OpenStack supports rich abstractions to handle virtual networking needs in a cloud. As a user the most visible entities are the Network, Subnets, Routers, Firewall etc. But if we consider ingress and egress points for data traffic, the most critical entity is the Port. OpenStack Neutron Ports are usually created automatically as part of other user operations. However the CLI allows users to create Ports independently as well.
In an earlier blog, I have talked about Linux bridge based virtual networking. Recently as part of a comment on my blog, I learnt how to view and interpret the MAC table of Linux bridge. In this installment of WILT (What I Learnt Today) series, I will share how MAC Table can be used for troubleshooting Linux bridges.
In data center and cloud environment, servers used for hosting the virtual machines usually have more than one wired networking interfaces. In fact there are multiple Ethernet interfaces on each server. It is common practice to use one of the interface for ‘managing’ the host itself. This interface is usually accessible from corporate networks and administrators will use this interface for doing SSH into the server. The other interfaces are usually used for virtual machine traffic or storage traffic.
If you were to ask someone “what is the most popular open source hypervisor” chances are that the answer will be KVM. Indeed KVM (or Kernel-based Virtual Machine) has played a key role in the open source Linux based virtualization environment. However is it really a hypervisor? Moreover, can KVM by itself run virtual machines? We will delve more into such questions in this blog. We will also understand the relationship between KVM and QEMU (Quick EMUlator).
In the previous blog of this series we saw that using Linux bridge we can connect a virtual Ethernet port of a VM to the physical Ethernet port of the hypervisor server. Let us now focus a bit more on these virtual ports to see what happens behind the scenes to make virtual networking actually work.
Software defined networking (SDN) is the current wave sweeping the networking industry. And one of the key enablers of SDN is virtual networking. While SDN and virtual networking are in vogue these days, the support for virtual networking is not a recent development. And Linux bridge has been the pioneer in this regard.
In the previous post we looked at the fundamental building blocks of physical and virtual networks. Now let us look at two key concepts in physical and virtual networks. They are Ports and VLAN.
In order understand Virtual Networking let us start with the simplest network that many of us operate every day – our home network. The picture below captures what a typical home network looks like. I am sure most of us use wireless rather than wired networks at home but the underlying concepts are very much alike.
Upcoming technologies like OpenFlow and SDN are altering the networking landscape very quickly. The underlying drivers are Cloud Computing and Virtualization. Servers, Storage and Networking make up the trinity for effective Cloud computing strategy. Servers and Storage Virtualization has helped drive the adoption of flexible cloud services already. Now it is time for Network Virtualization.