Mininet ex2

4.1 Start Network

We started a network with 3 hosts, one switch and one controller


mininet@mininet-vm:~$ sudo mn --topo single,3 --mac --switch ovsk --controller remote
*** Creating network
*** Adding controller
Unable to contact the remote controller at 127.0.0.1:6633
*** Adding hosts:
h1 h2 h3 
*** Adding switches:
s1 
*** Adding links:
(h1, s1) (h2, s1) (h3, s1) 
*** Configuring hosts
h1 h2 h3 
*** Starting controller
c0 
*** Starting 1 switches
s1 
*** Starting CLI:
mininet>

4.2 Brief Intro

Learning to use mininet, see the nodes, help,
Find the first mininet host IP (h1) and open xterm windows on two hosts

mininet> nodes
available nodes are: 
c0 h1 h2 h3 s1
mininet> help

Documented commands (type help <topic>):
========================================
EOF    gterm  iperfudp  nodes        pingpair      py      switch
dpctl  help   link      noecho       pingpairfull  quit    time  
dump   intfs  links     pingall      ports         sh      x     
exit   iperf  net       pingallfull  px            source  xterm 

You may also send a command to a node using:
  <node> command {args}
For example:
  mininet> h1 ifconfig

The interpreter automatically substitutes IP addresses
for node names when a node is the first arg, so commands
like
  mininet> h2 ping h3
should work.

Some character-oriented interactive commands require
noecho:
  mininet> noecho h2 vi foo.py
However, starting up an xterm/gterm is generally better:
  mininet> xterm h2



mininet> h1 ifconfig
h1-eth0   Link encap:Ethernet  HWaddr 00:00:00:00:00:01  
          inet addr:10.0.0.1  Bcast:10.255.255.255  Mask:255.0.0.0
          inet6 addr: fe80::200:ff:fe00:1/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:9 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:738 (738.0 B)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)


mininet> xterm h1 h2


mininet>

4.3 dpctl Example Usage

dpctl allow us to control a single switch's flow table


mininet@mininet-vm:~$ dpctl show tcp:127.0.0.1:6634
features_reply (xid=0x8caef9b0): ver:0x1, dpid:1
n_tables:254, n_buffers:256
features: capabilities:0xc7, actions:0xfff
 1(s1-eth1): addr:d2:45:80:d7:c4:0f, config: 0, state:0
     current:    10GB-FD COPPER 
 2(s1-eth2): addr:66:3a:2d:fc:4c:a4, config: 0, state:0
     current:    10GB-FD COPPER 
 3(s1-eth3): addr:6e:50:9c:90:fc:1e, config: 0, state:0
     current:    10GB-FD COPPER 
 LOCAL(s1): addr:de:d8:74:06:6f:4e, config: 0, state:0
get_config_reply (xid=0x6b587d9f): miss_send_len=0

mininet@mininet-vm:~$ dpctl dump-flows tcp:127.0.0.1:6634
stats_reply (xid=0xf3f77aa1): flags=none type=1(flow)

4.4 Ping test

we do a ping test from h1 to h2 through the controller 
but the switch flow table is empty and no controller connected to the switch so the switch doesn't know what to do with incoming traffic.
that's why the ping failed. 

mininet> h1 ping -c3 h2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
From 10.0.0.1 icmp_seq=1 Destination Host Unreachable
From 10.0.0.1 icmp_seq=2 Destination Host Unreachable
From 10.0.0.1 icmp_seq=3 Destination Host Unreachable

--- 10.0.0.2 ping statistics ---
3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2014ms
pipe 3
mininet>

now we will use dpctl to manually install this flows 

mininet@mininet-vm:~$ dpctl add-flow tcp:127.0.0.1:6634 in_port=1,actions=output:2
mininet@mininet-vm:~$ dpctl add-flow tcp:127.0.0.1:6634 in_port=2,actions=output:1

and we verify that by checking the flow-table

mininet@mininet-vm:~$ dpctl dump-flows tcp:127.0.0.1:6634
stats_reply (xid=0xb80bd821): flags=none type=1(flow)
  cookie=0, duration_sec=51s, duration_nsec=175000000s, table_id=0, priority=32768, n_packets=0, n_bytes=0, idle_timeout=60,hard_timeout=0,in_port=2,actions=output:1
mininet@mininet-vm:~$ 

try to ping again, it failed because I waited more then 60 seconds (the default time-out), I re-enter the flows and tried to ping right away.
this time it worked

mininet> h1 ping -c4 h2
PING 10.0.0.2 (10.0.0.2) 56(84) bytes of data.
64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=0.554 ms
64 bytes from 10.0.0.2: icmp_seq=2 ttl=64 time=0.040 ms
64 bytes from 10.0.0.2: icmp_seq=3 ttl=64 time=0.050 ms
64 bytes from 10.0.0.2: icmp_seq=4 ttl=64 time=0.051 ms

--- 10.0.0.2 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3002ms
rtt min/avg/max/mdev = 0.040/0.173/0.554/0.220 ms
mininet> 
 

4.5 Start WireShark

i started the wireshark and start capture lo interface(loopback), set 'of' filter

sudo wireshark &
[1] 5862
mininet@mininet-vm:~$ Gtk-Message: Failed to load module "pk-gtk-module"
Gtk-Message: Failed to load module "canberra-gtk-module"

4.6 Start Controller and view Startup messages in Wireshark & 4.7 View OpenFlow Messages for Ping

now the Wireshark is listening, we start the OpenFlow reference controller. 

mininet@mininet-vm:~$ controller ptcp:

This starts a simple controller that acts as a learning switch without installing any flow-entries.


now in the wireshark we see bunch of messages of the mininet.

i tried to set the filter in the wireshark in order to ignore echo-request/reply but the filter is not working.

i run the ping command again and saw the messages in the wireshark

---
first we see the broadcast when h1 is looking for h2
then we see h2 answer h1 (by mac address 00:00:00:00:00:02 -> ..00:01)
and after then we can see them "talking" (ping) form 10.0.0.1 to 10.0.0.2 back and forth

4.8 Benchmark Controller w. iperf

iperf is used to check speed between two computers

mininet> iperf
*** Iperf: testing TCP bandwidth between h1 and h3
Waiting for iperf to start up...*** Results: ['14.3 Gbits/sec', '14.3 Gbits/sec']

the mininet runs the iperf on two virtual hosts. once they connected they send packets between them and print out the result as shown above.

 
now we compare it to the user-space switch

mininet@mininet-vm:~$ sudo mn --topo single,3 --mac --controller remote --switch user
*** Creating network
*** Adding controller
*** Adding hosts:
h1 h2 h3 
*** Adding switches:
s1 
*** Adding links:
(h1, s1) (h2, s1) (h3, s1) 
*** Configuring hosts
h1 h2 h3 
*** Starting controller
c0 
*** Starting 1 switches
s1 
*** Starting CLI:
mininet> iperf
*** Iperf: testing TCP bandwidth between h1 and h3
Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...Waiting for iperf to start up...^C
Interrupt

it much slower this way, because the packets must cross from user-space to kernel-space and back on every hop.
we use user-space switch because it's easy to modify, but slower for simulation