bikeshed for all!

Bakul Shah bakul at
Thu Dec 13 12:26:17 PST 2007

Here is another idea spurred by this:

> I understand that this feature is something which swaps in a different 
> forwarding table for the application one is currently running?
> And that it works in a manner similar to chroot()?

Swapping in a different forwarding table is very much like
swapping in a different root as in chroot.  In that case how
about a more general command "with-resource" or just "with"?

    with (-<resource name> <resource-id>)* command [args]

    with (<resource-name>=<resource-id>)* command [args]

The latter syntax will allow a dynamic resource list (like
what you can do with sysctl).

So "chroot foo cmd" becomes "with root=foo cmd" and Julian's
baby can be "with net.FIB=bar cmd".  And if you want, even
"with root=foo net.FIB=bar cmd" will work!  And if ever
forwarding tables are associated with specific interfaces you
can do something like "with cmd" too!

I suggest this in the hope that more kernel things can be
resourcified and that we have a uniform way of dealing with
them all.

Now if resources were represented in the file system
namespace and mounts were local to a process, you could
achieve the above simply by doing a few mounts (or binds as
in plan9) such as

bind /resource/FIB/foo /net/FIB/default
exec cmd

and now all packets going out from cmd will use
/resource/FIB/foo to find their next hop.

-- bakul

FIB == forwarding information base, a pompous name for a
forwarding table. Also because sometimes it fibs, if not up
to date.

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