openstack team mailing list archive

[Mike Scherbakov <mihgen@xxxxxxxxx>]

On Thu, Apr 26, 2012 at 10:31 PM, Vishvananda Ishaya
<vishvananda@xxxxxxxxx>wrote:

>
> On Apr 25, 2012, at 7:31 PM, Jimmy Tsai wrote:
>
> >
> > Hi everyone,
> >
> > I'm running with Essex 2012.1,
> > and have some questions about the nova network operation,
> >
> > 1. Is it possible manually assigned IP address to a launched instance,
> my situation is :
> > after instance boot up (OS: CentOS 6.2), I changed the
> /etc/sysconfig/network-scripts/ifcfg-eth0 setting
> > from dhcp to static (the same subnet as created by command : nova-manage
> create network....), and restart the network service,
> > And then I couldn't ssh or ping the instance from other server with the
> same subnet.
> > What is the problem ?  I checked the iptables policies on the compute
> host, and find nothing about the DROP packets.
> > I also tried to changed the record from nova.fixed_ips table and
> libvirt.xml of the instance, then reboot the instance, still not worked.
> > I used FlatDHCP  as my network manager.
>
> You can't do this.  Libvirt sets up no mac spoofing and no ip spoofing so
> the ip address needs to match the dhcp'd one. You should be able to switch
> to a static and use the same info that you get from dhcp though.
> >
> > 2. According to the first question, I have another requirement to set up
> a loopback IP address (lo:0) on the running instance, after setting was
> completed,I couldn't ping or ssh the loopback IP from the same subnet, and
> I tried to set a alias IP address with eth0:0, but still not get worked.
> > Any ideas with this ?
>

> Not sure
>
I guess it's the same issue as with setting a different IP from what
dnsmasq provided. You can try ebtables -F; ebtables -t nat -F to flush
those anti spoofing rules.

>
> >
> > 3. Is there any way to use 2 NICs with different subnets on instances? I
> want to separate the network traffic.
> > Now I'm running with one bridged interface (br100), and it works well.
>  In order to backup the large log files,
> > I'm planing to use 2 NICs for the compute hosts, I want use 2 vNICs on
> instance, one for web service and the other for log backup,
> > I think I should create a new network for the second bridged interface,
> but I can't find any document to guild me.
>
> This is definitely possible with FlatManager (You could use cloud_config
> drive and some version of contrib/openstack-config converted to work with
> centos to set up the interfaces)
>
> It was possible at one point with FlatDHCPManager as well by creating
> multiple networks and using a specific combination of config options like
> use_single_default_gateway. I don' t know if anyone has tried this for a
> while so there may be issues with it. You might try creating a second
> network and setting use_single_default_gateway and see what happens.
>
Confirm that it works with Essex release.
If you don't specify  use_single_default_gateway=true your default route
will be jumping from one interface to another. If you both subnets are
covered by --fixed_network, it's fine even without setting
the use_single_default_gateway.


> There are plans underway to support this by only dhcping the first
> interface and allowing a guest agent to set up the other interfaces, but it
> isn't in place yet.
>
> Vish
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-- 
Mike Scherbakov