openstack team mailing list archive

[Leander Bessa Beernaert <leanderbb@xxxxxxxxx>]

Question follows inlined below.

On Tue, Sep 4, 2012 at 6:48 PM, Vishvananda Ishaya <vishvananda@xxxxxxxxx>wrote:

>
> On Sep 4, 2012, at 8:35 AM, Leander Bessa Beernaert <leanderbb@xxxxxxxxx>
> wrote:
>
> Hello all,
>
> I've had a few reports from users testing out the sample installation of
> OpenStack  i setup. The reports were all related to problems with inter-vm
> network speeds and connection timeouts as well as the inability to connect
> to the outside word from within the VM (e.g.: ping www.google.com). I'm
> not sure if i setup something wrong, so i have a few questions.
>
> The current installation of OpenStack is running with 1 controller node,
> and 8 compute nodes. Each node is running Ubuntu 12.04 and Essex with the
> default packages. I'm using the VLAN network manager. There is one
> peculiarity to this setup. Since each physical hosts only has 1 network
> interface,  i came up with the following configuration:
>   - For inter-node communications i set up  a VLAN with the ID 107
>   - Each tentant has it's private network on a separate VLAN. Currently
> there are two tenant, one on VLAN 109 (network: 10.0.9.0/24) and another
> on VLAN 110 (network: 10.0.9.0/24).
>
> I'm not a network expert, so please bear with me if i make any outrages
> statements.
>
> 1) When communicating on the private network, the packets are not routed
> through the controller right? That only happens when the VM needs to
> contact an external source (e.g.: google), correct? This report originated
> from users from VLAN 109. They are using network intensive applications
> which send a lot of data between each of the instances. They reported
> various time-out and connection drops as well as slow transfer speeds. I'm
> no network expert, but could this be related to the routing, VLANs or is it
> a hardware issue?
>
>
> There are a lot of things that could cause this. You would need to do some
> extensive debugging to find the source of this.
>

Any ideas where i can start looking?
Also, communications between two VMs on different compute nodes from the
same tenant do not need to be routed through the controller node right?


>
>
> 2) I've noticed that for external access (e.g.: google), all the packets
> seem to be routed through the nova-network on the controller node. If i
> setup a multi-host setup (install nova-network and nova-api-metadata on
> each compute node), the external packets no lounger need to be routed
> through the controller node right?
>
>
> Correct. You need to set multi_host = true on the networks when you create
> them as well (or update the flag directly in the database)
>
>
> 3) The setup has been running for about 1 month and a half. During that
> time, VMs on VLAN 109 could never reach the internet. However, VLAN 110
> worked just fine. Today, out of nowhere, VMs on VLAN 109 can suddenly reach
> the internet. I didn't touch or change anything since the initial setup, it
> simply happend. Before this bizarre occurrence i've sat down with our
> network specialist and told me that, based on the routing rule in iptables,
> this problem (VMs on VLAN 109 not being able to connect to the internet)
> should not be happening. Has this ever occurred to any of you?
>
>
> This sounds very strange. When I have had issues with certain vlans it has
> always been forgetting to trunk the vlan on the switch, although vm -> vm
> communication from one host to another should fail in this case as well.
>
>


-- 
Cumprimentos / Regards,
Leander