At a very high level software defined networking

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At a very high level, Software Defined Networking provides exactly the primitives that operators need to run the network better. In particular, SDN provides operators three things. The first is network-wide views of both topology and traffic. The second is the ability to satisfy network level objectives such as those that we talked about before including load balance, security, and other high level goals. The third thing that software defined networking provides (that network operators need) is direct control. In particular, rather than requiring network operators to configure each device individually with indirect configuration, SDN allows an operator to write a control program that directly affects the data plane. So rather than having to configure each device individually and guess or infer what might happen, software-defined networking allows a network operator to express network level objectives and direct control from a logically centralized controller.
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So to make network operations easier, routers should forward packets since router hardware is specialized to forward traffic at very high rates. They should collect measurements such as traffic statistics and topology information. But, on the other hand, there's no reason that a router should have to compute routes. Although conventionally routing has operated as a distributed computation of forwarding tables, the computation doesn't inherently need to run on the routers. Rather, the computation could be logically centralized and controlled from a centralized control program. This logical centralization is the fundamental tenant of SDN. So a simple way of summing up Software Defined Networking is simply to remove routing from the routers, and perform that routing computation at a logically centralized controller. Now of course, SDN has evolved to incorporate a much broader range of controls than simply routing decisions, and we'll talk about the range of control that SDN controllers enable in today's networks throughout this lesson. Software Defined Networking Let's start with a brief overview of Software Defined Networking, or SDN. We'll first start by defining SDN, and in particular we'll talk about what is a Software Defined Network. Then we'll talk about what are the advantages of SDN over a conventional network architecture. We'll overview the history of SDN, the infrastructure that supports it (in particular how SDNs are designed and built), and the applications of SDN. Specifically, what they can be used for and how they can be used to simplify various network management tasks.
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Perhaps the best way to understand what an SDN is, is to compare it to the behavior of today's networks. Today's networks have two functions. The first is the Data Plane, whose task it is to forward packets to their ultimate destination. But in order for the Data Plane to work, we also need a way of computing the state that each of these routers has that allows the routers to make the right decision in forwarding traffic to the destination. The state that lives in each of these
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  • Fall '08
  • Staff
  • IP address, Transmission Control Protocol

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