Changes between Version 13 and Version 14 of GENIEducation/SampleAssignments/OpenFlowLoadBalancerTutorial/ExerciseLayout/Execute


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Timestamp:
07/05/13 11:36:40 (6 years ago)
Author:
shuang@bbn.com
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  • GENIEducation/SampleAssignments/OpenFlowLoadBalancerTutorial/ExerciseLayout/Execute

    v13 v14  
    7979   
    8080== 2.5 Fetch experimental results from your iRods account ==
    81  - Log in your iRods account on https://www.irods.org/web/index.php, use "emmy9.casa.umass.edu"
     81 - Log in your iRods account on https://www.irods.org/web/index.php, use "emmy9.casa.umass.edu" as Host/IP, "1247" as Port.
     82 - Download your experimental results from your user directory under /geniRenci/home/
    8283
    83   '''Hints on the OpenFlow controller Script load-balancer.rb:'''
    84   -
    85     - Remember that the default OpenFlow policy for your switch or Open vSwitch instance will likely be to send any packets that do not match a flow spec to the controller, so you will have to handle or discard these packets.
     84== 2.6 Change network delay and lossrate parameter of left path using tc and repeat the experiment ==
     85 - use the following command to change network condition on node "Switch": here we assume eth2 is the interface connecting node "Left". User may use "ifconfig" to figure out the correct interface.
     86{{{
     87tc qdisc add dev eth2 root handle 1:0 netem delay 20ms loss 10%
     88}}}
     89 - Did you see any difference from the graphs plotted on !LabWiki, compared with the graphs plotted in the first experiment? why?
     90 - Check out the OpenFlow Load Balancing Controller's Log on node "Switch" at /tmp/lb.tmp and tell how many flows are directed to the left path and how many are on the right path, why?
     91 - To answer the above question, you need to understand the Load Balancing controller. Check out the "load-balancer.rb" file in your home directory on node "Switch". Check Section 3 for hints/explanations about this OpenFlow Controller.
    8692
    87   '''Process: ''' Upon the arrival of a new TCP flow, the OpenFlow controller should send out a `FlowStatsRequest` message to the OpenFlow switch. The OpenFlow switch will reply with statistics information about all flows in its flow table.
     93==  2.7 Modify the OpenFlow Controller to maximize per-flow throughput ==
     94 - You need to calculate the average per-flow throughput observed from both left and right path in function "stats_reply" in your load-balancer.rb
     95 - In function "packet_in", change the path decision based on the calculated average per-flow throughput: forward the flow onto the path with more average per-flow throughput. (Why? Hint: TCP tries its best to suck up the whole bandwidth)
     96 - If you do not know where to start, check the hints in Section 3. If you really do not know where to start after reading at the hints, download the answer from [http://www.gpolab.bbn.com/experiment-support/OpenFlowExampleExperiment/ExoGENI/load-balancer-solution.rb Here].
     97 - Redo the above experiment (the one with some lossrate on the left path), check the graphs plotted on !LabWiki as well as the controller's log on node "Switch" at /tmp/lb.tmp and see the difference.
     98 - If you have more time or are interested in trying out things, go ahead. The tutorial is over now and feel free to ask questions :-)
     99
     100= 3. Hints =
     101== 3.1 About the OpenFlow controller load-balancer.rb ==
     102  - '''Process: ''' Upon the arrival of a new TCP flow, the OpenFlow controller should send out a `FlowStatsRequest` message to the OpenFlow switch. The OpenFlow switch will reply with statistics information about all flows in its flow table.
    88103  This flow statistics message will be fetched by the `stats_reply` function in the openflow controller implemented by the user on node `switch`. Based on the statistics, experimenters can apply their own policy on which path to choose in different situations.
    89104  The !FlowStatsReply message is in the following format:
     
    104119)
    105120}}}
    106  
    107   '''Note: ''' since Trema does not yet support multi-thread mode, this simple implementation runs in one thread. As a result, users will experience some delay in fetching the flow statistics (i.e., `stats_reply` will not be called right after a !FlowStatsRequest message has been sent in `packet_in` handler).
     121  - '''Note: ''' since Trema does not yet support multi-thread mode, this simple implementation runs in one thread. As a result, users will experience some delay in fetching the flow statistics (i.e., `stats_reply` will not be called right after a !FlowStatsRequest message has been sent in `packet_in` handler).
    108122
    109123= [wiki:GENIEducation/SampleAssignments/OpenFlowLoadBalancerTutorial/ExerciseLayout/Finish Next: Teardown Experiment] =