Like many
network professionals, I feel the need to navigate through the frontal tide of
confusion, and grasp the essence of change. Initially, as I swallowed a lot of
information, I was easily confused and swayed one way or another. Let’s face
it, most materials out there are vendor affiliated, which is inherently partial
and biased. But over time, a clearer picture has emerged. However pure and
simple, it has given me consistency and continuation in the thought process. I
hope it will help you establish your own framework as well, and chart your own
course forward.
Virtual Networking – the beginning of
change
Let’s start
with why, why the change, why now. To me, change is not about doing what
networking already does, in a different way. Fundamentally, networking enables
communication and supports compute, which enables applications. Compute has
gone through its own revolution which is virtualization. Compute virtualization
brought networking into the hypervisor environment, thus creating an overlap
between two previously separate domains. This rudimentary form of virtual
networking can be seen in the form of current generation virtual switches.
In the
current generation architecture, virtual switches mainly serve to provide
virtual ports for VMs, while most of the feature and security remain with the
physical network. The advancement in compute virtualization has put more demand
on networking, more segmentation to support multi-tenancy and security, more agility
to support provisioning in minutes rather than days, requirements that hardware
based networking and security simply cannot keep up with. The
catalyst of change is virtualization.
The Rise of Software Defined Networking
In the
legacy model, virtualization is still closely coupled with network hardware. For
traditional networking to be more agile, it needs to be “programmable”. Earlier
OpenFlow architecture was proposed to be just that, but in reality hardware
replacement was a non-starter. The Nicira model took a different approach.
Rather than pushing programmability on hardware, it decouples virtualization
from traditional networking. A new
form of virtual networking emerges around the hypervisor, mostly in the form of
software. With emerging technology such as VXLAN, the virtual “edge” effectively becomes the new access layer,
where much of the complexity such as
segmentation as well as future services will reside. Traditional networking can
be greatly simplified.
Thus the
overlap between compute and networking has grown into a new layer. It has also
become clear that this new layer on the edge is optimally positioned to deliver
services such as load balancing, firewall and NAT.
·
Decoupling
of virtual from physical.
With new technology such as VXLAN, SDN provides an overlay network model which is mostly independent of the
physical network. Decoupling makes it possible to instantiate VXLAN and deliver
much of the cloud services without changing configurations on physical switches
·
Central decision making. The controller has
full knowledge of the virtualized networks. Its cloud level view is ideal for
managing resources centrally.
Networking, Redefined
Just as
networking exists to serve applications, SDN emerges to support data center
optimized for the cloud. In parallel with advancement in virtual switches (DVS,
1000v, Open vSwitch), a new class of cloud management system (vCloud, OpenStack)
is emerging. In order for SDN to be successful, it must be an integral part of
the Software Defined Data Center, supporting service/platform/application packaging,
rapid provisioning, and automated service deployment.
Virtual
networking is the new playground. The lines between network and virtualization
vendors have blurred, as well as those between network and compute domains. There
is a new domain emerging. I call it puzzle solving at the data center level,
putting all the pieces together, compute, network, storage, security, making
them fit seamlessly.
Networking’s growth area is with
virtualization, in software. In this emerging field, networking no longer runs
on dedicated hardware and ASIC. At the host level, it shares processing with
compute. At the data center level, the distributed architecture becomes more
centralized, with the controller becoming the new “supervisor”.
To remain
competitive in a hybrid cloud environment, organizations need to move forward
to take advantage of the power and features of Software Defined Networking. IT
architects need to unify network, virtualization and software at the cloud
level. I’ll brainstorm some concrete steps a network engineer can take in an
upcoming post.
