1 Reply Latest reply: May 6, 2013 10:17 AM by PoorFrodo RSS

    Issues with VLAN networks spanning multiple servers with OVM 3.2.1 & 3.2.2


      I am currently testing Oracle VM, and have the following (simplified) environment:



      Both Servers have eth0 as the 'untagged' management network, and eth1 supports all VLAN tags.

      All of the VMs have a single NIC per VM, which are on a 'VLAN Only' VM Network, which is built using a 'VLAN Group'-based Network (the VLAN group includes the eth1 card for both servers and defines VLAN tag 33, which is dedicated to this Network alone).

      The problem is with the network connectivity of machines on different servers. VM2 and VM3 can ping each other quite happily, but nether can see VM1. Similarly, VM1 cannot ping either VM2 or VM3. If I move VM1 onto Server 2, then all servers can ping each other. It is only when they are placed onto separate servers that communications break down. Before jumping to conclusions ;-), please note that switch is correctly passing packets between the servers...when VM2 pings VM1 I have run tcpdump on Server1 and have seen the ARP requests arriving, which seem to go to/through the eth1, eth1.33, 10f27ca67e (bridge), and 'tap' drivers stack...however no reply is ever transmitted in reply :-(

      Given that the logical network appears to be correct (since all VMs can communicate correctly when on the same server), and the physical network appears correct (since the packets are being transmitted between the servers to the correct ethernet card/driver stack), this seems to be an Oracle VM issue, but I'd appreciate thoughts/suggestions/recommendations in case I have overlooked something!

      Note: I found this article very useful to help understand how the network stack links together: http://www.oracle.com/technetwork/articles/servers-storage-admin/networking-ovm-x86-1873548.html
        • 1. Re: Issues with VLAN networks spanning multiple servers with OVM 3.2.1 & 3.2.2
          Of course, there could be quite a few reasons that the communication is not working between the servers. But I would have to understand your configuration quite a bit better. Let's start with a few simple things... can you provide output from the following commands on the Oracle VM Servers (Dom0):

          1. ifconfig (no -a)
          2. brctl show

          Also need the output from the following commands on the Oracle VM guests (DomU) for VM1, VM2 & VM3:

          1. ifconfig (no -a)
          2. netstat -rn