The OpenStack platform, specifically (the networking component) Neutron uses the concepts of Ports in order to connect the various Cloud instances to different networks and the corresponding Virtual Networking devices like Neutron Routers, Firewalls etc.
If you choose Network Option 2, you can also create a private virtual network for the project that connects to the physical network infrastructure via routing and NAT. This network includes a DHCP server that provides IP addresses to instances. An instance of this network can automatically access external networks such as the Internet. However, access to an instance of this network from an external network such as the Internet requires a floating IP address . Continue reading
In a previous post I explained the basic mode of network operation for OpenStack, namely FlatManager and its extension, FlatDHCPManager. In this post, I’ll talk about VlanManager. While flat managers are designed for simple, small scale deployments, VlanManager is a good choice for large scale internal clouds and public clouds. As its name implies, VlanManager relies on the use of vlans (“virtual LANs”). The purpose of vlans is to partition a physical network into distinct broadcast domains (so that host groups belonging to different vlans can’t see each other). VlanManager tries to address two main flaws of flat managers, those being: Continue reading
Recently I outlined how VlanManager works and how it ensures network scalability and tenant isolation. Up to this point, however, I’ve only dealt with fixed IP networks of different tenants. While fixed IPs are what instances are given by default, they do not ensure that the instance is immediately reachable from the outside world (or from the rest of the data center). Imagine the following scenario: Continue reading