2. LIMITATIONS OF EXISTING
NETWORKS
• Difficult to perform real world experiments on large scale
production networks.
• Research stagnation-huge costly equipment to be procured
and networks to be setup by each team for research
• Networks have remained the same for many years
• Rate of innovation in networks is slower as protocols are
defined in isolation-lack of high level abstraction.
• Closed systems
• Hard to collaborate meaningfully due to lack of standard
open interfaces.
• Vendors starting to open-up but not meaningfully.
• Innovation is limited to vendor/vendor partners
• Huge barriers for new ideas in networking.
3. Limitations of Current Networks
Million of
lines
of source
code
Billions of
gates
Many complex functions baked
into infrastructure
OSPF, BGP, multicast,
differentiated services,
Traffic Engineering, NAT,
firewalls, …
Specialized Packet
Forwarding Hardware
Operating
System
Featu
re
Feature
Cannot dynamically change according to network conditions
4. Idea: An OS for Networks
Specialized Packet
Forwarding Hardware
App App App
Specialized Packet
Forwarding Hardware
App App App
Specialized Packet
Forwarding Hardware
App App App
Specialized Packet
Forwarding Hardware
App App App
Specialized Packet
Forwarding Hardware
Operating
System
Operating
System
Operating
System
Operating
System
Operating
System
App App App
Network Operating System
Control
Programs
5. SOFTWARE DEFINED
NETWORKING
• Data Plane: processing and delivery of packets
Based on state in routers and endpoints
E.g., IP, TCP, Ethernet, etc.
• Control Plane: establishing the state in routers
Determines how and where packets are forwarded
Routing, traffic engineering, firewall state, …
• Separate control plane and data plane entities
• Have programmable data planes—maintain, control and
program data plane from a central entity i.e. control plane
software called controller.
• An architecture to control not just a networking device but an
entire network.
6. Global Network View
Protocols Protocols
Control via
open
forwarding
interface
Network Operating System
Control
Programs
Software-Defined Networking (SDN)
Control
Programs
Packet
forwarding
7. NEED FOR SDN
• Facilitate innovation in network.
• Layered architecture with standard Open interfaces.
• Experiment and research using non-bulky, non-expensive
equipment.
• More accessibility since software can be easily developed by
more vendors.
• More flexibility with programmability.
• Ease of customization and integration with other software
applications
• Program a network vs. configure a network
8. ARCHITECTURE OF SDN
In the SDN architecture, the control and data planes are
decoupled, network intelligence and state centralized, and the
underlying network infrastructure is abstracted from the
applications.
9. SDN LAYERS
• Infrastructure layer: it is the foundation layer consists of both
physical and virtual network devices such as switches and
routers. All the network devices will implement OpenFlow
protocol to implement traffic forwarding rules.
• Control layer: This layer consists of a centralized control plane
that is decoupled from the physical infrastructure to provide
centralized global view to entire network. The layer will use
OpenFlow protocol to communicate with below layer i.e.
infrastructure layer.
• Application layer: it consists of network services, application
and orchestration tools that are used to interact with control
layer. It provide an open interface to communicate with other
layers in the architecture.
10. OPENFLOW PROTOCOL
• OPENFLOW is an open API that provides a standard interface
for programming the data plane switches. It is a protocol for
remotely controlling the forwarding table of a switch or router
and is one element of SDN.
• It is implemented on Ethernet switches to allow the forwarding
plane i.e. data plane to be managed by a controller present on
control plain in SDN architecture. OpenFlow based controllers
will discover and maintain an inventory of all the links in the
network and then will create and store all possible paths in
entire network.
• OpenFlow protocol can instruct switches and routers to direct
the traffic by providing software-based access to flow tables that
can be used to quickly change the network layout and traffic
flows as per users requirements.
12. OPENFLOW SWITCH AND
CONTROLLER
• An OpenFlow Switch contain one or more flow tables that
implement packet lookups and forwarding, and an OpenFlow
channel to link to an external controller .The switch
interconnects with the controller and the controller directs the
switch using the OpenFlow protocol.
• The controller can delete, add or update flow entries in flow
tables existing in the switch, both reactively i.e. in response to
packets or proactively, using the OpenFlow protocol.
• Controller make this decision based on policies set by
administrator or depending on the conditions of the network and
the decision it makes is forwarded to flow table entries of all the
switches in the network.
14. CURRENT STATUS of SDN
• Google built hardware and software based on the
OpenFlow protocol
• VMware purchased Nicira for $1.26 billion in 2012
• IBM, HP, NEC, Cisco and Juniper also are offering
SDNs that may incorporate OpenFlow, but also
have other elements that are specific to that
vendor and their gear.
15. CONCLUSIONS and FUTURE
SCOPE
• In future, networking will rely more on software to pick up the
pace the innovations in networks.
• SDN can transform today’s static networks into more flexible,
programmable platforms to provide scalability to support large
data centers. It will also provide virtualization that is needed to
support automated, dynamic and secure cloud environment.
• Mostly implementations of newly proposed systems,
frameworks, or applications
