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Openstack Networking towards the internet

asked 2017-09-19 15:00:47 -0600

hdg88 gravatar image

My current set up has the controller node on one VM and a compute node on another VM. I have created an internal subnet for communication within the instances, and assigned an IP from that subnet to an instance (via DHCP). I created a router and and added one port to the internal subnet (so it serves as the default gateway to the instance). I have also created an external shared network on openstack, with the Provider Network Type: Flat and Physical Network: provider.

In the controller ml2_conf.ini file i have the following flat_networks = provider and in the controller (and in this case compute node as well) linuxbridge_agent.ini file I have this: physical_interface_mappings = provider:eth0.

Eth0 is my network on the host vm which connects out to the internet (so from my host vm, I can ping google through this interface).

My understanding is that creating a network which is built on this physical network (eth0), would sort of provide NAT functionality where any ip within this external ip address would be able to reach the internet through eth0. However the instances cannot even reach the host. (so from my ubuntu host, I cannot even ping any of the instances).

I cant seem to figure out where I am going wrong, or why my instances cannot reach the internet (let alone the host itself). I even tried putting in a router, with one interface towards the internal network and the other on the external network (supposedly towards the internet).

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answered 2017-09-19 19:05:47 -0600

felix001 gravatar image

You need to create an external provider network. And connect this to the L3 router. Traffic will only be NAT'd if you are using floating IPs (i.e static NAT 1-to-1 fixed ip to floating mapping) and/or have SNAT enabled upon the L3 router. I think the setup if pretty much what is covered here - https://www.fir3net.com/Cloud/OpenSta... - i.e external network plugged into L3 router, which a backend tenant network to a server. Hope this helps.

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Asked: 2017-09-19 15:00:47 -0600

Seen: 28 times

Last updated: Sep 19