On Sat, Sep 30, 2023 at 8:04 PM Owen DeLong via NANOG <nanog@nanog.org> wrote:
Not sure why you think FIB compression is a risk or will be a mess. It’s a pretty straightforward task.
Hi Owen, There are multiple levels of FIB compression. The simplest version merely aggregates adjacent routes with the same next hop. Straightforward, as you say. However, there are more advanced versions of FIB compression as well. Routers have an implicit default route to a drop-and-report target. Pragmatically, though, the user doesn't really care what happens to unroutable packets: they can't reach a destination regardless. If you replace that implicit default route with a "don't care," you can roll up the entire address space into a set of "send everything to this next hop with these exceptions." And you can build on that recursively to get extraordinary FIB compression. This latter version, however, is not straightforward. Bugs that escape QC are quite a bit more likely. Will Juniper stop with the simplest version of FIB compression where not much can go wrong? Not if it works and customers like it. Regards, Bill Herrin -- William Herrin bill@herrin.us https://bill.herrin.us/