[support] Binding Update problem

[Eriza Hafid Fazli]

Dear all,

We are currently using your NEMO implementation in our laboratory test-bed.
The network architecture is as follows:

           HA 
		|
		|
--------------------------
   |				|
   |				|
  AR1			     AR2
   |				|
   |________   _________|
            | |
	       MR
		  |
		  |
		 MNN

The MR has three Ethernet interfaces, eth1, eth2, and eth3. eth1 and eth2
are used for connection using access routers, AR1 and AR2 respectively,
whereas eth3 is used in the mobile network. The MR moves from AR1 to AR2,
with the handover triggered by stopping router advertisement (radvd) from
AR1, and starting one in AR2.

We collected the traffic trace at AR1 and AR2, and discovered that the
Binding Update (BU) is sent through AR1, whereas the Binding Acknowledgment
(BA) comes from AR2. We made additional tests by turning down the Ethernet
interface of AR1 in addition to stopping radvd. In this case the BU never
arrived at the HA and no handover took place.

We thought that this behaviour may happen because the MR keeps adding a new
default router entry in its routing table, every time it receives a new
router advertisement.

Is this the intended behaviour of the code? We had an expectation that the
BU should have been sent using AR2, since for instance in the case that the
handover is triggered due to AR1 failure, all communication from/to the MR
will be completely cut as no handover will ever take place.

We are using UMIP userland version 0.4, patched to enable network mobility,
running on Fedora Linux with kernel 2.6.23 on the MR and HA.

Thank you and best regards,
Eriza

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Eriza Hafid Fazli
TriaGnoSys GmbH 
Argelsrieder Feld 22
82234 Wessling-Oberpfaffenhofen 
Germany
 
Tel: +49 8153 88678-209 
Fax:+49 8153 88678-1
   
email: eriza.fazli at triagnosys.com 
www: http://www.triagnosys.com
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Geschäftsführer: Matthias Holzbock, Dr. Axel Jahn, Dr. Markus Werner

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