Linux Ethernet Bridging - Apr 2007 - [Bridge] Linux bridge on linksys WRT54GS running OpenWRT

Hi all,

Following the this thread opened by Olaf
(http://lists.osdl.org/mailman/htdig/bridge/2005-July/001026.html)

We performed some more tests with and without wireless. Latest one was
to remove CONFIG_BRIDGE_NETFILTER from kernel option at compilation
time on a 2.6.14-rc4. This change solved the problem and the bridge
was able to forward correctly MLD packets (IPv6 multicast subscription
message).

So the problem seems to be related to etables. Something related to
IP/SABOTAGE in br_netfilter.c?

As specified on the bridge FAQ "The bridge knows nothing about
protocols, it only sees Ethernet frames." it should not look at the
content of the packet.

Most of performed tests are described on
http://dbeacon.innerghost.net/LinuxBridgingMulticast

Thanks
Regards

S?bastien

On Thu, 17 Nov 2005 12:01:47 +0100
Sebastien Chaumontet <sebastien@chaumontet.net> wrote:
> Hi all,
> 
> Following the this thread opened by Olaf
> (http://lists.osdl.org/mailman/htdig/bridge/2005-July/001026.html)
> 
> We performed some more tests with and without wireless. Latest one was
> to remove CONFIG_BRIDGE_NETFILTER from kernel option at compilation
> time on a 2.6.14-rc4. This change solved the problem and the bridge
> was able to forward correctly MLD packets (IPv6 multicast subscription
> message).
> 
> So the problem seems to be related to etables. Something related to
> IP/SABOTAGE in br_netfilter.c?
The netfilter interface is really the responsibility of the ebtables
project. I maintain the hooks for them, but what happens in the filters
is their doing.
> As specified on the bridge FAQ "The bridge knows nothing about
> protocols, it only sees Ethernet frames." it should not look at the
> content of the packet.
> 
> Most of performed tests are described on
> http://dbeacon.innerghost.net/LinuxBridgingMulticast
> 
If you want put a link on http://linux-net.osdl.org on the bridge page.



-- 
Stephen Hemminger <shemminger@osdl.org>
OSDL http://developer.osdl.org/~shemminger

Hello,

I am experimenting with delivering IPv6 multicast traffic over the
WRT54GS, running OpenWRT. OpenWrt is currently running linux-2.4.30 for
the mipsel architecture and the OpenWRT distribution has bridged the 4
port LAN switch (vlan0) with the WLAN interface (eth1) by default.  On
the IP layer both devices are represented via the br0 interface. The
bridge work fine for IPv4 Unicast and Multicast and for IPv6 Unicast but
not for IPv6 multicast.

I went into a problem with forwarding the MLDv2_report message over the
bridge from a mobile client, connected over WLAN. The MLDv2 report
messages are received in in the eth1 (WLAN IF), but not in the eth0 nore
in the br0 interface. Does the bridge support IPv6 multicast compliant
MAC addresses, starting with 3333+LowByte(Ipv6 MulticastAddress) ?
Usually a bridge is working on L2 and should forward any ICMPv6 packages
.? The bridge  is forwarding any other IPv6 traffic without problems
e.g. ICMPv6 messages generated with ping6. MLDv2 report messages are a
subset of IPv6 ICMP messages with the link local IPv6 multicast address
FF02::16 ( all MLDv2 compliant router)  as destination address. The same
behavior I figured out with the MLDv2 query messages, sent by the
Multicast router to all nodes (FF02::1) on the local link. The MLD query
I have seen at the eth0  IF but not at the wireless link. Any other IPv6
link local multicast adresses are forwarded e.g. IPv6 router
advertisements or neighbour soicitation messages. Do you have any idea,
how to solve the problem ??


with best regards

Olaf


-- 
Dipl. Ing. Olaf Menzel - System Engineer
FOKUS - Fraunhofer Institute for Open Communication Systems:
- Competence Center for Advanced Satellite Communication
Schloss Birlinghoven, 53754 Sankt Augustin, Germany
Phone: +49-2241-14-3494 Mobile: +49-175-2616161 Fax:+49-2241-14-43494
email: olaf.menzel@fokus.fhg.de Internet: http://www.fokus.fhg.de/satcom

On Thu, 07 Jul 2005 18:37:07 +0200
Olaf Menzel <olaf.menzel@fokus.fraunhofer.de> wrote:
> Hello,
> 
> I am experimenting with delivering IPv6 multicast traffic over the
> WRT54GS, running OpenWRT. OpenWrt is currently running linux-2.4.30 for
> the mipsel architecture and the OpenWRT distribution has bridged the 4
> port LAN switch (vlan0) with the WLAN interface (eth1) by default.  On
> the IP layer both devices are represented via the br0 interface. The
> bridge work fine for IPv4 Unicast and Multicast and for IPv6 Unicast but
> not for IPv6 multicast.
> 
> I went into a problem with forwarding the MLDv2_report message over the
> bridge from a mobile client, connected over WLAN. The MLDv2 report
> messages are received in in the eth1 (WLAN IF), but not in the eth0 nore
> in the br0 interface. Does the bridge support IPv6 multicast compliant
> MAC addresses, starting with 3333+LowByte(Ipv6 MulticastAddress) ?
The bridge handles IEEE multicast mac addresses 
(ie. least significant bit of first byte of address is set).
What is a an example Ethernet MAC address of a MLDv2 message?
> Usually a bridge is working on L2 and should forward any ICMPv6 packages
> .? The bridge  is forwarding any other IPv6 traffic without problems
> e.g. ICMPv6 messages generated with ping6. MLDv2 report messages are a
> subset of IPv6 ICMP messages with the link local IPv6 multicast address
> FF02::16 ( all MLDv2 compliant router)  as destination address. The same
> behavior I figured out with the MLDv2 query messages, sent by the
> Multicast router to all nodes (FF02::1) on the local link. The MLD query
> I have seen at the eth0  IF but not at the wireless link. Any other IPv6
> link local multicast adresses are forwarded e.g. IPv6 router
> advertisements or neighbour soicitation messages. Do you have any idea,
> how to solve the problem ??
The bridge intentionally knows nothing about higher level protocols.
But if you are using ebtables/iptables perhaps a filtering rule is getting
in the way.