1. 虛擬化技術 Virtualization Techniques
Network Virtualization
Software Defined Netwrok

2. Software defined network
Introduction
Motivation
Concept
Character
Open Flow
Software defined network

3. Network Protocol and Model

4. Network Topologies Topologies
Topology refers to the physical or logical layout of the computers in a particular network.
Commonly used topologies are star, bus and ring.

5. Network Virtualization
What is network virtualization ?

6. Network Virtualization
What is network virtualization ?
In computing, Network Virtualization is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network.
Two categories :
External network virtualization
Combining many networks, or parts of networks, into a virtual unit.
Internal network virtualization
Providing network-like functionality to the software containers on a single system.

7. Network Virtualization
Desirable properties of network virtualization :
Scalability
Easy to extend resources in need
Administrator can dynamically create or delete virtual network connection
Resilience
Recover from the failures
Virtual network will automatically redirect packets by redundant links
Security
Increased path isolation and user segmentation
Virtual network should work with firewall software
Availability
Access network resource anytime

8. Network Virtualization
External network virtualization in different layers :
Layer 1
Seldom virtualization implement in this physical data transmission layer.
Layer 2
Use some tags in MAC address packet to provide virtualization.
Example, VLAN.
Layer 3
Use some tunnel techniques to form a virtual network.
Example, VPN.
Layer 4 or higher
Build up some overlay network for some application.
Example, P2P.

9. Network Virtualization
Internal network virtualization in different layers :
Layer 1
Hypervisor usually do not need to emulate the physical layer.
Layer 2
Implement virtual L2 network devices, such as switch, in hypervisor.
Example, Linux TAP driver + Linux bridge.
Layer 3
Implement virtual L3 network devices, such as router, in hypervisor.
Example, Linux TUN driver + Linux bridge + iptables.
Layer 4 or higher
Layer 4 or higher layers virtualization is usually implemented in guest OS.
Applications should make their own choice.

10. Network Virtualization
Protocol approach
Protocols usually used to approach data-path virtualization.
Three implementations
802.1Q – implement hop to hop data-path virtualization
MPLS ( Multiprotocol Label Switch ) – implement router and switch layer virtualization
GRE (Generic Routing Encapsulation ) – implement virtualization among wide variety of networks with tunneling technique.

11. Network Virtualization
802.1Q
Standard by IEEE 802.1
Not encapsulate the original frame
Add a 32-bit field between MAC address and EtherTypes field
ETYPE(2B): Protocol identifier
Dot1Q Tag(2B): VLAN number, Priority code
CE: Customer Edge router
PE: Provider Edge router

12. Network Virtualization
Example of 802.1Q
VN 1
Source
destination
Physical Network
VN 2
Source
destination

13. Network Virtualization
MPLS ( Multiprotocol Label Switch )
Also classified as layer 2.5 virtualization
Add one or more labels into package
Need Label Switch Router(LSR) to read MPLS header

14. Network Virtualization
Example of MPLS
VN 1 5 4 2 7 9 8
LSR
Physical Network
LER
LER CE
LSR CE
LER CE
VN 2 5 4 2 7 9

15. Network Virtualization
GRE ( Generic Routing Encapsulation )
GRE is a tunnel protocol developed by CISCO
Encapsulate a wide variety of network layer protocol
Stateless property
This means end-point doesn't keep information about the state
Built Tunnel

16. Internal Network Virtualization
A single system is configured with containers, such as the Xen domain, combined with hypervisor control programs or pseudo-interfaces such as the VNIC, to create a “network in a box”.
This solution improves overall efficiency of a single system by isolating applications to separate containers and/or pseudo interfaces.
Virtual machine and virtual switch :
The VMs are connected logically to each other so that they can send data to and receive data from each other.
Each virtual network is serviced by a single virtual switch.
A virtual network can be connected to a physical network by associating one or more network adapters (uplink adapters) with the virtual switch.

17. Software defined network
Introduction
Motivation
Concept
Character
Open Flow
Software defined network

18. Problem with Internet Infrastructure
Routing, management, mobility management,
access control, VPN,….
Feature
Feature
Million of lines of source code
Operating System
Specialized Packet
Forwarding Hardware
Billions of gates Bloated
Vertically integrated, complex, closed, proprietary
Not suitable for experimental ideas
Not good for network owners & users; Not good for researchers.

19. Problem: No Abstractions for Control Plane
Addition of a new function to the network
Highly complex distributed system problem
Networks too difficult to program and to reason about
No good abstractions and interfaces
Forwarding OS
Distributed Network Functions
Forwarding OS
Router/Switch/Appliance
Forwarding OS
Router/Switch/Appliance
Router/Switch/Appliance

20. Software-Defined Network with key Abstractions in the Control Plane
Network Virtualization
Well-defined API
Routing
Traffic Engineering
Other Applications
Network Map
Abstraction
Network Operating System
Forwarding
Separation of Data
and Control Plane
Forwarding
Forwarding
Forwarding

21. Software defined network
Introduction
Motivation
Concept
Character
Open Flow
Software defined network

22. Concept
In SDN architecture, the control and data planes are decoupled, network intelligence and state are logically centralized, and the underlying network infrastructure is abstracted from the applications.
By Open Networking Foundation white paper

23. Traditional network node: Router
Router can be partitioned into control and data plane
Management plane/ configuration
Control plane / Decision: OSPF (Open Shortest Path First)
Data plane / Forwarding
Adjacent Router
Router
Management/Policy plane
Configuration / CLI / GUI
Static routes
Control plane
OSPF
Neighbor table
Link state database
IP routing table
Forwarding table
Data plane
Routing
Switching

24. Traditional network node: Switch
Typical Networking Software
Management plane
Control Plane – The brain/decision maker
Data Plane – Packet forwarder

25. SDN entity SDN Protocol – Open Flow
A commonly protocol used to manage software defined network

26. SDN Software Defined Networking SDN Principles
Separate Control plane and Data plane entities
Execute or run Control plane software on general purpose hardware
Decouple from specific networking hardware
Use commodity servers
Have programmable data planes
Maintain, control and program data plane state from a central entity
An architecture to control not just a networking device but an entire network

27. Software defined network
Introduction
Motivation
Concept
Character
Open Flow
Software defined network

28. Key Characters for SDN Success
Architecture for a Network Operating System with a service/application oriented namespace
Resource virtualization and aggregation
pooling to achieve scaling
Appropriate abstractions to foster simplification
Decouple topology, traffic and inter-layer dependencies
Dynamic multi-layer networking

29. Software defined network
Introduction
Motivation
Concept
Character
Open Flow
Software defined network

30. What is OpenFlow
OpenFlow is like an x86 instruction set for the network
Provides open interface to “black box” networking node
(ie. Routers, L2/L3 switch) to enable visibility and openness in network
Separation of control plane and data plane.
The datapath of an OpenFlow Switch consists of a Flow Table, and an action associated with each flow entry
The control path consists of a controller which programs the flow entry in the flow table
OpenFlow is based on an
Ethernet switch, with an internal
flow-table, and a standardized
interface to add and remove flow
entries

31. Components of OpenFlow Network
Controller
OpenFlow Protocol Messages
Controlled channel
Flow Table
Flow entry
Processing
Pipeline Processing
Packet Matching
Instructions & Action Set

32. Controller: Centralized V.S. Distributed

33. OpenFlow Protocol Messages
Controller-to-Switch :
initiated by the controller and used to directly manage or inspect the state of the switch
EX: Features, Config, Modify State, Read-State, Packet-Out, Barrier.
Asynchronous :
Asynchronous messages are sent without the controller soliciting them from a switch
EX: Packet-in, Flow Removed / Expiration, Port-status, Error
Symmetric:
Symmetric messages are sent without solicitation, in either direction
EX: Hello, Echo, Experimenter / Vendor

34. Secure Channel (SC)
SC is the interface that connects each OpenFlow switch to controller
A controller configures and manages the switch via this interface.
Receives events from the switch
Send packets out the switch
SC establishes and terminates the connection between OpneFlow Switch and the controller using the procedures
Connection Setup
Connection Interrupt
The SC connection is a TLS connection. Switch and controller mutually authenticate by exchanging certificates signed by a site-specific private key.

35. Flow Table / Entry A flow table consists of flow entries Match fields
to match against packets. These consist of the ingress port and packet headers, and optionally metadata specified by a previous table
Counters
to update for matching packets
instructions
to modify the action set or pipeline processing
Match Fields
Counters
Instructions
In Port
Src MAC
Dst MAC
Eth Type
Vlan Id
IP Tos
IP Proto
IP Src
IP Dst
TCP Src Port
TCP Dst Port
Layer 2
Layer 3
Layer 4
Forward packet to port(s)
Encapsulate and forward to controller
Drop packet
Send to normal processing pipeline
1. Packet
2. Byte counters

36. Matching Fields & List of Counters
Figure From OpenFlow Switch Specification

37. Pipeline Processing

38. Packet Matching

39. Flowchart how to parsed for matching
Eth Type (commonly)
Vlan: 0x88a8, 0x8100
MPLS: 0x8847, 0x8848
ARP: 0x0806
IP: 0x0800

40. Instructions & Action Set
Each flow entry contains a set of instructions that are executed when a packet matches the entry
An Action set is associated with each packet. Its empty by default
Action set is carried between flow tables
A flow entry modifies action set using Write Action or Clear-Action instruction
Processing stops when the instruction does not contain Goto-Table and the actions in the set are executed

41. Dynamic load balancing
Usage: Load Balancing
Current methods use uniform distribution of traffic
Not based on network congestion and server load
More adaptive algorithms can be implemented by using OpenFlow
Monitor the network traffic
Program flows based on demand and server capacity
Network Operating System
Program Flow Entries
Data Forwarding (OpenFlow Switch)
Collect Statistics
Observe load patterns
Dynamic load balancing
using Open Flow

42. Summary SDN is an architecture of which OpenFlow is just a part
Clearly separation of control and data plane functionalities
Provides high level abstractions
Network topology
Application API
Standard vendor-agnostic interface to program the hardware
Scalability concerns
SDN is not a magic wand to solve the current problems
Many vendors are evaluating the direction SDN will take

43. References
"OpenFlow: Enabling Innovation in Campus Networks“ N. McKeown, T. Andershnan, G. Parulkar, L. Peterson, J. Rexford, S. Shenker, and J. Turneron, H. Balakris ACM Computer Communication Review, Vol. 38, Issue 2, pp April 2008
OpenFlow Switch Specication V
Richard Wang, Dana Butnariu, and Jennifer Rexford OpenFlow-based server load balancing gone wild, Workshop on Hot Topics in Management of Internet, Cloud, and Enterprise 66 IP Infusion Proprietary and Confidential, released under Customer NDA , Roadmap items subject to change without notice © 2011 IP Infusion Inc. gone wild, Workshop on Hot Topics in Management of Internet, Cloud, and Enterprise Networks and Services (Hot-ICE), Boston, MA, March 2011.
Saurav Das, Guru Parulkar, Preeti Singh, Daniel Getachew, Lyndon Ong, Nick McKeown, Packet and Circuit Network Convergence with OpenFlow, Optical Fiber Conference (OFC/NFOEC'10), San Diego, March 2010
Nikhil Handigol, Srini Seetharaman, Mario Flajslik, Nick McKeown, Ramesh Johari, Plug-n-Serve: Load-Balancing Web Traffic using OpenFlow, ACM SIGCOMM Demo, Aug 2009.
NOX: Towards an Operating System for Networks

44. Q & A