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A roadmap for traffic engineering in
SDN-OpenFlow networks
Presenter: Robert Huang
Advisor: Dr. Kai-Wei Ke
2015/5/20
Outline
 The evolution of IT technology
 The evolution of Traffic engineering
 Overview of SDN architecture
 Overview of SDN traffic engineering
 The scope of Traffic engineering in SDN
 Flow management
 Fault tolerance
 Topology update
 SDN traffic analysis
 Conclusion
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The Evolution of IT technology
(分久必合,合久必分)
Server
PC
PC
PC
Mainframe
PC
Clouding
SD
3
SD
SD
SD
Ter.
Ter.
Ter.
Ter.
Driving technology
• Semiconductor
• Data communication
• Virtualization
• Web I/F
• Processing+Sensor (Smart device)
• Big data
• Machine learning
• Artificial Intelligence
Characteristic of current network
• For Multi-media stream (Stable stream)
•
•
•
Dedicated path/Circuit switch
Admission control
No retransmission
• For data stream (Burst stream)
•
•
•
Shared path / OSPF routing algorithm)
No admission control / with congestion control
Retransmission mechanism to reach reliability target
• To reduced the business operation cost
•
•
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To build data convergence network
Increasing performance & utilization vs Traffic engineering
The evolution of Traffic engineering
• The purpose of Traffic engineering
• Lessons learned from the past
• TE for future data convergence network
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The purpose of Traffic engineering
• Traffic engineering (TE) is an important
mechanism to optimize the performance of a
data network by dynamically analyzing,
predicting, and regulating the behavior of the
transmitted data.
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Lessons learned from the past
ATM
Network
TCP/IP
Core
Network
RTP
SIP
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Routing
LoadBalance
Conges
tion
Distribut
ed/Int.
OSPF/B
GP/IGP
Static
ECMP
Implicit
(Reno)
Explicit
(ECN)
TE for future data convergence network
• Flow classification
• Routing / Load-balance / Utilization
• Hybrid (Central & Distributed) / Dynamic load
detection
• Bandwidth enforcement
• Admission / Congestion
• Reliability (Restoration / Protection)
• Scalability (Central & Distributed) (Resource lim.)
• Traffic monitoring (Effectiveness)
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The mission of SDN
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Object
Cost
• Enhancing the Network layer
function
• Decreasing the Application
layer efforts for improving
Network functions
• More complex core structure
• Separation of Data plane &
Control plane
• More powerful control
plane servers
• Simpler Data plane
devices
Overview of SDN architecture
• SDN architecture
• OpenFlow switch inside structure
• OF-Config protocol
• The OpenFlow protocol message types
• The critical issues in SDN
• OpenFlow multi-controller scheme
• OpenFlow multi-path scheme
• The major application scenario for SDN
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Overview of SDN architecture
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The scenario of SDN Application
SDN
Applications
SDN Applications
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Web I/F
OpenFlow switch inside structure
Action
set
Fail secure
Fail standalone
Group
Pipeline
Match
•
•
•
•
Adder
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Queue
Rate limit
• Drop
• Lower priority
Meter
Flow
•
•
Min. rate queue
Max. rate queue
All
Select
Indirect
Fast failover
Output Ports
Counter
(Flow / Port / Grp
/ Queue / Meter)
Open network foundation
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The OpenFlow protocol message types
• Controller-to-switch
• Features / Configuration / Modify-State / Read-
State / Packet-out / Barrier / Role-request /
Asynchronous-Configure
• Asynchronous
• Packet-in / Flow-Removed / Port-Status / Error
• Symmetric
• Hello / Echo / Experimenter
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A simple model of an OpenFlow switch
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The critical issues in SDN (Penalty)
• Reliability issue
• Controller single point failure
• Scalability issue
• New path setup latency
• Controller load
• The bandwidth between controller & switch
• Flow matching mechanism
• Match table size
• Matching speed
• WAN management
• Centralized vs distributed
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OpenFlow Multi-controller scheme
Clouding (Virtualization)
Controller
(EQU)
(Default)
Controller
(Master)
(Only one)
Controller
(Slave)
(Read only)
Switch
• Fast recovery from failure
• Controller load balance
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Controller
(Slave)
OpenFlow Multi-path scheme
Controller
Main
(Datapath ID)
AUX
(AUX ID)
Switch
• Bandwidth improvement between controller & switch
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The major application scenario for SDN
• Highly dynamic user demanding and sensitive
operation cost such as
• Clouding service provider
• Telecom. Operation service provider
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Overview of SDN Traffic
engineering
•
•
•
•
•
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The scope of TE approaches in SDN
Flow management
Fault tolerance
Topology update
SDN traffic analysis
The scope of TE approaches in SDN
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SDN stack
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Flow management
• Switch load-balancing
• Hash-based ECMP flow forwarding
• Wildcard rule flow forwarding
• Controller load-balancing
•
•
•
•
•
Logically distributed controller deployment
Physically distributed controller deployment
Hierarchical controller deployment
Multi-thread controllers
Generalized controllers
• Multiple flow tables
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DevoFlow
• OpenFlow switch:
• Making local routing decision with matching
microflows via wildcard OF rules
• OpenFlow controller:
• Maintaining the control over only targeted
“significant flows” such as “elephant flow” or “QoS
significant flows”
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DIFANE
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HyperFlow
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ONIX
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Kandoo
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Fault tolerance
• Fault tolerance for data plane
• Data plane restoration
• Data plane protection
• Fault tolerance for control plane
• Primary and backup controller coordination
• Backup controller deployment
• Distributed controller clusters in equal mode with a logical
central view
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Topology update
• Duplicate table entries in switches
• Per-packet consistency
• Per-flow consistency
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SDN traffic analysis
• Monitoring framework
• Checking network invariants
• Debugging programming errors
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Conclusion
• For availability & scalability issue
• Manage data flow efficiency at both the data plane and the
control plane with the tradeoffs between latency and loadbalance
• For consistency issue
• the SDN controller efficiently updates the network with
consistency in real-time and safety without packet drops,
and with low synchronization overhead
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Conclusion
• For reliability issue
• In the data plane, fast failure recovery mechanisms should
be implemented with low-overhead communications
between the controller and the switches
• In the control plane, the fault tolerance mechanisms must
consider a single point failure and should define an optimal
number of controllers and the best location of controllers for
the primary control and the backup controller(s) with a
tradeoff between reliability and latencies of a variety of
traffic patterns in the entire network
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Reference
 Ian F. Akyildiz, Ahyoung Lee, Pu Wang, Min Luo,
Wu Chou, “A roadmap for traffic engineering in
SDN-OpenFlow networks” Computer Networks 71
(2014) 1-30
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Thanks for listening
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