Filter-based forwarding (FBF) combines the firewall filter tools explored
in Chapter 6 with the
routing-instance tools of the preceding section
to create an entirely new instrument for manipulating traffic flow.
FBF brings the virtualization of the control plane’s
routing-instance down into the data plane’s
forwarding table. Rather than segmenting routing and forwarding simply at
the interface level as you did in the preceding section, FBF empowers you
to slice and dice traffic as you see fit.
As depicted in Figure 11-12, if you want web traffic going down one path to the Internet and all other traffic going down another path, you can do that. If you want your workstation using one link to the data center for VoIP calls and another for backups, you can do that too. In fact, there isn’t much that can be dreamt up in the realm of routing and forwarding that cannot be accomplished with the careful application of FBF.
Figure 11-12. Filter-based forwarding
FBF is sometimes confused with the policy-based routing (PBR) features of legacy and competing platforms. FBF goes far beyond PBR. PBR is, at best, a more extensible version of a static route. FBF is PBR on steroids. FBF has all the same traffic matching capabilities, but it ties them directly into the power of Junos’s full complement of dynamic routing protocols.
Ultimately, all this power in FBF is made possible ...