Some vendors are starting to leverage a truly open architecture for
optimization of unified fabrics with extensible service control applications.
One of the great opportunities in
software-defined networking is to amplify the efficiency of network and service
operations teams by allowing them to leverage a powerful set of logically
centralized and abstracted control functions for the infrastructures and
services they manage.
While this model is simple to
articulate it takes great vision and talent to realize in the world of real,
deployed solutions that deliver the result.
The goal is only partially
realized by the use of SDN controllers themselves. Controllers indeed do help
simplify by normalizing and abstracting control plane functions for the given
domain. In parallel, though, operators are driving to achieve additional
optimizations, efficiencies, and innovations by leveraging what I call SDN
Service Control applications that work in tandem with the centralized SDN
controller code. Examples of focus for these include traffic analytics, service
level monitoring and management, and custom traffic steering design for various
operating goals (application performance, service availability, cost
optimization, etc.).
The dynamics for how these goals
can be pursued vary a bit between internal data center and adjacent wide area
network infrastructures. I focus on data center implementations here.
The end game we’re looking at is
one where the logically centralized and streamlined controls for the network
being managed dynamically serve the needs of the applications and users relying
on it for their services. In many data centers this will include a sizable
overlay virtual network running in parallel with a high-performance physical
underlay network. It will include a blend of control plane and value-adding
service control apps to make it all work automatically and with maximum
performance, efficiency, security, and stakeholder satisfaction (phew!).
A challenge in getting to this
end game is achieving these results in a streamlined, integrated manner for both
underlay and overlay networks. As
implementing SDN in data center environments has gotten started, we’ve largely
had operationally separate deployments
of underlay and overlay networks. Services such as VXLAN and virtualized
router modules are operating in their own logical scopes, and a sometimes
heterogeneous fabric of underlying physical network nodes is implementing its
own L2 and L3 functions in parallel. Each piece can do its part on its own, but
it doesn’t create an especially streamlined operational model.
Some amount of overlay and
underlay integration has occurred. From the open networking point of view, a
number of OpenFlow controllers have started to bring a degree of integration of
underlay switches with a range of centralized control plane functions. And in a
proprietary context, Cisco’s ACI framework and APIC service control system have
brought a range of application policy controls to both overlay and underlay
network infrastructures—the only glitch from an optimization point of view is
it’s not being implemented on a fully open platform.
Neither of these early stage
developments has brought a design that unlocks the potential of the open
network control environment of SDN with the power of value-add that can be
obtained from service control applications running in parallel with the SDN
controller that have the ability to optimize both the virtual and the physical
network environments according to the operator’s service delivery requirements.
Most SDN controllers delivered to date open up control of either a virtual
overlay or a physical underlay but not both. And while the APIC is logically
elegant within its own technological silo, it’s not opening up the opportunity
for streamlining to the same extent—across a heterogeneous SDN infrastructure—as
a solution leveraging, say, and Open Daylight-based set of network control
plane functions could.
A glimpse into a more open
framework for streamlining whole data center networking fabrics has started to
appear in a set of recently introduced SDN service control applications from
Big Switch and Brocade. Each has the attribute of bringing a distinct set of
added value to managing a data center’s SDN deployment, while leveraging the
abstraction of the SDN controller as a means of streamlining the deployment of
the application’s work. In this manner they have the potential of leveraging
the versatility and openness of the SDN control plane for implementation of the
service controls they are generating in either a virtual or a physical
deployment or both.
Simplifying analytics, traffic
engineering, and application policy controls in this way brings an order of
magnitude increase in the level of efficiency that an operations and service
management team can achieve toward the services they are managing.
Big Switch’s Fabric Analytics
module and
Brocade’s Volumetric Traffic Management and Path Explorer
applications are each pursuing this path. Examples of implementations
approaching this design have been developed in wide-area or transport SDN
solutions such as
Cisco’s WAE and NCS solutions and
Ciena’s recently introduced
Agility software suite. But in the data center the Big Switch and Brocade
applications are early entrants in the market that are starting to leverage a
truly open architecture for optimization of unified fabrics with extensible
service control applications. Whether additional similar applications arrive in the market using a similar model in the near future will be interesting to see. But
in the meantime, kudos to both suppliers for advancing the state of the art in
managing open data center fabrics with the versatility and extensibility of
their designs.
Paul Parker-Johnson
ACGcc.com
