The Road to SDN Flashcards
Enabled innovation in how we design and manage
networks. Also separates the control and
data planes in computer networks.
Software Defined Networking (SDN)
This mode of operation has slowed innovation,
increased complexity, and inflated both the capital and operational
costs of running a network.
Network administrators typically configure
individual network devices using configuration interfaces
that vary across vendors—and even across different
products from the same vendor. Although some networkmanagement
tools offer a central vantage point for configuring
the network, these systems still operate at the level
of individual protocols, mechanisms, and configuration
interfaces.
changing the
way we design and manage networks
Software Defined Networking (SDN)
SDN has two defining
characteristics.
First, an SDN separates the control plane (which decides how to handle the traffic) from the data plane (which forwards traffic according to decisions that the control plane makes).
Second, an SDN consolidates the control plane, so that a single software control program controls multiple data-plane elements.
exercises direct control over the state in the network’s data-plane elements (i.e., routers, switches, and
other middleboxes) via a well-defined Application Programming Interface (API).
The SDN control plane
A prominent example of such an API that has one or
more tables of packet-handling rules. Each rule matches a subset of traffic and performs certain actions on the traffic that matches a rule; actions include dropping, forwarding, or flooding. Depending on the rules installed by a controller application, This API switch can behave like a router, switch, firewall, network address translator, or something in between.
Openflow
played an important role
throughout the historical evolution of SDN, substantially
predating SDN yet taking root as one of the first significant
use cases for SDN.
.Network virtualization
The active networking community pursued two programming
models:
the code to execute at the
nodes was carried in-band in data packets
1) the capsule model
the code to execute at the nodes was established by out-of-band mechanisms
2) the programmable router/switch model
Active networks offered these 3 intellectual
contributions that relate to SDN (among others)
1) Programmable functions in the network to lower the
barrier to innovation.
2) Network virtualization, and the ability to demultiplex
to software programs based on packet headers.
3) The vision of a unified architecture for middlebox orchestration.
network-management functions such as the control over the paths used to deliver traffic
(a practice commonly known as traffic engineering
Technology push and use pull.
These trends catalyzed two innovations:
1) open interface between the control and data planes
2) logically centralized control
a network-wide activity
network management
provides a wider range of functionality
(e.g., dropping, flooding, or modifying packets)
based on a wider range of header fields (e.g., MAC and
IP addresses, TCP and UDP port numbers)
Openflow
set the stage for the creation of OpenFlow
The Ethane project, and its operational deployment
in the Stanford computer science department
