One of the fascinating aspects in my job is understanding
how some of world’s largest networks will deploy Open networking platforms. It
is this continuous learning that keeps me passionate about what I do. When I first use “open networking” term,
people wondered what it may entails. Some
thought of it is all about using “open source” software and the other thought
of it as another connotation of confusing technical term that simply add to plethora
of jargons. Interestingly, open
networking is none of the said. It is about disaggregating hardware and software
in a way that allows relatively easier integration of each sub systems. In
doing so, the model innately provides three distinct benefits to customers:
1.
Eliminates
Vendor lock-in: There is no need to be enchained by vendor or vendors. With
state of the art merchant silicon available off the shelf, benefits of
technology can be realized without being locked into a specific vendor device.
2.
Cost
Reduction: As more and more vendors join the marketplace, price of hardware
and software becomes suddenly more affordable. This innately reduces CAPEX and
OPEX for customers.
3.
Choice of
HW and Software: The disaggregation model in which open networking conception
is born innately provides a choice for customers on hardware and software.
Figure 1‑1. Open Networking: Disaggregation model.
Central to open networking is the disaggregation model that
allows hardware and software vendors to deliver their capability on what they
do best. For example, hardware vendor can bring best breed of technology from
modularization of their platform to make use of state of the art market
silicons and on the other hand, software vendors to offer best NOS (Network
Operating Systems) or software means for data plane and control plane separation.
In doing so, the marketplace has created
an apparently robust eco-chain. Some will disagree here but the fact remains
that the eco-chain is improving and some parts of it is more realistic now then
perhaps a year before. To be more specific, I have elaborated the eco-chain in the
figure below. Rather than referring it to open networking eco-chain, I denoted
it as “SDN eco-chain” since the central to this initiative is about making
network more programmable and service aware.
Figure 1‑2. Typical SDN Eco-chain.
The programmability is the core element of SDN (Software
Defined Networking) for which pundits advocated the decoupling of control and
data plane. However, programmability can be done in many ways: through ZTP
(Zero touch provisioning), APIs (e.g. Netconf) and OpenFlow protocol (a more conventional
notion of decoupling).
To my experience, majority of network deployments thus far
refrained from purely decoupling model but there are exceptions and distinct
differences in deployment. For example, FBOSS that runs as agent daemon uses thrift
API instead of openflow to communicate route information with controller. Details
of this opensource decoupling software is available at https://github.com/facebook/fboss
.
Service Providers are more interested about CAPEX and OPEX
reduction with choice and flexibility that open networking offers. For example,
a provider edge switch that offers flexibility of advance MPLS networks with
APIs for model based network configuration and monitoring could best fit their
immediate need of transforming networks as oppose to overhauling the network in
one go using decoupling of data and control plane. It is in this phased
transformation, open networking offers best value but it is not confined by the
said as it is encompassing to traditional networks and decoupling of data and
control plane.
I conjectured even a bigger picture for “Open networking” as
it is the fundamental conduit of future network transformation. For it,
disaggregation model is paving the way for a more sophisticated network
transformation to occur. A vision towards that end would be “Intelligent
Networks” one that is provisionable in click, intent-based and self-healed, to
name few attributions.
Figure 1‑3. Networking Technology Trend.
Affordability, openness and choices are big factors in
network transformation especially for service providers since disaggregation
model is giving them ability to deliver more service at a fraction of cost that
would otherwise be. Moreover, open networking is offering best of both world,
the “traditional” and “NextGen”. For example, in a given network deployment
scenario customer may prefer to choose their own NOS depending upon southbound
API requirements and L2/L3 switching products. A NOS that combines both APIs
and decoupling protocols such OpenFlow is known hybrid NOS. The goal here would
be two folds, first allow traditional network protocols such BGP to be run at
NOS level forming traditional routing architecture and secondly, network
topology is passed to Openstack for visibility, orchestration and management.
The following picture depicts how such nextgen network abstraction can coexist
with traditional networks.
Figure 1‑4. Cloudification of Network.
Telemetry at each network device can be obtained through
Broadview™, an opensource software contributed by Broadcom®. Such deployment
not only allows physical networks to be virtualized and cloudified, it is done
so without compromising backward compatibility of physical network and the traditional
network routing architecture therein. The depiction herein is forward looking
and implementation of such network is at the discretion of its designer and
availability of suitable hybrid NOS. However, this notion of network
cloudification is possible only due to advances in open networking and the
eco-chain that supports it.
This article is provided herein for educational purpose only
implying the importance of “Open Networking” and how disaggregation model helps
in realizing NextGen network transformation.
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