[Openstack] instance cannot access external network (folsom quantum)

Gary Kotton gkotton at redhat.com
Thu Dec 13 12:38:24 UTC 2012


On 12/13/2012 12:07 PM, ZhiQiang Fan wrote:
> i can ping and ssh into instance with private ip and floating ip
> instance can ping the control node ip, but cannot ping the compute 
> node and any external network

In order to be able to help would it be possible that you provide IP 
addresses and maybe a bit of understanding about your topology.

Basically is there a route from the VM ip address to the IP address of 
the compute node?

In addition to this can you please let us know which plugin you are using?

Thanks
Gary
>
> i have installed quantum in the control node host, and it only got 1 
> nic (same as compute node), and use eth0:0 and eth0:1 to vitualize 2 
> other nic (eth0:0 on compute node)
>
> i use tcpdump on control node and compute node to monitor package from 
> instance, actually compute node will reply the icmp package but with 
> destination of instance private ip, since compute node has no route to 
> that network, it failed and no package receive on control node nic. 
> but when i add route via control node, it can reply to insance as expected
> then i use tcpdump on control node and instance to monitor package to 
> the floating ip, instance got nothing but control node captured the 
> package and reply it instead of instance
>
> so i think the problem may be that the control node will not modify 
> the source ip when forwad the icmp package, more exactly, the nat 
> functionality is not enabled?
>
> and i try some other command such as "iptables -t nat -A POSTROUTING 
> -o eth0 -j MASQUERADE" but it is not working
>
> i'll paste some output if anyone needs
> thanks
>
>
>
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