software defined networking data centre perspective ... · snd seminar: hedera | 04.03.2016 | ....
TRANSCRIPT
| | SND Seminar: Hedera
Seminar: Prof. Timothy Roscoe & Dr. Desislava Dimitrova
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Software Defined Networking Data centre perspective: Hedera
D. Dimitrova, T. Roscoe
| | SND Seminar: Hedera 04.03.2016 D. Dimitrova, T. Roscoe 2
Topologies
Source: Cornell, K. Weatherspoon
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How to assign flows to links in an optimal way to maximise the global capacity use
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Scheduling
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Scheduling
Link capacity vs Flow demand
Source: Google
Mice vs Elephant flows
| | SND Seminar: Hedera
Flow type detection Behave as normal switch Collect flow statistics Flow counter < Threshold Mice flow Flow counter > Threshold Elephant flow
Mice flows handled at switch with ECMP
Elephant flows go to the controller
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Flow demand
Scalable control channel communication
| | SND Seminar: Hedera 04.03.2016 D. Dimitrova, T. Roscoe 6
Flow demand
Network-limited
Host-limited • per scheduling period • low memory • low compute time
Source: Google
Source: Hedera @ Sigcomm
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“control network … is used in our testbed as a debugging and comparison tool. This network transports only traffic monitoring and management messages to and
from the switches;”
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Flow demand
Source: mdpi.com
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Global first fit
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Scheduling: Schemes
Why not best fit?
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Simulated Annealing Flow-to-core assignment link capacity matrix Energy = link overloaded capacity Temperature = remaining iterations
Step 1: Initial assignment Step 2: Neighbour swap Step 3: Energy recalculation Repeat until T>0
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Scheduling: Schemes
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Host-to-core association Compute efficient
Incremental energy calculation Compute efficient
Limited # iterations Time efficient
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Scheduling: Schemes
| | SND Seminar: Hedera
Simulated Annealing: Host-to-Core Fat Tree: N_core = N_host Step: 1Initial assignment
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Scheduling: Schemes
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Three ways for neighbour swap why swap, why random, why three strategies
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Scheduling
Per pod
Per edge switch
Per pair hosts
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“Complex algorithms can hinder the scalability and efficiency of the scheduler while gaining only incremental bandwidth returns.”
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Scheduling: Scalability
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Scheduling: Scalability
”the simplicity of our algorithms makes them both well-suited for implementation in hardware, such as in an FPGA”
SDN Controller
Local CPU/NPU
Switching fabric
Bandwidth Delay
| | SND Seminar: Hedera
PortLand: A Scalable Fault-Tolerant Layer 2 Data Center Network Fabric http://cseweb.ucsd.edu/~vahdat/papers/portland-sigcomm09.pdf Hedera presentation http://www.slideshare.net/jasonhoutw/hedera-dynamic-flow-scheduling-for-data-center-networks-an-application-of-softwaredefined-networking-sdn
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Fault tolerance
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ETH Zurich Systems Group Universitättrasse 6 8092 Zürich www.ethz.ch/en.html © ETH Zurich, February 2016
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Contact information and credits