Mininet: SDN Network Emulator

• Mininet is a network emulator used for creating virtual Software Defined Networking (SDN) networks
• It is a software tool that allows entire OpenFlow networks to be emulated on a single computer
• Mininet uses lightweight process-based virtualization to run many hosts and switches on a single operating system kernel
• It simplifies the initial development, debugging, testing, and deployment process
• New network applications can be developed and tested on an emulation of the anticipated deployment network before being moved to the actual operational infrastructure
• Code used in Mininet can be used with minimal or no changes on real SDN OpenFlow networks
• Mininet enables complex topology testing without physical wiring
• The mn utility creates Mininet networks from the command line
• It can create parameterized topologies, invoke the Mininet Command Line Interface (CLI), and run tests.
• A Terminal Emulator is needed to run Mininet commands

Mininet Commands

• mn: Starts Mininet with a minimal topology consisting of one switch, two hosts, and a controller.
• The default topology includes one OpenFlow switch connected to two hosts and an OpenFlow reference controller
• All four entities (2 host processes, 1 switch process, and 1 basic controller) are now running in the Virtual Machine
• mininet > help: displays a list of available commands
• mininet > nodes: displays a list of available nodes in the Mininet console
• mininet > dump: Dumps information about all nodes to see the IP addresses of each node in the simulated network
• mininet > net: Shows how network elements are connected to each other in the simulated network
• mininet > intfs: Lists interfaces of hosts and switches
• mininet > links: Reports on links between hosts and switches
• mininet > ports: Displays ports and interfaces for each switch
• mininet > pingall: Displays the connectivity between all hosts and indicates which hosts are connected to each other
• mininet > pingallfull: Provides more detailed connectivity information between hosts, including minimum, average, and maximum time
• mininet > h2 ping -c3 h1: tests connectivity between hosts; it replaces host name automatically
• mininet > h2 ifconfig: Run a single command on a node, prepending the command with the name of the node
• mininet> hl arp: shows the ARP table for host h1
• mininet> s1 ifconfig -a: displays the switch interfaces, plus the VM's connection out (eth0)
• mininet >link s1 h2 down: bring a link down manually
• mininet >link s1 h2 up: bring a link up manually
• mininet >switch sl start: starts a switch
• mininet >switch sl stop: stops a switch
• mininet >iperf h1 h2: Tests Transmission Control Protocol (TCP) speed between two hosts, running an iperf TCP server on one host and a client on another
• mininet >iperfudp bw h1 h2: performs a simple iperf User Datagram Protocol (UDP) test between two hosts
• mininet > exit: Quits Mininet, stopping all processes and virtual nodes
• $ sudo mn -c or mininet > EOF: Restarts mininet by cleaning residual states or processes, if mininet is not working correctly

Xterm Window Usage

• Opening an xterm window to a network element is best for performing more interactive tasks
• mininet> xterm h1: Opens an xterm window on host h1
• mininet> xterm h1 h2: Opens xterm windows for h1 and h2
• $ sudo mn -x: Starts an xterm for every host and switch
• It is possible to execute commands on a host or switch using xterm window
• $ iperf -s: Runs iperf on the xterm for h1 and starts a server
• $ iperf -c 10.0.0.1: Let one h2 start up a client