Networking on single server - RDO on CentOS 7 w/ public ip subnet

asked 2014-12-11 02:39:08 -0500

drewbertola gravatar image

Hi all,

I've leased a dedicated server from a US based datacenter. I'm trying to get RDO up and running, on top of a fresh CentOS 7 install (+ updates).

The server is nice and beefy, with two wired NICs, plenty of CPU and memory for testing and learning. Potentially, I'll do a migration from an ESXi server to KVM instances on this box. I have been issued a /27 public subnet by the DC and need this to get into the server and for floating IPs.

I started with a packstack --allinone install and have tweaked the answer file to provision the higher /28 of this subnet for floating ips.

So, for my physical NICs I have:

subnet a.b.c.160/27
Gateway: a.b.c.161
eno1: br-ex
br-ex: a.b.c.162
eno2: a.b.c.163

(a.b.c are some actual public ip block values)

This works fine. I can ssh into either ip on the host itself.

In my answers file:


First, does this sound like a good approach?

And second, I've been stumbling a lot with associating an IP to my first (demo) instance ("no available port"), and also with ping from the host to the guest VMs, though the guest instance does seem to pick up the ip. Any ideas on that?

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answered 2014-12-11 08:25:37 -0500

drewbertola gravatar image

updated 2014-12-11 08:26:50 -0500

I actually got this working, but it was more trial and error than good debugging skills (cuz I am a total noob and the target is moving faster than the available docs).

I went back to:


and then built the public network as admin specifiying:

(keystone_admin)]# neutron net-create --shared --router:external=True public
(keystone_admin)]# neutron subnet-create public a.b.c.160/27 --name public_subnet \
                                 --enable_dhcp=False \
                                 --allocation-pool start=a.b.c.164,end=a.b.c.190 \
(keystone_admin)]# . keystonerc_demo 
(keystone_demo)]# neutron router-create demo_router
(keystone_demo)]# neutron router-interface-add demo_router private_subnet
(keystone_demo)]# neutron router-gateway-set demo_router public

Following that, I demo had ports to which I could attach floating IPs and I could ping/ssh in and out.

Note: the important thing was getting the host network and public network (inside openstack) on the same subnet (but not including the host's IPs in the allocation pool), and then doing the steps above using the right keystone user for each step.

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Asked: 2014-12-11 02:39:08 -0500

Seen: 446 times

Last updated: Dec 11 '14