Assalamu alaikum wa rahmatullahi wa barakatuh,
Peace be upon you dear visitor 🙂
In this tutorial, I created a simple topology in Mininet (MN). Topology consists of one switch and two hosts. One of hosts is client and another is server. The topology is illustrated as below.
I disabled Forwarding and LearningSwitch modules of Floodlight (FL) by deleting them from /floodlight/src/main/resources/floodlightdefault.properties. Thus, I was able to see that my code works perfectly. If you disable these two modules and run your MN topology code, you see that client and server can not communicate with each other. Because, there will be no flow entry in the switch to forward packets.
In order to provide connection between these two nodes, at first we must insert ARP flow entry to the switch so that client can find server’s MAC address. I used Static Flow Pusher API of Floodlight to insert flows. In the Static Flow Pusher API page, there is a python script that allows developers to insert flow entries to switches. The following two flow codes do the job.
arp_client_server = {
'switch':"00:00:00:00:00:00:00:01", # DPID of SW
'name':"arp_client_server", # unique name of flow entry
'cookie':"1", # opaque identifier
'priority':"32767", # highest flow priority
'ingress-port':"1", # packet that comes in from port ### of sw
'ether-type':"0x806", # hex of ethernet type of ARP
'active':"true", # activate flow entry
'actions':"output=2" # forward matched packet from port ### of sw
}
arp_server_client = {
'switch':"00:00:00:00:00:00:00:01",
'name':"arp_server_client",
'cookie':"2",
'priority':"32767",
'ingress-port':"2",
'ether-type':"0x806",
'active':"true",
'actions':"output=1"
}
arp_client_server provides ARP packet forwarding from client to server. arp_server_client does the reverse.
As a next step, tcp flow entries must be inserted to the sw. To do so, I wrote the following codes.
ip_host_server = {
'switch':"00:00:00:00:00:00:00:01",
'name':"ip_host_server",
'cookie':"3",
'priority':"32767",
'ether-type':"0x800", # for TCP
'src-ip':"10.0.0.0/8", # source IP prefix matching
'active':"true",
'ingress-port':"1",
'actions':"output=2"
}
ip_server_host = {
'switch':"00:00:00:00:00:00:00:01",
'name':"ip_server_host",
'cookie':"4",
'priority':"32767",
'ether-type':"0x800",
'src-ip':"10.0.0.0/8",
'active':"true",
'ingress-port':"2",
'actions':"output=1"
}
Notice that, I used IP prefix matching in src-ip tag. That means, all packets sending from hosts with 10.0.0.0/8 match with this entry. If you do the same, you will have such a switch as shown in the figure below.
After insertion of required flow entries, I ping server from host. The result is as follows:
If you examine the ping result shown above, you will realize that ping time is a lot less when you use Forwarding or LearningSwitch module. That is because, switch already has required flow entries to forward packets.
Assalamu alaikum wa rahmatullahi wa barakatuh 🙂
