Hints about using GENI Infrastructure as well as other tools in the GENI system

GPO Wiki

• To find ppl: ​http://groups.geni.net/syseng/wiki/ContactInfo#CurrentGPOpeople
• New Experiment Tutorial Template: ​http://groups.geni.net/geni/wiki/GENIEducation/SampleAssignments/Template/ExerciseLayout

Traffic Control

• tc qdisc

  tc qdisc add dev eth2 root handle 1:0 netem delay 100ms loss 5%
  tc qdisc add dev eth2 parent 1:0 tbf rate 20mbit buffer 20000 limit 16000
  

It seems that tc qdisc tbf does not work well (in terms of controlling the throughput of TCP flows) on ovs when ovs switch is connected with a controller.
Instead, we use ovs-vsctl:

ovs-vsctl set Interface eth2 ingress_policing_rate=1000
ovs-vsctl set Interface eth2 ingress_policing_burst=100

The above sets the ingress rate to be in 900kbps-1100kbps.
To set it back to no rate control, use:

ovs-vsctl set Interface eth2 ingress_policing_rate=0

It is a little bit tricky to configure delay/loss on an OpenVZ virtual machine
Step 1: find our qdisc family number by executing "sudo /sbin/tc qdisc", a sample output could be like the following:

[shufeng@center ~]$ sudo /sbin/tc qdisc
qdisc htb 270: dev mv6.47 root refcnt 2 r2q 10 default 1 direct_packets_stat 0
qdisc netem 260: dev mv6.47 parent 270:1 limit 1000
qdisc htb 150: dev mv6.41 root refcnt 2 r2q 10 default 1 direct_packets_stat 0
qdisc netem 140: dev mv6.41 parent 150:1 limit 1000
qdisc htb 190: dev mv6.43 root refcnt 2 r2q 10 default 1 direct_packets_stat 0
qdisc netem 180: dev mv6.43 parent 190:1 limit 1000
qdisc htb 230: dev mv6.45 root refcnt 2 r2q 10 default 1 direct_packets_stat 0
qdisc netem 220: dev mv6.45 parent 230:1 limit 1000

Now if the ethernet card you want to change is mv6.43, you can find from following line:

qdisc htb 190: dev mv6.43 root refcnt 2 r2q 10 default 1 direct_packets_stat 0
qdisc netem 180: dev mv6.43 parent 190:1 limit 1000

As a result, you change the delay/loss by executing the following:

sudo /sbin/tc -s qdisc change dev mv6.43 parent 190:1 handle 180: netem limit 1000 delay 100ms loss 5%
sudo /sbin/tc -s qdisc change dev mv6.43 parent 190:1 handle 180: netem limit 1000

git Commands

git clone [url]
git add -A . (add all files and folders in the current directory)
git commit -m "commit message"
git status (to check the status of your local copy)
git fetch origin
git merge origin/master
git push origin master (upload your local copy to master (global) repository)

OpenFlow Trema

To restart Trema controller as well as the attached switch:

1. kill trema process: kill $(pidof ruby) 
2. delete lock file: rm /opt/trema...../tmp/pid/controller.pid  (controller is the name of your controller, in the case of Load Balancing, its `Load_Balancer`)
3. unlink the switches from controller: ovs-vsctl del-controller br0
4. start controller: /opt/trema....../trema run controller.rb (controller is the name of your controller, in the case of Load Balancing, its  load_balancer.rb)
5. link switches to the controller: ovs-vsctl set-controller br0 tcp:127.0.0.1 
 (might need to wait for 2 seconds for the switch to connect to the controller, to verify that, print something in the "switch_ready" function so that you can see the output when switch is connected)