Carrier SDN Next-gen carrier networking
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By Xu Xiaofei
The telco operations game is currently slow-to-adapt, closed off, and dependent on
expensive, specialized gear that is also slow to adapt. Carriers need a new operational
model that gives them more agility and openness, and Huawei offers one in the form
of carrier-grade software-defined networking (Carrier SDN).
Technological advances are making users more fickle by the day, as they demand
ubiquitous, zero-wait access to their favorite services regardless of terminal or time of
day. To bring this into being, carriers need to transform their networks on two fronts.
First, networks must become user-friendly and application-friendly, with added value,
and this requires the constant opening of network resources. Second, networks must
be highly efficient, with ubiquitous ultra-broadband coverage, and this can be
accomplished by transforming the cost structure. Though these two transformations
are quite different, they share a common ground in that both depend on their basic
technical infrastructure.
Thoughts on basic infrastructure
Currently, the basic technical infrastructure of carrier networks has three key
hindrances – protocol standardization, dedicated equipment, and a lack of network
exposure.
Protocol standardization – The telco industry has always been standards-based and
standards-driven. What propels such standardization are customer requirements and
technological evolution. Standardization makes interoperability possible and enables
carriers to replace equipment with that of different vendors. However, protracted
processes within different standardization bodies and conflicts of interest between the
relevant parties keep the commercialization process slow (one to five years); this
prolonged standardization cycle distracts carriers’ attention from innovation and
nascent technologies. The Internet, on the other hand, is more “ready, fire, aim,” and
the only standard is “survival of the fittest.” As such, a question arises – how can a
next-gen network guarantee interoperability, fair competition, and the acceleration of
business innovation, so that user needs are met in a timely fashion? Another issue
here is the fact that developing a standard requires comprehensive consideration of
each carrier’s diverse body of requirements and scenarios, which all vendors must
conform to if they are to compete, so the resultant costs are passed on to the former.
This begs another question – how can next-gen networking provide the most
streamlined and appropriate solutions that meet specific carrier requirements?
Dedicated equipment – Different categories of telco gear adopt different
architectures for their unique network functions, and each category carries out a
certain network function and nothing more. Consequently, the long process of bidding,
testing, integration, and installation has to be done for each piece of equipment.
Installing and maintaining dedicated gear requires personnel with the relevant
expertise and skills, and vendor selection is often limited, leading to exorbitant costs
for procurement and maintenance. This brings a third question to mind – how can
next-gen networks carry out diversified tasks using less specialized gear, and still
perform at a high level?
A lack of exposure – Legacy telco networks are not exposed, and this makes
customization of network resources difficult, leading to sub-optimal user experience
and resource utilization. The question is – how can next-gen networking spread
around the traffic dynamically, in a way that does not compromise the user
experience?
SDN relayers the logical network
Software-defined networking (SDN), proposed by the Open Networking Foundation
(ONF), is a new and vital form of technical infrastructure that answers these
aforementioned questions. It redefines the network into three logical layers –
application, control, and infrastructure.
The infrastructure layer forwards data at high speeds while the control layer centrally
implements network intelligence and communicates with the infrastructure layer (the
lower layer) using a standardized protocol (OpenFlow), provides access to network
resources, and invokes control capabilities to the application layer (the upper layer)
through open programming interface. Thanks to this openness, the application layer
enables innovation. The key to SDN is OpenFlow, a communications protocol
between the control and infrastructure layers, and the proposed functional
specification for the forwarding equipment.
As a complementary approach to SDN, the network function virtualization (NFV)
concept has been raised recently by a number of operators. NFV enables virtualization
of network functions based on commodity servers, switches, and storage devices with
functionality adjustable through software, including carrier-grade network address
translation (CGN), wide area network acceleration, and enterprise access routing.
With NFV, operators can reduce costs, shorten service TTM, use resources more
flexibly, and foster network innovation ecosystem.
Based on a thorough understanding of SDN/NFV, Huawei is advancing the industry
by pioneering the overall technical infrastructure of carrier SDN, an open and
programmable architecture that enables network elasticity, simplicity, and agility, as
well as added value, from end to end.
Carrier SDN decouples the forwarding and control gear, while virtualizing the
equipment in general; simplicity is achieved through centralized management and
streamlined operation & maintenance (O&M). Elasticity means that the network is
programmable, adaptable, and compatible with a variety of gear, while agility ensures
end-to-end network resource abstraction and programming, which greatly facilitates
new service delivery. By exposing network resources and enabling interaction
between applications and the network, network capabilities represent added value as
carriers can profit from various applications’ demands.
Next-gen network construction
Carrier SDN enables cloud-pipe collaboration, application openness, and traffic
monetization, thanks to its end-to-end management system. It will also bring about
transformation in the network O&M system, while providing end-to-end collaboration
that enables coordination between subscriber access and subscriber management,
between data centers (DCs) and bearer networks, between IP and optical networks,
and between multiple controllers. As a result, these separate and fragmented networks
become integrated entities that coordinate resources for the entire network, while
traffic & service visibility facilitates the flexible traffic charging and smart data
analysis that will support business innovation and service operation.
Future IP backbone networking will be DC-centric. Software-defined inter- and
intra-DC networks support automatic service deployment via collaboration between
IP and IT and interconnection between heterogeneous DCs. Such networks will
optimize the load balance and path scheduling via centralized traffic engineering and
path algorithms, laying the technical foundation for more flexible and efficient carrier
IP. Through software configuration, carrier SDN can flexibly support different DC
networks’ technologies without hardware upgrade of routers or switches, making
technical solution selection and subsequent evolution that much easier.
With carrier SDN, carriers can customize their basic bearer protocols based on site
requirements, without hardware upgrade of the routers, as the forwarding architecture
is oblivious to protocols. In other words, a software-defined router supports online
upgrade of bearer protocols, without hardware upgrade.
Carrier SDN also decouples the forwarding and control layers, so forwarding gear is
standardized and control is centralized, bringing down maintenance costs. In addition,
its high-performance distributed routing capability supports ultra-large-scale SDN
networks, while its customized and multi-dimensional routing algorithm meets the
traffic path selection requirements for different applications, thus maximizing network
utilization.
The software-defined service gateway facilitates business innovation so that customer
needs are quickly accommodated; forwarding is separated from service management
via a standardized interface, while services can also be managed for elastic expansion.
The programmable interface is available to the application layer, facilitating business
innovation, while the forwarding layer utilizes the high-performance gear with
flexibility and balance.
The software-defined transmission network is a programmable and flexible-rate
optical network, providing instantaneous bandwidth and elastic pipes. Transmission
speed, distance, grid, and wavelength spacing can all be set via software. What
carriers purchase are the overall capabilities, expressed as “distance multiplied by
speed.” Long-distance data transmission at a low speed or short-distance transmission
data at a high speed meet different application requirements, and improve
transmission resource utilization to boot.
The software-defined access network streamlines the maintenance of separate
equipment and centralizes management of various access resources. The forwarding
and control for the remote gear is decoupled, with the gear itself plug and play, and
centrally managed via the optical line terminal (OLT). The circuit technology is
programmable, so hardware need not be changed when upgrading different access
circuits. All access technologies (xDSL/FTTx) are also controlled and managed in a
unified manner.
The big picture
All these features sound dazzling, but without programmable lower-layer hardware
and software, the open and programmable value of SDN cannot be fully demonstrated.
For the short term, software-based reengineering can provide the appropriate network
programmability. In the long run, the hardware system must be improved to better
utilize SDN and reconstruct the cost structure for the network, so that those next-gen
network features of “elasticity, simplicity, agility, and added value” come into being.
The technical infrastructure for Huawei carrier SDN encompasses multiple networks,
equipment types, and technical layers, including the access network, metro network,
backbone network, and the data centers. In the short term, the architecture will
provide openness and programmability for the existing equipment so that the carrier’s
equipment investment is protected. In the long run, Huawei will plan the technical
evolution of both network architecture and equipment.
However, legacy evolution to SDN/NFV is an uphill climb, but Huawei carrier SDN
provides different solutions for different deployment scenarios. These solutions are
applicable to hybrid networks, newly constructed networks, networks that require
software upgrade, and networks that require upgrade to SDN/NFV hardware.
Whatever the need, Huawei is committed to carrier partnership for SDN/NFV-based
next-gen network construction.
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