How NICs work ? a quick dive !
I’ve written this post as a draft sometime ago, but forgot to post it. The reason I looked into it was to find out how DPDK physically works as the OS/Device level and how it bypasses the network stack. So, when you…
Neutron
11 posts on Neutron.
PCI passthrough: Type-PF, Type-VF and Type-PCI
Passthrough has became more and more popular with time. It started initially for simple PCI device assignment to VMs and then grew to be part of high performance network realm in the Cloud such as SR-IOV, Host-level…
VNI Ranges: What do they do ?
Deployment tools for Openstack have become very popular, including the very well known Openstack-Ansible. It makes deploying a Cloud an easy task, at the expense of losing access to the insights of “Behind the Scenes”…
Port security in Openstack
Openstack Neutron provides by default some protections for your VMs’ communications, those protections verify that VMs can not impersonate other VMs. You can easily see how it does that by checking the flow rules in an…
Private External Networks in Neutron
You might find yourself in a position where you need to restrict access by tenants to specific external networks. In Openstack there’s the notion that external networks are accessible by all tenants and anyone can…
VM getting a DHCP address
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…
VM to VM communication: different networks
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…
VM to VM communication, same network, different compute hosts
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…
VM to VM communication: Same network & same compute host
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…
Traffic flows from an Openstack VM
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…
Neutron: How a VM communicates
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…