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Network Stack Cloning Updates on FreeBSD
Dan writes "Network stack cloning patches on FreeBSD allow for multiple fully independent network stacks to simultaneously coexist in a single FreeBSD kernel. Marko Zec has prepared a latest snapshot of the patches (against 4.8-RELEASE). The latest snapshot includes (a) internal restructuring - - struct vimage is now separated in resource-specific containers, and (b) Kernel message buffers - each vimage / vprocg now has a private kernel message buffer instance. Julian Elischer gave a talk on this subject at the USENIX Annual Technical Conference (FreeNIX track) in San Antonio, TX, June 2003. Marko's slides were presented at BSDCon Europe 2002 in Amsterdam."
We're talking about a different level of abstraction, here. After all, from the OS's perspective, how can Plan9 "use the network stack of a remote machine" except via the network stack of the local machine? Nothing short of magic will let a machine "use another machine's nic" except via packets sent through its own. Yes, Plan9 supports user namespaces that allows network interfaces to be virtualized, but that's from the perspective of what BSD calls "userland" -- which is only partly related to what the article discusses.
This facility is about allowing multiple networks stacks from the kernel's perspective. Not just the illusion of separate stacks as seen from userland (though it certainly provides that, too). These stacks can then be treated independently from the perspective of packet filtering, traffic shaping, and so on, as well as providing a "virtual machine" from a user's perspective. This isn't to say that Plan9's capabilities aren't useful or interesting, especially from a theoretical perspective. But Plan9 has different goals than an OS like FreeBSD that first and foremost is designed to be used as on server in a datacenter. Thus the perspective is more along the lines of machine virtualization and really has little to do with Plan9's concept of a namespace.