A six-part walk through the Neutron data path — from a VM's virtual NIC, across bridges and tunnels, to the wire and back. Read in order; each part assumes the one before it.
In order to identify how a VM communicates in Openstack, we need to look into how it is connected logically when it’s created. This will allow us to know the steps that the VM traffic will have to go through before…
As we mentioned in the last post, traffic flows through a set of Linux virtual devices/switches to reach its destination after leaving the VM. Outbound traffic goes downward while inbound traffic moves upwards. The flow…
In a physical world, machines communicate with each other without routers when they belong to the same network. This is the same case with openstack, VMs communicate over the same network without routers. When two VMs…
In the last post, we spoke about VM to VM communication when they belong to the same network and happen to get deployed to the same host. This is a good scenario, but in a big openstack deployment, it’s unlikely that…
So far we have only spoken about VM communication when they belong to the same network. But what happens when the VM has to communicate with another VM on a different network. The common rule of networking is that…
DHCP requests are broadcast requests sent by the VM to its boradcast domain. If a DHCP server exists in this domain, it will respond back providing a DHCP IP lease following the DHCP protocol. In openstack, the same…
