Mininet on FreeBSD

This page describes the ongoing work of porting Mininet to FreeBSD.

Link to the repo: https://github.com/akoshibe/mininet

Mininet is a network emulation tool that has seen fairly wide usage in software defined networking (SDN). A good chunk of Mininet's appeal comes from how it bundles in tools, controllers, and software switches like Open vSwitch (OVS) that are useful for development and research related to, or for learning about, SDN.

Mininet relies on cgroups and network namespaces to emulate network nodes and links, and tools like tc to shape traffic, meaning that someone who currently wants to use it either must run Ubuntu(or another supported Linux distribution) or run it in a VM where Mininet can be installed and used.

Mininet also has a wish list, which includes support on other platforms.

Mininet mostly hides away platform-specific features into a few classes and methods that call the right shell commands to use them. The work here takes advantage of the fact that many of the commands and features that Mininet relies on has analogues in FreeBSD. To be specific:

• Hosts (processes in network namespaces) can be implemented with vnet jails
• Links (vnet links) can be implemented with epairs
• Traffic shaping links (tc) can be done with dummynet
• Resource-limited hosts (via cgroups) can (hopefully) be done with rctl
• “classic” network functions like NAT and bridging can use ipfw and if_bridge

As for bundled software, some, like OVS, is already available as a port (albeit as a userspace switch). Others, like the OpenFlow reference switch, aren't as readily available, and either need to be ported or replaced with suitable substitutes.

What's there, and/or working:

• Hosts and Links
• Built-in topologies e.g. Tree, Linear, etc.
• OpenFlow nodes: OVSSwitch
• Non-OpenFlow nodes: OVSBridge, IfBridge, NAT
• Controllers: Ryu ('built-in' controller), RemoteController, NullController (for 'classic' networks)
• ping-related tests ( “–test=pingall” with mn or pingall/pingpair from the CLI)

What's missing

• Nodes and Links for emulating resource constraints and traffic patterns (CPULimitedHosts, TCLinks)
• A dedicated OpenFlow 1.3 switch that covers what OVS doesn't in 1.3 mode (UserSwitch)
• Default controller when none are specified (--controller=ryu|none needs to be explicit)
• Hosts with private directories

What haven't been tested/tried

Aside from testing on releases other than 10.3 and 11.0:

• xterm/wireshark (things that need x11, e.g. h1 xterm)
• 'cluster-edition' features

Known bugs

• iperf from CLI or mn --test will hang and has to be killed.
• The CLI will sometimes not flush its input and re-run a previous input.
• The NAT node's (ipfw) rules are probably incorrect.

These are some things that might be interesting or nice to have.

• “Specialty” nodes like the LINC-OE optical emulator, and BMV2 P4 behavior model
• Something more scalable and performant than userspace OVS, for example some kind of 'Netmap/VALE/mSwitch' node (actually another wishlist item)
• netgraph network elements, which other emulators seem to incorporate