Xen Bridge Problem, dont allow more than 1 guest running

Question

Hello,
We have a curious problem with our Oracle VM Xen Bridge configuration. We have a 2 node server pool with a shared OCFS2 repository (this works great, ISCSI, multipath, etc.), HA enabled and some VM Guests.
The problem is that if we launch 2 or more guests that use the same xen bridge in the same VM Server (xenbr1 for example on node A) we have intermittent connection issues on those guests. Only 1 guest will respond to SSH, PING, etc. while the others don’t. After a while, one of the Guests that don’t have connection will respond and the one that seems to be fine won’t do it (like if they take turns to use that xenbr).
The VM Server version is a fresh downloaded and installed 2.2.1. Since we are using it as a test for future projects, the VM Servers aren’t patched from the ULN. The logs from xen or the server itself don’t show any related information to network problems.
We mainly use as a guide the chapters 6 (storage) and 7 (Networking) from the Roddy Rodstein – Underground Oracle VM Manual. We have tried to create the xen bridges manually (as many guides said so) and also we do it dynamic with a modified version of the default xen network-bridges script (My Oracle Support Note 730750.1), the results were the same problem mentioned before using both methods.
Do you know if this could be a configuration problem, or something already know like a bug??(I couldn’t find any info related for a similar problem)
*====Additional Information====*
Guests Info:
Paravirtualized OEL 5.6, vm.cfg example below (the guests have the same expecs)
bootloader = '/usr/bin/pygrub'
disk = ['file:/var/ovs/mount/3C4B132FC4316BE43BB9C81C8EFC8/running_pool/10_testvm01/System.img,xvda,w']
keymap = 'en-us'
memory = '4096'
name = '10_testvm01'
on_crash = 'restart'
on_reboot = 'restart'
uuid = '579cd1c0-b1df-aaa5-1b07-7345ff9490f0'
vcpus = 2
vfb = ['type=vnc,vncunused=1,vnclisten=0.0.0.0,vncpasswd=password']
vif = ['mac=00:16:3E:75:AB:B8, bridge=xenbr1']
NICs:
Intel 82576 Quad-Port x2 (8 total)
Brctl show output:
bridge name bridge id STP enabled interfaces
xenbr0 8000.001b218f9c50 no eth0
xenbr1 8000.001b218f9c51 no eth1
xenbr2 8000.001b21a91158 no eth4
xenbr3 8000.001b21a91159 no eth5
The other interfaces are used for iSCSI shared volume.
In advance, Thanks for any information that you could provide me in this problem.

Answer 1

Hello Sebastian, Thanks for taking your time into this.
In response to the first question, No, that was the brctl output when the VM Server didn’t have any guests running, my intention was only to show the basic bridge configuration that I made. The next is an example of the same output when there are 2 guests running on xenbr1.
Node A:
bridge name     bridge id               STP enabled     interfaces
xenbr0          8000.001b218f9c60       no              eth0
xenbr1          8000.001b218f9c61       no              vif8.0
vif7.0
eth1
xenbr2          8000.001b21a91138       no              eth4
xenbr3          8000.001b21a91139       no              eth5
Node B:
bridge name     bridge id               STP enabled     interfaces
xenbr0          8000.001b21932568       no              eth0
xenbr1          8000.001b21932569       no              vif6.0
vif5.0
eth1
xenbr2          8000.001b21a86ce8       no              eth4
xenbr3          8000.001b21a86ce9       no              eth5
Stopping or starting the iptables service won’t make any change in the behavior. Actually, I am quite confused about the iptables service, for example if I stop the service and then I start a machine (guest) the iptables service is started again. And as I said, stopping the service one more time doesn’t make any difference.
To the last question, these are the lines for my vif in the VM Guests (those running on xenbr1 only, the same hapends for the rest of the bridges, if you need me to post the rests just tell me):
Guest 1: vif = ['mac=00:16:3E:75:AB:B8, bridge=xenbr1']
Guest 2: vif = ['mac=00:16:3E:7B:49:99, bridge=xenbr1']
Guest 3: vif = ['mac=00:16:3E:17:98:04, bridge=xenbr1']
Guest 4: vif = ['mac=00:16:3E:46:92:AF, bridge=xenbr1']
I hope this helps to get a workaround in this problem, Thanks again for you time!