Understanding network architecture in Openstack

With the new Folsom Openstack release we have now access to new networking architectures called Quantum. Even more, network is no longer only an internal part of nova but rather become a new core component [1].

It is going to take some time before Quantum become the main single option for network configuration. Many small to medium deployments will probably never require such a complicated mechanism to manage network creation, ports assignments or IPs allocation.

Problem

• How many network configuration options do we have in Folsom.
• How does the old nova-network work.

Solution

In Folsom we have a choice and we can use either nova-network [1] or quantum [3] service for our  cloud infrastructure.

Depending on the complexity and flexibility we can use the the following configurations in nova-network [2]:

Configuring Flat Networking

Configuring Flat DHCP Networking

Configuring VLAN Networking

This picture shows an example interaction between 2 VMs. More in depth description of how the network flows look like and what role plays the hypervisor in routing or restricting the traffic can be found in [4].

References

1. http://docs.openstack.org/trunk/openstack-compute/admin/content/networking-options.html
2. http://docs.openstack.org/trunk/openstack-compute/admin/content/ch_networking.html
3. http://wiki.openstack.org/Quantum
4. Mirrantis 
http://www.mirantis.com/blog/openstack-networking-flatmanager-and-flatdhcpmanager/
http://www.mirantis.com/blog/openstack-networking-single-host-flatdhcpmanager/"
http://www.mirantis.com/blog/vlanmanager-network-flow-analysis/ 
http://www.mirantis.com/blog/openstack-networking-vlanmanager/
5. IBM OpenStack