Bridge Question

Hi,

I have installed SuSe 12.3 and got everything running. I have three network card, eth0, eth1 and eth2. I have configured eth0 to manage the unit remotely. Now I want to use the unit as a transparent bridge between the LAN and WAN. On the LAN side is the core switch and on the WAN side is my firewall.

I intend to use the unit to do transparent packet filtering with iptables and tc. I have a bridge br0 created with eth1 and eth2 as its member and up the interfaces. The moment I connect a UTP cable (single piece or cable loop back) between eth1 and eth2. Traffic is generated. When I run ifconfig it shows that eth1 and eth2 have alot of RX and TX traffic and on the br0 there is a lot of RX traffic but a few bytes of TX.

My guess is that there is a race round condition as there should no be any traffic going through the interface as in theory there is no traffic between the eth1 and eth0. Also all the eth1, eth2 and br0 are NOT assigned any IP. Can someone help me here? Thanks.

Regards,

sorry can not help you as I am having an issue with my network setup as well. I am hoping if you get your resolved it might help me as well, so please do post the fix when you find it.

but some thing is bothering me with your setup let me see if I understand it correctly.
you have 3 NICs eth0,eth1,eth2
eth0 is hooked up to a physical switch with it’s own IP and is used as admin interface only.

you are bridging the eth1 and eth2 with br0.
I assume eth1 should be hooked up to your WAN
and eth2 should be hooked up to the LAN switch

#1 what are you trying to achieve/Test doing the loop back with UTP cable?
#2 are you sure your cable is wired correctly.
#3 are your NICs have automatic cable reversing capability.
many new switches can detect incorrectly wired cables as in a cross-over cable used as regular drop etc.
and compensate for this automatically, but many NICs can not do this.

what you describing feels like a network loop. that usually happens if some one makes a loop in the network hub as in plugging both ends of the same cable into the same hub/switch creating a closed loop.

Hi,

#1 what are you trying to achieve/Test doing the loop back with UTP cable?
This is to test that the two ports are working and should not be emitting any traffic. If I were to use it as transparent bridge I would not want the bridge to inject any traffic.

#2 are you sure your cable is wired correctly.
I am sure as I have used straight as well as cross over cable. Both type of cables have the same result.

#3 are your NICs have automatic cable reversing capability.
Yes, the network ports are on the motherboard based on Intel 82574L Gigabit Ethernet.

When I do the following the traffic “loop” stopped. Can someone explain?

>brctl stp br0 on
>brctl stp br0 off

Thanks.