Open Stack

Hi all,

I have a Multi-Node, Single-NIC setup. All machines only have a single
NIC. I created a virtual network (using gretap tunnels - aka
layer2-over-layer3 tunnel) to connect all machines and have one br-int
bridge which all VMs are attached to.

nova-network runs on all machines and correctly binds dnsmasq to the
hosts bridge itself, though I noticed that each host-bridge gets the .1
IP. This seems to work, because dnsmasq is configured by nova-network to
only answer to DHCP requests the specific instance has a MAC address
for, though I find it a bit irritating.

I try to give a picture of it:

controller
    - br-int (dnsmasq with .1 address)
        - gretap tunnel to compute-1 (using the static IPs of eth0)
        - gretap tunnel to compute-2 (using the static IPs of eth0)
        - vnet1-n (instances running on this host)
    - eth0 (routes between external network and br-int, NAT / ip
            forwarding active, static IP used also for OpenStack
            managing)

compute-1
    - br-int (dnsmasq with .1 address)
        - gretap tunnel to controller (using the static IPs of eth0)
        - vnet1-n (instances running on this host)
    - eth0 (OpenStack managing)

compute-2
    - br-int (dnsmasq with .1 address)
        - gretap tunnel to controller (using the static IPs of eth0)
        - vnet1-n (instances running on this host)
    - eth0 (OpenStack managing)

I'm using the FlatDHCPManager, and if you substitue eth0/the-switch in
this picture
http://www.mirantis.com/wp-content/uploads/2012/07/flat-dhcp-networking-diagrams-4.png
with the gretap tunnels I basically have that topology. In that picture
the dnsmasqs/br100 have different IPs. How did they get that? ;)

Greetings
-Sascha-