[Bluez-devel] PAN and bridge problem when bnep0 disconnects before bnep1

[Bluez-devel] PAN and bridge problem when bnep0 disconnects before bnep1

[Christoph Scholz]

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Hi,

I experienced the same problem as Matthias Thomae. I already posted this
to the mailing-list some time ago (see attached mail). It is actually a
problem with the Linux bridge code. It does not seem to be able to cope
with multiple interfaces using the same MAC-Address.

Unfortunately, I have no real solution to the problem.

Regards,

Christoph

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From: Christoph Scholz <scholz@cs.uni-bonn.de>
To: bluez-users@lists.sourceforge.net
Subject: Problems with Bridging and PAN Profile
Date: Fri, 09 Jan 2004 14:49:02 +0100
Message-ID: <1073656142.3037.32.camel@willie.informatik.uni-bonn.de>

Hi all,

I am experiencing problems with the Linux transparent bridge
implementation combined with BlueZ. Probably it is not BlueZ' fault but
related. Just wanted to know if someone else knows about this problem.

I used a very simple PAN scenario with one master (GN) and two slaves
(PANU). The GN runs a Linux bridge and the individual devices for the
slaves are added to the bridge by using the "/etc/bluetooth/pan/dev-up"
script. All similar to the PAN Howto.

After establishing the two connections everything works fine. But after
disconnecting the first slave (the one that was connected to the master
first) communication between the master and the remaining slave does not
work any more. Closer investigation shows that the failure is found in
the bridge device that does not accept the received frames any more.
Interestingly, when runing tcpdump on the bridged device everything
seems to work fine again. This is probably due to the bridge device
entering promiscuous mode. Probably, the problem is related to the
following message found in /var/log/messages:

"bnep1: attempt to add interface with same source address."

This is due to the fact that all the bnep interfaces own the same MAC
address (= BD_ADDR of the Bluetooth device).

It seems the Linux bridge does not work reliably with duplicate mac
addresses on its interface. 

Does anyone of you experienced similar problems? Any ideas on how to
resolve this?

Thanks.


Regards,

Christoph
-- 
Christoph Scholz <scholz@cs.uni-bonn.de>
University of Bonn, Institut of Computer Science IV
Römerstraße 164,
D-53117 Bonn, Germany
Phone: +49 228 73 4117
Fax: +49 228 73 4571
http://web.informatik.uni-bonn.de/IV/Mitarbeiter/scholz/

Re: [Bluez-devel] PAN and bridge problem when bnep0 disconnects before bnep1

[Diego Liziero]

Maybe I'm hitting a related bug.
I'm trying to setup a PAN bridge with kernel 2.6.6-rc3-mm2
with ipv6 enabled (same result with other 2.6 kernels) and when I try
to add bnep1 to the bridge I got the following error:

# brctl addif pan0 bnep1
br_add_interface: File exists

Everithing works fine with 2.4.* kernels (without ipv6).

It seems like in linux-2.6.* + ipv6 it's impossible to have
two bnep interfaces in the same bridge.

Any suggestion?

Regards,

Diego.

On Thu, 2004-05-13 at 14:51, Christoph Scholz wrote:
> Hi,
> 
> I experienced the same problem as Matthias Thomae. I already posted this
> to the mailing-list some time ago (see attached mail). It is actually a
> problem with the Linux bridge code. It does not seem to be able to cope
> with multiple interfaces using the same MAC-Address.
> 
> Unfortunately, I have no real solution to the problem.
> 
> Regards,
> 
> Christoph




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Re: [Bluez-devel] PAN and bridge problem when bnep0 disconnects before bnep1

[Diego Liziero]

I've solved my issue.

Mine was just a bridge bug introduced in 2.6.6
and already solved.

http://lists.osdl.org/pipermail/bridge/2004-May/000321.html

Regards,

Diego.

On Thu, 2004-05-13 at 16:07, Diego Liziero wrote:
> Maybe I'm hitting a related bug.
> I'm trying to setup a PAN bridge with kernel 2.6.6-rc3-mm2
> with ipv6 enabled (same result with other 2.6 kernels) and when I try
> to add bnep1 to the bridge I got the following error:
> 
> # brctl addif pan0 bnep1
> br_add_interface: File exists
> 
> Everything works fine with 2.4.* kernels (without ipv6).
> 
> It seems like in linux-2.6.* + ipv6 it's impossible to have
> two bnep interfaces in the same bridge.
> 
> Any suggestion?
> 
> Regards,
> 
> Diego.




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Re: [Bluez-devel] PAN and bridge problem when bnep0 disconnects before bnep1

[Matthias Thomae]

Hi Christoph,

Christoph Scholz wrote:
> I experienced the same problem as Matthias Thomae. I already posted this

Glad there's others with the same problem ;)

> to the mailing-list some time ago (see attached mail). It is actually a

Missed your mail although I searched the archives...

> problem with the Linux bridge code. It does not seem to be able to cope
> with multiple interfaces using the same MAC-Address.

Aha. These MAC addresses seem to be used in the forwarding database. 
Maybe setting the ageing time to 0 (man brctl) would help...

> Unfortunately, I have no real solution to the problem.

What kernel version are you using (on the GN)? I noticed in the 
changelog for 2.6.6 there were a number of bridge-related changes, e.g.:

<shemminger@osdl.org>
	[BRIDGE]: Forwarding database changes.
	
	Make forwarding database more robust.
	  + Don't insert invalid ether address,
	  + Report errors back so adding an interface to bridge can fail
	  + get rid of unneeded explicit pads in data structure
	  + replace bitfields with byte's for simple booleans.

Maybe that fixes our problem? I might be able to try 2.6.6 and the 
ageing timer tonight...

BTW, have you written to the bridge people?

Regards.
Matthias


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[Bluez-devel] PAN and bridge problem when bnep0 disconnects before bnep1

[Matthias Thomae]

Hello,

I have a BlueZ NAP setup with bridging (essentially following the PAN
HOWTO), which works quite nicely (thanks to all developers :) except
when the first connected bnep0 client is killed before the 2nd client
(bnep1).

I am running a DHCP server on the server's bridge (pan0), and eth0 is
NOT part of the bridge, I use IP forwarding instead.

The problem is, that after bnep0 is removed (by killing it on the
respective client with 'pand -K'), bnep1 doesn't 'work' any longer,
meaning ping etc. don't work any more. And I couldn't find anything in
the syslogs, except that after a while the client's DHCP client starts
to issue DHCPDISCOVERs.

ifdown/ifup on bnep1 don't seem to help either, the only way I could
find to make it work again was to issue 'pand -K' on the server and
reconnect the clients.

If bnep1 disconnects before bnep0, no problem.

I'm using quite late BlueZ versions on all machines (at least kernel
2.6.5-mh3 and the latest Debian bluez-utils 2.6-1 and bluez-pan
1.1rel-4), and I can reproduce the behaviour also with a Windows client
on bnep0.

Any clues?

Regards.
Matthias



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Re: [Bluez-devel] PAN and bridge problem when bnep0 disconnects before bnep1

[Marcel Holtmann]

Hi Matthias,

> I have a BlueZ NAP setup with bridging (essentially following the PAN
> HOWTO), which works quite nicely (thanks to all developers :) except
> when the first connected bnep0 client is killed before the 2nd client
> (bnep1).
> 
> I am running a DHCP server on the server's bridge (pan0), and eth0 is
> NOT part of the bridge, I use IP forwarding instead.
> 
> The problem is, that after bnep0 is removed (by killing it on the
> respective client with 'pand -K'), bnep1 doesn't 'work' any longer,
> meaning ping etc. don't work any more. And I couldn't find anything in
> the syslogs, except that after a while the client's DHCP client starts
> to issue DHCPDISCOVERs.
> 
> ifdown/ifup on bnep1 don't seem to help either, the only way I could
> find to make it work again was to issue 'pand -K' on the server and
> reconnect the clients.
> 
> If bnep1 disconnects before bnep0, no problem.
> 
> I'm using quite late BlueZ versions on all machines (at least kernel
> 2.6.5-mh3 and the latest Debian bluez-utils 2.6-1 and bluez-pan
> 1.1rel-4), and I can reproduce the behaviour also with a Windows client
> on bnep0.

sounds like a bridge problem to me. Are you sure that your bridge is
setup correctly. Take a look at the bridge howto's.

Regards

Marcel




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Re: [Bluez-devel] PAN and bridge problem when bnep0 disconnects before bnep1

[Paulo Marques]

>>
>>If bnep1 disconnects before bnep0, no problem.
>>

I had a similar problem a while ago (it was a 2.4.xx kernel, didn't try a 2.6 
kernel yet).

The problem was that the bridge interface borrowed the mac address from one of 
the interfaces attached to it.

When this interface disconnected, the bridge would start using the MAC from some 
other interface. Because of this, other computers on the network, relying on 
their arp cache, could not contact the bridge any more.

I tried "arp-pinging" the network to announce the new mac, but couldn't make it 
work. (maybe I was doing something wrong)

I eventually gave up, without finding any solution.

As I said, I didn't try kernel 2.6. I remember reading somewhere that there was 
a new kernel internal API to get a "valid" random MAC address and that the 
bridging code was using it, but I'm not sure I didn't got it wrong.

Just my 2 cents,

-- 
Paulo Marques - www.grupopie.com
"In a world without walls and fences who needs windows and gates?"