This document provides an introduction to Software Defined Networks (SDN). It discusses: 1) The drawbacks of existing networks that led to the development of SDN, including difficulty performing experiments, slow innovation, and closed/proprietary systems. 2) The key aspects of the SDN architecture, including separating the control plane and data plane, running the control plane on general purpose hardware, and having programmable data planes. 3) The main components of SDN including the controller, which provides network-wide control and management via northbound APIs, and OpenFlow switches, which can be dynamically reconfigured through OpenFlow rules installed by the controller.

1. Damascus University
Faculty of Information Technology Engineering
Department of Computer Systems and Networks
‫دمشق‬ ‫جامعة‬
‫المعلوماتية‬ ‫الهندسة‬ ‫كلية‬
‫الحاسوب‬ ‫والشبكات‬ ‫النظم‬ ‫قسم‬
‫ة‬ّ‫ي‬
‫الشبكات‬ ‫ة‬
‫إدار‬ ‫عملي‬
Network Management
Session 5: Introduction to Software Defined Networks (SDN)
‫اعداد‬
:
‫م‬
.
‫غاندي‬
‫هسام‬
Ghandi
Hessam

2. PART 1:
BACKGROUND
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3. Introduction
• Drawbacks of existing network:
➢Difficult to perform real world experiments on large scale
production networks.
➢Networks have remained the same for many years.
➢Rate of innovation in networks is slower.
➢Closed Systems: Vendor specific software.
➢Non-standard interfaces to H/W.
➢Traditional networks are known to be “inside the box” paradigm.
• Thus, proposals for a new networking paradigm, namely
programmable networks
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4. Software Defined Networking
• Separate Control plane and Data plane entities.
• Execute or run Control plane software on general purpose
hardware.
• Have programmable data planes.
• An architecture to control not just a networking device but an
entire network.
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5. SDN Architecture
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6. SDN Components: Controller
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7. Existing SDN Controller Implementations
 Java-based versions:
 Python-based versions:
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8. Controller northbound API
 Data Plane managed via
Network Controller
providing high level
services like:
– Firewall
– Load Balancing
– VPN
– Intrusion Detection
– …
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9. SDN Components: OpenFlow Switch
 Plug-in services at the switch
layer
 Filtering traffic based on open
flow rules
 Create a underlay network
 Dynamically reconfigure
network based Events
 The widely known one is:
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10. OpenFlow Protocol
 OpenFlow Basics:
❖ Ports and Port Queues
❖ Flow Table
❖ Packet Matching
❖ Actions and Packet
Forwarding
❖ Messaging Between
Controller and Switch
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11. OF v1.0: Flow Table Entry
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12. OF v1.3: Flow Table Entry
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13. Basic Packet matching function
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14. OpenFlow: Types of Messages (1)
• Asynchronous (Controller-to-Switch)
• Send-packet
• Flow-mod
• Asynchronous (initiated by the switch)
• Read-state
• Features
• Configuration
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15. OpenFlow: Types of Messages (2)
• Asynchronous (initiated by the switch)
• Packet-in
• Flow-removed
• Port-status
• Error
• Symmetric (can be sent in either direction without solicitation)
• Hello
• Echo
• Vendor
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16. Dimension of SDN Applications:
Rule installation
Proactive Rules Reactive Rules
Controller (N. O.S.)
Applications
Applications
Applications
Switch H.W
O.S
Controller (N. O.S.)
Applications
Applications
Applications
Switch H.W
O.S
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17. Dimensions of SDN Applications:
Granularity of Rules (1)
Microflow WildCards (aggregated rules)
Controller (N. O.S.)
Applications
Applications
Applications
Switch H.W
O.S
Controller (N. O.S.)
Applications
Applications
Applications
Switch H.W
O.S
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18. Dimensions of SDN Applications:
Granularity of Rules (2)
Distributed Controller Centralized Controller
Controller (N. O.S.)
Applications
Applications
Applications
Switch O.S
Switch HW
Switch O.S
Switch HW
Switch O.S
Switch HW
Controller (N. O.S.)
Applications
Applications
Applications
Switch O.S
Switch HW
Switch O.S
Switch HW
Switch O.S
Switch HW
Controller (N. O.S.)
Applications
Applications
Applications
Controller (N. O.S.)
Applications
Applications
Applications
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19. Google’ B4 Application
 Rule installation
 Proactive
 Rule Granularity
 Aggregate
 Distributed
 Multiple instances
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20. End of Session 5
By Eng. Ghandy Hessam
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