openstack team mailing list archive

[Vishvananda Ishaya <vishvananda@xxxxxxxxx>]

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

> 
> 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.

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