Are you sure you are ready for the Cloud: SDN

Software defined network (SDN) in the cloud

Winding down this discussion thread, we only have a couple of topics left: SDNs and SDI.  Although SDNs are part of a solid SDI, we want to talk directly about it now.

Many cloud management tools have the ability to create a virtual network.  But creating a true VXLAN would require support of the layer 2 to UDP protocol encapsulation.  But that raises another question: Is a VXLAN a true SDN?

First, what is a SDN? SDN stands for Software Defined Networking.  This means than a very robust network can be created and ran through a software system.  That being said, exactly how robust it is, is determined by the package that is either included in your cloud management software, or a third party software that you add to your environment.

So, now that we know what it is, how do we use it?  Lets try this example first.  You have a basic cloud setup; several tenants (or projects based on your cloud management software (CMS)) are setup.  You are using basic network connectivity through your CMS to talk to the physical VLAN that connects your COMPUTE nodes of your cloud.

You can communicate with other systems across your physical network.  But now, you would like to add some additional services, such as load balancing (LB), firewalls (FW), and advanced routing (RTR).

Not all SDNs have all of these capabilities, but most that I have worked with do.  So here you are, and you want to expand the network first. You would like to have several subnets, with each tenant having its’ own network range of IPs. Firing up your management software, you create a virtual router first. This router makes the connection from the CMS and the SDN to the physical layer of the network.  This is at Layer 2 and possibly Layer 3 of the OSI model.

We will discuss more about this on my next POST.

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