> On 21.12.2024 19:34, Bjoern A. Zeeb wrote: > > How much use are FIBs still these days? Half of the original use cases > > I can think of could easily and better be overcome by using vnet jails > > with a physical or virtual interface (e.g, vcc) being delegated to the > > vnet.
Among the other half is simple multihoming. If a host has interfaces on two networks then it needs two default routes which means two FIBs. Many of us use ipfw to select a FIB for an outbound packet based on its IP source address. Without this the next-next- hop will wonder why we're failing BCP38 source address validation, and it may be a firewall which only passes traffic it expects, and it may be a differently congested network that upsets TCP pacing since the payloads take one path and the ACKs take the other. Path symmetry is an unalloyed good. Path assymetry is a livable problem but worthy of avoidance. Some operators just avoid multi-homing. As an operator I often don't have a choice about multi-homing or else my other choices are worse. FIBs make all of this better, and easily. > > I would honestly know who and how FIBs are still in use today or if they > > should be put on a list to be removed for 16 (I assume I might be > > surprised). I have a refactor to propose for the networking stack in 16 but more for performance and clarity than for correctness or simplicity. More on that another day. In any case I use FIBs everywhere all the time. On Monday, December 23, 2024 10:29:01 AM UTC Andrey V. Elsukov wrote: > Some might say that VNET is useless and should be removed instead. We > have bhyve and old-style jails. Without VNET the kernel code will be > robust and simple again, and easy for debugging. I introduced Mr. Zec to NL-Net when he was first looking for sponsors, and I was very happy with the results, and even more so when the FreeBSD Foundation got involved and more so after that when Mr. Zeeb got involved. I think VNET has earned a place in FreeBSD's pantheon but that the form it takes in the source code (all those macros) could be simplified. > FIBs are useful as is, but also can be used with "ipfw setfib" that make > it irreplaceable. For my primary FIB use case, ipfw is OK, but I think we need a different default. To that end, see Message-ID <38589000.xm6rczx...@dhcp-151.access.rits.tisf.net>. -- Paul Vixie
