Sequence Numbers and Rollover
Handling" of RFC3344
(and bis) says:

"If a mobile node detects two successive values of the
sequence number
in the Agent Advertisements from the foreign agent with
which it is
registered, the second of which is less than the first and
inside the
range 0 to 255, the mobile node SHOULD register
again."

If the FA is restarted before it has sent a second
advertisement the
MN will not reregister. The text should either say "...
the second is
less than or equal to the first ..." or alternatively
"... the second
is 0 or less than the first ...".

Regards,
Björn Andersson

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Hi Bjorn,
I do not see any problem in the text. May be I am missing
something. More inline.

Regards,
Ahmad
 

> -----Original Message-----
> From: Bjorn Andersson [mailto:bjorniki.fi] 
> Sent: Thursday, March 22, 2007 3:12 PM
> To: mip4ietf.org
> Subject: [Mip4] Minor issue with MN advertisement
sequence 
> number handling
> 
> Section "2.4.4. Sequence Numbers and Rollover
Handling" of 
> RFC3344 (and bis) says:
> 
> "If a mobile node detects two successive values of
the 
> sequence number in the Agent Advertisements from the
foreign 
> agent with which it is registered, the second of which
is 
> less than the first and inside the range 0 to 255, the
mobile 
> node SHOULD register again."
> 
> If the FA is restarted before it has sent a second 
> advertisement the MN will not reregister. 

[Ahmad]
Why? Can you please explain.

> The text should 
> either say "... the second is less than or equal
to the first 
> ..." or alternatively "... the second is 0 or
less than the 
> first ...".
> 
> Regards,
> Björn Andersson
> 
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> 

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On 3/23/07, Ahmad Muhanna <amuhannanortel.com> wrote:
> Bjorn Andersson [mailto:bjorniki.fi]:
> > If the FA is restarted before it has sent a
second
> > advertisement the MN will not reregister.
>
> Why? Can you please explain.

1. FA starts
2. FA sends advertisement with sequence number 0
3. MN registers via FA
4. FA restarts
5. FA sends advertisement with sequence number 0
6. Sequence number is equal to, not less than, previous
sequence
number. MN does not register.
7. MN sends packet to FA for tunneling, but MN is not
registered to FA
(since the FA restarted after the registration), so the FA
does not
tunnel the packet to the HA. This will be the case until
the
registration expires.

But as I said, it is minor issues since it quite unlikely to
occur,
but it could still be improved and fixed in the RFC. Or am I
missing
something?

  Bjorn

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Now I understand what you meant by "If the FA is
restarted before it has
sent a second advertisement"
I also agree that this case is very unlikely.

Regards,
Ahmad
 

> -----Original Message-----
> From: bjonderssongmail.com [mailto:bjonderssongmail.com] On 
> Behalf Of Bjorn Andersson
> Sent: Friday, March 23, 2007 8:27 AM
> To: Muhanna, Ahmad (RICH1:2H10)
> Cc: mip4ietf.org
> Subject: Re: [Mip4] Minor issue with MN advertisement 
> sequence number handling
> 
> On 3/23/07, Ahmad Muhanna <amuhannanortel.com> wrote:
> > Bjorn Andersson [mailto:bjorniki.fi]:
> > > If the FA is restarted before it has sent a
second 
> advertisement the 
> > > MN will not reregister.
> >
> > Why? Can you please explain.
> 
> 1. FA starts
> 2. FA sends advertisement with sequence number 0 3. MN

> registers via FA 4. FA restarts 5. FA sends
advertisement 
> with sequence number 0 6. Sequence number is equal to,
not 
> less than, previous sequence number. MN does not
register.
> 7. MN sends packet to FA for tunneling, but MN is not 
> registered to FA (since the FA restarted after the 
> registration), so the FA does not tunnel the packet to
the 
> HA. This will be the case until the registration
expires.
> 
> But as I said, it is minor issues since it quite
unlikely to 
> occur, but it could still be improved and fixed in the
RFC. 
> Or am I missing something?
> 
>   Bjorn
> 

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