FreeBSD & FIBs (setfib) - How to modify?

Brent Bloxam brentb at
Thu Jul 16 18:04:26 UTC 2009

Mel Flynn wrote:
  > I guess the main question here is "what is 10?" or what is an FIB?. 
How does
> one create such an FIB id (which I can't find in docs either). For example, on 
> my system if I do:
> % setfib 2 fetch
> setfib: 2: invalid FIB (max 0)
> I would expect to see some info in
> Naturally there's some info here:
> but that doesn't have any practical information on how to create one.

I'm not sure if you're curious or trying to clarify on my question, but 
I'm past the point of creating and was interested in modifying.

Just incase anyone is interested, see the end of the 7.1-RELEASE Errata 

> FreeBSD now supports multiple routing tables. To enable this, the following steps are needed:
>     *
>       Add the following kernel configuration option and rebuild the kernel. The 2 is the number of FIB (Forward Information Base, synonym for a routing table here). The maximum value is 16.
>       options    ROUTETABLES=2
>       The procedure for rebuilding the FreeBSD kernel is described in the FreeBSD Handbook.
>       This number can be modified on boot time. To do so, add the following to /boot/loader.conf and reboot the system:
>       net.fibs=6

Note that net.fibs can only be modified _after_ the kernel has been 
compiled with the ROUTETABLES option. You can view the current settings 
related to FIBs with sysctl

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