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Software Defined Networking (SDN) : UG3 Computer Communications & Networks (COMN)

The document discusses Software Defined Networking (SDN), which proposes a shift from distributed router-based network control to a logically centralized controller model. SDN aims to simplify network management, enable flexible traffic flows, and ease innovation through an open and programmable control plane.

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J Roger
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46 views5 pages

Software Defined Networking (SDN) : UG3 Computer Communications & Networks (COMN)

The document discusses Software Defined Networking (SDN), which proposes a shift from distributed router-based network control to a logically centralized controller model. SDN aims to simplify network management, enable flexible traffic flows, and ease innovation through an open and programmable control plane.

Uploaded by

J Roger
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Software Defined Networking (SDN)

UG3 Computer Communications & Networks


(COMN)

Mahesh Marina
mahesh@ed.ac.uk

Slides copyright of Kurose and Ross


Software defined networking (SDN)
• Internet network layer: historically has been
implemented via distributed, per-router
approach
– monolithic router contains switching hardware,
runs proprietary implementation of Internet
standard protocols (IP, RIP, IS-IS, OSPF, BGP) in
proprietary router OS (e.g., Cisco IOS)
– different “middleboxes” for different network layer
functions: firewalls, load balancers, NAT boxes, ..

• ~2005: renewed interest in rethinking network


control plane

Network Layer: Control Plane 5-2


Recall: per-router control plane
Individual routing algorithm components in each and every
router interact with each other in control plane to compute
forwarding tables

4.1 • OVERVIEW OF NETWORK LAYER 309

Routing
Algorithm
Routing algorithm control
Control plane plane
Data plane

Local forwarding data


table
header output
plane
0100 3
0110 2
0111 2
1001 1

Values in arriving
packet’s header
1
1101

2
3

Network Layer: Control Plane 5-3


Figure 4.2 ♦ Routing algorithms determine values in forward tables
Recall: logically centralized control plane
A distinct (typically remote) controller interacts with local
control agents (CAs) in routers to compute forwarding tables

Remote Controller

control
plane

data
plane

CA
CA CA CA CA

Network Layer: Control Plane 5-4


Software defined networking (SDN)
Why a logically centralized control plane?
• easier network management: avoid router
misconfigurations, greater flexibility of traffic flows
• table-based forwarding (OpenFlow API coming up
shortly) allows “programming” routers
– centralized “programming” easier: compute tables centrally
and distribute
– distributed “programming: more difficult: compute tables as
result of distributed algorithm (protocol) implemented in
each and every router
• open (non-proprietary) implementation of control
plane
• Enables and eases innovation

Network Layer: Control Plane 5-5

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