Changes between Version 14 and Version 15 of GENIEducation/SampleAssignments/OpenFlowLoadBalancerTutorial/ExerciseLayout/Execute


Ignore:
Timestamp:
07/05/13 12:06:02 (6 years ago)
Author:
shuang@bbn.com
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • GENIEducation/SampleAssignments/OpenFlowLoadBalancerTutorial/ExerciseLayout/Execute

    v14 v15  
    100100= 3. Hints =
    101101== 3.1 About the OpenFlow controller load-balancer.rb ==
     102  - Trema web site: http://trema.github.io/trema/
     103  - Treme ruby API document: http://rubydoc.info/github/trema/trema/master/frames
     104  - '''Functions used in our tutorial:'''
     105    - start: is the function that will be called when the OpenFlow Controller is started. Here in our case, we read the file /tmp/portmap and figures out which OpenFlow port points to which path
     106    - switch_ready: is the function that will be called each time a switch connects to the OpenFlow Controller. Here in our case, we allow all non-TCP flows to pass (including ARP and ICMP packets) and ask new inbound TCP flow to go to the controller.
     107    - packet_in: is the function that will be called each time a packet arrives at the controller. Here in our case, we send out a flow_stats_request to get the current statistics about each flow. Then based on the last received statistics (so we are not using the current statistics to make path decisions--there is a delay of two flows), we make our path choices.
     108    - stats_reply: is the function that will be called when the OpenFlow Controller receives a flow_stats_reply message from the OpenFlow Switch. Here in our case, we update the flow statistics here in this function.
     109    - send_flow_mod_add(): is the function that you should use to add a flow entry into an OpenFlow Switch.
    102110  - '''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.
    103111  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.