Today I have the pleasure to announce a new promising blogger for Hyper-V.nu. An introduction:
Marc van Eijk has a great interest in Microsoft virtualization and fabric management. Starting his IT career in 2000 at a Microsoft Partner he become responsible for all consultants after three years. A steep learning curve combined with a determined mind, resulted in great projects and helped the organization to evolve. After 13 years of combining two jobs, he decided to follow his heart and agreed to start as a Consultant at Inovativ, the System Center and Microsoft virtualization specialists in the Netherlands. His job description has a clear focus on Hyper-V, System Center VMM, Service Provider Foundation and Windows Azure Pack. Enjoys sharing knowledge by blogging for www.hyper-v.nu and speaking at events. Known to be persistent and driven by passion.
Marc told me he had been following Hyper-V.nu for quite a while now and that it had helped him on several occasions in his own IT consultancy practice. Now he wants to give back his knowledge and experience to the Hyper-V community. When Marc handed in his first blog for review, I was very happy to see the result. Without much further ado … here is Marc’s blog on Microsoft Hyper-V Network Virtualization. Please give him a warm welcome and many RT’s. If you have any questions about this very interesting subject, please use the comment and I will make sure you are answered.
In the early days of Virtualization we tried get our heads around the idea of abstracting a server from its hardware, disks presented as a files and even movability of a guest. Today it is just business as usual. At least for most of us I hope.
Looking at the reimagined Windows Server 2012 a new concept called Network Virtualization is emerging. This feature is the basis of a larger trend called software defined networking (SDN).
Is this something like the networks we created in the Windows 2008 R2 virtual switch? On the contrary!
What is Network Virtualization?
Similar to running multiple virtual servers on a single host, with network virtualization it is possible to run multiple isolated virtual networks on a single host. In essence this is not a new feature, because with VLANs this has already become possible in the Windows 2008 hypervisor. But VLANs – for larger organizations – have limitations (4096 to be exact) and in these environments VLAN maintenance can be error-prone and cumbersome. Network virtualization is a great feature for hosters, but many private clouds can take advantage of this in multiple ways as well. It should be noted that when a VM uses network virtualization it cannot use VLANs and vice versa.
With network virtualization the virtual networks get abstracted from the physical network topology. The physical network called the Provider Address (PA) Space is maintained by the fabric administrator. The virtual isolated networks called the Customer Address (CA) Space can be maintained by the customer (or a division or unit in your organization).
Similar to VLANs, you can create multiple subnets. Every virtual subnet is a single broadcast domain and has a unique Virtual Subnet ID (VSID). A virtual subnet routes traffic to other virtual subnets that belong to the same routing domain (called the customer network). If you have a single routing domain with two virtual subnets, the virtual subnets are allowed to automatically route traffic to each other. If you have virtual subnets within different routing domains there is no routing between them.
The routing within the routing domain is enabled by default, you cannot disable it. If you do not want routing between virtual subnets you are advised to configure them in separate routing domains. The default gateway within a virtual subnet is the first usable IP address within the IP range.